[Patch] pg_rewind: options to use restore_command from recovery.conf or command line

diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
index 2bcfcc61af2e..a22fef1352b9 100644
--- a/src/bin/pg_rewind/Makefile
+++ b/src/bin/pg_rewind/Makefile
@@ -20,6 +20,7 @@ LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
 	fetch.o file_ops.o copy_fetch.o libpq_fetch.o filemap.o logging.o \
+	guc-file-fe.o \
 	$(WIN32RES)
 
 EXTRA_CLEAN = xlogreader.c
diff --git a/src/bin/pg_rewind/RewindTest.pm b/src/bin/pg_rewind/RewindTest.pm
index 1dce56d0352e..a5499c7027b1 100644
--- a/src/bin/pg_rewind/RewindTest.pm
+++ b/src/bin/pg_rewind/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions 'catpath';
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -249,6 +251,48 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my $test_master_datadir = $node_master->data_dir;
+		my @wal_files = bsd_glob catpath($test_master_datadir, 'pg_wal', '0000000*');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir/") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-R", $restore_command
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/src/bin/pg_rewind/guc-file-fe.h b/src/bin/pg_rewind/guc-file-fe.h
new file mode 100644
index 000000000000..cf480b806ae5
--- /dev/null
+++ b/src/bin/pg_rewind/guc-file-fe.h
@@ -0,0 +1,40 @@
+#ifndef PG_REWIND_GUC_FILE_FE_H
+#define PG_REWIND_GUC_FILE_FE_H
+
+#include "c.h"
+
+#define RECOVERY_COMMAND_FILE	"recovery.conf"
+
+/*
+ * Parsing the configuration file(s) will return a list of name-value pairs
+ * with source location info.  We also abuse this data structure to carry
+ * error reports about the config files.  An entry reporting an error will
+ * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
+ *
+ * If "ignore" is true, don't attempt to apply the item (it might be an error
+ * report, or an item we determined to be duplicate).  "applied" is set true
+ * if we successfully applied, or could have applied, the setting.
+ */
+typedef struct ConfigVariable
+{
+	char	   *name;
+	char	   *value;
+	char	   *errmsg;
+	char	   *filename;
+	int			sourceline;
+	bool		ignore;
+	bool		applied;
+	struct ConfigVariable *next;
+} ConfigVariable;
+
+extern bool ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+
+extern bool ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+
+extern void FreeConfigVariables(ConfigVariable *list);
+
+#endif							/* PG_REWIND_GUC_FILE_FE_H */
diff --git a/src/bin/pg_rewind/guc-file-fe.l b/src/bin/pg_rewind/guc-file-fe.l
new file mode 100644
index 000000000000..b7ef47111a79
--- /dev/null
+++ b/src/bin/pg_rewind/guc-file-fe.l
@@ -0,0 +1,776 @@
+/* -*-pgsql-c-*- */
+/*
+ * Configuration files parser for usage in frontend.
+ *
+ * Copyright (c) 2000-2018, PostgreSQL Global Development Group
+ *
+ * src/bin/pg_rewind/guc-file-fe.l
+ * Modified version of src/backend/utils/misc/guc-file.l
+ */
+
+%{
+
+#include "postgres_fe.h"
+
+#include <ctype.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <setjmp.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "guc-file-fe.h"
+#include "logging.h"
+
+#include "common/fe_memutils.h"
+
+/*
+ * flex emits a yy_fatal_error() function that it calls in response to
+ * critical errors like malloc failure, file I/O errors, and detection of
+ * internal inconsistency.  That function prints a message and calls exit().
+ * Mutate it to instead call our handler, which jumps out of the parser.
+ */
+#undef fprintf
+#define fprintf(file, fmt, msg) GUC_flex_fatal(msg)
+
+enum
+{
+	GUC_ID = 1,
+	GUC_STRING = 2,
+	GUC_INTEGER = 3,
+	GUC_REAL = 4,
+	GUC_EQUALS = 5,
+	GUC_UNQUOTED_STRING = 6,
+	GUC_QUALIFIED_ID = 7,
+	GUC_EOL = 99,
+	GUC_ERROR = 100
+};
+
+static unsigned int ConfigFileLineno;
+static const char *GUC_flex_fatal_errmsg;
+static sigjmp_buf *GUC_flex_fatal_jmp;
+
+static void FreeConfigVariable(ConfigVariable *item);
+
+static void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+static int	GUC_flex_fatal(const char *msg);
+static char *GUC_scanstr(const char *s);
+static bool ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p);
+
+/* LCOV_EXCL_START */
+
+%}
+
+%option 8bit
+%option never-interactive
+%option nodefault
+%option noinput
+%option nounput
+%option noyywrap
+%option warn
+%option prefix="GUC_yy"
+
+
+SIGN			("-"|"+")
+DIGIT			[0-9]
+HEXDIGIT		[0-9a-fA-F]
+
+UNIT_LETTER		[a-zA-Z]
+
+INTEGER			{SIGN}?({DIGIT}+|0x{HEXDIGIT}+){UNIT_LETTER}*
+
+EXPONENT		[Ee]{SIGN}?{DIGIT}+
+REAL			{SIGN}?{DIGIT}*"."{DIGIT}*{EXPONENT}?
+
+LETTER			[A-Za-z_\200-\377]
+LETTER_OR_DIGIT [A-Za-z_0-9\200-\377]
+
+ID				{LETTER}{LETTER_OR_DIGIT}*
+QUALIFIED_ID	{ID}"."{ID}
+
+UNQUOTED_STRING {LETTER}({LETTER_OR_DIGIT}|[-._:/])*
+STRING			\'([^'\\\n]|\\.|\'\')*\'
+
+%%
+
+\n				ConfigFileLineno++; return GUC_EOL;
+[ \t\r]+		/* eat whitespace */
+#.*				/* eat comment (.* matches anything until newline) */
+
+{ID}			return GUC_ID;
+{QUALIFIED_ID}	return GUC_QUALIFIED_ID;
+{STRING}		return GUC_STRING;
+{UNQUOTED_STRING} return GUC_UNQUOTED_STRING;
+{INTEGER}		return GUC_INTEGER;
+{REAL}			return GUC_REAL;
+=				return GUC_EQUALS;
+
+.				return GUC_ERROR;
+
+%%
+
+/* LCOV_EXCL_STOP */
+
+/*
+ * the bare comparison function for GUC names
+ */
+static int
+guc_name_compare(const char *namea, const char *nameb)
+{
+	/*
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
+	 */
+	while (*namea && *nameb)
+	{
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
+	}
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
+}
+
+/*
+ * Given a configuration file or directory location that may be a relative
+ * path, return an absolute one.  We consider the location to be relative to
+ * the directory holding the calling file.
+ */
+static char *
+AbsoluteConfigLocation(const char *location, const char *calling_file)
+{
+	char abs_path[MAXPGPATH];
+
+	if (is_absolute_path(location))
+		return pstrdup(location);
+	else
+	{
+		strlcpy(abs_path, calling_file, sizeof(abs_path));
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, location);
+		canonicalize_path(abs_path);
+
+		return pstrdup(abs_path);
+	}
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * If "strict" is true, treat failure to open the config file as an error,
+ * otherwise just skip the file.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.  This one merely adds opening the
+ * config file rather than working from a caller-supplied file descriptor,
+ * and absolute-ifying the path name if necessary.
+ */
+bool
+ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p,
+				ConfigVariable **tail_p)
+{
+	char	   *abs_path;
+	bool		OK = true;
+	FILE	   *fp;
+
+	/*
+	 * Reject too-deep include nesting depth.  This is just a safety check to
+	 * avoid dumping core due to stack overflow if an include file loops back
+	 * to itself.  The maximum nesting depth is pretty arbitrary.
+	 */
+	if (depth > 10)
+	{
+		pg_log(PG_WARNING, 
+				"could not open configuration file \"%s\": maximum nesting depth exceeded\n",
+				config_file);
+		record_config_file_error("nesting depth exceeded",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+	fp = fopen(abs_path, "r");
+	if (!fp)
+	{
+		if (strict)
+		{
+			pg_log(PG_WARNING, 
+				"could not open configuration file \"%s\"\n",
+				abs_path);
+			record_config_file_error(psprintf("could not open file \"%s\"",
+											  abs_path),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			OK = false;
+		}
+		else
+		{
+			pg_log(PG_WARNING, 
+				"skipping missing configuration file \"%s\"\n",
+				abs_path);
+		}
+		goto cleanup;
+	}
+
+	OK = ParseConfigFp(fp, abs_path, depth, elevel, head_p, tail_p);
+
+cleanup:
+	if (fp)
+		fclose(fp);
+	pfree(abs_path);
+
+	return OK;
+}
+
+/*
+ * Capture an error message in the ConfigVariable list returned by
+ * config file parsing.
+ */
+static void
+record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p)
+{
+	ConfigVariable *item;
+
+	item = palloc(sizeof *item);
+	item->name = NULL;
+	item->value = NULL;
+	item->errmsg = pstrdup(errmsg);
+	item->filename = config_file ? pstrdup(config_file) : NULL;
+	item->sourceline = lineno;
+	item->ignore = true;
+	item->applied = false;
+	item->next = NULL;
+	if (*head_p == NULL)
+		*head_p = item;
+	else
+		(*tail_p)->next = item;
+	*tail_p = item;
+}
+
+/*
+ * Flex fatal errors bring us here.  Stash the error message and jump back to
+ * ParseConfigFp().  Assume all msg arguments point to string constants; this
+ * holds for flex 2.5.31 (earliest we support) and flex 2.5.35 (latest as of
+ * this writing).  Otherwise, we would need to copy the message.
+ *
+ * We return "int" since this takes the place of calls to fprintf().
+*/
+static int
+GUC_flex_fatal(const char *msg)
+{
+	GUC_flex_fatal_errmsg = msg;
+	siglongjmp(*GUC_flex_fatal_jmp, 1);
+	return 0;					/* keep compiler quiet */
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * Input parameters:
+ *	fp: file pointer from AllocateFile for the configuration file to parse
+ *	config_file: absolute or relative path name of the configuration file
+ *	depth: recursion depth (should be 0 in the outermost call)
+ *	elevel: error logging level to use
+ * Input/Output parameters:
+ *	head_p, tail_p: head and tail of linked list of name/value pairs
+ *
+ * *head_p and *tail_p must be initialized, either to NULL or valid pointers
+ * to a ConfigVariable list, before calling the outer recursion level.  Any
+ * name-value pairs read from the input file(s) will be appended to the list.
+ * Error reports will also be appended to the list, if elevel < ERROR.
+ *
+ * Returns TRUE if successful, FALSE if an error occurred.
+ *
+ * Note: this function is used to parse not only postgresql.conf, but
+ * various other configuration files that use the same "name = value"
+ * syntax.  Hence, do not do anything here or in the subsidiary routines
+ * ParseConfigFile/ParseConfigDirectory that assumes we are processing
+ * GUCs specifically.
+ */
+bool
+ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p)
+{
+	volatile bool OK = true;
+	unsigned int save_ConfigFileLineno = ConfigFileLineno;
+	sigjmp_buf *save_GUC_flex_fatal_jmp = GUC_flex_fatal_jmp;
+	sigjmp_buf	flex_fatal_jmp;
+	volatile YY_BUFFER_STATE lex_buffer = NULL;
+	int			errorcount;
+	int			token;
+
+	if (sigsetjmp(flex_fatal_jmp, 1) == 0)
+		GUC_flex_fatal_jmp = &flex_fatal_jmp;
+	else
+	{
+		/*
+		 * Regain control after a fatal, internal flex error.  It may have
+		 * corrupted parser state.  Consequently, abandon the file, but trust
+		 * that the state remains sane enough for yy_delete_buffer().
+		 */
+		pg_log(PG_WARNING, "%s at file \"%s\" line %u\n", GUC_flex_fatal_errmsg,
+				config_file, ConfigFileLineno);
+		record_config_file_error(GUC_flex_fatal_errmsg,
+								 config_file, ConfigFileLineno,
+								 head_p, tail_p);
+		OK = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Parse
+	 */
+	ConfigFileLineno = 1;
+	errorcount = 0;
+
+	lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
+	yy_switch_to_buffer(lex_buffer);
+
+	/* This loop iterates once per logical line */
+	while ((token = yylex()))
+	{
+		char	   *opt_name = NULL;
+		char	   *opt_value = NULL;
+		ConfigVariable *item;
+
+		if (token == GUC_EOL)	/* empty or comment line */
+			continue;
+
+		/* first token on line is option name */
+		if (token != GUC_ID && token != GUC_QUALIFIED_ID)
+			goto parse_error;
+		opt_name = pstrdup(yytext);
+
+		/* next we have an optional equal sign; discard if present */
+		token = yylex();
+		if (token == GUC_EQUALS)
+			token = yylex();
+
+		/* now we must have the option value */
+		if (token != GUC_ID &&
+			token != GUC_STRING &&
+			token != GUC_INTEGER &&
+			token != GUC_REAL &&
+			token != GUC_UNQUOTED_STRING)
+			goto parse_error;
+		if (token == GUC_STRING)	/* strip quotes and escapes */
+			opt_value = GUC_scanstr(yytext);
+		else
+			opt_value = pstrdup(yytext);
+
+		/* now we'd like an end of line, or possibly EOF */
+		token = yylex();
+		if (token != GUC_EOL)
+		{
+			if (token != 0)
+				goto parse_error;
+			/* treat EOF like \n for line numbering purposes, cf bug 4752 */
+			ConfigFileLineno++;
+		}
+
+		/* OK, process the option name and value */
+		if (guc_name_compare(opt_name, "include_dir") == 0)
+		{
+			/*
+			 * An include_dir directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigDirectory(opt_value,
+									  config_file, ConfigFileLineno - 1,
+									  depth + 1, elevel,
+									  head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include_if_exists") == 0)
+		{
+			/*
+			 * An include_if_exists directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigFile(opt_value, false,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include") == 0)
+		{
+			/*
+			 * An include directive isn't a variable and should be processed
+			 * immediately.
+			 */
+			if (!ParseConfigFile(opt_value, true,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else
+		{
+			/* ordinary variable, append to list */
+			item = palloc(sizeof *item);
+			item->name = opt_name;
+			item->value = opt_value;
+			item->errmsg = NULL;
+			item->filename = pstrdup(config_file);
+			item->sourceline = ConfigFileLineno - 1;
+			item->ignore = false;
+			item->applied = false;
+			item->next = NULL;
+			if (*head_p == NULL)
+				*head_p = item;
+			else
+				(*tail_p)->next = item;
+			*tail_p = item;
+		}
+
+		/* break out of loop if read EOF, else loop for next line */
+		if (token == 0)
+			break;
+		continue;
+
+parse_error:
+		/* release storage if we allocated any on this line */
+		if (opt_name)
+			pfree(opt_name);
+		if (opt_value)
+			pfree(opt_value);
+
+		/* report the error */
+		if (token == GUC_EOL || token == 0)
+		{
+			pg_log(PG_WARNING, "syntax error in file \"%s\" line %u, near end of line\n",
+					config_file, ConfigFileLineno - 1);
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno - 1,
+									 head_p, tail_p);
+		}
+		else
+		{
+			pg_log(PG_WARNING, "syntax error in file \"%s\" line %u, near token \"%s\"\n",
+				config_file, ConfigFileLineno, yytext);
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno,
+									 head_p, tail_p);
+		}
+		OK = false;
+		errorcount++;
+
+		/*
+		 * To avoid producing too much noise when fed a totally bogus file,
+		 * give up after 100 syntax errors per file (an arbitrary number).
+		 */
+		if (errorcount >= 100)
+		{
+			pg_log(PG_WARNING, "too many syntax errors found, abandoning file \"%s\"\n",
+					config_file);
+			break;
+		}
+
+		/* resync to next end-of-line or EOF */
+		while (token != GUC_EOL && token != 0)
+			token = yylex();
+		/* break out of loop on EOF */
+		if (token == 0)
+			break;
+	}
+
+cleanup:
+	yy_delete_buffer(lex_buffer);
+	/* Each recursion level must save and restore these static variables. */
+	ConfigFileLineno = save_ConfigFileLineno;
+	GUC_flex_fatal_jmp = save_GUC_flex_fatal_jmp;
+	return OK;
+}
+
+/*
+ * Read and parse all config files in a subdirectory in alphabetical order
+ *
+ * includedir is the absolute or relative path to the subdirectory to scan.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.
+ */
+bool
+ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p)
+{
+	char	   *directory;
+	DIR		   *d;
+	struct dirent *de;
+	char	  **filenames;
+	int			num_filenames;
+	int			size_filenames;
+	bool		status;
+
+	directory = AbsoluteConfigLocation(includedir, calling_file);
+	d = opendir(directory);
+	if (d == NULL)
+	{
+		pg_log(PG_WARNING, "could not open configuration directory \"%s\"\n",
+			directory);
+		record_config_file_error(psprintf("could not open directory \"%s\"",
+										  directory),
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		status = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Read the directory and put the filenames in an array, so we can sort
+	 * them prior to processing the contents.
+	 */
+	size_filenames = 32;
+	filenames = (char **) palloc(size_filenames * sizeof(char *));
+	num_filenames = 0;
+
+	while ((de = readdir(d)) != NULL)
+	{
+		struct stat st;
+		char		filename[MAXPGPATH];
+
+		/*
+		 * Only parse files with names ending in ".conf".  Explicitly reject
+		 * files starting with ".".  This excludes things like "." and "..",
+		 * as well as typical hidden files, backup files, and editor debris.
+		 */
+		if (strlen(de->d_name) < 6)
+			continue;
+		if (de->d_name[0] == '.')
+			continue;
+		if (strcmp(de->d_name + strlen(de->d_name) - 5, ".conf") != 0)
+			continue;
+
+		join_path_components(filename, directory, de->d_name);
+		canonicalize_path(filename);
+		if (stat(filename, &st) == 0)
+		{
+			if (!S_ISDIR(st.st_mode))
+			{
+				/* Add file to array, increasing its size in blocks of 32 */
+				if (num_filenames >= size_filenames)
+				{
+					size_filenames += 32;
+					filenames = (char **) repalloc(filenames,
+											size_filenames * sizeof(char *));
+				}
+				filenames[num_filenames] = pstrdup(filename);
+				num_filenames++;
+			}
+		}
+		else
+		{
+			/*
+			 * stat does not care about permissions, so the most likely reason
+			 * a file can't be accessed now is if it was removed between the
+			 * directory listing and now.
+			 */
+			pg_log(PG_WARNING, "could not stat file \"%s\"\n", filename);
+			record_config_file_error(psprintf("could not stat file \"%s\"",
+											  filename),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			status = false;
+			goto cleanup;
+		}
+	}
+
+	if (num_filenames > 0)
+	{
+		int			i;
+
+		qsort(filenames, num_filenames, sizeof(char *), pg_qsort_strcmp);
+		for (i = 0; i < num_filenames; i++)
+		{
+			if (!ParseConfigFile(filenames[i], true,
+								 calling_file, calling_lineno,
+								 depth, elevel,
+								 head_p, tail_p))
+			{
+				status = false;
+				goto cleanup;
+			}
+		}
+	}
+	status = true;
+
+cleanup:
+	if (d)
+		closedir(d);
+	pfree(directory);
+	return status;
+}
+
+/*
+ * Free a list of ConfigVariables, including the names and the values
+ */
+void
+FreeConfigVariables(ConfigVariable *list)
+{
+	ConfigVariable *item;
+
+	item = list;
+	while (item)
+	{
+		ConfigVariable *next = item->next;
+
+		FreeConfigVariable(item);
+		item = next;
+	}
+}
+
+/*
+ * Free a single ConfigVariable
+ */
+static void
+FreeConfigVariable(ConfigVariable *item)
+{
+	if (item->name)
+		pfree(item->name);
+	if (item->value)
+		pfree(item->value);
+	if (item->errmsg)
+		pfree(item->errmsg);
+	if (item->filename)
+		pfree(item->filename);
+	pfree(item);
+}
+
+
+/*
+ *		scanstr
+ *
+ * Strip the quotes surrounding the given string, and collapse any embedded
+ * '' sequences and backslash escapes.
+ *
+ * the string returned is palloc'd and should eventually be pfree'd by the
+ * caller.
+ */
+static char *
+GUC_scanstr(const char *s)
+{
+	char	   *newStr;
+	int			len,
+				i,
+				j;
+
+	Assert(s != NULL && s[0] == '\'');
+	len = strlen(s);
+	Assert(len >= 2);
+	Assert(s[len - 1] == '\'');
+
+	/* Skip the leading quote; we'll handle the trailing quote below */
+	s++, len--;
+
+	/* Since len still includes trailing quote, this is enough space */
+	newStr = palloc(len);
+
+	for (i = 0, j = 0; i < len; i++)
+	{
+		if (s[i] == '\\')
+		{
+			i++;
+			switch (s[i])
+			{
+				case 'b':
+					newStr[j] = '\b';
+					break;
+				case 'f':
+					newStr[j] = '\f';
+					break;
+				case 'n':
+					newStr[j] = '\n';
+					break;
+				case 'r':
+					newStr[j] = '\r';
+					break;
+				case 't':
+					newStr[j] = '\t';
+					break;
+				case '0':
+				case '1':
+				case '2':
+				case '3':
+				case '4':
+				case '5':
+				case '6':
+				case '7':
+					{
+						int			k;
+						long		octVal = 0;
+
+						for (k = 0;
+							 s[i + k] >= '0' && s[i + k] <= '7' && k < 3;
+							 k++)
+							octVal = (octVal << 3) + (s[i + k] - '0');
+						i += k - 1;
+						newStr[j] = ((char) octVal);
+					}
+					break;
+				default:
+					newStr[j] = s[i];
+					break;
+			}					/* switch */
+		}
+		else if (s[i] == '\'' && s[i + 1] == '\'')
+		{
+			/* doubled quote becomes just one quote */
+			newStr[j] = s[++i];
+		}
+		else
+			newStr[j] = s[i];
+		j++;
+	}
+
+	/* We copied the ending quote to newStr, so replace with \0 */
+	Assert(j > 0 && j <= len);
+	newStr[--j] = '\0';
+
+	return newStr;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 40028471bf6e..11a9c26cd23a 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,7 +46,10 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
+	XLogRecPtr  oldrecptr;
+	TimeLineID  oldtli;
 } XLogPageReadPrivate;
 
 static int SimpleXLogPageRead(XLogReaderState *xlogreader,
@@ -53,6 +57,10 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static bool RestoreArchivedWAL(const char *path, const char *xlogfname, 
+					off_t expectedSize, const char *restoreCommand,
+					const char *lastRestartPointFname);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,15 +68,19 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   ControlFileData *targetCF, const char *restore_command)
 {
 	XLogRecord *record;
+	XLogRecPtr endpoint = targetCF->checkPoint;
 	XLogReaderState *xlogreader;
 	char	   *errormsg;
 	XLogPageReadPrivate private;
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -154,9 +166,9 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
  * Find the previous checkpoint preceding given WAL location.
  */
 void
-findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
+findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +193,9 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +306,53 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+			bool  restore_ok;
+			char  lastRestartPointFname[MAXFNAMELEN];
+			XLogSegNo restartSegNo;
+
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
 				   strerror(errno));
-			return -1;
+				return -1;
+			}
+			
+			XLByteToSeg(private->oldrecptr, restartSegNo, WalSegSz);
+			XLogFileName(lastRestartPointFname, private->oldtli, restartSegNo,
+						 WalSegSz);
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			restore_ok = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand,
+											lastRestartPointFname);
+
+			if (restore_ok)
+			{
+				xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogreadfd < 0)
+				{
+					printf(_("could not open restored from archive file \"%s\": %s\n"), xlogfpath,
+				    	   strerror(errno));
+				    return -1;
+				}
+				else
+					pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n", xlogfpath);
+			}
+			else
+			{
+				printf(_("could not restore file \"%s\" from archive: %s\n"), xlogfname,
+					   strerror(errno));
+				return -1;
+			}
 		}
 	}
 
@@ -409,3 +468,116 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return true.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ * 
+ * This is an adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+bool
+RestoreArchivedWAL(const char *path, const char *xlogfname, off_t expectedSize,
+				   const char *restoreCommand, const char *lastRestartPointFname)
+{
+	char		xlogpath[MAXPGPATH];
+	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *dp;
+	char	   *endp;
+	const char *sp;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+					   	xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize,
+					   	strerror(errno));
+			}
+			else
+				return true;
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+				   	xlogpath,
+					strerror(errno));
+		}
+	}
+
+	return false;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 96531063869c..3acac817eb4f 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -19,11 +19,13 @@
 #include "file_ops.h"
 #include "filemap.h"
 #include "logging.h"
+#include "guc-file-fe.h"
 
 #include "access/timeline.h"
 #include "access/xlog_internal.h"
 #include "catalog/catversion.h"
 #include "catalog/pg_control.h"
+#include "common/controldata_utils.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
@@ -52,11 +54,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +79,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-recovery-conf        use restore_command in the recovery.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,9 +101,12 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-recovery-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
+	char		recfile_fullpath[MAXPGPATH];
 	int			option_index;
 	int			c;
 	XLogRecPtr	divergerec;
@@ -129,7 +139,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "DR:nNPr", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -140,6 +150,10 @@ main(int argc, char **argv)
 			case 'P':
 				showprogress = true;
 				break;
+			
+			case 'r':
+				restore_wals = true;
+				break;
 
 			case 'n':
 				dry_run = true;
@@ -157,6 +171,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +241,71 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		FILE	   *recovery_conf_file;
+
+		/* 
+		 * Look for recovery.conf in the target data directory and
+		 * try to get restore_command from there.
+		 */
+		snprintf(recfile_fullpath, sizeof(recfile_fullpath), "%s/%s", datadir_target, RECOVERY_COMMAND_FILE);
+		recovery_conf_file = fopen(recfile_fullpath, "r");
+
+		if (recovery_conf_file == NULL)
+		{
+			fprintf(stderr, _("%s: option -r/--use-recovery-conf is specified, but recovery.conf is absent in the target directory\n"),
+					progname);
+			fprintf(stdout, _("You have to add recovery.conf or pass restore_command with -R/--restore-command option.\n"));
+			exit(1);
+		}
+		else
+		{
+			ConfigVariable *item,
+						   *head = NULL,
+						   *tail = NULL;
+			bool			config_is_parsed;
+
+			/*
+			 * We pass a fullpath to the recovery.conf as calling_file here, since
+			 * parser will use its parent directory as base for all further includes
+			 * if any exist.
+			 */
+			config_is_parsed = ParseConfigFile(RECOVERY_COMMAND_FILE, true,
+											   recfile_fullpath, 0, 0,
+											   PG_WARNING, &head, &tail);
+			fclose(recovery_conf_file);
+
+			if (config_is_parsed)
+			{
+				for (item = head; item; item = item->next)
+				{
+					if (strcmp(item->name, "restore_command") == 0)
+					{
+						if (restore_command != NULL)
+						{
+							pfree(restore_command);
+							restore_command = NULL;
+						}
+						restore_command = pstrdup(item->value);
+						pg_log(PG_DEBUG, "using restore_command=\'%s\' from recovery.conf.\n", restore_command);
+					}
+				}
+
+				if (restore_command == NULL)
+					pg_fatal("could not find restore_command in recovery.conf file %s\n", recfile_fullpath);
+			}
+			else
+				pg_fatal("could not parse recovery.conf file %s\n", recfile_fullpath);
+
+			FreeConfigVariables(head);
+		}
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +377,9 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
+	findLastCheckpoint(datadir_target, &ControlFile_target, divergerec,
 					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +402,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   &ControlFile_target, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 3f4ba7a26760..ba9d13e9bd04 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -14,6 +14,7 @@
 #include "datapagemap.h"
 
 #include "access/timeline.h"
+#include "catalog/pg_control.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
 
@@ -32,11 +33,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
-extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+			   int tliIndex, ControlFileData *targetCF, const char *restoreCommand);
+extern void findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr searchptr,
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 53dbf45be29d..22777bff82d4 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 15;
 
 use RewindTest;
 
@@ -103,5 +103,6 @@ sub run_test
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 2c9e42783113..10c835efc136 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 9;
 
 use RewindTest;
 
@@ -59,5 +59,6 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index 496f38c4570c..f94ce329f473 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 6;
 
 use File::Find;
 
@@ -87,5 +87,6 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index b562044fa716..674e4a1df5ac 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -73,6 +73,7 @@ my $frontend_extraincludes = {
 };
 my $frontend_extrasource = {
 	'psql' => ['src/bin/psql/psqlscanslash.l'],
+	'pg_rewind' => ['src/bin/pg_rewind/guc-file-fe.l'],
 	'pgbench' =>
 	  [ 'src/bin/pgbench/exprscan.l', 'src/bin/pgbench/exprparse.y' ]
 };

From 521f62872d4e95cd02ddb535b8320256ff5e90cc Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <alex.lumir@gmail.com>
Date: Fri, 21 Dec 2018 14:00:30 +0300
Subject: [PATCH] pg_rewind: options to use restore_command from
 postgresql.conf or command line.

---
 src/bin/pg_rewind/Makefile            |   5 +-
 src/bin/pg_rewind/RewindTest.pm       |  46 +-
 src/bin/pg_rewind/guc-file-fe.h       |  40 ++
 src/bin/pg_rewind/guc-file-fe.l       | 776 ++++++++++++++++++++++++++
 src/bin/pg_rewind/parsexlog.c         | 182 +++++-
 src/bin/pg_rewind/pg_rewind.c         |  91 ++-
 src/bin/pg_rewind/pg_rewind.h         |  10 +-
 src/bin/pg_rewind/t/001_basic.pl      |   3 +-
 src/bin/pg_rewind/t/002_databases.pl  |   3 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   3 +-
 src/tools/msvc/Mkvcbuild.pm           |   1 +
 11 files changed, 1141 insertions(+), 19 deletions(-)
 create mode 100644 src/bin/pg_rewind/guc-file-fe.h
 create mode 100644 src/bin/pg_rewind/guc-file-fe.l

diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
index 2bcfcc61af..a0f5f97544 100644
--- a/src/bin/pg_rewind/Makefile
+++ b/src/bin/pg_rewind/Makefile
@@ -15,11 +15,12 @@ subdir = src/bin/pg_rewind
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
+override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
 	fetch.o file_ops.o copy_fetch.o libpq_fetch.o filemap.o logging.o \
+	guc-file-fe.o \
 	$(WIN32RES)
 
 EXTRA_CLEAN = xlogreader.c
@@ -32,6 +33,8 @@ pg_rewind: $(OBJS) | submake-libpq submake-libpgport
 xlogreader.c: % : $(top_srcdir)/src/backend/access/transam/%
 	rm -f $@ && $(LN_S) $< .
 
+distprep: guc-file-fe.c
+
 install: all installdirs
 	$(INSTALL_PROGRAM) pg_rewind$(X) '$(DESTDIR)$(bindir)/pg_rewind$(X)'
 
diff --git a/src/bin/pg_rewind/RewindTest.pm b/src/bin/pg_rewind/RewindTest.pm
index 3d07da5d94..b43c18a8c3 100644
--- a/src/bin/pg_rewind/RewindTest.pm
+++ b/src/bin/pg_rewind/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions 'catpath';
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -250,6 +252,48 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my $test_master_datadir = $node_master->data_dir;
+		my @wal_files = bsd_glob catpath($test_master_datadir, 'pg_wal', '0000000*');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir/") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-R", $restore_command
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/src/bin/pg_rewind/guc-file-fe.h b/src/bin/pg_rewind/guc-file-fe.h
new file mode 100644
index 0000000000..3a078c5cdd
--- /dev/null
+++ b/src/bin/pg_rewind/guc-file-fe.h
@@ -0,0 +1,40 @@
+#ifndef PG_REWIND_GUC_FILE_FE_H
+#define PG_REWIND_GUC_FILE_FE_H
+
+#include "c.h"
+
+#define RECOVERY_COMMAND_FILE	"postgresql.conf"
+
+/*
+ * Parsing the configuration file(s) will return a list of name-value pairs
+ * with source location info.  We also abuse this data structure to carry
+ * error reports about the config files.  An entry reporting an error will
+ * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
+ *
+ * If "ignore" is true, don't attempt to apply the item (it might be an error
+ * report, or an item we determined to be duplicate).  "applied" is set true
+ * if we successfully applied, or could have applied, the setting.
+ */
+typedef struct ConfigVariable
+{
+	char	   *name;
+	char	   *value;
+	char	   *errmsg;
+	char	   *filename;
+	int			sourceline;
+	bool		ignore;
+	bool		applied;
+	struct ConfigVariable *next;
+} ConfigVariable;
+
+extern bool ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+
+extern bool ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+
+extern void FreeConfigVariables(ConfigVariable *list);
+
+#endif							/* PG_REWIND_GUC_FILE_FE_H */
diff --git a/src/bin/pg_rewind/guc-file-fe.l b/src/bin/pg_rewind/guc-file-fe.l
new file mode 100644
index 0000000000..b7ef47111a
--- /dev/null
+++ b/src/bin/pg_rewind/guc-file-fe.l
@@ -0,0 +1,776 @@
+/* -*-pgsql-c-*- */
+/*
+ * Configuration files parser for usage in frontend.
+ *
+ * Copyright (c) 2000-2018, PostgreSQL Global Development Group
+ *
+ * src/bin/pg_rewind/guc-file-fe.l
+ * Modified version of src/backend/utils/misc/guc-file.l
+ */
+
+%{
+
+#include "postgres_fe.h"
+
+#include <ctype.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <setjmp.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+#include "guc-file-fe.h"
+#include "logging.h"
+
+#include "common/fe_memutils.h"
+
+/*
+ * flex emits a yy_fatal_error() function that it calls in response to
+ * critical errors like malloc failure, file I/O errors, and detection of
+ * internal inconsistency.  That function prints a message and calls exit().
+ * Mutate it to instead call our handler, which jumps out of the parser.
+ */
+#undef fprintf
+#define fprintf(file, fmt, msg) GUC_flex_fatal(msg)
+
+enum
+{
+	GUC_ID = 1,
+	GUC_STRING = 2,
+	GUC_INTEGER = 3,
+	GUC_REAL = 4,
+	GUC_EQUALS = 5,
+	GUC_UNQUOTED_STRING = 6,
+	GUC_QUALIFIED_ID = 7,
+	GUC_EOL = 99,
+	GUC_ERROR = 100
+};
+
+static unsigned int ConfigFileLineno;
+static const char *GUC_flex_fatal_errmsg;
+static sigjmp_buf *GUC_flex_fatal_jmp;
+
+static void FreeConfigVariable(ConfigVariable *item);
+
+static void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+static int	GUC_flex_fatal(const char *msg);
+static char *GUC_scanstr(const char *s);
+static bool ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p);
+
+/* LCOV_EXCL_START */
+
+%}
+
+%option 8bit
+%option never-interactive
+%option nodefault
+%option noinput
+%option nounput
+%option noyywrap
+%option warn
+%option prefix="GUC_yy"
+
+
+SIGN			("-"|"+")
+DIGIT			[0-9]
+HEXDIGIT		[0-9a-fA-F]
+
+UNIT_LETTER		[a-zA-Z]
+
+INTEGER			{SIGN}?({DIGIT}+|0x{HEXDIGIT}+){UNIT_LETTER}*
+
+EXPONENT		[Ee]{SIGN}?{DIGIT}+
+REAL			{SIGN}?{DIGIT}*"."{DIGIT}*{EXPONENT}?
+
+LETTER			[A-Za-z_\200-\377]
+LETTER_OR_DIGIT [A-Za-z_0-9\200-\377]
+
+ID				{LETTER}{LETTER_OR_DIGIT}*
+QUALIFIED_ID	{ID}"."{ID}
+
+UNQUOTED_STRING {LETTER}({LETTER_OR_DIGIT}|[-._:/])*
+STRING			\'([^'\\\n]|\\.|\'\')*\'
+
+%%
+
+\n				ConfigFileLineno++; return GUC_EOL;
+[ \t\r]+		/* eat whitespace */
+#.*				/* eat comment (.* matches anything until newline) */
+
+{ID}			return GUC_ID;
+{QUALIFIED_ID}	return GUC_QUALIFIED_ID;
+{STRING}		return GUC_STRING;
+{UNQUOTED_STRING} return GUC_UNQUOTED_STRING;
+{INTEGER}		return GUC_INTEGER;
+{REAL}			return GUC_REAL;
+=				return GUC_EQUALS;
+
+.				return GUC_ERROR;
+
+%%
+
+/* LCOV_EXCL_STOP */
+
+/*
+ * the bare comparison function for GUC names
+ */
+static int
+guc_name_compare(const char *namea, const char *nameb)
+{
+	/*
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
+	 */
+	while (*namea && *nameb)
+	{
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
+	}
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
+}
+
+/*
+ * Given a configuration file or directory location that may be a relative
+ * path, return an absolute one.  We consider the location to be relative to
+ * the directory holding the calling file.
+ */
+static char *
+AbsoluteConfigLocation(const char *location, const char *calling_file)
+{
+	char abs_path[MAXPGPATH];
+
+	if (is_absolute_path(location))
+		return pstrdup(location);
+	else
+	{
+		strlcpy(abs_path, calling_file, sizeof(abs_path));
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, location);
+		canonicalize_path(abs_path);
+
+		return pstrdup(abs_path);
+	}
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * If "strict" is true, treat failure to open the config file as an error,
+ * otherwise just skip the file.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.  This one merely adds opening the
+ * config file rather than working from a caller-supplied file descriptor,
+ * and absolute-ifying the path name if necessary.
+ */
+bool
+ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p,
+				ConfigVariable **tail_p)
+{
+	char	   *abs_path;
+	bool		OK = true;
+	FILE	   *fp;
+
+	/*
+	 * Reject too-deep include nesting depth.  This is just a safety check to
+	 * avoid dumping core due to stack overflow if an include file loops back
+	 * to itself.  The maximum nesting depth is pretty arbitrary.
+	 */
+	if (depth > 10)
+	{
+		pg_log(PG_WARNING, 
+				"could not open configuration file \"%s\": maximum nesting depth exceeded\n",
+				config_file);
+		record_config_file_error("nesting depth exceeded",
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		return false;
+	}
+
+	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+	fp = fopen(abs_path, "r");
+	if (!fp)
+	{
+		if (strict)
+		{
+			pg_log(PG_WARNING, 
+				"could not open configuration file \"%s\"\n",
+				abs_path);
+			record_config_file_error(psprintf("could not open file \"%s\"",
+											  abs_path),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			OK = false;
+		}
+		else
+		{
+			pg_log(PG_WARNING, 
+				"skipping missing configuration file \"%s\"\n",
+				abs_path);
+		}
+		goto cleanup;
+	}
+
+	OK = ParseConfigFp(fp, abs_path, depth, elevel, head_p, tail_p);
+
+cleanup:
+	if (fp)
+		fclose(fp);
+	pfree(abs_path);
+
+	return OK;
+}
+
+/*
+ * Capture an error message in the ConfigVariable list returned by
+ * config file parsing.
+ */
+static void
+record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p)
+{
+	ConfigVariable *item;
+
+	item = palloc(sizeof *item);
+	item->name = NULL;
+	item->value = NULL;
+	item->errmsg = pstrdup(errmsg);
+	item->filename = config_file ? pstrdup(config_file) : NULL;
+	item->sourceline = lineno;
+	item->ignore = true;
+	item->applied = false;
+	item->next = NULL;
+	if (*head_p == NULL)
+		*head_p = item;
+	else
+		(*tail_p)->next = item;
+	*tail_p = item;
+}
+
+/*
+ * Flex fatal errors bring us here.  Stash the error message and jump back to
+ * ParseConfigFp().  Assume all msg arguments point to string constants; this
+ * holds for flex 2.5.31 (earliest we support) and flex 2.5.35 (latest as of
+ * this writing).  Otherwise, we would need to copy the message.
+ *
+ * We return "int" since this takes the place of calls to fprintf().
+*/
+static int
+GUC_flex_fatal(const char *msg)
+{
+	GUC_flex_fatal_errmsg = msg;
+	siglongjmp(*GUC_flex_fatal_jmp, 1);
+	return 0;					/* keep compiler quiet */
+}
+
+/*
+ * Read and parse a single configuration file.  This function recurses
+ * to handle "include" directives.
+ *
+ * Input parameters:
+ *	fp: file pointer from AllocateFile for the configuration file to parse
+ *	config_file: absolute or relative path name of the configuration file
+ *	depth: recursion depth (should be 0 in the outermost call)
+ *	elevel: error logging level to use
+ * Input/Output parameters:
+ *	head_p, tail_p: head and tail of linked list of name/value pairs
+ *
+ * *head_p and *tail_p must be initialized, either to NULL or valid pointers
+ * to a ConfigVariable list, before calling the outer recursion level.  Any
+ * name-value pairs read from the input file(s) will be appended to the list.
+ * Error reports will also be appended to the list, if elevel < ERROR.
+ *
+ * Returns TRUE if successful, FALSE if an error occurred.
+ *
+ * Note: this function is used to parse not only postgresql.conf, but
+ * various other configuration files that use the same "name = value"
+ * syntax.  Hence, do not do anything here or in the subsidiary routines
+ * ParseConfigFile/ParseConfigDirectory that assumes we are processing
+ * GUCs specifically.
+ */
+bool
+ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p)
+{
+	volatile bool OK = true;
+	unsigned int save_ConfigFileLineno = ConfigFileLineno;
+	sigjmp_buf *save_GUC_flex_fatal_jmp = GUC_flex_fatal_jmp;
+	sigjmp_buf	flex_fatal_jmp;
+	volatile YY_BUFFER_STATE lex_buffer = NULL;
+	int			errorcount;
+	int			token;
+
+	if (sigsetjmp(flex_fatal_jmp, 1) == 0)
+		GUC_flex_fatal_jmp = &flex_fatal_jmp;
+	else
+	{
+		/*
+		 * Regain control after a fatal, internal flex error.  It may have
+		 * corrupted parser state.  Consequently, abandon the file, but trust
+		 * that the state remains sane enough for yy_delete_buffer().
+		 */
+		pg_log(PG_WARNING, "%s at file \"%s\" line %u\n", GUC_flex_fatal_errmsg,
+				config_file, ConfigFileLineno);
+		record_config_file_error(GUC_flex_fatal_errmsg,
+								 config_file, ConfigFileLineno,
+								 head_p, tail_p);
+		OK = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Parse
+	 */
+	ConfigFileLineno = 1;
+	errorcount = 0;
+
+	lex_buffer = yy_create_buffer(fp, YY_BUF_SIZE);
+	yy_switch_to_buffer(lex_buffer);
+
+	/* This loop iterates once per logical line */
+	while ((token = yylex()))
+	{
+		char	   *opt_name = NULL;
+		char	   *opt_value = NULL;
+		ConfigVariable *item;
+
+		if (token == GUC_EOL)	/* empty or comment line */
+			continue;
+
+		/* first token on line is option name */
+		if (token != GUC_ID && token != GUC_QUALIFIED_ID)
+			goto parse_error;
+		opt_name = pstrdup(yytext);
+
+		/* next we have an optional equal sign; discard if present */
+		token = yylex();
+		if (token == GUC_EQUALS)
+			token = yylex();
+
+		/* now we must have the option value */
+		if (token != GUC_ID &&
+			token != GUC_STRING &&
+			token != GUC_INTEGER &&
+			token != GUC_REAL &&
+			token != GUC_UNQUOTED_STRING)
+			goto parse_error;
+		if (token == GUC_STRING)	/* strip quotes and escapes */
+			opt_value = GUC_scanstr(yytext);
+		else
+			opt_value = pstrdup(yytext);
+
+		/* now we'd like an end of line, or possibly EOF */
+		token = yylex();
+		if (token != GUC_EOL)
+		{
+			if (token != 0)
+				goto parse_error;
+			/* treat EOF like \n for line numbering purposes, cf bug 4752 */
+			ConfigFileLineno++;
+		}
+
+		/* OK, process the option name and value */
+		if (guc_name_compare(opt_name, "include_dir") == 0)
+		{
+			/*
+			 * An include_dir directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigDirectory(opt_value,
+									  config_file, ConfigFileLineno - 1,
+									  depth + 1, elevel,
+									  head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include_if_exists") == 0)
+		{
+			/*
+			 * An include_if_exists directive isn't a variable and should be
+			 * processed immediately.
+			 */
+			if (!ParseConfigFile(opt_value, false,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else if (guc_name_compare(opt_name, "include") == 0)
+		{
+			/*
+			 * An include directive isn't a variable and should be processed
+			 * immediately.
+			 */
+			if (!ParseConfigFile(opt_value, true,
+								 config_file, ConfigFileLineno - 1,
+								 depth + 1, elevel,
+								 head_p, tail_p))
+				OK = false;
+			yy_switch_to_buffer(lex_buffer);
+			pfree(opt_name);
+			pfree(opt_value);
+		}
+		else
+		{
+			/* ordinary variable, append to list */
+			item = palloc(sizeof *item);
+			item->name = opt_name;
+			item->value = opt_value;
+			item->errmsg = NULL;
+			item->filename = pstrdup(config_file);
+			item->sourceline = ConfigFileLineno - 1;
+			item->ignore = false;
+			item->applied = false;
+			item->next = NULL;
+			if (*head_p == NULL)
+				*head_p = item;
+			else
+				(*tail_p)->next = item;
+			*tail_p = item;
+		}
+
+		/* break out of loop if read EOF, else loop for next line */
+		if (token == 0)
+			break;
+		continue;
+
+parse_error:
+		/* release storage if we allocated any on this line */
+		if (opt_name)
+			pfree(opt_name);
+		if (opt_value)
+			pfree(opt_value);
+
+		/* report the error */
+		if (token == GUC_EOL || token == 0)
+		{
+			pg_log(PG_WARNING, "syntax error in file \"%s\" line %u, near end of line\n",
+					config_file, ConfigFileLineno - 1);
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno - 1,
+									 head_p, tail_p);
+		}
+		else
+		{
+			pg_log(PG_WARNING, "syntax error in file \"%s\" line %u, near token \"%s\"\n",
+				config_file, ConfigFileLineno, yytext);
+			record_config_file_error("syntax error",
+									 config_file, ConfigFileLineno,
+									 head_p, tail_p);
+		}
+		OK = false;
+		errorcount++;
+
+		/*
+		 * To avoid producing too much noise when fed a totally bogus file,
+		 * give up after 100 syntax errors per file (an arbitrary number).
+		 */
+		if (errorcount >= 100)
+		{
+			pg_log(PG_WARNING, "too many syntax errors found, abandoning file \"%s\"\n",
+					config_file);
+			break;
+		}
+
+		/* resync to next end-of-line or EOF */
+		while (token != GUC_EOL && token != 0)
+			token = yylex();
+		/* break out of loop on EOF */
+		if (token == 0)
+			break;
+	}
+
+cleanup:
+	yy_delete_buffer(lex_buffer);
+	/* Each recursion level must save and restore these static variables. */
+	ConfigFileLineno = save_ConfigFileLineno;
+	GUC_flex_fatal_jmp = save_GUC_flex_fatal_jmp;
+	return OK;
+}
+
+/*
+ * Read and parse all config files in a subdirectory in alphabetical order
+ *
+ * includedir is the absolute or relative path to the subdirectory to scan.
+ *
+ * calling_file/calling_lineno identify the source of the request.
+ * Pass NULL/0 if not recursing from an inclusion request.
+ *
+ * See ParseConfigFp for further details.
+ */
+bool
+ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p)
+{
+	char	   *directory;
+	DIR		   *d;
+	struct dirent *de;
+	char	  **filenames;
+	int			num_filenames;
+	int			size_filenames;
+	bool		status;
+
+	directory = AbsoluteConfigLocation(includedir, calling_file);
+	d = opendir(directory);
+	if (d == NULL)
+	{
+		pg_log(PG_WARNING, "could not open configuration directory \"%s\"\n",
+			directory);
+		record_config_file_error(psprintf("could not open directory \"%s\"",
+										  directory),
+								 calling_file, calling_lineno,
+								 head_p, tail_p);
+		status = false;
+		goto cleanup;
+	}
+
+	/*
+	 * Read the directory and put the filenames in an array, so we can sort
+	 * them prior to processing the contents.
+	 */
+	size_filenames = 32;
+	filenames = (char **) palloc(size_filenames * sizeof(char *));
+	num_filenames = 0;
+
+	while ((de = readdir(d)) != NULL)
+	{
+		struct stat st;
+		char		filename[MAXPGPATH];
+
+		/*
+		 * Only parse files with names ending in ".conf".  Explicitly reject
+		 * files starting with ".".  This excludes things like "." and "..",
+		 * as well as typical hidden files, backup files, and editor debris.
+		 */
+		if (strlen(de->d_name) < 6)
+			continue;
+		if (de->d_name[0] == '.')
+			continue;
+		if (strcmp(de->d_name + strlen(de->d_name) - 5, ".conf") != 0)
+			continue;
+
+		join_path_components(filename, directory, de->d_name);
+		canonicalize_path(filename);
+		if (stat(filename, &st) == 0)
+		{
+			if (!S_ISDIR(st.st_mode))
+			{
+				/* Add file to array, increasing its size in blocks of 32 */
+				if (num_filenames >= size_filenames)
+				{
+					size_filenames += 32;
+					filenames = (char **) repalloc(filenames,
+											size_filenames * sizeof(char *));
+				}
+				filenames[num_filenames] = pstrdup(filename);
+				num_filenames++;
+			}
+		}
+		else
+		{
+			/*
+			 * stat does not care about permissions, so the most likely reason
+			 * a file can't be accessed now is if it was removed between the
+			 * directory listing and now.
+			 */
+			pg_log(PG_WARNING, "could not stat file \"%s\"\n", filename);
+			record_config_file_error(psprintf("could not stat file \"%s\"",
+											  filename),
+									 calling_file, calling_lineno,
+									 head_p, tail_p);
+			status = false;
+			goto cleanup;
+		}
+	}
+
+	if (num_filenames > 0)
+	{
+		int			i;
+
+		qsort(filenames, num_filenames, sizeof(char *), pg_qsort_strcmp);
+		for (i = 0; i < num_filenames; i++)
+		{
+			if (!ParseConfigFile(filenames[i], true,
+								 calling_file, calling_lineno,
+								 depth, elevel,
+								 head_p, tail_p))
+			{
+				status = false;
+				goto cleanup;
+			}
+		}
+	}
+	status = true;
+
+cleanup:
+	if (d)
+		closedir(d);
+	pfree(directory);
+	return status;
+}
+
+/*
+ * Free a list of ConfigVariables, including the names and the values
+ */
+void
+FreeConfigVariables(ConfigVariable *list)
+{
+	ConfigVariable *item;
+
+	item = list;
+	while (item)
+	{
+		ConfigVariable *next = item->next;
+
+		FreeConfigVariable(item);
+		item = next;
+	}
+}
+
+/*
+ * Free a single ConfigVariable
+ */
+static void
+FreeConfigVariable(ConfigVariable *item)
+{
+	if (item->name)
+		pfree(item->name);
+	if (item->value)
+		pfree(item->value);
+	if (item->errmsg)
+		pfree(item->errmsg);
+	if (item->filename)
+		pfree(item->filename);
+	pfree(item);
+}
+
+
+/*
+ *		scanstr
+ *
+ * Strip the quotes surrounding the given string, and collapse any embedded
+ * '' sequences and backslash escapes.
+ *
+ * the string returned is palloc'd and should eventually be pfree'd by the
+ * caller.
+ */
+static char *
+GUC_scanstr(const char *s)
+{
+	char	   *newStr;
+	int			len,
+				i,
+				j;
+
+	Assert(s != NULL && s[0] == '\'');
+	len = strlen(s);
+	Assert(len >= 2);
+	Assert(s[len - 1] == '\'');
+
+	/* Skip the leading quote; we'll handle the trailing quote below */
+	s++, len--;
+
+	/* Since len still includes trailing quote, this is enough space */
+	newStr = palloc(len);
+
+	for (i = 0, j = 0; i < len; i++)
+	{
+		if (s[i] == '\\')
+		{
+			i++;
+			switch (s[i])
+			{
+				case 'b':
+					newStr[j] = '\b';
+					break;
+				case 'f':
+					newStr[j] = '\f';
+					break;
+				case 'n':
+					newStr[j] = '\n';
+					break;
+				case 'r':
+					newStr[j] = '\r';
+					break;
+				case 't':
+					newStr[j] = '\t';
+					break;
+				case '0':
+				case '1':
+				case '2':
+				case '3':
+				case '4':
+				case '5':
+				case '6':
+				case '7':
+					{
+						int			k;
+						long		octVal = 0;
+
+						for (k = 0;
+							 s[i + k] >= '0' && s[i + k] <= '7' && k < 3;
+							 k++)
+							octVal = (octVal << 3) + (s[i + k] - '0');
+						i += k - 1;
+						newStr[j] = ((char) octVal);
+					}
+					break;
+				default:
+					newStr[j] = s[i];
+					break;
+			}					/* switch */
+		}
+		else if (s[i] == '\'' && s[i + 1] == '\'')
+		{
+			/* doubled quote becomes just one quote */
+			newStr[j] = s[++i];
+		}
+		else
+			newStr[j] = s[i];
+		j++;
+	}
+
+	/* We copied the ending quote to newStr, so replace with \0 */
+	Assert(j > 0 && j <= len);
+	newStr[--j] = '\0';
+
+	return newStr;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 40028471bf..11a9c26cd2 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,7 +46,10 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
+	XLogRecPtr  oldrecptr;
+	TimeLineID  oldtli;
 } XLogPageReadPrivate;
 
 static int SimpleXLogPageRead(XLogReaderState *xlogreader,
@@ -53,6 +57,10 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static bool RestoreArchivedWAL(const char *path, const char *xlogfname, 
+					off_t expectedSize, const char *restoreCommand,
+					const char *lastRestartPointFname);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,15 +68,19 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   ControlFileData *targetCF, const char *restore_command)
 {
 	XLogRecord *record;
+	XLogRecPtr endpoint = targetCF->checkPoint;
 	XLogReaderState *xlogreader;
 	char	   *errormsg;
 	XLogPageReadPrivate private;
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -154,9 +166,9 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
  * Find the previous checkpoint preceding given WAL location.
  */
 void
-findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
+findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +193,9 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +306,53 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+			bool  restore_ok;
+			char  lastRestartPointFname[MAXFNAMELEN];
+			XLogSegNo restartSegNo;
+
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
 				   strerror(errno));
-			return -1;
+				return -1;
+			}
+			
+			XLByteToSeg(private->oldrecptr, restartSegNo, WalSegSz);
+			XLogFileName(lastRestartPointFname, private->oldtli, restartSegNo,
+						 WalSegSz);
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			restore_ok = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand,
+											lastRestartPointFname);
+
+			if (restore_ok)
+			{
+				xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogreadfd < 0)
+				{
+					printf(_("could not open restored from archive file \"%s\": %s\n"), xlogfpath,
+				    	   strerror(errno));
+				    return -1;
+				}
+				else
+					pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n", xlogfpath);
+			}
+			else
+			{
+				printf(_("could not restore file \"%s\" from archive: %s\n"), xlogfname,
+					   strerror(errno));
+				return -1;
+			}
 		}
 	}
 
@@ -409,3 +468,116 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return true.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ * 
+ * This is an adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+bool
+RestoreArchivedWAL(const char *path, const char *xlogfname, off_t expectedSize,
+				   const char *restoreCommand, const char *lastRestartPointFname)
+{
+	char		xlogpath[MAXPGPATH];
+	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *dp;
+	char	   *endp;
+	const char *sp;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+					   	xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize,
+					   	strerror(errno));
+			}
+			else
+				return true;
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+				   	xlogpath,
+					strerror(errno));
+		}
+	}
+
+	return false;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 9653106386..816a91fd78 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -19,11 +19,13 @@
 #include "file_ops.h"
 #include "filemap.h"
 #include "logging.h"
+#include "guc-file-fe.h"
 
 #include "access/timeline.h"
 #include "access/xlog_internal.h"
 #include "catalog/catversion.h"
 #include "catalog/pg_control.h"
+#include "common/controldata_utils.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
@@ -52,11 +54,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +79,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,9 +101,12 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
+	char		recfile_fullpath[MAXPGPATH];
 	int			option_index;
 	int			c;
 	XLogRecPtr	divergerec;
@@ -129,7 +139,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "DR:nNPr", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -140,6 +150,10 @@ main(int argc, char **argv)
 			case 'P':
 				showprogress = true;
 				break;
+			
+			case 'r':
+				restore_wals = true;
+				break;
 
 			case 'n':
 				dry_run = true;
@@ -157,6 +171,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +241,71 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		FILE	   *recovery_conf_file;
+
+		/* 
+		 * Look for recovery.conf in the target data directory and
+		 * try to get restore_command from there.
+		 */
+		snprintf(recfile_fullpath, sizeof(recfile_fullpath), "%s/%s", datadir_target, RECOVERY_COMMAND_FILE);
+		recovery_conf_file = fopen(recfile_fullpath, "r");
+
+		if (recovery_conf_file == NULL)
+		{
+			fprintf(stderr, _("%s: option -r/--use-postgresql-conf is specified, but postgreslq.conf is absent in the target directory\n"),
+					progname);
+			fprintf(stdout, _("You have to add postgresql.conf or pass restore_command with -R/--restore-command option.\n"));
+			exit(1);
+		}
+		else
+		{
+			ConfigVariable *item,
+						   *head = NULL,
+						   *tail = NULL;
+			bool			config_is_parsed;
+
+			/*
+			 * We pass a fullpath to the recovery.conf as calling_file here, since
+			 * parser will use its parent directory as base for all further includes
+			 * if any exist.
+			 */
+			config_is_parsed = ParseConfigFile(RECOVERY_COMMAND_FILE, true,
+											   recfile_fullpath, 0, 0,
+											   PG_WARNING, &head, &tail);
+			fclose(recovery_conf_file);
+
+			if (config_is_parsed)
+			{
+				for (item = head; item; item = item->next)
+				{
+					if (strcmp(item->name, "restore_command") == 0)
+					{
+						if (restore_command != NULL)
+						{
+							pfree(restore_command);
+							restore_command = NULL;
+						}
+						restore_command = pstrdup(item->value);
+						pg_log(PG_DEBUG, "using restore_command=\'%s\' from recovery.conf.\n", restore_command);
+					}
+				}
+
+				if (restore_command == NULL)
+					pg_fatal("could not find restore_command in recovery.conf file %s\n", recfile_fullpath);
+			}
+			else
+				pg_fatal("could not parse recovery.conf file %s\n", recfile_fullpath);
+
+			FreeConfigVariables(head);
+		}
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +377,9 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
+	findLastCheckpoint(datadir_target, &ControlFile_target, divergerec,
 					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +402,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   &ControlFile_target, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 3f4ba7a267..ba9d13e9bd 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -14,6 +14,7 @@
 #include "datapagemap.h"
 
 #include "access/timeline.h"
+#include "catalog/pg_control.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
 
@@ -32,11 +33,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
-extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+			   int tliIndex, ControlFileData *targetCF, const char *restoreCommand);
+extern void findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr searchptr,
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 53dbf45be2..22777bff82 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 15;
 
 use RewindTest;
 
@@ -103,5 +103,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 2c9e427831..10c835efc1 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 9;
 
 use RewindTest;
 
@@ -59,5 +59,6 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index 496f38c457..f94ce329f4 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 6;
 
 use File::Find;
 
@@ -87,5 +87,6 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 2921d193a1..3da0fdc956 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -73,6 +73,7 @@ my $frontend_extraincludes = {
 };
 my $frontend_extrasource = {
 	'psql' => ['src/bin/psql/psqlscanslash.l'],
+	'pg_rewind' => ['src/bin/pg_rewind/guc-file-fe.l'],
 	'pgbench' =>
 	  [ 'src/bin/pgbench/exprscan.l', 'src/bin/pgbench/exprparse.y' ]
 };
-- 
2.17.1

From 8a6c9f89f45c9568d95e05b0586d1cc54905e6de Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <alex.lumir@gmail.com>
Date: Fri, 21 Dec 2018 14:00:30 +0300
Subject: [PATCH] pg_rewind: options to use restore_command from
 postgresql.conf or command line.

---
 src/backend/Makefile                          |   4 +-
 src/backend/commands/extension.c              |   1 +
 src/backend/utils/misc/Makefile               |   8 -
 src/backend/utils/misc/guc.c                  | 434 +++++++++++++--
 src/bin/pg_rewind/Makefile                    |   2 +-
 src/bin/pg_rewind/RewindTest.pm               |  96 +++-
 src/bin/pg_rewind/parsexlog.c                 | 182 ++++++-
 src/bin/pg_rewind/pg_rewind.c                 |  91 +++-
 src/bin/pg_rewind/pg_rewind.h                 |  12 +-
 src/bin/pg_rewind/t/001_basic.pl              |   4 +-
 src/bin/pg_rewind/t/002_databases.pl          |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl         |   4 +-
 src/common/Makefile                           |   7 +-
 src/{backend/utils/misc => common}/guc-file.l | 514 ++++--------------
 src/include/common/guc-file.h                 |  50 ++
 src/include/utils/guc.h                       |  39 +-
 src/tools/msvc/Mkvcbuild.pm                   |   2 +-
 src/tools/msvc/clean.bat                      |   2 +-
 18 files changed, 952 insertions(+), 504 deletions(-)
 rename src/{backend/utils/misc => common}/guc-file.l (60%)
 create mode 100644 src/include/common/guc-file.h

diff --git a/src/backend/Makefile b/src/backend/Makefile
index 25eb043941..ddbe2f3fce 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -186,7 +186,7 @@ distprep:
 	$(MAKE) -C replication	repl_gram.c repl_scanner.c syncrep_gram.c syncrep_scanner.c
 	$(MAKE) -C storage/lmgr	lwlocknames.h lwlocknames.c
 	$(MAKE) -C utils	distprep
-	$(MAKE) -C utils/misc	guc-file.c
+	$(MAKE) -C common	guc-file.c
 	$(MAKE) -C utils/sort	qsort_tuple.c
 
 
@@ -307,7 +307,7 @@ maintainer-clean: distclean
 	      replication/syncrep_scanner.c \
 	      storage/lmgr/lwlocknames.c \
 	      storage/lmgr/lwlocknames.h \
-	      utils/misc/guc-file.c \
+	      common/guc-file.c \
 	      utils/sort/qsort_tuple.c
 
 
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index 31dcfe7b11..ec0367d068 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -47,6 +47,7 @@
 #include "commands/defrem.h"
 #include "commands/extension.h"
 #include "commands/schemacmds.h"
+#include "common/guc-file.h"
 #include "funcapi.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
diff --git a/src/backend/utils/misc/Makefile b/src/backend/utils/misc/Makefile
index a53fcdf188..2e6a879c46 100644
--- a/src/backend/utils/misc/Makefile
+++ b/src/backend/utils/misc/Makefile
@@ -25,11 +25,3 @@ override CPPFLAGS += -DPG_KRB_SRVTAB='"$(krb_srvtab)"'
 endif
 
 include $(top_srcdir)/src/backend/common.mk
-
-# guc-file is compiled as part of guc
-guc.o: guc-file.c
-
-# Note: guc-file.c is not deleted by 'make clean',
-# since we want to ship it in distribution tarballs.
-clean:
-	@rm -f lex.yy.c
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 6fe1939881..a866503186 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -41,6 +41,7 @@
 #include "commands/vacuum.h"
 #include "commands/variable.h"
 #include "commands/trigger.h"
+#include "common/guc-file.h"
 #include "common/string.h"
 #include "funcapi.h"
 #include "jit/jit.h"
@@ -210,7 +211,6 @@ static bool check_recovery_target_lsn(char **newval, void **extra, GucSource sou
 static void assign_recovery_target_lsn(const char *newval, void *extra);
 static bool check_primary_slot_name(char **newval, void **extra, GucSource source);
 
-/* Private functions in guc-file.l that need to be called from guc.c */
 static ConfigVariable *ProcessConfigFileInternal(GucContext context,
 						  bool applySettings, int elevel);
 
@@ -4445,7 +4445,6 @@ static int	GUCNestLevel = 0;	/* 1 when in main transaction */
 
 
 static int	guc_var_compare(const void *a, const void *b);
-static int	guc_name_compare(const char *namea, const char *nameb);
 static void InitializeGUCOptionsFromEnvironment(void);
 static void InitializeOneGUCOption(struct config_generic *gconf);
 static void push_old_value(struct config_generic *gconf, GucAction action);
@@ -4922,37 +4921,6 @@ guc_var_compare(const void *a, const void *b)
 	return guc_name_compare(confa->name, confb->name);
 }
 
-/*
- * the bare comparison function for GUC names
- */
-static int
-guc_name_compare(const char *namea, const char *nameb)
-{
-	/*
-	 * The temptation to use strcasecmp() here must be resisted, because the
-	 * array ordering has to remain stable across setlocale() calls. So, build
-	 * our own with a simple ASCII-only downcasing.
-	 */
-	while (*namea && *nameb)
-	{
-		char		cha = *namea++;
-		char		chb = *nameb++;
-
-		if (cha >= 'A' && cha <= 'Z')
-			cha += 'a' - 'A';
-		if (chb >= 'A' && chb <= 'Z')
-			chb += 'a' - 'A';
-		if (cha != chb)
-			return cha - chb;
-	}
-	if (*namea)
-		return 1;				/* a is longer */
-	if (*nameb)
-		return -1;				/* b is longer */
-	return 0;
-}
-
-
 /*
  * Initialize GUC options during program startup.
  *
@@ -11310,4 +11278,402 @@ check_primary_slot_name(char **newval, void **extra, GucSource source)
 	return true;
 }
 
-#include "guc-file.c"
+/*
+ * Exported function to read and process the configuration file. The
+ * parameter indicates in what context the file is being read --- either
+ * postmaster startup (including standalone-backend startup) or SIGHUP.
+ * All options mentioned in the configuration file are set to new values.
+ * If a hard error occurs, no values will be changed.  (There can also be
+ * errors that prevent just one value from being changed.)
+ */
+void
+ProcessConfigFile(GucContext context)
+{
+	int			elevel;
+	MemoryContext config_cxt;
+	MemoryContext caller_cxt;
+
+	/*
+	 * Config files are processed on startup (by the postmaster only) and on
+	 * SIGHUP (by the postmaster and its children)
+	 */
+	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
+		   context == PGC_SIGHUP);
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+
+	/*
+	 * This function is usually called within a process-lifespan memory
+	 * context.  To ensure that any memory leaked during GUC processing does
+	 * not accumulate across repeated SIGHUP cycles, do the work in a private
+	 * context that we can free at exit.
+	 */
+	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
+									   "config file processing",
+									   ALLOCSET_DEFAULT_SIZES);
+	caller_cxt = MemoryContextSwitchTo(config_cxt);
+
+	/*
+	 * Read and apply the config file.  We don't need to examine the result.
+	 */
+	(void) ProcessConfigFileInternal(context, true, elevel);
+
+	/* Clean up */
+	MemoryContextSwitchTo(caller_cxt);
+	MemoryContextDelete(config_cxt);
+}
+
+/*
+ * This function handles both actual config file (re)loads and execution of
+ * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
+ * case we don't apply any of the settings, but we make all the usual validity
+ * checks, and we return the ConfigVariable list so that it can be printed out
+ * by show_all_file_settings().
+ */
+static ConfigVariable *
+ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+{
+	bool		error = false;
+	bool		applying = false;
+	const char *ConfFileWithError;
+	ConfigVariable *item,
+			   *head,
+			   *tail;
+	int			i;
+
+	/* Parse the main config file into a list of option names and values */
+	ConfFileWithError = ConfigFileName;
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, true,
+						 NULL, 0, 0, elevel,
+						 &head, &tail))
+	{
+		/* Syntax error(s) detected in the file, so bail out */
+		error = true;
+		goto bail_out;
+	}
+
+	/*
+	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
+	 * replace any parameters set by ALTER SYSTEM command.  Because this file
+	 * is in the data directory, we can't read it until the DataDir has been
+	 * set.
+	 */
+	if (DataDir)
+	{
+		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
+							 NULL, 0, 0, elevel,
+							 &head, &tail))
+		{
+			/* Syntax error(s) detected in the file, so bail out */
+			error = true;
+			ConfFileWithError = PG_AUTOCONF_FILENAME;
+			goto bail_out;
+		}
+	}
+	else
+	{
+		/*
+		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
+		 * read.  In this case, we don't want to accept any settings but
+		 * data_directory from postgresql.conf, because they might be
+		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
+		 * will be read later. OTOH, since data_directory isn't allowed in the
+		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
+		 */
+		ConfigVariable *newlist = NULL;
+
+		/*
+		 * Prune all items except the last "data_directory" from the list.
+		 */
+		for (item = head; item; item = item->next)
+		{
+			if (!item->ignore &&
+				strcmp(item->name, "data_directory") == 0)
+				newlist = item;
+		}
+
+		if (newlist)
+			newlist->next = NULL;
+		head = tail = newlist;
+
+		/*
+		 * Quick exit if data_directory is not present in file.
+		 *
+		 * We need not do any further processing, in particular we don't set
+		 * PgReloadTime; that will be set soon by subsequent full loading of
+		 * the config file.
+		 */
+		if (head == NULL)
+			goto bail_out;
+	}
+
+	/*
+	 * Mark all extant GUC variables as not present in the config file. We
+	 * need this so that we can tell below which ones have been removed from
+	 * the file since we last processed it.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		gconf->status &= ~GUC_IS_IN_FILE;
+	}
+
+	/*
+	 * Check if all the supplied option names are valid, as an additional
+	 * quasi-syntactic check on the validity of the config file.  It is
+	 * important that the postmaster and all backends agree on the results of
+	 * this phase, else we will have strange inconsistencies about which
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
+	 *
+	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
+	 * variable mentioned in the file; and we detect duplicate entries in the
+	 * file and mark the earlier occurrences as ignorable.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		struct config_generic *record;
+
+		/* Ignore anything already marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/*
+		 * Try to find the variable; but do not create a custom placeholder if
+		 * it's not there already.
+		 */
+		record = find_option(item->name, false, elevel);
+
+		if (record)
+		{
+			/* If it's already marked, then this is a duplicate entry */
+			if (record->status & GUC_IS_IN_FILE)
+			{
+				/*
+				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
+				 * avoid the O(N^2) behavior here with some additional state,
+				 * but it seems unlikely to be worth the trouble.
+				 */
+				ConfigVariable *pitem;
+
+				for (pitem = head; pitem != item; pitem = pitem->next)
+				{
+					if (!pitem->ignore &&
+						strcmp(pitem->name, item->name) == 0)
+						pitem->ignore = true;
+				}
+			}
+			/* Now mark it as present in file */
+			record->status |= GUC_IS_IN_FILE;
+		}
+		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
+		{
+			/* Invalid non-custom variable, so complain */
+			ereport(elevel,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
+							item->name,
+							item->filename, item->sourceline)));
+			item->errmsg = pstrdup("unrecognized configuration parameter");
+			error = true;
+			ConfFileWithError = item->filename;
+		}
+	}
+
+	/*
+	 * If we've detected any errors so far, we don't want to risk applying any
+	 * changes.
+	 */
+	if (error)
+		goto bail_out;
+
+	/* Otherwise, set flag that we're beginning to apply changes */
+	applying = true;
+
+	/*
+	 * Check for variables having been removed from the config file, and
+	 * revert their reset values (and perhaps also effective values) to the
+	 * boot-time defaults.  If such a variable can't be changed after startup,
+	 * report that and continue.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		if (gconf->reset_source != PGC_S_FILE ||
+			(gconf->status & GUC_IS_IN_FILE))
+			continue;
+		if (gconf->context < PGC_SIGHUP)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+							gconf->name)));
+			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
+											  gconf->name),
+									 NULL, 0,
+									 &head, &tail);
+			error = true;
+			continue;
+		}
+
+		/* No more to do if we're just doing show_all_file_settings() */
+		if (!applySettings)
+			continue;
+
+		/*
+		 * Reset any "file" sources to "default", else set_config_option will
+		 * not override those settings.
+		 */
+		if (gconf->reset_source == PGC_S_FILE)
+			gconf->reset_source = PGC_S_DEFAULT;
+		if (gconf->source == PGC_S_FILE)
+			gconf->source = PGC_S_DEFAULT;
+		for (stack = gconf->stack; stack; stack = stack->prev)
+		{
+			if (stack->source == PGC_S_FILE)
+				stack->source = PGC_S_DEFAULT;
+		}
+
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
+		if (set_config_option(gconf->name, NULL,
+							  context, PGC_S_DEFAULT,
+							  GUC_ACTION_SET, true, 0, false) > 0)
+		{
+			/* Log the change if appropriate */
+			if (context == PGC_SIGHUP)
+				ereport(elevel,
+						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
+								gconf->name)));
+		}
+	}
+
+	/*
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
+	 *
+	 * In particular, we *must not* do this during the postmaster's initial
+	 * loading of the file, since the timezone functions in particular should
+	 * be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how to set
+	 * (or at least what to call to set) every variable that could potentially
+	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
+	 * time to redesign it for 9.1.
+	 */
+	if (context == PGC_SIGHUP && applySettings)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
+
+	/*
+	 * Now apply the values from the config file.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		char	   *pre_value = NULL;
+		int			scres;
+
+		/* Ignore anything marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/* In SIGHUP cases in the postmaster, we want to report changes */
+		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
+		{
+			const char *preval = GetConfigOption(item->name, true, false);
+
+			/* If option doesn't exist yet or is NULL, treat as empty string */
+			if (!preval)
+				preval = "";
+			/* must dup, else might have dangling pointer below */
+			pre_value = pstrdup(preval);
+		}
+
+		scres = set_config_option(item->name, item->value,
+								  context, PGC_S_FILE,
+								  GUC_ACTION_SET, applySettings, 0, false);
+		if (scres > 0)
+		{
+			/* variable was updated, so log the change if appropriate */
+			if (pre_value)
+			{
+				const char *post_value = GetConfigOption(item->name, true, false);
+
+				if (!post_value)
+					post_value = "";
+				if (strcmp(pre_value, post_value) != 0)
+					ereport(elevel,
+							(errmsg("parameter \"%s\" changed to \"%s\"",
+									item->name, item->value)));
+			}
+			item->applied = true;
+		}
+		else if (scres == 0)
+		{
+			error = true;
+			item->errmsg = pstrdup("setting could not be applied");
+			ConfFileWithError = item->filename;
+		}
+		else
+		{
+			/* no error, but variable's active value was not changed */
+			item->applied = true;
+		}
+
+		/*
+		 * We should update source location unless there was an error, since
+		 * even if the active value didn't change, the reset value might have.
+		 * (In the postmaster, there won't be a difference, but it does matter
+		 * in backends.)
+		 */
+		if (scres != 0 && applySettings)
+			set_config_sourcefile(item->name, item->filename,
+								  item->sourceline);
+
+		if (pre_value)
+			pfree(pre_value);
+	}
+
+	/* Remember when we last successfully loaded the config file. */
+	if (applySettings)
+		PgReloadTime = GetCurrentTimestamp();
+
+bail_out:
+	if (error && applySettings)
+	{
+		/* During postmaster startup, any error is fatal */
+		if (context == PGC_POSTMASTER)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors",
+							ConfFileWithError)));
+		else if (applying)
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
+							ConfFileWithError)));
+		else
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
+							ConfFileWithError)));
+	}
+
+	/* Successful or otherwise, return the collected data list */
+	return head;
+}
diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
index 2bcfcc61af..e2b99e32c3 100644
--- a/src/bin/pg_rewind/Makefile
+++ b/src/bin/pg_rewind/Makefile
@@ -15,7 +15,7 @@ subdir = src/bin/pg_rewind
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
+override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
diff --git a/src/bin/pg_rewind/RewindTest.pm b/src/bin/pg_rewind/RewindTest.pm
index 3d07da5d94..f650570741 100644
--- a/src/bin/pg_rewind/RewindTest.pm
+++ b/src/bin/pg_rewind/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catpath catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -250,6 +252,98 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-R", $restore_command
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		print "Using restore_command=$restore_command\n";
+		print "Conf path $master_conf_path\n";
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 40028471bf..f56eb89448 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,7 +46,10 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
+	XLogRecPtr  oldrecptr;
+	TimeLineID  oldtli;
 } XLogPageReadPrivate;
 
 static int SimpleXLogPageRead(XLogReaderState *xlogreader,
@@ -53,6 +57,10 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static bool RestoreArchivedWAL(const char *path, const char *xlogfname,
+					off_t expectedSize, const char *restoreCommand,
+					const char *lastRestartPointFname);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,15 +68,19 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   ControlFileData *targetCF, const char *restore_command)
 {
 	XLogRecord *record;
+	XLogRecPtr endpoint = targetCF->checkPoint;
 	XLogReaderState *xlogreader;
 	char	   *errormsg;
 	XLogPageReadPrivate private;
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -154,9 +166,9 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
  * Find the previous checkpoint preceding given WAL location.
  */
 void
-findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
+findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +193,9 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +306,53 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+			bool  restore_ok;
+			char  lastRestartPointFname[MAXFNAMELEN];
+			XLogSegNo restartSegNo;
+
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
 				   strerror(errno));
-			return -1;
+				return -1;
+			}
+
+			XLByteToSeg(private->oldrecptr, restartSegNo, WalSegSz);
+			XLogFileName(lastRestartPointFname, private->oldtli, restartSegNo,
+						 WalSegSz);
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			restore_ok = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand,
+											lastRestartPointFname);
+
+			if (restore_ok)
+			{
+				xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogreadfd < 0)
+				{
+					printf(_("could not open restored from archive file \"%s\": %s\n"), xlogfpath,
+							strerror(errno));
+					return -1;
+				}
+				else
+					pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n", xlogfpath);
+			}
+			else
+			{
+				printf(_("could not restore file \"%s\" from archive: %s\n"), xlogfname,
+					   strerror(errno));
+				return -1;
+			}
 		}
 	}
 
@@ -409,3 +468,116 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return true.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ *
+ * This is an adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+bool
+RestoreArchivedWAL(const char *path, const char *xlogfname, off_t expectedSize,
+				   const char *restoreCommand, const char *lastRestartPointFname)
+{
+	char		xlogpath[MAXPGPATH];
+	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *dp;
+	char	   *endp;
+	const char *sp;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize,
+						strerror(errno));
+			}
+			else
+				return true;
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath,
+					strerror(errno));
+		}
+	}
+
+	return false;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 9653106386..9075ebba5d 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -24,8 +24,10 @@
 #include "access/xlog_internal.h"
 #include "catalog/catversion.h"
 #include "catalog/pg_control.h"
+#include "common/controldata_utils.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"
+#include "common/guc-file.h"
 #include "common/restricted_token.h"
 #include "getopt_long.h"
 #include "storage/bufpage.h"
@@ -52,11 +54,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +79,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,9 +101,12 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
+	char		recfile_fullpath[MAXPGPATH];
 	int			option_index;
 	int			c;
 	XLogRecPtr	divergerec;
@@ -129,7 +139,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "DR:nNPr", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +151,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +171,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +241,71 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		FILE	   *conf_file;
+
+		/*
+		 * Look for configuration file in the target data directory and
+		 * try to get restore_command from there.
+		 */
+		snprintf(recfile_fullpath, sizeof(recfile_fullpath), "%s/%s", datadir_target, RESTORE_COMMAND_FILE);
+		conf_file = fopen(recfile_fullpath, "r");
+
+		if (conf_file == NULL)
+		{
+			fprintf(stderr, _("%s: option -r/--use-postgresql-conf is specified, but postgreslq.conf is absent in the target directory\n"),
+					progname);
+			fprintf(stdout, _("You have to add postgresql.conf or pass restore_command with -R/--restore-command option.\n"));
+			exit(1);
+		}
+		else
+		{
+			ConfigVariable *item,
+						   *head = NULL,
+						   *tail = NULL;
+			bool			config_is_parsed;
+
+			/*
+			 * We pass a fullpath to the configuration file as calling_file here, since
+			 * parser will use its parent directory as base for all further includes
+			 * if any exist.
+			 */
+			config_is_parsed = ParseConfigFile(RESTORE_COMMAND_FILE, true,
+											   recfile_fullpath, 0, 0,
+											   PG_WARNING, &head, &tail);
+			fclose(conf_file);
+
+			if (config_is_parsed)
+			{
+				for (item = head; item; item = item->next)
+				{
+					if (strcmp(item->name, "restore_command") == 0)
+					{
+						if (restore_command != NULL)
+						{
+							pfree(restore_command);
+							restore_command = NULL;
+						}
+						restore_command = pstrdup(item->value);
+						pg_log(PG_DEBUG, "using restore_command=\'%s\' from %s.\n", restore_command, RESTORE_COMMAND_FILE);
+					}
+				}
+
+				if (restore_command == NULL)
+					pg_fatal("could not find restore_command in %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+			}
+			else
+				pg_fatal("could not parse %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+
+			FreeConfigVariables(head);
+		}
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +377,9 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
+	findLastCheckpoint(datadir_target, &ControlFile_target, divergerec,
 					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +402,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   &ControlFile_target, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 3f4ba7a267..d4d04ca981 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -14,9 +14,12 @@
 #include "datapagemap.h"
 
 #include "access/timeline.h"
+#include "catalog/pg_control.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
 
+#define RESTORE_COMMAND_FILE "postgresql.conf"
+
 /* Configuration options */
 extern char *datadir_target;
 extern char *datadir_source;
@@ -32,11 +35,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
-extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+			   int tliIndex, ControlFileData *targetCF, const char *restoreCommand);
+extern void findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr searchptr,
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 53dbf45be2..1860ce2fe3 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use RewindTest;
 
@@ -103,5 +103,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 2c9e427831..42d708dfbd 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use RewindTest;
 
@@ -59,5 +59,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index 496f38c457..96665ac2f4 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -87,5 +87,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/common/Makefile b/src/common/Makefile
index ec8139f014..73f27cf8ac 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -48,7 +48,7 @@ OBJS_COMMON = base64.o config_info.o controldata_utils.o exec.o file_perm.o \
 	ip.o keywords.o link-canary.o md5.o pg_lzcompress.o \
 	pgfnames.o psprintf.o relpath.o \
 	rmtree.o saslprep.o scram-common.o string.o unicode_norm.o \
-	username.o wait_error.o
+	username.o wait_error.o guc-file.o
 
 ifeq ($(with_openssl),yes)
 OBJS_COMMON += sha2_openssl.o
@@ -65,6 +65,8 @@ OBJS_SRV = $(OBJS_COMMON:%.o=%_srv.o)
 
 all: libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 
+distprep: guc-file.c
+
 # libpgcommon is needed by some contrib
 install: all installdirs
 	$(INSTALL_STLIB) libpgcommon.a '$(DESTDIR)$(libdir)/libpgcommon.a'
@@ -125,6 +127,9 @@ keywords.o: $(top_srcdir)/src/include/parser/kwlist.h
 keywords_shlib.o: $(top_srcdir)/src/include/parser/kwlist.h
 keywords_srv.o: $(top_builddir)/src/include/parser/gram.h $(top_srcdir)/src/include/parser/kwlist.h
 
+# Note: guc-file.c is not deleted by 'make clean',
+# since we want to ship it in distribution tarballs.
 clean distclean maintainer-clean:
 	rm -f libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 	rm -f $(OBJS_FRONTEND) $(OBJS_SHLIB) $(OBJS_SRV)
+	@rm -f lex.yy.c
diff --git a/src/backend/utils/misc/guc-file.l b/src/common/guc-file.l
similarity index 60%
rename from src/backend/utils/misc/guc-file.l
rename to src/common/guc-file.l
index afe4fe6d77..58af8a1cab 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/common/guc-file.l
@@ -4,21 +4,33 @@
  *
  * Copyright (c) 2000-2018, PostgreSQL Global Development Group
  *
- * src/backend/utils/misc/guc-file.l
+ * src/common/guc-file.l
  */
 
 %{
 
-#include "postgres.h"
-
 #include <ctype.h>
 #include <unistd.h>
+#include <sys/stat.h>
+
+#ifndef FRONTEND
+#include "postgres.h"
 
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "utils/guc.h"
+#include "utils/elog.h"
+#else
+#include <dirent.h>
+#include <setjmp.h>
+
+#include "postgres_fe.h"
 
+#include "common/fe_memutils.h"
+#endif
+
+#include "common/guc-file.h"
 
 /*
  * flex emits a yy_fatal_error() function that it calls in response to
@@ -48,12 +60,6 @@ static sigjmp_buf *GUC_flex_fatal_jmp;
 
 static void FreeConfigVariable(ConfigVariable *item);
 
-static void record_config_file_error(const char *errmsg,
-						 const char *config_file,
-						 int lineno,
-						 ConfigVariable **head_p,
-						 ConfigVariable **tail_p);
-
 static int	GUC_flex_fatal(const char *msg);
 static char *GUC_scanstr(const char *s);
 
@@ -111,404 +117,35 @@ STRING			\'([^'\\\n]|\\.|\'\')*\'
 
 /* LCOV_EXCL_STOP */
 
-/*
- * Exported function to read and process the configuration file. The
- * parameter indicates in what context the file is being read --- either
- * postmaster startup (including standalone-backend startup) or SIGHUP.
- * All options mentioned in the configuration file are set to new values.
- * If a hard error occurs, no values will be changed.  (There can also be
- * errors that prevent just one value from being changed.)
- */
-void
-ProcessConfigFile(GucContext context)
-{
-	int			elevel;
-	MemoryContext config_cxt;
-	MemoryContext caller_cxt;
-
-	/*
-	 * Config files are processed on startup (by the postmaster only) and on
-	 * SIGHUP (by the postmaster and its children)
-	 */
-	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
-		   context == PGC_SIGHUP);
-
-	/*
-	 * To avoid cluttering the log, only the postmaster bleats loudly about
-	 * problems with the config file.
-	 */
-	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
-
-	/*
-	 * This function is usually called within a process-lifespan memory
-	 * context.  To ensure that any memory leaked during GUC processing does
-	 * not accumulate across repeated SIGHUP cycles, do the work in a private
-	 * context that we can free at exit.
-	 */
-	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
-									   "config file processing",
-									   ALLOCSET_DEFAULT_SIZES);
-	caller_cxt = MemoryContextSwitchTo(config_cxt);
-
-	/*
-	 * Read and apply the config file.  We don't need to examine the result.
-	 */
-	(void) ProcessConfigFileInternal(context, true, elevel);
-
-	/* Clean up */
-	MemoryContextSwitchTo(caller_cxt);
-	MemoryContextDelete(config_cxt);
-}
 
 /*
- * This function handles both actual config file (re)loads and execution of
- * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
- * case we don't apply any of the settings, but we make all the usual validity
- * checks, and we return the ConfigVariable list so that it can be printed out
- * by show_all_file_settings().
+ * The bare comparison function for GUC names.
  */
-static ConfigVariable *
-ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+int
+guc_name_compare(const char *namea, const char *nameb)
 {
-	bool		error = false;
-	bool		applying = false;
-	const char *ConfFileWithError;
-	ConfigVariable *item,
-			   *head,
-			   *tail;
-	int			i;
-
-	/* Parse the main config file into a list of option names and values */
-	ConfFileWithError = ConfigFileName;
-	head = tail = NULL;
-
-	if (!ParseConfigFile(ConfigFileName, true,
-						 NULL, 0, 0, elevel,
-						 &head, &tail))
-	{
-		/* Syntax error(s) detected in the file, so bail out */
-		error = true;
-		goto bail_out;
-	}
-
-	/*
-	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
-	 * replace any parameters set by ALTER SYSTEM command.  Because this file
-	 * is in the data directory, we can't read it until the DataDir has been
-	 * set.
-	 */
-	if (DataDir)
-	{
-		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
-							 NULL, 0, 0, elevel,
-							 &head, &tail))
-		{
-			/* Syntax error(s) detected in the file, so bail out */
-			error = true;
-			ConfFileWithError = PG_AUTOCONF_FILENAME;
-			goto bail_out;
-		}
-	}
-	else
-	{
-		/*
-		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
-		 * read.  In this case, we don't want to accept any settings but
-		 * data_directory from postgresql.conf, because they might be
-		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
-		 * will be read later. OTOH, since data_directory isn't allowed in the
-		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
-		 */
-		ConfigVariable *newlist = NULL;
-
-		/*
-		 * Prune all items except the last "data_directory" from the list.
-		 */
-		for (item = head; item; item = item->next)
-		{
-			if (!item->ignore &&
-				strcmp(item->name, "data_directory") == 0)
-				newlist = item;
-		}
-
-		if (newlist)
-			newlist->next = NULL;
-		head = tail = newlist;
-
-		/*
-		 * Quick exit if data_directory is not present in file.
-		 *
-		 * We need not do any further processing, in particular we don't set
-		 * PgReloadTime; that will be set soon by subsequent full loading of
-		 * the config file.
-		 */
-		if (head == NULL)
-			goto bail_out;
-	}
-
 	/*
-	 * Mark all extant GUC variables as not present in the config file. We
-	 * need this so that we can tell below which ones have been removed from
-	 * the file since we last processed it.
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
 	 */
-	for (i = 0; i < num_guc_variables; i++)
+	while (*namea && *nameb)
 	{
-		struct config_generic *gconf = guc_variables[i];
-
-		gconf->status &= ~GUC_IS_IN_FILE;
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
 	}
-
-	/*
-	 * Check if all the supplied option names are valid, as an additional
-	 * quasi-syntactic check on the validity of the config file.  It is
-	 * important that the postmaster and all backends agree on the results of
-	 * this phase, else we will have strange inconsistencies about which
-	 * processes accept a config file update and which don't.  Hence, unknown
-	 * custom variable names have to be accepted without complaint.  For the
-	 * same reason, we don't attempt to validate the options' values here.
-	 *
-	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
-	 * variable mentioned in the file; and we detect duplicate entries in the
-	 * file and mark the earlier occurrences as ignorable.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		struct config_generic *record;
-
-		/* Ignore anything already marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/*
-		 * Try to find the variable; but do not create a custom placeholder if
-		 * it's not there already.
-		 */
-		record = find_option(item->name, false, elevel);
-
-		if (record)
-		{
-			/* If it's already marked, then this is a duplicate entry */
-			if (record->status & GUC_IS_IN_FILE)
-			{
-				/*
-				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
-				 * avoid the O(N^2) behavior here with some additional state,
-				 * but it seems unlikely to be worth the trouble.
-				 */
-				ConfigVariable *pitem;
-
-				for (pitem = head; pitem != item; pitem = pitem->next)
-				{
-					if (!pitem->ignore &&
-						strcmp(pitem->name, item->name) == 0)
-						pitem->ignore = true;
-				}
-			}
-			/* Now mark it as present in file */
-			record->status |= GUC_IS_IN_FILE;
-		}
-		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
-		{
-			/* Invalid non-custom variable, so complain */
-			ereport(elevel,
-					(errcode(ERRCODE_UNDEFINED_OBJECT),
-					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
-							item->name,
-							item->filename, item->sourceline)));
-			item->errmsg = pstrdup("unrecognized configuration parameter");
-			error = true;
-			ConfFileWithError = item->filename;
-		}
-	}
-
-	/*
-	 * If we've detected any errors so far, we don't want to risk applying any
-	 * changes.
-	 */
-	if (error)
-		goto bail_out;
-
-	/* Otherwise, set flag that we're beginning to apply changes */
-	applying = true;
-
-	/*
-	 * Check for variables having been removed from the config file, and
-	 * revert their reset values (and perhaps also effective values) to the
-	 * boot-time defaults.  If such a variable can't be changed after startup,
-	 * report that and continue.
-	 */
-	for (i = 0; i < num_guc_variables; i++)
-	{
-		struct config_generic *gconf = guc_variables[i];
-		GucStack   *stack;
-
-		if (gconf->reset_source != PGC_S_FILE ||
-			(gconf->status & GUC_IS_IN_FILE))
-			continue;
-		if (gconf->context < PGC_SIGHUP)
-		{
-			ereport(elevel,
-					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
-							gconf->name)));
-			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
-											  gconf->name),
-									 NULL, 0,
-									 &head, &tail);
-			error = true;
-			continue;
-		}
-
-		/* No more to do if we're just doing show_all_file_settings() */
-		if (!applySettings)
-			continue;
-
-		/*
-		 * Reset any "file" sources to "default", else set_config_option will
-		 * not override those settings.
-		 */
-		if (gconf->reset_source == PGC_S_FILE)
-			gconf->reset_source = PGC_S_DEFAULT;
-		if (gconf->source == PGC_S_FILE)
-			gconf->source = PGC_S_DEFAULT;
-		for (stack = gconf->stack; stack; stack = stack->prev)
-		{
-			if (stack->source == PGC_S_FILE)
-				stack->source = PGC_S_DEFAULT;
-		}
-
-		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
-		if (set_config_option(gconf->name, NULL,
-							  context, PGC_S_DEFAULT,
-							  GUC_ACTION_SET, true, 0, false) > 0)
-		{
-			/* Log the change if appropriate */
-			if (context == PGC_SIGHUP)
-				ereport(elevel,
-						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
-								gconf->name)));
-		}
-	}
-
-	/*
-	 * Restore any variables determined by environment variables or
-	 * dynamically-computed defaults.  This is a no-op except in the case
-	 * where one of these had been in the config file and is now removed.
-	 *
-	 * In particular, we *must not* do this during the postmaster's initial
-	 * loading of the file, since the timezone functions in particular should
-	 * be run only after initialization is complete.
-	 *
-	 * XXX this is an unmaintainable crock, because we have to know how to set
-	 * (or at least what to call to set) every variable that could potentially
-	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
-	 * time to redesign it for 9.1.
-	 */
-	if (context == PGC_SIGHUP && applySettings)
-	{
-		InitializeGUCOptionsFromEnvironment();
-		pg_timezone_abbrev_initialize();
-		/* this selects SQL_ASCII in processes not connected to a database */
-		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
-						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
-	}
-
-	/*
-	 * Now apply the values from the config file.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		char	   *pre_value = NULL;
-		int			scres;
-
-		/* Ignore anything marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/* In SIGHUP cases in the postmaster, we want to report changes */
-		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
-		{
-			const char *preval = GetConfigOption(item->name, true, false);
-
-			/* If option doesn't exist yet or is NULL, treat as empty string */
-			if (!preval)
-				preval = "";
-			/* must dup, else might have dangling pointer below */
-			pre_value = pstrdup(preval);
-		}
-
-		scres = set_config_option(item->name, item->value,
-								  context, PGC_S_FILE,
-								  GUC_ACTION_SET, applySettings, 0, false);
-		if (scres > 0)
-		{
-			/* variable was updated, so log the change if appropriate */
-			if (pre_value)
-			{
-				const char *post_value = GetConfigOption(item->name, true, false);
-
-				if (!post_value)
-					post_value = "";
-				if (strcmp(pre_value, post_value) != 0)
-					ereport(elevel,
-							(errmsg("parameter \"%s\" changed to \"%s\"",
-									item->name, item->value)));
-			}
-			item->applied = true;
-		}
-		else if (scres == 0)
-		{
-			error = true;
-			item->errmsg = pstrdup("setting could not be applied");
-			ConfFileWithError = item->filename;
-		}
-		else
-		{
-			/* no error, but variable's active value was not changed */
-			item->applied = true;
-		}
-
-		/*
-		 * We should update source location unless there was an error, since
-		 * even if the active value didn't change, the reset value might have.
-		 * (In the postmaster, there won't be a difference, but it does matter
-		 * in backends.)
-		 */
-		if (scres != 0 && applySettings)
-			set_config_sourcefile(item->name, item->filename,
-								  item->sourceline);
-
-		if (pre_value)
-			pfree(pre_value);
-	}
-
-	/* Remember when we last successfully loaded the config file. */
-	if (applySettings)
-		PgReloadTime = GetCurrentTimestamp();
-
-bail_out:
-	if (error && applySettings)
-	{
-		/* During postmaster startup, any error is fatal */
-		if (context == PGC_POSTMASTER)
-			ereport(ERROR,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors",
-							ConfFileWithError)));
-		else if (applying)
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
-							ConfFileWithError)));
-		else
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
-							ConfFileWithError)));
-	}
-
-	/* Successful or otherwise, return the collected data list */
-	return head;
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
 }
 
 /*
@@ -525,6 +162,7 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 		return pstrdup(location);
 	else
 	{
+		#ifndef FRONTEND
 		if (calling_file != NULL)
 		{
 			strlcpy(abs_path, calling_file, sizeof(abs_path));
@@ -538,6 +176,12 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 			join_path_components(abs_path, DataDir, location);
 			canonicalize_path(abs_path);
 		}
+		#else
+		strlcpy(abs_path, calling_file, sizeof(abs_path));
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, location);
+		canonicalize_path(abs_path);
+		#endif
 		return pstrdup(abs_path);
 	}
 }
@@ -574,10 +218,15 @@ ParseConfigFile(const char *config_file, bool strict,
 	 */
 	if (depth > 10)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
 						config_file)));
+		#else
+		printf(_("could not open configuration file \"%s\": maximum nesting depth exceeded\n"),
+				config_file);
+		#endif
 		record_config_file_error("nesting depth exceeded",
 								 calling_file, calling_lineno,
 								 head_p, tail_p);
@@ -585,15 +234,23 @@ ParseConfigFile(const char *config_file, bool strict,
 	}
 
 	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+	#ifndef FRONTEND
 	fp = AllocateFile(abs_path, "r");
+	#else
+	fp = fopen(abs_path, "r");
+	#endif
 	if (!fp)
 	{
 		if (strict)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not open configuration file \"%s\": %m",
 							abs_path)));
+			#else
+			printf(_("could not open configuration file \"%s\"\n"), abs_path);
+			#endif
 			record_config_file_error(psprintf("could not open file \"%s\"",
 											  abs_path),
 									 calling_file, calling_lineno,
@@ -602,9 +259,13 @@ ParseConfigFile(const char *config_file, bool strict,
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(LOG,
 					(errmsg("skipping missing configuration file \"%s\"",
 							abs_path)));
+			#else
+			printf(_("skipping missing configuration file \"%s\"\n"), abs_path);
+			#endif
 		}
 		goto cleanup;
 	}
@@ -613,7 +274,14 @@ ParseConfigFile(const char *config_file, bool strict,
 
 cleanup:
 	if (fp)
+	{
+		#ifndef FRONTEND
 		FreeFile(fp);
+		#else
+		fclose(fp);
+		#endif
+	}
+
 	pfree(abs_path);
 
 	return OK;
@@ -623,7 +291,7 @@ cleanup:
  * Capture an error message in the ConfigVariable list returned by
  * config file parsing.
  */
-static void
+void
 record_config_file_error(const char *errmsg,
 						 const char *config_file,
 						 int lineno,
@@ -715,8 +383,13 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		 * corrupted parser state.  Consequently, abandon the file, but trust
 		 * that the state remains sane enough for yy_delete_buffer().
 		 */
+		#ifndef FRONTEND
 		elog(elevel, "%s at file \"%s\" line %u",
 			 GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#else
+		printf(_("%s at file \"%s\" line %u\n"),
+				GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#endif
 		record_config_file_error(GUC_flex_fatal_errmsg,
 								 config_file, ConfigFileLineno,
 								 head_p, tail_p);
@@ -855,20 +528,30 @@ parse_error:
 		/* report the error */
 		if (token == GUC_EOL || token == 0)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			  errmsg("syntax error in file \"%s\" line %u, near end of line",
 					 config_file, ConfigFileLineno - 1)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near end of line\n"),
+											config_file, ConfigFileLineno - 1);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno - 1,
 									 head_p, tail_p);
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
 					config_file, ConfigFileLineno, yytext)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near token \"%s\"\n"),
+										config_file, ConfigFileLineno, yytext);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno,
 									 head_p, tail_p);
@@ -883,12 +566,21 @@ parse_error:
 		 * as well give up immediately.  (This prevents postmaster children
 		 * from bloating the logs with duplicate complaints.)
 		 */
+		#ifndef FRONTEND
 		if (errorcount >= 100 || elevel <= DEBUG1)
+		#else
+		if (errorcount >= 100)
+		#endif
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 			   errmsg("too many syntax errors found, abandoning file \"%s\"",
 					  config_file)));
+			#else
+			printf(_("too many syntax errors found, abandoning file \"%s\"\n"),
+																config_file);
+			#endif
 			break;
 		}
 
@@ -934,13 +626,21 @@ ParseConfigDirectory(const char *includedir,
 	bool		status;
 
 	directory = AbsoluteConfigLocation(includedir, calling_file);
+	#ifndef FRONTEND
 	d = AllocateDir(directory);
+	#else
+	d = opendir(directory);
+	#endif
 	if (d == NULL)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode_for_file_access(),
 				 errmsg("could not open configuration directory \"%s\": %m",
 						directory)));
+		#else
+		printf(_("could not open configuration directory \"%s\"\n"), directory);
+		#endif
 		record_config_file_error(psprintf("could not open directory \"%s\"",
 										  directory),
 								 calling_file, calling_lineno,
@@ -957,7 +657,11 @@ ParseConfigDirectory(const char *includedir,
 	filenames = (char **) palloc(size_filenames * sizeof(char *));
 	num_filenames = 0;
 
+	#ifndef FRONTEND
 	while ((de = ReadDir(d, directory)) != NULL)
+	#else
+	while ((de = readdir(d)) != NULL)
+	#endif
 	{
 		struct stat st;
 		char		filename[MAXPGPATH];
@@ -998,10 +702,14 @@ ParseConfigDirectory(const char *includedir,
 			 * a file can't be accessed now is if it was removed between the
 			 * directory listing and now.
 			 */
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not stat file \"%s\": %m",
 							filename)));
+			#else
+			printf(_("could not stat file \"%s\"\n"), filename);
+			#endif
 			record_config_file_error(psprintf("could not stat file \"%s\"",
 											  filename),
 									 calling_file, calling_lineno,
@@ -1032,7 +740,13 @@ ParseConfigDirectory(const char *includedir,
 
 cleanup:
 	if (d)
+	{
+		#ifndef FRONTEND
 		FreeDir(d);
+		#else
+		closedir(d);
+		#endif
+	}
 	pfree(directory);
 	return status;
 }
diff --git a/src/include/common/guc-file.h b/src/include/common/guc-file.h
new file mode 100644
index 0000000000..ca969e2aed
--- /dev/null
+++ b/src/include/common/guc-file.h
@@ -0,0 +1,50 @@
+#ifndef GUC_FILE_H
+#define GUC_FILE_H
+
+#include "c.h"
+
+/*
+ * Parsing the configuration file(s) will return a list of name-value pairs
+ * with source location info.  We also abuse this data structure to carry
+ * error reports about the config files.  An entry reporting an error will
+ * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
+ *
+ * If "ignore" is true, don't attempt to apply the item (it might be an error
+ * report, or an item we determined to be duplicate).  "applied" is set true
+ * if we successfully applied, or could have applied, the setting.
+ */
+typedef struct ConfigVariable
+{
+	char	   *name;
+	char	   *value;
+	char	   *errmsg;
+	char	   *filename;
+	int			sourceline;
+	bool		ignore;
+	bool		applied;
+	struct ConfigVariable *next;
+} ConfigVariable;
+
+extern bool ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigFp(FILE *fp, const char *config_file,
+			  int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p);
+extern void FreeConfigVariables(ConfigVariable *list);
+
+extern int	guc_name_compare(const char *namea, const char *nameb);
+
+extern void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+#endif							/* GUC_FILE_H */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 64457c792a..fe37adbf87 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -1,8 +1,7 @@
 /*--------------------------------------------------------------------
  * guc.h
  *
- * External declarations pertaining to backend/utils/misc/guc.c and
- * backend/utils/misc/guc-file.l
+ * External declarations pertaining to backend/utils/misc/guc.c
  *
  * Copyright (c) 2000-2018, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -120,42 +119,6 @@ typedef enum
 	PGC_S_SESSION				/* SET command */
 } GucSource;
 
-/*
- * Parsing the configuration file(s) will return a list of name-value pairs
- * with source location info.  We also abuse this data structure to carry
- * error reports about the config files.  An entry reporting an error will
- * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
- *
- * If "ignore" is true, don't attempt to apply the item (it might be an error
- * report, or an item we determined to be duplicate).  "applied" is set true
- * if we successfully applied, or could have applied, the setting.
- */
-typedef struct ConfigVariable
-{
-	char	   *name;
-	char	   *value;
-	char	   *errmsg;
-	char	   *filename;
-	int			sourceline;
-	bool		ignore;
-	bool		applied;
-	struct ConfigVariable *next;
-} ConfigVariable;
-
-extern bool ParseConfigFile(const char *config_file, bool strict,
-				const char *calling_file, int calling_lineno,
-				int depth, int elevel,
-				ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigFp(FILE *fp, const char *config_file,
-			  int depth, int elevel,
-			  ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigDirectory(const char *includedir,
-					 const char *calling_file, int calling_lineno,
-					 int depth, int elevel,
-					 ConfigVariable **head_p,
-					 ConfigVariable **tail_p);
-extern void FreeConfigVariables(ConfigVariable *list);
-
 /*
  * The possible values of an enum variable are specified by an array of
  * name-value pairs.  The "hidden" flag means the value is accepted but
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 2921d193a1..f9ebb63a9c 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -172,7 +172,7 @@ sub mkvcbuild
 	$postgres->AddFiles('src/backend/parser', 'scan.l', 'gram.y');
 	$postgres->AddFiles('src/backend/bootstrap', 'bootscanner.l',
 		'bootparse.y');
-	$postgres->AddFiles('src/backend/utils/misc', 'guc-file.l');
+	$postgres->AddFiles('src/common', 'guc-file.l');
 	$postgres->AddFiles(
 		'src/backend/replication', 'repl_scanner.l',
 		'repl_gram.y',             'syncrep_scanner.l',
diff --git a/src/tools/msvc/clean.bat b/src/tools/msvc/clean.bat
index 7a23a2b55f..f1adb56c96 100755
--- a/src/tools/msvc/clean.bat
+++ b/src/tools/msvc/clean.bat
@@ -75,7 +75,7 @@ if %DIST%==1 if exist src\backend\parser\scan.c del /q src\backend\parser\scan.c
 if %DIST%==1 if exist src\backend\parser\gram.c del /q src\backend\parser\gram.c
 if %DIST%==1 if exist src\backend\bootstrap\bootscanner.c del /q src\backend\bootstrap\bootscanner.c
 if %DIST%==1 if exist src\backend\bootstrap\bootparse.c del /q src\backend\bootstrap\bootparse.c
-if %DIST%==1 if exist src\backend\utils\misc\guc-file.c del /q src\backend\utils\misc\guc-file.c
+if %DIST%==1 if exist src\common\guc-file.c del /q src\common\guc-file.c
 if %DIST%==1 if exist src\backend\replication\repl_scanner.c del /q src\backend\replication\repl_scanner.c
 if %DIST%==1 if exist src\backend\replication\repl_gram.c del /q src\backend\replication\repl_gram.c
 if %DIST%==1 if exist src\backend\replication\syncrep_scanner.c del /q src\backend\replication\syncrep_scanner.c
-- 
2.17.1

From cc64d7943e220ba6434b76db63a579ccb547517a Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <alex.lumir@gmail.com>
Date: Fri, 21 Dec 2018 14:00:30 +0300
Subject: [PATCH] pg_rewind: options to use restore_command from
 postgresql.conf or command line.

---
 doc/src/sgml/ref/pg_rewind.sgml               |  30 +-
 src/backend/Makefile                          |   4 +-
 src/backend/commands/extension.c              |   1 +
 src/backend/utils/misc/Makefile               |   8 -
 src/backend/utils/misc/guc.c                  | 434 +++++++++++++--
 src/bin/pg_rewind/Makefile                    |   2 +-
 src/bin/pg_rewind/RewindTest.pm               |  96 +++-
 src/bin/pg_rewind/parsexlog.c                 | 180 +++++-
 src/bin/pg_rewind/pg_rewind.c                 | 100 +++-
 src/bin/pg_rewind/pg_rewind.h                 |  12 +-
 src/bin/pg_rewind/t/001_basic.pl              |   4 +-
 src/bin/pg_rewind/t/002_databases.pl          |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl         |   4 +-
 src/common/Makefile                           |   9 +-
 src/{backend/utils/misc => common}/guc-file.l | 514 ++++--------------
 src/include/common/guc-file.h                 |  50 ++
 src/include/utils/guc.h                       |  39 +-
 src/tools/msvc/Mkvcbuild.pm                   |   2 +-
 src/tools/msvc/clean.bat                      |   2 +-
 19 files changed, 987 insertions(+), 508 deletions(-)
 rename src/{backend/utils/misc => common}/guc-file.l (60%)
 create mode 100644 src/include/common/guc-file.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 53a64ee29e..34046d6404 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> options are specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -200,6 +202,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retreive missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/backend/Makefile b/src/backend/Makefile
index 478a96db9b..721cb57e89 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -186,7 +186,7 @@ distprep:
 	$(MAKE) -C replication	repl_gram.c repl_scanner.c syncrep_gram.c syncrep_scanner.c
 	$(MAKE) -C storage/lmgr	lwlocknames.h lwlocknames.c
 	$(MAKE) -C utils	distprep
-	$(MAKE) -C utils/misc	guc-file.c
+	$(MAKE) -C common	guc-file.c
 	$(MAKE) -C utils/sort	qsort_tuple.c
 
 
@@ -307,7 +307,7 @@ maintainer-clean: distclean
 	      replication/syncrep_scanner.c \
 	      storage/lmgr/lwlocknames.c \
 	      storage/lmgr/lwlocknames.h \
-	      utils/misc/guc-file.c \
+	      common/guc-file.c \
 	      utils/sort/qsort_tuple.c
 
 
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index 4fe71196c4..b64dece236 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -49,6 +49,7 @@
 #include "commands/defrem.h"
 #include "commands/extension.h"
 #include "commands/schemacmds.h"
+#include "common/guc-file.h"
 #include "funcapi.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
diff --git a/src/backend/utils/misc/Makefile b/src/backend/utils/misc/Makefile
index ec7ec131e5..2205956a9f 100644
--- a/src/backend/utils/misc/Makefile
+++ b/src/backend/utils/misc/Makefile
@@ -25,11 +25,3 @@ override CPPFLAGS += -DPG_KRB_SRVTAB='"$(krb_srvtab)"'
 endif
 
 include $(top_srcdir)/src/backend/common.mk
-
-# guc-file is compiled as part of guc
-guc.o: guc-file.c
-
-# Note: guc-file.c is not deleted by 'make clean',
-# since we want to ship it in distribution tarballs.
-clean:
-	@rm -f lex.yy.c
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index c216ed0922..c52d1bc7e5 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -41,6 +41,7 @@
 #include "commands/vacuum.h"
 #include "commands/variable.h"
 #include "commands/trigger.h"
+#include "common/guc-file.h"
 #include "common/string.h"
 #include "funcapi.h"
 #include "jit/jit.h"
@@ -211,7 +212,6 @@ static void assign_recovery_target_lsn(const char *newval, void *extra);
 static bool check_primary_slot_name(char **newval, void **extra, GucSource source);
 static bool check_default_with_oids(bool *newval, void **extra, GucSource source);
 
-/* Private functions in guc-file.l that need to be called from guc.c */
 static ConfigVariable *ProcessConfigFileInternal(GucContext context,
 						  bool applySettings, int elevel);
 
@@ -4467,7 +4467,6 @@ static int	GUCNestLevel = 0;	/* 1 when in main transaction */
 
 
 static int	guc_var_compare(const void *a, const void *b);
-static int	guc_name_compare(const char *namea, const char *nameb);
 static void InitializeGUCOptionsFromEnvironment(void);
 static void InitializeOneGUCOption(struct config_generic *gconf);
 static void push_old_value(struct config_generic *gconf, GucAction action);
@@ -4944,37 +4943,6 @@ guc_var_compare(const void *a, const void *b)
 	return guc_name_compare(confa->name, confb->name);
 }
 
-/*
- * the bare comparison function for GUC names
- */
-static int
-guc_name_compare(const char *namea, const char *nameb)
-{
-	/*
-	 * The temptation to use strcasecmp() here must be resisted, because the
-	 * array ordering has to remain stable across setlocale() calls. So, build
-	 * our own with a simple ASCII-only downcasing.
-	 */
-	while (*namea && *nameb)
-	{
-		char		cha = *namea++;
-		char		chb = *nameb++;
-
-		if (cha >= 'A' && cha <= 'Z')
-			cha += 'a' - 'A';
-		if (chb >= 'A' && chb <= 'Z')
-			chb += 'a' - 'A';
-		if (cha != chb)
-			return cha - chb;
-	}
-	if (*namea)
-		return 1;				/* a is longer */
-	if (*nameb)
-		return -1;				/* b is longer */
-	return 0;
-}
-
-
 /*
  * Initialize GUC options during program startup.
  *
@@ -11348,4 +11316,402 @@ check_default_with_oids(bool *newval, void **extra, GucSource source)
 	return true;
 }
 
-#include "guc-file.c"
+/*
+ * Exported function to read and process the configuration file. The
+ * parameter indicates in what context the file is being read --- either
+ * postmaster startup (including standalone-backend startup) or SIGHUP.
+ * All options mentioned in the configuration file are set to new values.
+ * If a hard error occurs, no values will be changed.  (There can also be
+ * errors that prevent just one value from being changed.)
+ */
+void
+ProcessConfigFile(GucContext context)
+{
+	int			elevel;
+	MemoryContext config_cxt;
+	MemoryContext caller_cxt;
+
+	/*
+	 * Config files are processed on startup (by the postmaster only) and on
+	 * SIGHUP (by the postmaster and its children)
+	 */
+	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
+		   context == PGC_SIGHUP);
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+
+	/*
+	 * This function is usually called within a process-lifespan memory
+	 * context.  To ensure that any memory leaked during GUC processing does
+	 * not accumulate across repeated SIGHUP cycles, do the work in a private
+	 * context that we can free at exit.
+	 */
+	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
+									   "config file processing",
+									   ALLOCSET_DEFAULT_SIZES);
+	caller_cxt = MemoryContextSwitchTo(config_cxt);
+
+	/*
+	 * Read and apply the config file.  We don't need to examine the result.
+	 */
+	(void) ProcessConfigFileInternal(context, true, elevel);
+
+	/* Clean up */
+	MemoryContextSwitchTo(caller_cxt);
+	MemoryContextDelete(config_cxt);
+}
+
+/*
+ * This function handles both actual config file (re)loads and execution of
+ * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
+ * case we don't apply any of the settings, but we make all the usual validity
+ * checks, and we return the ConfigVariable list so that it can be printed out
+ * by show_all_file_settings().
+ */
+static ConfigVariable *
+ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+{
+	bool		error = false;
+	bool		applying = false;
+	const char *ConfFileWithError;
+	ConfigVariable *item,
+			   *head,
+			   *tail;
+	int			i;
+
+	/* Parse the main config file into a list of option names and values */
+	ConfFileWithError = ConfigFileName;
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, true,
+						 NULL, 0, 0, elevel,
+						 &head, &tail))
+	{
+		/* Syntax error(s) detected in the file, so bail out */
+		error = true;
+		goto bail_out;
+	}
+
+	/*
+	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
+	 * replace any parameters set by ALTER SYSTEM command.  Because this file
+	 * is in the data directory, we can't read it until the DataDir has been
+	 * set.
+	 */
+	if (DataDir)
+	{
+		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
+							 NULL, 0, 0, elevel,
+							 &head, &tail))
+		{
+			/* Syntax error(s) detected in the file, so bail out */
+			error = true;
+			ConfFileWithError = PG_AUTOCONF_FILENAME;
+			goto bail_out;
+		}
+	}
+	else
+	{
+		/*
+		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
+		 * read.  In this case, we don't want to accept any settings but
+		 * data_directory from postgresql.conf, because they might be
+		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
+		 * will be read later. OTOH, since data_directory isn't allowed in the
+		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
+		 */
+		ConfigVariable *newlist = NULL;
+
+		/*
+		 * Prune all items except the last "data_directory" from the list.
+		 */
+		for (item = head; item; item = item->next)
+		{
+			if (!item->ignore &&
+				strcmp(item->name, "data_directory") == 0)
+				newlist = item;
+		}
+
+		if (newlist)
+			newlist->next = NULL;
+		head = tail = newlist;
+
+		/*
+		 * Quick exit if data_directory is not present in file.
+		 *
+		 * We need not do any further processing, in particular we don't set
+		 * PgReloadTime; that will be set soon by subsequent full loading of
+		 * the config file.
+		 */
+		if (head == NULL)
+			goto bail_out;
+	}
+
+	/*
+	 * Mark all extant GUC variables as not present in the config file. We
+	 * need this so that we can tell below which ones have been removed from
+	 * the file since we last processed it.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		gconf->status &= ~GUC_IS_IN_FILE;
+	}
+
+	/*
+	 * Check if all the supplied option names are valid, as an additional
+	 * quasi-syntactic check on the validity of the config file.  It is
+	 * important that the postmaster and all backends agree on the results of
+	 * this phase, else we will have strange inconsistencies about which
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
+	 *
+	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
+	 * variable mentioned in the file; and we detect duplicate entries in the
+	 * file and mark the earlier occurrences as ignorable.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		struct config_generic *record;
+
+		/* Ignore anything already marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/*
+		 * Try to find the variable; but do not create a custom placeholder if
+		 * it's not there already.
+		 */
+		record = find_option(item->name, false, elevel);
+
+		if (record)
+		{
+			/* If it's already marked, then this is a duplicate entry */
+			if (record->status & GUC_IS_IN_FILE)
+			{
+				/*
+				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
+				 * avoid the O(N^2) behavior here with some additional state,
+				 * but it seems unlikely to be worth the trouble.
+				 */
+				ConfigVariable *pitem;
+
+				for (pitem = head; pitem != item; pitem = pitem->next)
+				{
+					if (!pitem->ignore &&
+						strcmp(pitem->name, item->name) == 0)
+						pitem->ignore = true;
+				}
+			}
+			/* Now mark it as present in file */
+			record->status |= GUC_IS_IN_FILE;
+		}
+		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
+		{
+			/* Invalid non-custom variable, so complain */
+			ereport(elevel,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
+							item->name,
+							item->filename, item->sourceline)));
+			item->errmsg = pstrdup("unrecognized configuration parameter");
+			error = true;
+			ConfFileWithError = item->filename;
+		}
+	}
+
+	/*
+	 * If we've detected any errors so far, we don't want to risk applying any
+	 * changes.
+	 */
+	if (error)
+		goto bail_out;
+
+	/* Otherwise, set flag that we're beginning to apply changes */
+	applying = true;
+
+	/*
+	 * Check for variables having been removed from the config file, and
+	 * revert their reset values (and perhaps also effective values) to the
+	 * boot-time defaults.  If such a variable can't be changed after startup,
+	 * report that and continue.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		if (gconf->reset_source != PGC_S_FILE ||
+			(gconf->status & GUC_IS_IN_FILE))
+			continue;
+		if (gconf->context < PGC_SIGHUP)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+							gconf->name)));
+			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
+											  gconf->name),
+									 NULL, 0,
+									 &head, &tail);
+			error = true;
+			continue;
+		}
+
+		/* No more to do if we're just doing show_all_file_settings() */
+		if (!applySettings)
+			continue;
+
+		/*
+		 * Reset any "file" sources to "default", else set_config_option will
+		 * not override those settings.
+		 */
+		if (gconf->reset_source == PGC_S_FILE)
+			gconf->reset_source = PGC_S_DEFAULT;
+		if (gconf->source == PGC_S_FILE)
+			gconf->source = PGC_S_DEFAULT;
+		for (stack = gconf->stack; stack; stack = stack->prev)
+		{
+			if (stack->source == PGC_S_FILE)
+				stack->source = PGC_S_DEFAULT;
+		}
+
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
+		if (set_config_option(gconf->name, NULL,
+							  context, PGC_S_DEFAULT,
+							  GUC_ACTION_SET, true, 0, false) > 0)
+		{
+			/* Log the change if appropriate */
+			if (context == PGC_SIGHUP)
+				ereport(elevel,
+						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
+								gconf->name)));
+		}
+	}
+
+	/*
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
+	 *
+	 * In particular, we *must not* do this during the postmaster's initial
+	 * loading of the file, since the timezone functions in particular should
+	 * be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how to set
+	 * (or at least what to call to set) every variable that could potentially
+	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
+	 * time to redesign it for 9.1.
+	 */
+	if (context == PGC_SIGHUP && applySettings)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
+
+	/*
+	 * Now apply the values from the config file.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		char	   *pre_value = NULL;
+		int			scres;
+
+		/* Ignore anything marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/* In SIGHUP cases in the postmaster, we want to report changes */
+		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
+		{
+			const char *preval = GetConfigOption(item->name, true, false);
+
+			/* If option doesn't exist yet or is NULL, treat as empty string */
+			if (!preval)
+				preval = "";
+			/* must dup, else might have dangling pointer below */
+			pre_value = pstrdup(preval);
+		}
+
+		scres = set_config_option(item->name, item->value,
+								  context, PGC_S_FILE,
+								  GUC_ACTION_SET, applySettings, 0, false);
+		if (scres > 0)
+		{
+			/* variable was updated, so log the change if appropriate */
+			if (pre_value)
+			{
+				const char *post_value = GetConfigOption(item->name, true, false);
+
+				if (!post_value)
+					post_value = "";
+				if (strcmp(pre_value, post_value) != 0)
+					ereport(elevel,
+							(errmsg("parameter \"%s\" changed to \"%s\"",
+									item->name, item->value)));
+			}
+			item->applied = true;
+		}
+		else if (scres == 0)
+		{
+			error = true;
+			item->errmsg = pstrdup("setting could not be applied");
+			ConfFileWithError = item->filename;
+		}
+		else
+		{
+			/* no error, but variable's active value was not changed */
+			item->applied = true;
+		}
+
+		/*
+		 * We should update source location unless there was an error, since
+		 * even if the active value didn't change, the reset value might have.
+		 * (In the postmaster, there won't be a difference, but it does matter
+		 * in backends.)
+		 */
+		if (scres != 0 && applySettings)
+			set_config_sourcefile(item->name, item->filename,
+								  item->sourceline);
+
+		if (pre_value)
+			pfree(pre_value);
+	}
+
+	/* Remember when we last successfully loaded the config file. */
+	if (applySettings)
+		PgReloadTime = GetCurrentTimestamp();
+
+bail_out:
+	if (error && applySettings)
+	{
+		/* During postmaster startup, any error is fatal */
+		if (context == PGC_POSTMASTER)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors",
+							ConfFileWithError)));
+		else if (applying)
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
+							ConfFileWithError)));
+		else
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
+							ConfFileWithError)));
+	}
+
+	/* Successful or otherwise, return the collected data list */
+	return head;
+}
diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
index 04f3b8f520..65ebf3c78c 100644
--- a/src/bin/pg_rewind/Makefile
+++ b/src/bin/pg_rewind/Makefile
@@ -15,7 +15,7 @@ subdir = src/bin/pg_rewind
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
+override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
diff --git a/src/bin/pg_rewind/RewindTest.pm b/src/bin/pg_rewind/RewindTest.pm
index 85cae7e47b..b07ca3617f 100644
--- a/src/bin/pg_rewind/RewindTest.pm
+++ b/src/bin/pg_rewind/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catpath catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -249,6 +251,98 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		print "Using restore_command=$restore_command\n";
+		print "Conf path $master_conf_path\n";
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index e19c265cbb..537d50e231 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,7 +46,10 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
+	XLogRecPtr  oldrecptr;
+	TimeLineID  oldtli;
 } XLogPageReadPrivate;
 
 static int SimpleXLogPageRead(XLogReaderState *xlogreader,
@@ -53,6 +57,10 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static bool RestoreArchivedWAL(const char *path, const char *xlogfname,
+					off_t expectedSize, const char *restoreCommand,
+					const char *lastRestartPointFname);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,15 +68,19 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   ControlFileData *targetCF, const char *restore_command)
 {
 	XLogRecord *record;
+	XLogRecPtr endpoint = targetCF->checkPoint;
 	XLogReaderState *xlogreader;
 	char	   *errormsg;
 	XLogPageReadPrivate private;
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -154,9 +166,9 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
  * Find the previous checkpoint preceding given WAL location.
  */
 void
-findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
+findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +193,9 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
+	private.oldrecptr = targetCF->checkPointCopy.redo;
+	private.oldtli = targetCF->checkPointCopy.ThisTimeLineID;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +306,53 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+			bool  restore_ok;
+			char  lastRestartPointFname[MAXFNAMELEN];
+			XLogSegNo restartSegNo;
+
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
 				   strerror(errno));
-			return -1;
+				return -1;
+			}
+
+			XLByteToSeg(private->oldrecptr, restartSegNo, WalSegSz);
+			XLogFileName(lastRestartPointFname, private->oldtli, restartSegNo,
+						 WalSegSz);
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			restore_ok = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand,
+											lastRestartPointFname);
+
+			if (restore_ok)
+			{
+				xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogreadfd < 0)
+				{
+					printf(_("could not open restored from archive file \"%s\": %s\n"), xlogfpath,
+							strerror(errno));
+					return -1;
+				}
+				else
+					pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n", xlogfpath);
+			}
+			else
+			{
+				printf(_("could not restore file \"%s\" from archive: %s\n"), xlogfname,
+					   strerror(errno));
+				return -1;
+			}
 		}
 	}
 
@@ -409,3 +468,114 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return true.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ *
+ * This is a simplified and adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+bool
+RestoreArchivedWAL(const char *path, const char *xlogfname, off_t expectedSize,
+				   const char *restoreCommand, const char *lastRestartPointFname)
+{
+	char		xlogpath[MAXPGPATH];
+	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *dp;
+	char	   *endp;
+	const char *sp;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used during rewind process.\n");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize,
+						strerror(errno));
+			}
+			else
+				return true;
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath,
+					strerror(errno));
+		}
+	}
+
+	return false;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 7ccde5c87f..abe593a588 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -24,8 +24,10 @@
 #include "access/xlog_internal.h"
 #include "catalog/catversion.h"
 #include "catalog/pg_control.h"
+#include "common/controldata_utils.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"
+#include "common/guc-file.h"
 #include "common/restricted_token.h"
 #include "getopt_long.h"
 #include "storage/bufpage.h"
@@ -52,11 +54,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +79,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,9 +101,12 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
+	char		recfile_fullpath[MAXPGPATH];
 	int			option_index;
 	int			c;
 	XLogRecPtr	divergerec;
@@ -129,7 +139,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +151,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +171,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +241,80 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			fprintf(stderr, _("%s: redundant options: both -r and -R are specified\n"),
+				progname);
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf or -R/--restore-command.\n"),
+				progname);
+			exit(1);
+		}
+
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		FILE	*conf_file;
+
+		/*
+		 * Look for configuration file in the target data directory and
+		 * try to get restore_command from there.
+		 */
+		snprintf(recfile_fullpath, sizeof(recfile_fullpath), "%s/%s", datadir_target, RESTORE_COMMAND_FILE);
+		conf_file = fopen(recfile_fullpath, "r");
+
+		if (conf_file == NULL)
+		{
+			fprintf(stderr, _("%s: option -r/--use-postgresql-conf is specified, but postgreslq.conf is absent in the target directory\n"),
+					progname);
+			fprintf(stderr, _("You have to add postgresql.conf or pass restore_command with -R/--restore-command option.\n"));
+			exit(1);
+		}
+		else
+		{
+			ConfigVariable *item,
+						   *head = NULL,
+						   *tail = NULL;
+			bool			config_is_parsed;
+
+			/*
+			 * We pass a fullpath to the configuration file as calling_file here, since
+			 * parser will use its parent directory as base for all further includes
+			 * if any exist.
+			 */
+			config_is_parsed = ParseConfigFile(RESTORE_COMMAND_FILE, true,
+											   recfile_fullpath, 0, 0,
+											   PG_WARNING, &head, &tail);
+			fclose(conf_file);
+
+			if (config_is_parsed)
+			{
+				for (item = head; item; item = item->next)
+				{
+					if (strcmp(item->name, "restore_command") == 0)
+					{
+						if (restore_command != NULL)
+						{
+							pfree(restore_command);
+							restore_command = NULL;
+						}
+						restore_command = pstrdup(item->value);
+						pg_log(PG_DEBUG, "using restore_command=\'%s\' from %s.\n", restore_command, RESTORE_COMMAND_FILE);
+					}
+				}
+
+				if (restore_command == NULL)
+					pg_fatal("could not find restore_command in %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+			}
+			else
+				pg_fatal("could not parse %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+
+			FreeConfigVariables(head);
+		}
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +386,9 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
+	findLastCheckpoint(datadir_target, &ControlFile_target, divergerec,
 					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +411,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   &ControlFile_target, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 83b2898b8b..5dc6f5b1ba 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -14,9 +14,12 @@
 #include "datapagemap.h"
 
 #include "access/timeline.h"
+#include "catalog/pg_control.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
 
+#define RESTORE_COMMAND_FILE "postgresql.conf"
+
 /* Configuration options */
 extern char *datadir_target;
 extern char *datadir_source;
@@ -32,11 +35,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
-extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+			   int tliIndex, ControlFileData *targetCF, const char *restoreCommand);
+extern void findLastCheckpoint(const char *datadir, ControlFileData *targetCF, XLogRecPtr searchptr,
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 53dbf45be2..1860ce2fe3 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use RewindTest;
 
@@ -103,5 +103,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 2c9e427831..42d708dfbd 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use RewindTest;
 
@@ -59,5 +59,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index 496f38c457..96665ac2f4 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -87,5 +87,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/common/Makefile b/src/common/Makefile
index d0c2b970eb..3d7da47f56 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -48,7 +48,7 @@ OBJS_COMMON = base64.o config_info.o controldata_utils.o exec.o file_perm.o \
 	ip.o keywords.o kwlookup.o link-canary.o md5.o pg_lzcompress.o \
 	pgfnames.o psprintf.o relpath.o \
 	rmtree.o saslprep.o scram-common.o string.o unicode_norm.o \
-	username.o wait_error.o
+	username.o wait_error.o guc-file.o
 
 ifeq ($(with_openssl),yes)
 OBJS_COMMON += sha2_openssl.o
@@ -70,7 +70,7 @@ GEN_KEYWORDLIST_DEPS = $(TOOLSDIR)/gen_keywordlist.pl $(TOOLSDIR)/PerfectHash.pm
 
 all: libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 
-distprep: kwlist_d.h
+distprep: kwlist_d.h guc-file.c
 
 # libpgcommon is needed by some contrib
 install: all installdirs
@@ -130,10 +130,13 @@ kwlist_d.h: $(top_srcdir)/src/include/parser/kwlist.h $(GEN_KEYWORDLIST_DEPS)
 # that you don't get broken parsing code, even in a non-enable-depend build.
 keywords.o keywords_shlib.o keywords_srv.o: kwlist_d.h
 
-# kwlist_d.h is in the distribution tarball, so it is not cleaned here.
+# Note: guc-file.c and kwlist_d.h are not deleted by 'make clean',
+# since we want to ship them in distribution tarballs.
 clean distclean:
 	rm -f libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 	rm -f $(OBJS_FRONTEND) $(OBJS_SHLIB) $(OBJS_SRV)
+	@rm -f lex.yy.c
 
 maintainer-clean: distclean
 	rm -f kwlist_d.h
+	rm -f guc-file.c
diff --git a/src/backend/utils/misc/guc-file.l b/src/common/guc-file.l
similarity index 60%
rename from src/backend/utils/misc/guc-file.l
rename to src/common/guc-file.l
index 1c8b5f7d84..4117a1dcbc 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/common/guc-file.l
@@ -4,21 +4,33 @@
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/backend/utils/misc/guc-file.l
+ * src/common/guc-file.l
  */
 
 %{
 
-#include "postgres.h"
-
 #include <ctype.h>
 #include <unistd.h>
+#include <sys/stat.h>
+
+#ifndef FRONTEND
+#include "postgres.h"
 
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "utils/guc.h"
+#include "utils/elog.h"
+#else
+#include <dirent.h>
+#include <setjmp.h>
+
+#include "postgres_fe.h"
 
+#include "common/fe_memutils.h"
+#endif
+
+#include "common/guc-file.h"
 
 /*
  * flex emits a yy_fatal_error() function that it calls in response to
@@ -48,12 +60,6 @@ static sigjmp_buf *GUC_flex_fatal_jmp;
 
 static void FreeConfigVariable(ConfigVariable *item);
 
-static void record_config_file_error(const char *errmsg,
-						 const char *config_file,
-						 int lineno,
-						 ConfigVariable **head_p,
-						 ConfigVariable **tail_p);
-
 static int	GUC_flex_fatal(const char *msg);
 static char *GUC_scanstr(const char *s);
 
@@ -111,404 +117,35 @@ STRING			\'([^'\\\n]|\\.|\'\')*\'
 
 /* LCOV_EXCL_STOP */
 
-/*
- * Exported function to read and process the configuration file. The
- * parameter indicates in what context the file is being read --- either
- * postmaster startup (including standalone-backend startup) or SIGHUP.
- * All options mentioned in the configuration file are set to new values.
- * If a hard error occurs, no values will be changed.  (There can also be
- * errors that prevent just one value from being changed.)
- */
-void
-ProcessConfigFile(GucContext context)
-{
-	int			elevel;
-	MemoryContext config_cxt;
-	MemoryContext caller_cxt;
-
-	/*
-	 * Config files are processed on startup (by the postmaster only) and on
-	 * SIGHUP (by the postmaster and its children)
-	 */
-	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
-		   context == PGC_SIGHUP);
-
-	/*
-	 * To avoid cluttering the log, only the postmaster bleats loudly about
-	 * problems with the config file.
-	 */
-	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
-
-	/*
-	 * This function is usually called within a process-lifespan memory
-	 * context.  To ensure that any memory leaked during GUC processing does
-	 * not accumulate across repeated SIGHUP cycles, do the work in a private
-	 * context that we can free at exit.
-	 */
-	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
-									   "config file processing",
-									   ALLOCSET_DEFAULT_SIZES);
-	caller_cxt = MemoryContextSwitchTo(config_cxt);
-
-	/*
-	 * Read and apply the config file.  We don't need to examine the result.
-	 */
-	(void) ProcessConfigFileInternal(context, true, elevel);
-
-	/* Clean up */
-	MemoryContextSwitchTo(caller_cxt);
-	MemoryContextDelete(config_cxt);
-}
 
 /*
- * This function handles both actual config file (re)loads and execution of
- * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
- * case we don't apply any of the settings, but we make all the usual validity
- * checks, and we return the ConfigVariable list so that it can be printed out
- * by show_all_file_settings().
+ * The bare comparison function for GUC names.
  */
-static ConfigVariable *
-ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+int
+guc_name_compare(const char *namea, const char *nameb)
 {
-	bool		error = false;
-	bool		applying = false;
-	const char *ConfFileWithError;
-	ConfigVariable *item,
-			   *head,
-			   *tail;
-	int			i;
-
-	/* Parse the main config file into a list of option names and values */
-	ConfFileWithError = ConfigFileName;
-	head = tail = NULL;
-
-	if (!ParseConfigFile(ConfigFileName, true,
-						 NULL, 0, 0, elevel,
-						 &head, &tail))
-	{
-		/* Syntax error(s) detected in the file, so bail out */
-		error = true;
-		goto bail_out;
-	}
-
-	/*
-	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
-	 * replace any parameters set by ALTER SYSTEM command.  Because this file
-	 * is in the data directory, we can't read it until the DataDir has been
-	 * set.
-	 */
-	if (DataDir)
-	{
-		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
-							 NULL, 0, 0, elevel,
-							 &head, &tail))
-		{
-			/* Syntax error(s) detected in the file, so bail out */
-			error = true;
-			ConfFileWithError = PG_AUTOCONF_FILENAME;
-			goto bail_out;
-		}
-	}
-	else
-	{
-		/*
-		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
-		 * read.  In this case, we don't want to accept any settings but
-		 * data_directory from postgresql.conf, because they might be
-		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
-		 * will be read later. OTOH, since data_directory isn't allowed in the
-		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
-		 */
-		ConfigVariable *newlist = NULL;
-
-		/*
-		 * Prune all items except the last "data_directory" from the list.
-		 */
-		for (item = head; item; item = item->next)
-		{
-			if (!item->ignore &&
-				strcmp(item->name, "data_directory") == 0)
-				newlist = item;
-		}
-
-		if (newlist)
-			newlist->next = NULL;
-		head = tail = newlist;
-
-		/*
-		 * Quick exit if data_directory is not present in file.
-		 *
-		 * We need not do any further processing, in particular we don't set
-		 * PgReloadTime; that will be set soon by subsequent full loading of
-		 * the config file.
-		 */
-		if (head == NULL)
-			goto bail_out;
-	}
-
 	/*
-	 * Mark all extant GUC variables as not present in the config file. We
-	 * need this so that we can tell below which ones have been removed from
-	 * the file since we last processed it.
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
 	 */
-	for (i = 0; i < num_guc_variables; i++)
+	while (*namea && *nameb)
 	{
-		struct config_generic *gconf = guc_variables[i];
-
-		gconf->status &= ~GUC_IS_IN_FILE;
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
 	}
-
-	/*
-	 * Check if all the supplied option names are valid, as an additional
-	 * quasi-syntactic check on the validity of the config file.  It is
-	 * important that the postmaster and all backends agree on the results of
-	 * this phase, else we will have strange inconsistencies about which
-	 * processes accept a config file update and which don't.  Hence, unknown
-	 * custom variable names have to be accepted without complaint.  For the
-	 * same reason, we don't attempt to validate the options' values here.
-	 *
-	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
-	 * variable mentioned in the file; and we detect duplicate entries in the
-	 * file and mark the earlier occurrences as ignorable.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		struct config_generic *record;
-
-		/* Ignore anything already marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/*
-		 * Try to find the variable; but do not create a custom placeholder if
-		 * it's not there already.
-		 */
-		record = find_option(item->name, false, elevel);
-
-		if (record)
-		{
-			/* If it's already marked, then this is a duplicate entry */
-			if (record->status & GUC_IS_IN_FILE)
-			{
-				/*
-				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
-				 * avoid the O(N^2) behavior here with some additional state,
-				 * but it seems unlikely to be worth the trouble.
-				 */
-				ConfigVariable *pitem;
-
-				for (pitem = head; pitem != item; pitem = pitem->next)
-				{
-					if (!pitem->ignore &&
-						strcmp(pitem->name, item->name) == 0)
-						pitem->ignore = true;
-				}
-			}
-			/* Now mark it as present in file */
-			record->status |= GUC_IS_IN_FILE;
-		}
-		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
-		{
-			/* Invalid non-custom variable, so complain */
-			ereport(elevel,
-					(errcode(ERRCODE_UNDEFINED_OBJECT),
-					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
-							item->name,
-							item->filename, item->sourceline)));
-			item->errmsg = pstrdup("unrecognized configuration parameter");
-			error = true;
-			ConfFileWithError = item->filename;
-		}
-	}
-
-	/*
-	 * If we've detected any errors so far, we don't want to risk applying any
-	 * changes.
-	 */
-	if (error)
-		goto bail_out;
-
-	/* Otherwise, set flag that we're beginning to apply changes */
-	applying = true;
-
-	/*
-	 * Check for variables having been removed from the config file, and
-	 * revert their reset values (and perhaps also effective values) to the
-	 * boot-time defaults.  If such a variable can't be changed after startup,
-	 * report that and continue.
-	 */
-	for (i = 0; i < num_guc_variables; i++)
-	{
-		struct config_generic *gconf = guc_variables[i];
-		GucStack   *stack;
-
-		if (gconf->reset_source != PGC_S_FILE ||
-			(gconf->status & GUC_IS_IN_FILE))
-			continue;
-		if (gconf->context < PGC_SIGHUP)
-		{
-			ereport(elevel,
-					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
-							gconf->name)));
-			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
-											  gconf->name),
-									 NULL, 0,
-									 &head, &tail);
-			error = true;
-			continue;
-		}
-
-		/* No more to do if we're just doing show_all_file_settings() */
-		if (!applySettings)
-			continue;
-
-		/*
-		 * Reset any "file" sources to "default", else set_config_option will
-		 * not override those settings.
-		 */
-		if (gconf->reset_source == PGC_S_FILE)
-			gconf->reset_source = PGC_S_DEFAULT;
-		if (gconf->source == PGC_S_FILE)
-			gconf->source = PGC_S_DEFAULT;
-		for (stack = gconf->stack; stack; stack = stack->prev)
-		{
-			if (stack->source == PGC_S_FILE)
-				stack->source = PGC_S_DEFAULT;
-		}
-
-		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
-		if (set_config_option(gconf->name, NULL,
-							  context, PGC_S_DEFAULT,
-							  GUC_ACTION_SET, true, 0, false) > 0)
-		{
-			/* Log the change if appropriate */
-			if (context == PGC_SIGHUP)
-				ereport(elevel,
-						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
-								gconf->name)));
-		}
-	}
-
-	/*
-	 * Restore any variables determined by environment variables or
-	 * dynamically-computed defaults.  This is a no-op except in the case
-	 * where one of these had been in the config file and is now removed.
-	 *
-	 * In particular, we *must not* do this during the postmaster's initial
-	 * loading of the file, since the timezone functions in particular should
-	 * be run only after initialization is complete.
-	 *
-	 * XXX this is an unmaintainable crock, because we have to know how to set
-	 * (or at least what to call to set) every variable that could potentially
-	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
-	 * time to redesign it for 9.1.
-	 */
-	if (context == PGC_SIGHUP && applySettings)
-	{
-		InitializeGUCOptionsFromEnvironment();
-		pg_timezone_abbrev_initialize();
-		/* this selects SQL_ASCII in processes not connected to a database */
-		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
-						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
-	}
-
-	/*
-	 * Now apply the values from the config file.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		char	   *pre_value = NULL;
-		int			scres;
-
-		/* Ignore anything marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/* In SIGHUP cases in the postmaster, we want to report changes */
-		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
-		{
-			const char *preval = GetConfigOption(item->name, true, false);
-
-			/* If option doesn't exist yet or is NULL, treat as empty string */
-			if (!preval)
-				preval = "";
-			/* must dup, else might have dangling pointer below */
-			pre_value = pstrdup(preval);
-		}
-
-		scres = set_config_option(item->name, item->value,
-								  context, PGC_S_FILE,
-								  GUC_ACTION_SET, applySettings, 0, false);
-		if (scres > 0)
-		{
-			/* variable was updated, so log the change if appropriate */
-			if (pre_value)
-			{
-				const char *post_value = GetConfigOption(item->name, true, false);
-
-				if (!post_value)
-					post_value = "";
-				if (strcmp(pre_value, post_value) != 0)
-					ereport(elevel,
-							(errmsg("parameter \"%s\" changed to \"%s\"",
-									item->name, item->value)));
-			}
-			item->applied = true;
-		}
-		else if (scres == 0)
-		{
-			error = true;
-			item->errmsg = pstrdup("setting could not be applied");
-			ConfFileWithError = item->filename;
-		}
-		else
-		{
-			/* no error, but variable's active value was not changed */
-			item->applied = true;
-		}
-
-		/*
-		 * We should update source location unless there was an error, since
-		 * even if the active value didn't change, the reset value might have.
-		 * (In the postmaster, there won't be a difference, but it does matter
-		 * in backends.)
-		 */
-		if (scres != 0 && applySettings)
-			set_config_sourcefile(item->name, item->filename,
-								  item->sourceline);
-
-		if (pre_value)
-			pfree(pre_value);
-	}
-
-	/* Remember when we last successfully loaded the config file. */
-	if (applySettings)
-		PgReloadTime = GetCurrentTimestamp();
-
-bail_out:
-	if (error && applySettings)
-	{
-		/* During postmaster startup, any error is fatal */
-		if (context == PGC_POSTMASTER)
-			ereport(ERROR,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors",
-							ConfFileWithError)));
-		else if (applying)
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
-							ConfFileWithError)));
-		else
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
-							ConfFileWithError)));
-	}
-
-	/* Successful or otherwise, return the collected data list */
-	return head;
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
 }
 
 /*
@@ -525,6 +162,7 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 		return pstrdup(location);
 	else
 	{
+		#ifndef FRONTEND
 		if (calling_file != NULL)
 		{
 			strlcpy(abs_path, calling_file, sizeof(abs_path));
@@ -538,6 +176,12 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 			join_path_components(abs_path, DataDir, location);
 			canonicalize_path(abs_path);
 		}
+		#else
+		strlcpy(abs_path, calling_file, sizeof(abs_path));
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, location);
+		canonicalize_path(abs_path);
+		#endif
 		return pstrdup(abs_path);
 	}
 }
@@ -574,10 +218,15 @@ ParseConfigFile(const char *config_file, bool strict,
 	 */
 	if (depth > 10)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
 						config_file)));
+		#else
+		printf(_("could not open configuration file \"%s\": maximum nesting depth exceeded\n"),
+				config_file);
+		#endif
 		record_config_file_error("nesting depth exceeded",
 								 calling_file, calling_lineno,
 								 head_p, tail_p);
@@ -585,15 +234,23 @@ ParseConfigFile(const char *config_file, bool strict,
 	}
 
 	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+	#ifndef FRONTEND
 	fp = AllocateFile(abs_path, "r");
+	#else
+	fp = fopen(abs_path, "r");
+	#endif
 	if (!fp)
 	{
 		if (strict)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not open configuration file \"%s\": %m",
 							abs_path)));
+			#else
+			printf(_("could not open configuration file \"%s\"\n"), abs_path);
+			#endif
 			record_config_file_error(psprintf("could not open file \"%s\"",
 											  abs_path),
 									 calling_file, calling_lineno,
@@ -602,9 +259,13 @@ ParseConfigFile(const char *config_file, bool strict,
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(LOG,
 					(errmsg("skipping missing configuration file \"%s\"",
 							abs_path)));
+			#else
+			printf(_("skipping missing configuration file \"%s\"\n"), abs_path);
+			#endif
 		}
 		goto cleanup;
 	}
@@ -613,7 +274,14 @@ ParseConfigFile(const char *config_file, bool strict,
 
 cleanup:
 	if (fp)
+	{
+		#ifndef FRONTEND
 		FreeFile(fp);
+		#else
+		fclose(fp);
+		#endif
+	}
+
 	pfree(abs_path);
 
 	return OK;
@@ -623,7 +291,7 @@ cleanup:
  * Capture an error message in the ConfigVariable list returned by
  * config file parsing.
  */
-static void
+void
 record_config_file_error(const char *errmsg,
 						 const char *config_file,
 						 int lineno,
@@ -715,8 +383,13 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		 * corrupted parser state.  Consequently, abandon the file, but trust
 		 * that the state remains sane enough for yy_delete_buffer().
 		 */
+		#ifndef FRONTEND
 		elog(elevel, "%s at file \"%s\" line %u",
 			 GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#else
+		printf(_("%s at file \"%s\" line %u\n"),
+				GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#endif
 		record_config_file_error(GUC_flex_fatal_errmsg,
 								 config_file, ConfigFileLineno,
 								 head_p, tail_p);
@@ -855,20 +528,30 @@ parse_error:
 		/* report the error */
 		if (token == GUC_EOL || token == 0)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			  errmsg("syntax error in file \"%s\" line %u, near end of line",
 					 config_file, ConfigFileLineno - 1)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near end of line\n"),
+											config_file, ConfigFileLineno - 1);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno - 1,
 									 head_p, tail_p);
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
 					config_file, ConfigFileLineno, yytext)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near token \"%s\"\n"),
+										config_file, ConfigFileLineno, yytext);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno,
 									 head_p, tail_p);
@@ -883,12 +566,21 @@ parse_error:
 		 * as well give up immediately.  (This prevents postmaster children
 		 * from bloating the logs with duplicate complaints.)
 		 */
+		#ifndef FRONTEND
 		if (errorcount >= 100 || elevel <= DEBUG1)
+		#else
+		if (errorcount >= 100)
+		#endif
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 			   errmsg("too many syntax errors found, abandoning file \"%s\"",
 					  config_file)));
+			#else
+			printf(_("too many syntax errors found, abandoning file \"%s\"\n"),
+																config_file);
+			#endif
 			break;
 		}
 
@@ -934,13 +626,21 @@ ParseConfigDirectory(const char *includedir,
 	bool		status;
 
 	directory = AbsoluteConfigLocation(includedir, calling_file);
+	#ifndef FRONTEND
 	d = AllocateDir(directory);
+	#else
+	d = opendir(directory);
+	#endif
 	if (d == NULL)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode_for_file_access(),
 				 errmsg("could not open configuration directory \"%s\": %m",
 						directory)));
+		#else
+		printf(_("could not open configuration directory \"%s\"\n"), directory);
+		#endif
 		record_config_file_error(psprintf("could not open directory \"%s\"",
 										  directory),
 								 calling_file, calling_lineno,
@@ -957,7 +657,11 @@ ParseConfigDirectory(const char *includedir,
 	filenames = (char **) palloc(size_filenames * sizeof(char *));
 	num_filenames = 0;
 
+	#ifndef FRONTEND
 	while ((de = ReadDir(d, directory)) != NULL)
+	#else
+	while ((de = readdir(d)) != NULL)
+	#endif
 	{
 		struct stat st;
 		char		filename[MAXPGPATH];
@@ -998,10 +702,14 @@ ParseConfigDirectory(const char *includedir,
 			 * a file can't be accessed now is if it was removed between the
 			 * directory listing and now.
 			 */
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not stat file \"%s\": %m",
 							filename)));
+			#else
+			printf(_("could not stat file \"%s\"\n"), filename);
+			#endif
 			record_config_file_error(psprintf("could not stat file \"%s\"",
 											  filename),
 									 calling_file, calling_lineno,
@@ -1032,7 +740,13 @@ ParseConfigDirectory(const char *includedir,
 
 cleanup:
 	if (d)
+	{
+		#ifndef FRONTEND
 		FreeDir(d);
+		#else
+		closedir(d);
+		#endif
+	}
 	pfree(directory);
 	return status;
 }
diff --git a/src/include/common/guc-file.h b/src/include/common/guc-file.h
new file mode 100644
index 0000000000..ca969e2aed
--- /dev/null
+++ b/src/include/common/guc-file.h
@@ -0,0 +1,50 @@
+#ifndef GUC_FILE_H
+#define GUC_FILE_H
+
+#include "c.h"
+
+/*
+ * Parsing the configuration file(s) will return a list of name-value pairs
+ * with source location info.  We also abuse this data structure to carry
+ * error reports about the config files.  An entry reporting an error will
+ * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
+ *
+ * If "ignore" is true, don't attempt to apply the item (it might be an error
+ * report, or an item we determined to be duplicate).  "applied" is set true
+ * if we successfully applied, or could have applied, the setting.
+ */
+typedef struct ConfigVariable
+{
+	char	   *name;
+	char	   *value;
+	char	   *errmsg;
+	char	   *filename;
+	int			sourceline;
+	bool		ignore;
+	bool		applied;
+	struct ConfigVariable *next;
+} ConfigVariable;
+
+extern bool ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigFp(FILE *fp, const char *config_file,
+			  int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p);
+extern void FreeConfigVariables(ConfigVariable *list);
+
+extern int	guc_name_compare(const char *namea, const char *nameb);
+
+extern void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+#endif							/* GUC_FILE_H */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index c07e7b945e..0b3391004c 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -1,8 +1,7 @@
 /*--------------------------------------------------------------------
  * guc.h
  *
- * External declarations pertaining to backend/utils/misc/guc.c and
- * backend/utils/misc/guc-file.l
+ * External declarations pertaining to backend/utils/misc/guc.c
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -120,42 +119,6 @@ typedef enum
 	PGC_S_SESSION				/* SET command */
 } GucSource;
 
-/*
- * Parsing the configuration file(s) will return a list of name-value pairs
- * with source location info.  We also abuse this data structure to carry
- * error reports about the config files.  An entry reporting an error will
- * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
- *
- * If "ignore" is true, don't attempt to apply the item (it might be an error
- * report, or an item we determined to be duplicate).  "applied" is set true
- * if we successfully applied, or could have applied, the setting.
- */
-typedef struct ConfigVariable
-{
-	char	   *name;
-	char	   *value;
-	char	   *errmsg;
-	char	   *filename;
-	int			sourceline;
-	bool		ignore;
-	bool		applied;
-	struct ConfigVariable *next;
-} ConfigVariable;
-
-extern bool ParseConfigFile(const char *config_file, bool strict,
-				const char *calling_file, int calling_lineno,
-				int depth, int elevel,
-				ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigFp(FILE *fp, const char *config_file,
-			  int depth, int elevel,
-			  ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigDirectory(const char *includedir,
-					 const char *calling_file, int calling_lineno,
-					 int depth, int elevel,
-					 ConfigVariable **head_p,
-					 ConfigVariable **tail_p);
-extern void FreeConfigVariables(ConfigVariable *list);
-
 /*
  * The possible values of an enum variable are specified by an array of
  * name-value pairs.  The "hidden" flag means the value is accepted but
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 56192f1b20..6952e60550 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -172,7 +172,7 @@ sub mkvcbuild
 	$postgres->AddFiles('src/backend/parser', 'scan.l', 'gram.y');
 	$postgres->AddFiles('src/backend/bootstrap', 'bootscanner.l',
 		'bootparse.y');
-	$postgres->AddFiles('src/backend/utils/misc', 'guc-file.l');
+	$postgres->AddFiles('src/common', 'guc-file.l');
 	$postgres->AddFiles(
 		'src/backend/replication', 'repl_scanner.l',
 		'repl_gram.y',             'syncrep_scanner.l',
diff --git a/src/tools/msvc/clean.bat b/src/tools/msvc/clean.bat
index 069d6eb569..53d77aaf0a 100755
--- a/src/tools/msvc/clean.bat
+++ b/src/tools/msvc/clean.bat
@@ -80,7 +80,7 @@ if %DIST%==1 if exist src\backend\parser\scan.c del /q src\backend\parser\scan.c
 if %DIST%==1 if exist src\backend\parser\gram.c del /q src\backend\parser\gram.c
 if %DIST%==1 if exist src\backend\bootstrap\bootscanner.c del /q src\backend\bootstrap\bootscanner.c
 if %DIST%==1 if exist src\backend\bootstrap\bootparse.c del /q src\backend\bootstrap\bootparse.c
-if %DIST%==1 if exist src\backend\utils\misc\guc-file.c del /q src\backend\utils\misc\guc-file.c
+if %DIST%==1 if exist src\common\guc-file.c del /q src\common\guc-file.c
 if %DIST%==1 if exist src\backend\replication\repl_scanner.c del /q src\backend\replication\repl_scanner.c
 if %DIST%==1 if exist src\backend\replication\repl_gram.c del /q src\backend\replication\repl_gram.c
 if %DIST%==1 if exist src\backend\replication\syncrep_scanner.c del /q src\backend\replication\syncrep_scanner.c
-- 
2.19.1

From 99c6d94f37a797400d41545a271ff111b92e9361 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <alex.lumir@gmail.com>
Date: Fri, 21 Dec 2018 14:00:30 +0300
Subject: [PATCH] pg_rewind: options to use restore_command from
 postgresql.conf or command line.

---
 doc/src/sgml/ref/pg_rewind.sgml               |  30 +-
 src/backend/Makefile                          |   4 +-
 src/backend/commands/extension.c              |   1 +
 src/backend/utils/misc/.gitignore             |   1 -
 src/backend/utils/misc/Makefile               |   8 -
 src/backend/utils/misc/guc.c                  | 434 +++++++++++++--
 src/bin/pg_rewind/Makefile                    |   2 +-
 src/bin/pg_rewind/parsexlog.c                 | 166 +++++-
 src/bin/pg_rewind/pg_rewind.c                 | 100 +++-
 src/bin/pg_rewind/pg_rewind.h                 |  10 +-
 src/bin/pg_rewind/t/001_basic.pl              |   4 +-
 src/bin/pg_rewind/t/002_databases.pl          |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl         |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm             |  93 +++-
 src/common/.gitignore                         |   1 +
 src/common/Makefile                           |   9 +-
 src/{backend/utils/misc => common}/guc-file.l | 518 ++++--------------
 src/include/common/guc-file.h                 |  50 ++
 src/include/utils/guc.h                       |  39 +-
 src/tools/msvc/Mkvcbuild.pm                   |   7 +-
 src/tools/msvc/clean.bat                      |   2 +-
 21 files changed, 973 insertions(+), 514 deletions(-)
 delete mode 100644 src/backend/utils/misc/.gitignore
 rename src/{backend/utils/misc => common}/guc-file.l (60%)
 create mode 100644 src/include/common/guc-file.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 53a64ee29e..0c2441afa7 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> option is specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -200,6 +202,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retreive missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/backend/Makefile b/src/backend/Makefile
index 478a96db9b..721cb57e89 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -186,7 +186,7 @@ distprep:
 	$(MAKE) -C replication	repl_gram.c repl_scanner.c syncrep_gram.c syncrep_scanner.c
 	$(MAKE) -C storage/lmgr	lwlocknames.h lwlocknames.c
 	$(MAKE) -C utils	distprep
-	$(MAKE) -C utils/misc	guc-file.c
+	$(MAKE) -C common	guc-file.c
 	$(MAKE) -C utils/sort	qsort_tuple.c
 
 
@@ -307,7 +307,7 @@ maintainer-clean: distclean
 	      replication/syncrep_scanner.c \
 	      storage/lmgr/lwlocknames.c \
 	      storage/lmgr/lwlocknames.h \
-	      utils/misc/guc-file.c \
+	      common/guc-file.c \
 	      utils/sort/qsort_tuple.c
 
 
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..195eb8a821 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -50,6 +50,7 @@
 #include "commands/defrem.h"
 #include "commands/extension.h"
 #include "commands/schemacmds.h"
+#include "common/guc-file.h"
 #include "funcapi.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
diff --git a/src/backend/utils/misc/.gitignore b/src/backend/utils/misc/.gitignore
deleted file mode 100644
index 495b1aec76..0000000000
--- a/src/backend/utils/misc/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/guc-file.c
diff --git a/src/backend/utils/misc/Makefile b/src/backend/utils/misc/Makefile
index ec7ec131e5..2205956a9f 100644
--- a/src/backend/utils/misc/Makefile
+++ b/src/backend/utils/misc/Makefile
@@ -25,11 +25,3 @@ override CPPFLAGS += -DPG_KRB_SRVTAB='"$(krb_srvtab)"'
 endif
 
 include $(top_srcdir)/src/backend/common.mk
-
-# guc-file is compiled as part of guc
-guc.o: guc-file.c
-
-# Note: guc-file.c is not deleted by 'make clean',
-# since we want to ship it in distribution tarballs.
-clean:
-	@rm -f lex.yy.c
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index ea5444c6f1..eff5b5aefa 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -41,6 +41,7 @@
 #include "commands/vacuum.h"
 #include "commands/variable.h"
 #include "commands/trigger.h"
+#include "common/guc-file.h"
 #include "common/string.h"
 #include "funcapi.h"
 #include "jit/jit.h"
@@ -212,7 +213,6 @@ static void assign_recovery_target_lsn(const char *newval, void *extra);
 static bool check_primary_slot_name(char **newval, void **extra, GucSource source);
 static bool check_default_with_oids(bool *newval, void **extra, GucSource source);
 
-/* Private functions in guc-file.l that need to be called from guc.c */
 static ConfigVariable *ProcessConfigFileInternal(GucContext context,
 						  bool applySettings, int elevel);
 
@@ -4491,7 +4491,6 @@ static int	GUCNestLevel = 0;	/* 1 when in main transaction */
 
 
 static int	guc_var_compare(const void *a, const void *b);
-static int	guc_name_compare(const char *namea, const char *nameb);
 static void InitializeGUCOptionsFromEnvironment(void);
 static void InitializeOneGUCOption(struct config_generic *gconf);
 static void push_old_value(struct config_generic *gconf, GucAction action);
@@ -4968,37 +4967,6 @@ guc_var_compare(const void *a, const void *b)
 	return guc_name_compare(confa->name, confb->name);
 }
 
-/*
- * the bare comparison function for GUC names
- */
-static int
-guc_name_compare(const char *namea, const char *nameb)
-{
-	/*
-	 * The temptation to use strcasecmp() here must be resisted, because the
-	 * array ordering has to remain stable across setlocale() calls. So, build
-	 * our own with a simple ASCII-only downcasing.
-	 */
-	while (*namea && *nameb)
-	{
-		char		cha = *namea++;
-		char		chb = *nameb++;
-
-		if (cha >= 'A' && cha <= 'Z')
-			cha += 'a' - 'A';
-		if (chb >= 'A' && chb <= 'Z')
-			chb += 'a' - 'A';
-		if (cha != chb)
-			return cha - chb;
-	}
-	if (*namea)
-		return 1;				/* a is longer */
-	if (*nameb)
-		return -1;				/* b is longer */
-	return 0;
-}
-
-
 /*
  * Initialize GUC options during program startup.
  *
@@ -11372,4 +11340,402 @@ check_default_with_oids(bool *newval, void **extra, GucSource source)
 	return true;
 }
 
-#include "guc-file.c"
+/*
+ * Exported function to read and process the configuration file. The
+ * parameter indicates in what context the file is being read --- either
+ * postmaster startup (including standalone-backend startup) or SIGHUP.
+ * All options mentioned in the configuration file are set to new values.
+ * If a hard error occurs, no values will be changed.  (There can also be
+ * errors that prevent just one value from being changed.)
+ */
+void
+ProcessConfigFile(GucContext context)
+{
+	int			elevel;
+	MemoryContext config_cxt;
+	MemoryContext caller_cxt;
+
+	/*
+	 * Config files are processed on startup (by the postmaster only) and on
+	 * SIGHUP (by the postmaster and its children)
+	 */
+	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
+		   context == PGC_SIGHUP);
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+
+	/*
+	 * This function is usually called within a process-lifespan memory
+	 * context.  To ensure that any memory leaked during GUC processing does
+	 * not accumulate across repeated SIGHUP cycles, do the work in a private
+	 * context that we can free at exit.
+	 */
+	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
+									   "config file processing",
+									   ALLOCSET_DEFAULT_SIZES);
+	caller_cxt = MemoryContextSwitchTo(config_cxt);
+
+	/*
+	 * Read and apply the config file.  We don't need to examine the result.
+	 */
+	(void) ProcessConfigFileInternal(context, true, elevel);
+
+	/* Clean up */
+	MemoryContextSwitchTo(caller_cxt);
+	MemoryContextDelete(config_cxt);
+}
+
+/*
+ * This function handles both actual config file (re)loads and execution of
+ * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
+ * case we don't apply any of the settings, but we make all the usual validity
+ * checks, and we return the ConfigVariable list so that it can be printed out
+ * by show_all_file_settings().
+ */
+static ConfigVariable *
+ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+{
+	bool		error = false;
+	bool		applying = false;
+	const char *ConfFileWithError;
+	ConfigVariable *item,
+			   *head,
+			   *tail;
+	int			i;
+
+	/* Parse the main config file into a list of option names and values */
+	ConfFileWithError = ConfigFileName;
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, true,
+						 NULL, 0, 0, elevel,
+						 &head, &tail))
+	{
+		/* Syntax error(s) detected in the file, so bail out */
+		error = true;
+		goto bail_out;
+	}
+
+	/*
+	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
+	 * replace any parameters set by ALTER SYSTEM command.  Because this file
+	 * is in the data directory, we can't read it until the DataDir has been
+	 * set.
+	 */
+	if (DataDir)
+	{
+		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
+							 NULL, 0, 0, elevel,
+							 &head, &tail))
+		{
+			/* Syntax error(s) detected in the file, so bail out */
+			error = true;
+			ConfFileWithError = PG_AUTOCONF_FILENAME;
+			goto bail_out;
+		}
+	}
+	else
+	{
+		/*
+		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
+		 * read.  In this case, we don't want to accept any settings but
+		 * data_directory from postgresql.conf, because they might be
+		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
+		 * will be read later. OTOH, since data_directory isn't allowed in the
+		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
+		 */
+		ConfigVariable *newlist = NULL;
+
+		/*
+		 * Prune all items except the last "data_directory" from the list.
+		 */
+		for (item = head; item; item = item->next)
+		{
+			if (!item->ignore &&
+				strcmp(item->name, "data_directory") == 0)
+				newlist = item;
+		}
+
+		if (newlist)
+			newlist->next = NULL;
+		head = tail = newlist;
+
+		/*
+		 * Quick exit if data_directory is not present in file.
+		 *
+		 * We need not do any further processing, in particular we don't set
+		 * PgReloadTime; that will be set soon by subsequent full loading of
+		 * the config file.
+		 */
+		if (head == NULL)
+			goto bail_out;
+	}
+
+	/*
+	 * Mark all extant GUC variables as not present in the config file. We
+	 * need this so that we can tell below which ones have been removed from
+	 * the file since we last processed it.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		gconf->status &= ~GUC_IS_IN_FILE;
+	}
+
+	/*
+	 * Check if all the supplied option names are valid, as an additional
+	 * quasi-syntactic check on the validity of the config file.  It is
+	 * important that the postmaster and all backends agree on the results of
+	 * this phase, else we will have strange inconsistencies about which
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
+	 *
+	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
+	 * variable mentioned in the file; and we detect duplicate entries in the
+	 * file and mark the earlier occurrences as ignorable.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		struct config_generic *record;
+
+		/* Ignore anything already marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/*
+		 * Try to find the variable; but do not create a custom placeholder if
+		 * it's not there already.
+		 */
+		record = find_option(item->name, false, elevel);
+
+		if (record)
+		{
+			/* If it's already marked, then this is a duplicate entry */
+			if (record->status & GUC_IS_IN_FILE)
+			{
+				/*
+				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
+				 * avoid the O(N^2) behavior here with some additional state,
+				 * but it seems unlikely to be worth the trouble.
+				 */
+				ConfigVariable *pitem;
+
+				for (pitem = head; pitem != item; pitem = pitem->next)
+				{
+					if (!pitem->ignore &&
+						strcmp(pitem->name, item->name) == 0)
+						pitem->ignore = true;
+				}
+			}
+			/* Now mark it as present in file */
+			record->status |= GUC_IS_IN_FILE;
+		}
+		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
+		{
+			/* Invalid non-custom variable, so complain */
+			ereport(elevel,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
+							item->name,
+							item->filename, item->sourceline)));
+			item->errmsg = pstrdup("unrecognized configuration parameter");
+			error = true;
+			ConfFileWithError = item->filename;
+		}
+	}
+
+	/*
+	 * If we've detected any errors so far, we don't want to risk applying any
+	 * changes.
+	 */
+	if (error)
+		goto bail_out;
+
+	/* Otherwise, set flag that we're beginning to apply changes */
+	applying = true;
+
+	/*
+	 * Check for variables having been removed from the config file, and
+	 * revert their reset values (and perhaps also effective values) to the
+	 * boot-time defaults.  If such a variable can't be changed after startup,
+	 * report that and continue.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		if (gconf->reset_source != PGC_S_FILE ||
+			(gconf->status & GUC_IS_IN_FILE))
+			continue;
+		if (gconf->context < PGC_SIGHUP)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+							gconf->name)));
+			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
+											  gconf->name),
+									 NULL, 0,
+									 &head, &tail);
+			error = true;
+			continue;
+		}
+
+		/* No more to do if we're just doing show_all_file_settings() */
+		if (!applySettings)
+			continue;
+
+		/*
+		 * Reset any "file" sources to "default", else set_config_option will
+		 * not override those settings.
+		 */
+		if (gconf->reset_source == PGC_S_FILE)
+			gconf->reset_source = PGC_S_DEFAULT;
+		if (gconf->source == PGC_S_FILE)
+			gconf->source = PGC_S_DEFAULT;
+		for (stack = gconf->stack; stack; stack = stack->prev)
+		{
+			if (stack->source == PGC_S_FILE)
+				stack->source = PGC_S_DEFAULT;
+		}
+
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
+		if (set_config_option(gconf->name, NULL,
+							  context, PGC_S_DEFAULT,
+							  GUC_ACTION_SET, true, 0, false) > 0)
+		{
+			/* Log the change if appropriate */
+			if (context == PGC_SIGHUP)
+				ereport(elevel,
+						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
+								gconf->name)));
+		}
+	}
+
+	/*
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
+	 *
+	 * In particular, we *must not* do this during the postmaster's initial
+	 * loading of the file, since the timezone functions in particular should
+	 * be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how to set
+	 * (or at least what to call to set) every variable that could potentially
+	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
+	 * time to redesign it for 9.1.
+	 */
+	if (context == PGC_SIGHUP && applySettings)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
+
+	/*
+	 * Now apply the values from the config file.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		char	   *pre_value = NULL;
+		int			scres;
+
+		/* Ignore anything marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/* In SIGHUP cases in the postmaster, we want to report changes */
+		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
+		{
+			const char *preval = GetConfigOption(item->name, true, false);
+
+			/* If option doesn't exist yet or is NULL, treat as empty string */
+			if (!preval)
+				preval = "";
+			/* must dup, else might have dangling pointer below */
+			pre_value = pstrdup(preval);
+		}
+
+		scres = set_config_option(item->name, item->value,
+								  context, PGC_S_FILE,
+								  GUC_ACTION_SET, applySettings, 0, false);
+		if (scres > 0)
+		{
+			/* variable was updated, so log the change if appropriate */
+			if (pre_value)
+			{
+				const char *post_value = GetConfigOption(item->name, true, false);
+
+				if (!post_value)
+					post_value = "";
+				if (strcmp(pre_value, post_value) != 0)
+					ereport(elevel,
+							(errmsg("parameter \"%s\" changed to \"%s\"",
+									item->name, item->value)));
+			}
+			item->applied = true;
+		}
+		else if (scres == 0)
+		{
+			error = true;
+			item->errmsg = pstrdup("setting could not be applied");
+			ConfFileWithError = item->filename;
+		}
+		else
+		{
+			/* no error, but variable's active value was not changed */
+			item->applied = true;
+		}
+
+		/*
+		 * We should update source location unless there was an error, since
+		 * even if the active value didn't change, the reset value might have.
+		 * (In the postmaster, there won't be a difference, but it does matter
+		 * in backends.)
+		 */
+		if (scres != 0 && applySettings)
+			set_config_sourcefile(item->name, item->filename,
+								  item->sourceline);
+
+		if (pre_value)
+			pfree(pre_value);
+	}
+
+	/* Remember when we last successfully loaded the config file. */
+	if (applySettings)
+		PgReloadTime = GetCurrentTimestamp();
+
+bail_out:
+	if (error && applySettings)
+	{
+		/* During postmaster startup, any error is fatal */
+		if (context == PGC_POSTMASTER)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors",
+							ConfFileWithError)));
+		else if (applying)
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
+							ConfFileWithError)));
+		else
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
+							ConfFileWithError)));
+	}
+
+	/* Successful or otherwise, return the collected data list */
+	return head;
+}
diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
index 04f3b8f520..65ebf3c78c 100644
--- a/src/bin/pg_rewind/Makefile
+++ b/src/bin/pg_rewind/Makefile
@@ -15,7 +15,7 @@ subdir = src/bin/pg_rewind
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
+override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index e19c265cbb..39cbe78f84 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,6 +46,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -53,6 +55,9 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static bool RestoreArchivedWAL(const char *path, const char *xlogfname,
+					off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,15 +65,17 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   ControlFileData *targetCF, const char *restore_command)
 {
 	XLogRecord *record;
+	XLogRecPtr endpoint = targetCF->checkPoint;
 	XLogReaderState *xlogreader;
 	char	   *errormsg;
 	XLogPageReadPrivate private;
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -156,7 +163,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +188,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +299,46 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
-				   strerror(errno));
-			return -1;
+			bool  restore_ok;
+
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+					   strerror(errno));
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			restore_ok = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (restore_ok)
+			{
+				xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogreadfd < 0)
+				{
+					printf(_("could not open restored from archive file \"%s\": %s\n"), xlogfpath,
+							strerror(errno));
+					return -1;
+				}
+				else
+					pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n", xlogfpath);
+			}
+			else
+			{
+				printf(_("could not restore file \"%s\" from archive: %s\n"), xlogfname,
+					   strerror(errno));
+				return -1;
+			}
 		}
 	}
 
@@ -409,3 +454,114 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return true.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ *
+ * This is a simplified and adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+bool
+RestoreArchivedWAL(const char *path, const char *xlogfname, off_t expectedSize,
+				   const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *dp;
+	char	   *endp;
+	const char *sp;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used during rewind process.\n");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size, (unsigned long) expectedSize,
+						strerror(errno));
+			}
+			else
+				return true;
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath,
+					strerror(errno));
+		}
+	}
+
+	return false;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 7ccde5c87f..a89fdde7cc 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -26,6 +26,7 @@
 #include "catalog/pg_control.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"
+#include "common/guc-file.h"
 #include "common/restricted_token.h"
 #include "getopt_long.h"
 #include "storage/bufpage.h"
@@ -52,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +78,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,9 +100,12 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
+	char		recfile_fullpath[MAXPGPATH];
 	int			option_index;
 	int			c;
 	XLogRecPtr	divergerec;
@@ -129,7 +138,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +150,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +170,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +240,80 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			fprintf(stderr, _("%s: conflicting options: both -r and -R are specified\n"),
+				progname);
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf or -R/--restore-command.\n"),
+				progname);
+			exit(1);
+		}
+
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		FILE	*conf_file;
+
+		/*
+		 * Look for configuration file in the target data directory and
+		 * try to get restore_command from there.
+		 */
+		snprintf(recfile_fullpath, sizeof(recfile_fullpath), "%s/%s", datadir_target, RESTORE_COMMAND_FILE);
+		conf_file = fopen(recfile_fullpath, "r");
+
+		if (conf_file == NULL)
+		{
+			fprintf(stderr, _("%s: option -r/--use-postgresql-conf is specified, but postgreslq.conf is absent in the target directory\n"),
+					progname);
+			fprintf(stderr, _("You have to add postgresql.conf or pass restore_command with -R/--restore-command option.\n"));
+			exit(1);
+		}
+		else
+		{
+			ConfigVariable *item,
+						   *head = NULL,
+						   *tail = NULL;
+			bool			config_is_parsed;
+
+			/*
+			 * We pass a fullpath to the configuration file as calling_file here, since
+			 * parser will use its parent directory as base for all further includes
+			 * if any exist.
+			 */
+			config_is_parsed = ParseConfigFile(RESTORE_COMMAND_FILE, true,
+											   recfile_fullpath, 0, 0,
+											   PG_WARNING, &head, &tail);
+			fclose(conf_file);
+
+			if (config_is_parsed)
+			{
+				for (item = head; item; item = item->next)
+				{
+					if (strcmp(item->name, "restore_command") == 0)
+					{
+						if (restore_command != NULL)
+						{
+							pfree(restore_command);
+							restore_command = NULL;
+						}
+						restore_command = pstrdup(item->value);
+						pg_log(PG_DEBUG, "using restore_command=\'%s\' from %s.\n", restore_command, RESTORE_COMMAND_FILE);
+					}
+				}
+
+				if (restore_command == NULL)
+					pg_fatal("could not find restore_command in %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+			}
+			else
+				pg_fatal("could not parse %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+
+			FreeConfigVariables(head);
+		}
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +385,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +409,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   &ControlFile_target, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 83b2898b8b..0df8637e6d 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -14,9 +14,12 @@
 #include "datapagemap.h"
 
 #include "access/timeline.h"
+#include "catalog/pg_control.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
 
+#define RESTORE_COMMAND_FILE "postgresql.conf"
+
 /* Configuration options */
 extern char *datadir_target;
 extern char *datadir_source;
@@ -32,11 +35,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
+			   int tliIndex, ControlFileData *targetCF, const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 6dc05720a1..99ea821cfe 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -62,5 +62,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 85cae7e47b..79bd6434b4 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catpath catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -249,6 +251,95 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/.gitignore b/src/common/.gitignore
index ffa3284fbf..424beacbc9 100644
--- a/src/common/.gitignore
+++ b/src/common/.gitignore
@@ -1 +1,2 @@
 /kwlist_d.h
+/guc-file.c
diff --git a/src/common/Makefile b/src/common/Makefile
index d0c2b970eb..3d7da47f56 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -48,7 +48,7 @@ OBJS_COMMON = base64.o config_info.o controldata_utils.o exec.o file_perm.o \
 	ip.o keywords.o kwlookup.o link-canary.o md5.o pg_lzcompress.o \
 	pgfnames.o psprintf.o relpath.o \
 	rmtree.o saslprep.o scram-common.o string.o unicode_norm.o \
-	username.o wait_error.o
+	username.o wait_error.o guc-file.o
 
 ifeq ($(with_openssl),yes)
 OBJS_COMMON += sha2_openssl.o
@@ -70,7 +70,7 @@ GEN_KEYWORDLIST_DEPS = $(TOOLSDIR)/gen_keywordlist.pl $(TOOLSDIR)/PerfectHash.pm
 
 all: libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 
-distprep: kwlist_d.h
+distprep: kwlist_d.h guc-file.c
 
 # libpgcommon is needed by some contrib
 install: all installdirs
@@ -130,10 +130,13 @@ kwlist_d.h: $(top_srcdir)/src/include/parser/kwlist.h $(GEN_KEYWORDLIST_DEPS)
 # that you don't get broken parsing code, even in a non-enable-depend build.
 keywords.o keywords_shlib.o keywords_srv.o: kwlist_d.h
 
-# kwlist_d.h is in the distribution tarball, so it is not cleaned here.
+# Note: guc-file.c and kwlist_d.h are not deleted by 'make clean',
+# since we want to ship them in distribution tarballs.
 clean distclean:
 	rm -f libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 	rm -f $(OBJS_FRONTEND) $(OBJS_SHLIB) $(OBJS_SRV)
+	@rm -f lex.yy.c
 
 maintainer-clean: distclean
 	rm -f kwlist_d.h
+	rm -f guc-file.c
diff --git a/src/backend/utils/misc/guc-file.l b/src/common/guc-file.l
similarity index 60%
rename from src/backend/utils/misc/guc-file.l
rename to src/common/guc-file.l
index 1c8b5f7d84..175685c9b5 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/common/guc-file.l
@@ -4,21 +4,31 @@
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/backend/utils/misc/guc-file.l
+ * src/common/guc-file.l
  */
 
 %{
 
+#ifndef FRONTEND
 #include "postgres.h"
 
-#include <ctype.h>
-#include <unistd.h>
-
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "utils/guc.h"
+#include "utils/elog.h"
+#else
+#include "postgres_fe.h"
+
+#include <dirent.h>
+#include <setjmp.h>
+#endif
+
+#include <ctype.h>
+#include <unistd.h>
+#include <sys/stat.h>
 
+#include "common/guc-file.h"
 
 /*
  * flex emits a yy_fatal_error() function that it calls in response to
@@ -48,12 +58,6 @@ static sigjmp_buf *GUC_flex_fatal_jmp;
 
 static void FreeConfigVariable(ConfigVariable *item);
 
-static void record_config_file_error(const char *errmsg,
-						 const char *config_file,
-						 int lineno,
-						 ConfigVariable **head_p,
-						 ConfigVariable **tail_p);
-
 static int	GUC_flex_fatal(const char *msg);
 static char *GUC_scanstr(const char *s);
 
@@ -111,404 +115,35 @@ STRING			\'([^'\\\n]|\\.|\'\')*\'
 
 /* LCOV_EXCL_STOP */
 
-/*
- * Exported function to read and process the configuration file. The
- * parameter indicates in what context the file is being read --- either
- * postmaster startup (including standalone-backend startup) or SIGHUP.
- * All options mentioned in the configuration file are set to new values.
- * If a hard error occurs, no values will be changed.  (There can also be
- * errors that prevent just one value from being changed.)
- */
-void
-ProcessConfigFile(GucContext context)
-{
-	int			elevel;
-	MemoryContext config_cxt;
-	MemoryContext caller_cxt;
-
-	/*
-	 * Config files are processed on startup (by the postmaster only) and on
-	 * SIGHUP (by the postmaster and its children)
-	 */
-	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
-		   context == PGC_SIGHUP);
-
-	/*
-	 * To avoid cluttering the log, only the postmaster bleats loudly about
-	 * problems with the config file.
-	 */
-	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
-
-	/*
-	 * This function is usually called within a process-lifespan memory
-	 * context.  To ensure that any memory leaked during GUC processing does
-	 * not accumulate across repeated SIGHUP cycles, do the work in a private
-	 * context that we can free at exit.
-	 */
-	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
-									   "config file processing",
-									   ALLOCSET_DEFAULT_SIZES);
-	caller_cxt = MemoryContextSwitchTo(config_cxt);
-
-	/*
-	 * Read and apply the config file.  We don't need to examine the result.
-	 */
-	(void) ProcessConfigFileInternal(context, true, elevel);
-
-	/* Clean up */
-	MemoryContextSwitchTo(caller_cxt);
-	MemoryContextDelete(config_cxt);
-}
 
 /*
- * This function handles both actual config file (re)loads and execution of
- * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
- * case we don't apply any of the settings, but we make all the usual validity
- * checks, and we return the ConfigVariable list so that it can be printed out
- * by show_all_file_settings().
+ * The bare comparison function for GUC names.
  */
-static ConfigVariable *
-ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+int
+guc_name_compare(const char *namea, const char *nameb)
 {
-	bool		error = false;
-	bool		applying = false;
-	const char *ConfFileWithError;
-	ConfigVariable *item,
-			   *head,
-			   *tail;
-	int			i;
-
-	/* Parse the main config file into a list of option names and values */
-	ConfFileWithError = ConfigFileName;
-	head = tail = NULL;
-
-	if (!ParseConfigFile(ConfigFileName, true,
-						 NULL, 0, 0, elevel,
-						 &head, &tail))
-	{
-		/* Syntax error(s) detected in the file, so bail out */
-		error = true;
-		goto bail_out;
-	}
-
-	/*
-	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
-	 * replace any parameters set by ALTER SYSTEM command.  Because this file
-	 * is in the data directory, we can't read it until the DataDir has been
-	 * set.
-	 */
-	if (DataDir)
-	{
-		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
-							 NULL, 0, 0, elevel,
-							 &head, &tail))
-		{
-			/* Syntax error(s) detected in the file, so bail out */
-			error = true;
-			ConfFileWithError = PG_AUTOCONF_FILENAME;
-			goto bail_out;
-		}
-	}
-	else
-	{
-		/*
-		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
-		 * read.  In this case, we don't want to accept any settings but
-		 * data_directory from postgresql.conf, because they might be
-		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
-		 * will be read later. OTOH, since data_directory isn't allowed in the
-		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
-		 */
-		ConfigVariable *newlist = NULL;
-
-		/*
-		 * Prune all items except the last "data_directory" from the list.
-		 */
-		for (item = head; item; item = item->next)
-		{
-			if (!item->ignore &&
-				strcmp(item->name, "data_directory") == 0)
-				newlist = item;
-		}
-
-		if (newlist)
-			newlist->next = NULL;
-		head = tail = newlist;
-
-		/*
-		 * Quick exit if data_directory is not present in file.
-		 *
-		 * We need not do any further processing, in particular we don't set
-		 * PgReloadTime; that will be set soon by subsequent full loading of
-		 * the config file.
-		 */
-		if (head == NULL)
-			goto bail_out;
-	}
-
 	/*
-	 * Mark all extant GUC variables as not present in the config file. We
-	 * need this so that we can tell below which ones have been removed from
-	 * the file since we last processed it.
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
 	 */
-	for (i = 0; i < num_guc_variables; i++)
+	while (*namea && *nameb)
 	{
-		struct config_generic *gconf = guc_variables[i];
-
-		gconf->status &= ~GUC_IS_IN_FILE;
-	}
-
-	/*
-	 * Check if all the supplied option names are valid, as an additional
-	 * quasi-syntactic check on the validity of the config file.  It is
-	 * important that the postmaster and all backends agree on the results of
-	 * this phase, else we will have strange inconsistencies about which
-	 * processes accept a config file update and which don't.  Hence, unknown
-	 * custom variable names have to be accepted without complaint.  For the
-	 * same reason, we don't attempt to validate the options' values here.
-	 *
-	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
-	 * variable mentioned in the file; and we detect duplicate entries in the
-	 * file and mark the earlier occurrences as ignorable.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		struct config_generic *record;
-
-		/* Ignore anything already marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/*
-		 * Try to find the variable; but do not create a custom placeholder if
-		 * it's not there already.
-		 */
-		record = find_option(item->name, false, elevel);
-
-		if (record)
-		{
-			/* If it's already marked, then this is a duplicate entry */
-			if (record->status & GUC_IS_IN_FILE)
-			{
-				/*
-				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
-				 * avoid the O(N^2) behavior here with some additional state,
-				 * but it seems unlikely to be worth the trouble.
-				 */
-				ConfigVariable *pitem;
-
-				for (pitem = head; pitem != item; pitem = pitem->next)
-				{
-					if (!pitem->ignore &&
-						strcmp(pitem->name, item->name) == 0)
-						pitem->ignore = true;
-				}
-			}
-			/* Now mark it as present in file */
-			record->status |= GUC_IS_IN_FILE;
-		}
-		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
-		{
-			/* Invalid non-custom variable, so complain */
-			ereport(elevel,
-					(errcode(ERRCODE_UNDEFINED_OBJECT),
-					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
-							item->name,
-							item->filename, item->sourceline)));
-			item->errmsg = pstrdup("unrecognized configuration parameter");
-			error = true;
-			ConfFileWithError = item->filename;
-		}
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
 	}
-
-	/*
-	 * If we've detected any errors so far, we don't want to risk applying any
-	 * changes.
-	 */
-	if (error)
-		goto bail_out;
-
-	/* Otherwise, set flag that we're beginning to apply changes */
-	applying = true;
-
-	/*
-	 * Check for variables having been removed from the config file, and
-	 * revert their reset values (and perhaps also effective values) to the
-	 * boot-time defaults.  If such a variable can't be changed after startup,
-	 * report that and continue.
-	 */
-	for (i = 0; i < num_guc_variables; i++)
-	{
-		struct config_generic *gconf = guc_variables[i];
-		GucStack   *stack;
-
-		if (gconf->reset_source != PGC_S_FILE ||
-			(gconf->status & GUC_IS_IN_FILE))
-			continue;
-		if (gconf->context < PGC_SIGHUP)
-		{
-			ereport(elevel,
-					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
-							gconf->name)));
-			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
-											  gconf->name),
-									 NULL, 0,
-									 &head, &tail);
-			error = true;
-			continue;
-		}
-
-		/* No more to do if we're just doing show_all_file_settings() */
-		if (!applySettings)
-			continue;
-
-		/*
-		 * Reset any "file" sources to "default", else set_config_option will
-		 * not override those settings.
-		 */
-		if (gconf->reset_source == PGC_S_FILE)
-			gconf->reset_source = PGC_S_DEFAULT;
-		if (gconf->source == PGC_S_FILE)
-			gconf->source = PGC_S_DEFAULT;
-		for (stack = gconf->stack; stack; stack = stack->prev)
-		{
-			if (stack->source == PGC_S_FILE)
-				stack->source = PGC_S_DEFAULT;
-		}
-
-		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
-		if (set_config_option(gconf->name, NULL,
-							  context, PGC_S_DEFAULT,
-							  GUC_ACTION_SET, true, 0, false) > 0)
-		{
-			/* Log the change if appropriate */
-			if (context == PGC_SIGHUP)
-				ereport(elevel,
-						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
-								gconf->name)));
-		}
-	}
-
-	/*
-	 * Restore any variables determined by environment variables or
-	 * dynamically-computed defaults.  This is a no-op except in the case
-	 * where one of these had been in the config file and is now removed.
-	 *
-	 * In particular, we *must not* do this during the postmaster's initial
-	 * loading of the file, since the timezone functions in particular should
-	 * be run only after initialization is complete.
-	 *
-	 * XXX this is an unmaintainable crock, because we have to know how to set
-	 * (or at least what to call to set) every variable that could potentially
-	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
-	 * time to redesign it for 9.1.
-	 */
-	if (context == PGC_SIGHUP && applySettings)
-	{
-		InitializeGUCOptionsFromEnvironment();
-		pg_timezone_abbrev_initialize();
-		/* this selects SQL_ASCII in processes not connected to a database */
-		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
-						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
-	}
-
-	/*
-	 * Now apply the values from the config file.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		char	   *pre_value = NULL;
-		int			scres;
-
-		/* Ignore anything marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/* In SIGHUP cases in the postmaster, we want to report changes */
-		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
-		{
-			const char *preval = GetConfigOption(item->name, true, false);
-
-			/* If option doesn't exist yet or is NULL, treat as empty string */
-			if (!preval)
-				preval = "";
-			/* must dup, else might have dangling pointer below */
-			pre_value = pstrdup(preval);
-		}
-
-		scres = set_config_option(item->name, item->value,
-								  context, PGC_S_FILE,
-								  GUC_ACTION_SET, applySettings, 0, false);
-		if (scres > 0)
-		{
-			/* variable was updated, so log the change if appropriate */
-			if (pre_value)
-			{
-				const char *post_value = GetConfigOption(item->name, true, false);
-
-				if (!post_value)
-					post_value = "";
-				if (strcmp(pre_value, post_value) != 0)
-					ereport(elevel,
-							(errmsg("parameter \"%s\" changed to \"%s\"",
-									item->name, item->value)));
-			}
-			item->applied = true;
-		}
-		else if (scres == 0)
-		{
-			error = true;
-			item->errmsg = pstrdup("setting could not be applied");
-			ConfFileWithError = item->filename;
-		}
-		else
-		{
-			/* no error, but variable's active value was not changed */
-			item->applied = true;
-		}
-
-		/*
-		 * We should update source location unless there was an error, since
-		 * even if the active value didn't change, the reset value might have.
-		 * (In the postmaster, there won't be a difference, but it does matter
-		 * in backends.)
-		 */
-		if (scres != 0 && applySettings)
-			set_config_sourcefile(item->name, item->filename,
-								  item->sourceline);
-
-		if (pre_value)
-			pfree(pre_value);
-	}
-
-	/* Remember when we last successfully loaded the config file. */
-	if (applySettings)
-		PgReloadTime = GetCurrentTimestamp();
-
-bail_out:
-	if (error && applySettings)
-	{
-		/* During postmaster startup, any error is fatal */
-		if (context == PGC_POSTMASTER)
-			ereport(ERROR,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors",
-							ConfFileWithError)));
-		else if (applying)
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
-							ConfFileWithError)));
-		else
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
-							ConfFileWithError)));
-	}
-
-	/* Successful or otherwise, return the collected data list */
-	return head;
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
 }
 
 /*
@@ -525,6 +160,7 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 		return pstrdup(location);
 	else
 	{
+		#ifndef FRONTEND
 		if (calling_file != NULL)
 		{
 			strlcpy(abs_path, calling_file, sizeof(abs_path));
@@ -538,6 +174,12 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 			join_path_components(abs_path, DataDir, location);
 			canonicalize_path(abs_path);
 		}
+		#else
+		strlcpy(abs_path, calling_file, sizeof(abs_path));
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, location);
+		canonicalize_path(abs_path);
+		#endif
 		return pstrdup(abs_path);
 	}
 }
@@ -574,10 +216,15 @@ ParseConfigFile(const char *config_file, bool strict,
 	 */
 	if (depth > 10)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
 						config_file)));
+		#else
+		printf(_("could not open configuration file \"%s\": maximum nesting depth exceeded\n"),
+				config_file);
+		#endif
 		record_config_file_error("nesting depth exceeded",
 								 calling_file, calling_lineno,
 								 head_p, tail_p);
@@ -585,15 +232,23 @@ ParseConfigFile(const char *config_file, bool strict,
 	}
 
 	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+	#ifndef FRONTEND
 	fp = AllocateFile(abs_path, "r");
+	#else
+	fp = fopen(abs_path, "r");
+	#endif
 	if (!fp)
 	{
 		if (strict)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not open configuration file \"%s\": %m",
 							abs_path)));
+			#else
+			printf(_("could not open configuration file \"%s\"\n"), abs_path);
+			#endif
 			record_config_file_error(psprintf("could not open file \"%s\"",
 											  abs_path),
 									 calling_file, calling_lineno,
@@ -602,9 +257,13 @@ ParseConfigFile(const char *config_file, bool strict,
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(LOG,
 					(errmsg("skipping missing configuration file \"%s\"",
 							abs_path)));
+			#else
+			printf(_("skipping missing configuration file \"%s\"\n"), abs_path);
+			#endif
 		}
 		goto cleanup;
 	}
@@ -613,7 +272,14 @@ ParseConfigFile(const char *config_file, bool strict,
 
 cleanup:
 	if (fp)
+	{
+		#ifndef FRONTEND
 		FreeFile(fp);
+		#else
+		fclose(fp);
+		#endif
+	}
+
 	pfree(abs_path);
 
 	return OK;
@@ -623,7 +289,7 @@ cleanup:
  * Capture an error message in the ConfigVariable list returned by
  * config file parsing.
  */
-static void
+void
 record_config_file_error(const char *errmsg,
 						 const char *config_file,
 						 int lineno,
@@ -715,8 +381,13 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		 * corrupted parser state.  Consequently, abandon the file, but trust
 		 * that the state remains sane enough for yy_delete_buffer().
 		 */
+		#ifndef FRONTEND
 		elog(elevel, "%s at file \"%s\" line %u",
 			 GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#else
+		printf(_("%s at file \"%s\" line %u\n"),
+				GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#endif
 		record_config_file_error(GUC_flex_fatal_errmsg,
 								 config_file, ConfigFileLineno,
 								 head_p, tail_p);
@@ -855,20 +526,30 @@ parse_error:
 		/* report the error */
 		if (token == GUC_EOL || token == 0)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			  errmsg("syntax error in file \"%s\" line %u, near end of line",
 					 config_file, ConfigFileLineno - 1)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near end of line\n"),
+											config_file, ConfigFileLineno - 1);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno - 1,
 									 head_p, tail_p);
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
 					config_file, ConfigFileLineno, yytext)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near token \"%s\"\n"),
+										config_file, ConfigFileLineno, yytext);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno,
 									 head_p, tail_p);
@@ -883,14 +564,23 @@ parse_error:
 		 * as well give up immediately.  (This prevents postmaster children
 		 * from bloating the logs with duplicate complaints.)
 		 */
+		#ifndef FRONTEND
 		if (errorcount >= 100 || elevel <= DEBUG1)
 		{
 			ereport(elevel,
 					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-			   errmsg("too many syntax errors found, abandoning file \"%s\"",
-					  config_file)));
+					 errmsg("too many syntax errors found, abandoning file \"%s\"",
+							config_file)));
 			break;
 		}
+		#else
+		if (errorcount >= 100)
+		{
+			printf(_("too many syntax errors found, abandoning file \"%s\"\n"),
+					config_file);
+			break;
+		}
+		#endif
 
 		/* resync to next end-of-line or EOF */
 		while (token != GUC_EOL && token != 0)
@@ -934,13 +624,21 @@ ParseConfigDirectory(const char *includedir,
 	bool		status;
 
 	directory = AbsoluteConfigLocation(includedir, calling_file);
+	#ifndef FRONTEND
 	d = AllocateDir(directory);
+	#else
+	d = opendir(directory);
+	#endif
 	if (d == NULL)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode_for_file_access(),
 				 errmsg("could not open configuration directory \"%s\": %m",
 						directory)));
+		#else
+		printf(_("could not open configuration directory \"%s\"\n"), directory);
+		#endif
 		record_config_file_error(psprintf("could not open directory \"%s\"",
 										  directory),
 								 calling_file, calling_lineno,
@@ -957,7 +655,11 @@ ParseConfigDirectory(const char *includedir,
 	filenames = (char **) palloc(size_filenames * sizeof(char *));
 	num_filenames = 0;
 
+	#ifndef FRONTEND
 	while ((de = ReadDir(d, directory)) != NULL)
+	#else
+	while ((de = readdir(d)) != NULL)
+	#endif
 	{
 		struct stat st;
 		char		filename[MAXPGPATH];
@@ -998,10 +700,14 @@ ParseConfigDirectory(const char *includedir,
 			 * a file can't be accessed now is if it was removed between the
 			 * directory listing and now.
 			 */
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not stat file \"%s\": %m",
 							filename)));
+			#else
+			printf(_("could not stat file \"%s\"\n"), filename);
+			#endif
 			record_config_file_error(psprintf("could not stat file \"%s\"",
 											  filename),
 									 calling_file, calling_lineno,
@@ -1032,7 +738,13 @@ ParseConfigDirectory(const char *includedir,
 
 cleanup:
 	if (d)
+	{
+		#ifndef FRONTEND
 		FreeDir(d);
+		#else
+		closedir(d);
+		#endif
+	}
 	pfree(directory);
 	return status;
 }
diff --git a/src/include/common/guc-file.h b/src/include/common/guc-file.h
new file mode 100644
index 0000000000..ca969e2aed
--- /dev/null
+++ b/src/include/common/guc-file.h
@@ -0,0 +1,50 @@
+#ifndef GUC_FILE_H
+#define GUC_FILE_H
+
+#include "c.h"
+
+/*
+ * Parsing the configuration file(s) will return a list of name-value pairs
+ * with source location info.  We also abuse this data structure to carry
+ * error reports about the config files.  An entry reporting an error will
+ * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
+ *
+ * If "ignore" is true, don't attempt to apply the item (it might be an error
+ * report, or an item we determined to be duplicate).  "applied" is set true
+ * if we successfully applied, or could have applied, the setting.
+ */
+typedef struct ConfigVariable
+{
+	char	   *name;
+	char	   *value;
+	char	   *errmsg;
+	char	   *filename;
+	int			sourceline;
+	bool		ignore;
+	bool		applied;
+	struct ConfigVariable *next;
+} ConfigVariable;
+
+extern bool ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigFp(FILE *fp, const char *config_file,
+			  int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p);
+extern void FreeConfigVariables(ConfigVariable *list);
+
+extern int	guc_name_compare(const char *namea, const char *nameb);
+
+extern void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+#endif							/* GUC_FILE_H */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index c07e7b945e..0b3391004c 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -1,8 +1,7 @@
 /*--------------------------------------------------------------------
  * guc.h
  *
- * External declarations pertaining to backend/utils/misc/guc.c and
- * backend/utils/misc/guc-file.l
+ * External declarations pertaining to backend/utils/misc/guc.c
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -120,42 +119,6 @@ typedef enum
 	PGC_S_SESSION				/* SET command */
 } GucSource;
 
-/*
- * Parsing the configuration file(s) will return a list of name-value pairs
- * with source location info.  We also abuse this data structure to carry
- * error reports about the config files.  An entry reporting an error will
- * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
- *
- * If "ignore" is true, don't attempt to apply the item (it might be an error
- * report, or an item we determined to be duplicate).  "applied" is set true
- * if we successfully applied, or could have applied, the setting.
- */
-typedef struct ConfigVariable
-{
-	char	   *name;
-	char	   *value;
-	char	   *errmsg;
-	char	   *filename;
-	int			sourceline;
-	bool		ignore;
-	bool		applied;
-	struct ConfigVariable *next;
-} ConfigVariable;
-
-extern bool ParseConfigFile(const char *config_file, bool strict,
-				const char *calling_file, int calling_lineno,
-				int depth, int elevel,
-				ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigFp(FILE *fp, const char *config_file,
-			  int depth, int elevel,
-			  ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigDirectory(const char *includedir,
-					 const char *calling_file, int calling_lineno,
-					 int depth, int elevel,
-					 ConfigVariable **head_p,
-					 ConfigVariable **tail_p);
-extern void FreeConfigVariables(ConfigVariable *list);
-
 /*
  * The possible values of an enum variable are specified by an array of
  * name-value pairs.  The "hidden" flag means the value is accepted but
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 56192f1b20..dd83329681 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -117,8 +117,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c exec.c file_perm.c ip.c
-	  keywords.c kwlookup.c link-canary.c md5.c
+	  base64.c config_info.c controldata_utils.c exec.c file_perm.c
+	  guc-file.c ip.c keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c unicode_norm.c username.c
 	  wait_error.c);
@@ -147,6 +147,7 @@ sub mkvcbuild
 
 	$libpgcommon = $solution->AddProject('libpgcommon', 'lib', 'misc');
 	$libpgcommon->AddDefine('FRONTEND');
+	$libpgcommon->AddFiles('src/common', 'guc-file.l');
 	$libpgcommon->AddFiles('src/common', @pgcommonfrontendfiles);
 
 	$libpgfeutils = $solution->AddProject('libpgfeutils', 'lib', 'misc');
@@ -163,6 +164,7 @@ sub mkvcbuild
 	$postgres->ReplaceFile('src/backend/port/pg_shmem.c',
 		'src/backend/port/win32_shmem.c');
 	$postgres->AddFiles('src/port',   @pgportfiles);
+	$postgres->AddFiles('src/common', 'guc-file.l');
 	$postgres->AddFiles('src/common', @pgcommonbkndfiles);
 	$postgres->AddDir('src/timezone');
 
@@ -172,7 +174,6 @@ sub mkvcbuild
 	$postgres->AddFiles('src/backend/parser', 'scan.l', 'gram.y');
 	$postgres->AddFiles('src/backend/bootstrap', 'bootscanner.l',
 		'bootparse.y');
-	$postgres->AddFiles('src/backend/utils/misc', 'guc-file.l');
 	$postgres->AddFiles(
 		'src/backend/replication', 'repl_scanner.l',
 		'repl_gram.y',             'syncrep_scanner.l',
diff --git a/src/tools/msvc/clean.bat b/src/tools/msvc/clean.bat
index 069d6eb569..53d77aaf0a 100755
--- a/src/tools/msvc/clean.bat
+++ b/src/tools/msvc/clean.bat
@@ -80,7 +80,7 @@ if %DIST%==1 if exist src\backend\parser\scan.c del /q src\backend\parser\scan.c
 if %DIST%==1 if exist src\backend\parser\gram.c del /q src\backend\parser\gram.c
 if %DIST%==1 if exist src\backend\bootstrap\bootscanner.c del /q src\backend\bootstrap\bootscanner.c
 if %DIST%==1 if exist src\backend\bootstrap\bootparse.c del /q src\backend\bootstrap\bootparse.c
-if %DIST%==1 if exist src\backend\utils\misc\guc-file.c del /q src\backend\utils\misc\guc-file.c
+if %DIST%==1 if exist src\common\guc-file.c del /q src\common\guc-file.c
 if %DIST%==1 if exist src\backend\replication\repl_scanner.c del /q src\backend\replication\repl_scanner.c
 if %DIST%==1 if exist src\backend\replication\repl_gram.c del /q src\backend\replication\repl_gram.c
 if %DIST%==1 if exist src\backend\replication\syncrep_scanner.c del /q src\backend\replication\syncrep_scanner.c

base-commit: 46682705986207795fa3eec9459df0b975c5ce03
-- 
2.17.1

From c012e1e1149d04abc39bb4099fe1e18a4cd2ca2d Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Mon, 18 Feb 2019 12:23:37 +0300
Subject: [PATCH v3 2/2] Options to use restore_command with pg_rewind

---
 doc/src/sgml/ref/pg_rewind.sgml       |  30 ++++-
 src/bin/pg_rewind/Makefile            |   2 +-
 src/bin/pg_rewind/parsexlog.c         | 163 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         | 100 +++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h         |  10 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  93 ++++++++++++++-
 9 files changed, 388 insertions(+), 22 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 53a64ee29e..0c2441afa7 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> option is specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -200,6 +202,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retreive missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/bin/pg_rewind/Makefile b/src/bin/pg_rewind/Makefile
index 04f3b8f520..65ebf3c78c 100644
--- a/src/bin/pg_rewind/Makefile
+++ b/src/bin/pg_rewind/Makefile
@@ -15,7 +15,7 @@ subdir = src/bin/pg_rewind
 top_builddir = ../../..
 include $(top_builddir)/src/Makefile.global
 
-override CPPFLAGS := -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
+override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) -DFRONTEND $(CPPFLAGS)
 LDFLAGS_INTERNAL += $(libpq_pgport)
 
 OBJS	= pg_rewind.o parsexlog.o xlogreader.o datapagemap.o timeline.o \
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index e19c265cbb..35c75cd8b9 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,6 +46,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -53,6 +55,9 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+					off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,7 +65,7 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -69,6 +74,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -156,7 +162,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +187,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -285,15 +292,37 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 		XLogFileName(xlogfname, targetHistory[private->tliIndex].tli,
 					 xlogreadsegno, WalSegSz);
 
-		snprintf(xlogfpath, MAXPGPATH, "%s/" XLOGDIR "/%s", private->datadir, xlogfname);
+		snprintf(xlogfpath, MAXPGPATH, "%s/" XLOGDIR "/%s",
+				 private->datadir, xlogfname);
 
 		xlogreadfd = open(xlogfpath, O_RDONLY | PG_BINARY, 0);
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
-				   strerror(errno));
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+					   strerror(errno));
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n",
+					   xlogfpath);
 		}
 	}
 
@@ -409,3 +438,125 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return true.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ *
+ * This is a simplified and adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *dp;
+	char	   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used during rewind process.\n");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size,
+						(unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					printf(_("could not open restored from archive file \"%s\": %s\n"),
+							xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath, strerror(errno));
+		}
+	}
+
+	printf(_("could not restore file \"%s\" from archive: %s\n"),
+			xlogfname, strerror(errno));
+
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 7ccde5c87f..5abfeec26c 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -26,6 +26,7 @@
 #include "catalog/pg_control.h"
 #include "common/file_perm.h"
 #include "common/file_utils.h"
+#include "common/guc-file.h"
 #include "common/restricted_token.h"
 #include "getopt_long.h"
 #include "storage/bufpage.h"
@@ -52,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +78,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,9 +100,12 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
+	char		recfile_fullpath[MAXPGPATH];
 	int			option_index;
 	int			c;
 	XLogRecPtr	divergerec;
@@ -129,7 +138,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +150,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +170,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +240,80 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			fprintf(stderr, _("%s: conflicting options: both -r and -R are specified\n"),
+				progname);
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf or -R/--restore-command.\n"),
+				progname);
+			exit(1);
+		}
+
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		FILE	*conf_file;
+
+		/*
+		 * Look for configuration file in the target data directory and
+		 * try to get restore_command from there.
+		 */
+		snprintf(recfile_fullpath, sizeof(recfile_fullpath), "%s/%s", datadir_target, RESTORE_COMMAND_FILE);
+		conf_file = fopen(recfile_fullpath, "r");
+
+		if (conf_file == NULL)
+		{
+			fprintf(stderr, _("%s: option -r/--use-postgresql-conf is specified, but postgresql.conf is absent in the target directory\n"),
+					progname);
+			fprintf(stderr, _("You have to add postgresql.conf or pass restore_command with -R/--restore-command option.\n"));
+			exit(1);
+		}
+		else
+		{
+			ConfigVariable *item,
+						   *head = NULL,
+						   *tail = NULL;
+			bool			config_is_parsed;
+
+			/*
+			 * We pass a fullpath to the configuration file as calling_file here, since
+			 * parser will use its parent directory as base for all further includes
+			 * if any exist.
+			 */
+			config_is_parsed = ParseConfigFile(RESTORE_COMMAND_FILE, true,
+											   recfile_fullpath, 0, 0,
+											   PG_WARNING, &head, &tail);
+			fclose(conf_file);
+
+			if (config_is_parsed)
+			{
+				for (item = head; item; item = item->next)
+				{
+					if (strcmp(item->name, "restore_command") == 0)
+					{
+						if (restore_command != NULL)
+						{
+							pfree(restore_command);
+							restore_command = NULL;
+						}
+						restore_command = pstrdup(item->value);
+						pg_log(PG_DEBUG, "using restore_command=\'%s\' from %s.\n", restore_command, RESTORE_COMMAND_FILE);
+					}
+				}
+
+				if (restore_command == NULL)
+					pg_fatal("could not find restore_command in %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+			}
+			else
+				pg_fatal("could not parse %s file %s\n", RESTORE_COMMAND_FILE, recfile_fullpath);
+
+			FreeConfigVariables(head);
+		}
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +385,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +409,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 83b2898b8b..23b9526f5d 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -14,9 +14,12 @@
 #include "datapagemap.h"
 
 #include "access/timeline.h"
+#include "catalog/pg_control.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
 
+#define RESTORE_COMMAND_FILE "postgresql.conf"
+
 /* Configuration options */
 extern char *datadir_target;
 extern char *datadir_source;
@@ -32,11 +35,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
+			   int tliIndex, XLogRecPtr endpoint, const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 6dc05720a1..99ea821cfe 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -62,5 +62,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 85cae7e47b..79bd6434b4 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catpath catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -249,6 +251,95 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $wals_archive_dir = catpath(${TestLib::tmp_check}, 'master_wals_archive');
+		my @wal_files = bsd_glob catpath($master_pgdata, 'pg_wal', '0000000*');
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command;
+
+		remove_tree($wals_archive_dir);
+		make_path($wals_archive_dir) or die;
+
+		# Move all old master WAL files to the archive.
+		# Old master should be stopped at this point.
+		foreach my $wal_file (@wal_files)
+		{
+			move($wal_file, "$wals_archive_dir") or die;
+		}
+
+		if ($windows_os)
+		{
+			$restore_command = "copy $wals_archive_dir\\\%f \%p";
+		}
+		else
+		{
+			$restore_command = "cp $wals_archive_dir/\%f \%p";
+		}
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
-- 
2.17.1

From 898caa8e7a46db63a1f182085dfde8ea1478ad62 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Mon, 18 Feb 2019 12:22:12 +0300
Subject: [PATCH v3 1/2] Make guc-file.l common for frontend and backend

---
 src/backend/Makefile                          |   4 +-
 src/backend/commands/extension.c              |   1 +
 src/backend/utils/misc/.gitignore             |   1 -
 src/backend/utils/misc/Makefile               |   8 -
 src/backend/utils/misc/guc.c                  | 434 +++++++++++++--
 src/common/.gitignore                         |   1 +
 src/common/Makefile                           |   9 +-
 src/{backend/utils/misc => common}/guc-file.l | 518 ++++--------------
 src/include/common/guc-file.h                 |  50 ++
 src/include/utils/guc.h                       |  39 +-
 src/tools/msvc/Mkvcbuild.pm                   |   7 +-
 src/tools/msvc/clean.bat                      |   2 +-
 12 files changed, 581 insertions(+), 493 deletions(-)
 delete mode 100644 src/backend/utils/misc/.gitignore
 rename src/{backend/utils/misc => common}/guc-file.l (60%)
 create mode 100644 src/include/common/guc-file.h

diff --git a/src/backend/Makefile b/src/backend/Makefile
index 478a96db9b..721cb57e89 100644
--- a/src/backend/Makefile
+++ b/src/backend/Makefile
@@ -186,7 +186,7 @@ distprep:
 	$(MAKE) -C replication	repl_gram.c repl_scanner.c syncrep_gram.c syncrep_scanner.c
 	$(MAKE) -C storage/lmgr	lwlocknames.h lwlocknames.c
 	$(MAKE) -C utils	distprep
-	$(MAKE) -C utils/misc	guc-file.c
+	$(MAKE) -C common	guc-file.c
 	$(MAKE) -C utils/sort	qsort_tuple.c
 
 
@@ -307,7 +307,7 @@ maintainer-clean: distclean
 	      replication/syncrep_scanner.c \
 	      storage/lmgr/lwlocknames.c \
 	      storage/lmgr/lwlocknames.h \
-	      utils/misc/guc-file.c \
+	      common/guc-file.c \
 	      utils/sort/qsort_tuple.c
 
 
diff --git a/src/backend/commands/extension.c b/src/backend/commands/extension.c
index daf3f51636..195eb8a821 100644
--- a/src/backend/commands/extension.c
+++ b/src/backend/commands/extension.c
@@ -50,6 +50,7 @@
 #include "commands/defrem.h"
 #include "commands/extension.h"
 #include "commands/schemacmds.h"
+#include "common/guc-file.h"
 #include "funcapi.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
diff --git a/src/backend/utils/misc/.gitignore b/src/backend/utils/misc/.gitignore
deleted file mode 100644
index 495b1aec76..0000000000
--- a/src/backend/utils/misc/.gitignore
+++ /dev/null
@@ -1 +0,0 @@
-/guc-file.c
diff --git a/src/backend/utils/misc/Makefile b/src/backend/utils/misc/Makefile
index ec7ec131e5..2205956a9f 100644
--- a/src/backend/utils/misc/Makefile
+++ b/src/backend/utils/misc/Makefile
@@ -25,11 +25,3 @@ override CPPFLAGS += -DPG_KRB_SRVTAB='"$(krb_srvtab)"'
 endif
 
 include $(top_srcdir)/src/backend/common.mk
-
-# guc-file is compiled as part of guc
-guc.o: guc-file.c
-
-# Note: guc-file.c is not deleted by 'make clean',
-# since we want to ship it in distribution tarballs.
-clean:
-	@rm -f lex.yy.c
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c
index 156d147c85..a784738e57 100644
--- a/src/backend/utils/misc/guc.c
+++ b/src/backend/utils/misc/guc.c
@@ -41,6 +41,7 @@
 #include "commands/vacuum.h"
 #include "commands/variable.h"
 #include "commands/trigger.h"
+#include "common/guc-file.h"
 #include "common/string.h"
 #include "funcapi.h"
 #include "jit/jit.h"
@@ -213,7 +214,6 @@ static void assign_recovery_target_lsn(const char *newval, void *extra);
 static bool check_primary_slot_name(char **newval, void **extra, GucSource source);
 static bool check_default_with_oids(bool *newval, void **extra, GucSource source);
 
-/* Private functions in guc-file.l that need to be called from guc.c */
 static ConfigVariable *ProcessConfigFileInternal(GucContext context,
 						  bool applySettings, int elevel);
 
@@ -4492,7 +4492,6 @@ static int	GUCNestLevel = 0;	/* 1 when in main transaction */
 
 
 static int	guc_var_compare(const void *a, const void *b);
-static int	guc_name_compare(const char *namea, const char *nameb);
 static void InitializeGUCOptionsFromEnvironment(void);
 static void InitializeOneGUCOption(struct config_generic *gconf);
 static void push_old_value(struct config_generic *gconf, GucAction action);
@@ -4969,37 +4968,6 @@ guc_var_compare(const void *a, const void *b)
 	return guc_name_compare(confa->name, confb->name);
 }
 
-/*
- * the bare comparison function for GUC names
- */
-static int
-guc_name_compare(const char *namea, const char *nameb)
-{
-	/*
-	 * The temptation to use strcasecmp() here must be resisted, because the
-	 * array ordering has to remain stable across setlocale() calls. So, build
-	 * our own with a simple ASCII-only downcasing.
-	 */
-	while (*namea && *nameb)
-	{
-		char		cha = *namea++;
-		char		chb = *nameb++;
-
-		if (cha >= 'A' && cha <= 'Z')
-			cha += 'a' - 'A';
-		if (chb >= 'A' && chb <= 'Z')
-			chb += 'a' - 'A';
-		if (cha != chb)
-			return cha - chb;
-	}
-	if (*namea)
-		return 1;				/* a is longer */
-	if (*nameb)
-		return -1;				/* b is longer */
-	return 0;
-}
-
-
 /*
  * Initialize GUC options during program startup.
  *
@@ -11384,4 +11352,402 @@ check_default_with_oids(bool *newval, void **extra, GucSource source)
 	return true;
 }
 
-#include "guc-file.c"
+/*
+ * Exported function to read and process the configuration file. The
+ * parameter indicates in what context the file is being read --- either
+ * postmaster startup (including standalone-backend startup) or SIGHUP.
+ * All options mentioned in the configuration file are set to new values.
+ * If a hard error occurs, no values will be changed.  (There can also be
+ * errors that prevent just one value from being changed.)
+ */
+void
+ProcessConfigFile(GucContext context)
+{
+	int			elevel;
+	MemoryContext config_cxt;
+	MemoryContext caller_cxt;
+
+	/*
+	 * Config files are processed on startup (by the postmaster only) and on
+	 * SIGHUP (by the postmaster and its children)
+	 */
+	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
+		   context == PGC_SIGHUP);
+
+	/*
+	 * To avoid cluttering the log, only the postmaster bleats loudly about
+	 * problems with the config file.
+	 */
+	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
+
+	/*
+	 * This function is usually called within a process-lifespan memory
+	 * context.  To ensure that any memory leaked during GUC processing does
+	 * not accumulate across repeated SIGHUP cycles, do the work in a private
+	 * context that we can free at exit.
+	 */
+	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
+									   "config file processing",
+									   ALLOCSET_DEFAULT_SIZES);
+	caller_cxt = MemoryContextSwitchTo(config_cxt);
+
+	/*
+	 * Read and apply the config file.  We don't need to examine the result.
+	 */
+	(void) ProcessConfigFileInternal(context, true, elevel);
+
+	/* Clean up */
+	MemoryContextSwitchTo(caller_cxt);
+	MemoryContextDelete(config_cxt);
+}
+
+/*
+ * This function handles both actual config file (re)loads and execution of
+ * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
+ * case we don't apply any of the settings, but we make all the usual validity
+ * checks, and we return the ConfigVariable list so that it can be printed out
+ * by show_all_file_settings().
+ */
+static ConfigVariable *
+ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+{
+	bool		error = false;
+	bool		applying = false;
+	const char *ConfFileWithError;
+	ConfigVariable *item,
+			   *head,
+			   *tail;
+	int			i;
+
+	/* Parse the main config file into a list of option names and values */
+	ConfFileWithError = ConfigFileName;
+	head = tail = NULL;
+
+	if (!ParseConfigFile(ConfigFileName, true,
+						 NULL, 0, 0, elevel,
+						 &head, &tail))
+	{
+		/* Syntax error(s) detected in the file, so bail out */
+		error = true;
+		goto bail_out;
+	}
+
+	/*
+	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
+	 * replace any parameters set by ALTER SYSTEM command.  Because this file
+	 * is in the data directory, we can't read it until the DataDir has been
+	 * set.
+	 */
+	if (DataDir)
+	{
+		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
+							 NULL, 0, 0, elevel,
+							 &head, &tail))
+		{
+			/* Syntax error(s) detected in the file, so bail out */
+			error = true;
+			ConfFileWithError = PG_AUTOCONF_FILENAME;
+			goto bail_out;
+		}
+	}
+	else
+	{
+		/*
+		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
+		 * read.  In this case, we don't want to accept any settings but
+		 * data_directory from postgresql.conf, because they might be
+		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
+		 * will be read later. OTOH, since data_directory isn't allowed in the
+		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
+		 */
+		ConfigVariable *newlist = NULL;
+
+		/*
+		 * Prune all items except the last "data_directory" from the list.
+		 */
+		for (item = head; item; item = item->next)
+		{
+			if (!item->ignore &&
+				strcmp(item->name, "data_directory") == 0)
+				newlist = item;
+		}
+
+		if (newlist)
+			newlist->next = NULL;
+		head = tail = newlist;
+
+		/*
+		 * Quick exit if data_directory is not present in file.
+		 *
+		 * We need not do any further processing, in particular we don't set
+		 * PgReloadTime; that will be set soon by subsequent full loading of
+		 * the config file.
+		 */
+		if (head == NULL)
+			goto bail_out;
+	}
+
+	/*
+	 * Mark all extant GUC variables as not present in the config file. We
+	 * need this so that we can tell below which ones have been removed from
+	 * the file since we last processed it.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+
+		gconf->status &= ~GUC_IS_IN_FILE;
+	}
+
+	/*
+	 * Check if all the supplied option names are valid, as an additional
+	 * quasi-syntactic check on the validity of the config file.  It is
+	 * important that the postmaster and all backends agree on the results of
+	 * this phase, else we will have strange inconsistencies about which
+	 * processes accept a config file update and which don't.  Hence, unknown
+	 * custom variable names have to be accepted without complaint.  For the
+	 * same reason, we don't attempt to validate the options' values here.
+	 *
+	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
+	 * variable mentioned in the file; and we detect duplicate entries in the
+	 * file and mark the earlier occurrences as ignorable.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		struct config_generic *record;
+
+		/* Ignore anything already marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/*
+		 * Try to find the variable; but do not create a custom placeholder if
+		 * it's not there already.
+		 */
+		record = find_option(item->name, false, elevel);
+
+		if (record)
+		{
+			/* If it's already marked, then this is a duplicate entry */
+			if (record->status & GUC_IS_IN_FILE)
+			{
+				/*
+				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
+				 * avoid the O(N^2) behavior here with some additional state,
+				 * but it seems unlikely to be worth the trouble.
+				 */
+				ConfigVariable *pitem;
+
+				for (pitem = head; pitem != item; pitem = pitem->next)
+				{
+					if (!pitem->ignore &&
+						strcmp(pitem->name, item->name) == 0)
+						pitem->ignore = true;
+				}
+			}
+			/* Now mark it as present in file */
+			record->status |= GUC_IS_IN_FILE;
+		}
+		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
+		{
+			/* Invalid non-custom variable, so complain */
+			ereport(elevel,
+					(errcode(ERRCODE_UNDEFINED_OBJECT),
+					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
+							item->name,
+							item->filename, item->sourceline)));
+			item->errmsg = pstrdup("unrecognized configuration parameter");
+			error = true;
+			ConfFileWithError = item->filename;
+		}
+	}
+
+	/*
+	 * If we've detected any errors so far, we don't want to risk applying any
+	 * changes.
+	 */
+	if (error)
+		goto bail_out;
+
+	/* Otherwise, set flag that we're beginning to apply changes */
+	applying = true;
+
+	/*
+	 * Check for variables having been removed from the config file, and
+	 * revert their reset values (and perhaps also effective values) to the
+	 * boot-time defaults.  If such a variable can't be changed after startup,
+	 * report that and continue.
+	 */
+	for (i = 0; i < num_guc_variables; i++)
+	{
+		struct config_generic *gconf = guc_variables[i];
+		GucStack   *stack;
+
+		if (gconf->reset_source != PGC_S_FILE ||
+			(gconf->status & GUC_IS_IN_FILE))
+			continue;
+		if (gconf->context < PGC_SIGHUP)
+		{
+			ereport(elevel,
+					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
+					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
+							gconf->name)));
+			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
+											  gconf->name),
+									 NULL, 0,
+									 &head, &tail);
+			error = true;
+			continue;
+		}
+
+		/* No more to do if we're just doing show_all_file_settings() */
+		if (!applySettings)
+			continue;
+
+		/*
+		 * Reset any "file" sources to "default", else set_config_option will
+		 * not override those settings.
+		 */
+		if (gconf->reset_source == PGC_S_FILE)
+			gconf->reset_source = PGC_S_DEFAULT;
+		if (gconf->source == PGC_S_FILE)
+			gconf->source = PGC_S_DEFAULT;
+		for (stack = gconf->stack; stack; stack = stack->prev)
+		{
+			if (stack->source == PGC_S_FILE)
+				stack->source = PGC_S_DEFAULT;
+		}
+
+		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
+		if (set_config_option(gconf->name, NULL,
+							  context, PGC_S_DEFAULT,
+							  GUC_ACTION_SET, true, 0, false) > 0)
+		{
+			/* Log the change if appropriate */
+			if (context == PGC_SIGHUP)
+				ereport(elevel,
+						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
+								gconf->name)));
+		}
+	}
+
+	/*
+	 * Restore any variables determined by environment variables or
+	 * dynamically-computed defaults.  This is a no-op except in the case
+	 * where one of these had been in the config file and is now removed.
+	 *
+	 * In particular, we *must not* do this during the postmaster's initial
+	 * loading of the file, since the timezone functions in particular should
+	 * be run only after initialization is complete.
+	 *
+	 * XXX this is an unmaintainable crock, because we have to know how to set
+	 * (or at least what to call to set) every variable that could potentially
+	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
+	 * time to redesign it for 9.1.
+	 */
+	if (context == PGC_SIGHUP && applySettings)
+	{
+		InitializeGUCOptionsFromEnvironment();
+		pg_timezone_abbrev_initialize();
+		/* this selects SQL_ASCII in processes not connected to a database */
+		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
+						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
+	}
+
+	/*
+	 * Now apply the values from the config file.
+	 */
+	for (item = head; item; item = item->next)
+	{
+		char	   *pre_value = NULL;
+		int			scres;
+
+		/* Ignore anything marked as ignorable */
+		if (item->ignore)
+			continue;
+
+		/* In SIGHUP cases in the postmaster, we want to report changes */
+		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
+		{
+			const char *preval = GetConfigOption(item->name, true, false);
+
+			/* If option doesn't exist yet or is NULL, treat as empty string */
+			if (!preval)
+				preval = "";
+			/* must dup, else might have dangling pointer below */
+			pre_value = pstrdup(preval);
+		}
+
+		scres = set_config_option(item->name, item->value,
+								  context, PGC_S_FILE,
+								  GUC_ACTION_SET, applySettings, 0, false);
+		if (scres > 0)
+		{
+			/* variable was updated, so log the change if appropriate */
+			if (pre_value)
+			{
+				const char *post_value = GetConfigOption(item->name, true, false);
+
+				if (!post_value)
+					post_value = "";
+				if (strcmp(pre_value, post_value) != 0)
+					ereport(elevel,
+							(errmsg("parameter \"%s\" changed to \"%s\"",
+									item->name, item->value)));
+			}
+			item->applied = true;
+		}
+		else if (scres == 0)
+		{
+			error = true;
+			item->errmsg = pstrdup("setting could not be applied");
+			ConfFileWithError = item->filename;
+		}
+		else
+		{
+			/* no error, but variable's active value was not changed */
+			item->applied = true;
+		}
+
+		/*
+		 * We should update source location unless there was an error, since
+		 * even if the active value didn't change, the reset value might have.
+		 * (In the postmaster, there won't be a difference, but it does matter
+		 * in backends.)
+		 */
+		if (scres != 0 && applySettings)
+			set_config_sourcefile(item->name, item->filename,
+								  item->sourceline);
+
+		if (pre_value)
+			pfree(pre_value);
+	}
+
+	/* Remember when we last successfully loaded the config file. */
+	if (applySettings)
+		PgReloadTime = GetCurrentTimestamp();
+
+bail_out:
+	if (error && applySettings)
+	{
+		/* During postmaster startup, any error is fatal */
+		if (context == PGC_POSTMASTER)
+			ereport(ERROR,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors",
+							ConfFileWithError)));
+		else if (applying)
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
+							ConfFileWithError)));
+		else
+			ereport(elevel,
+					(errcode(ERRCODE_CONFIG_FILE_ERROR),
+					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
+							ConfFileWithError)));
+	}
+
+	/* Successful or otherwise, return the collected data list */
+	return head;
+}
diff --git a/src/common/.gitignore b/src/common/.gitignore
index ffa3284fbf..424beacbc9 100644
--- a/src/common/.gitignore
+++ b/src/common/.gitignore
@@ -1 +1,2 @@
 /kwlist_d.h
+/guc-file.c
diff --git a/src/common/Makefile b/src/common/Makefile
index d84c7b6e6a..706e832811 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -50,7 +50,7 @@ OBJS_COMMON = base64.o config_info.o controldata_utils.o d2s.o exec.o f2s.o \
 	file_perm.o ip.o keywords.o kwlookup.o link-canary.o md5.o \
 	pg_lzcompress.o pgfnames.o psprintf.o relpath.o \
 	rmtree.o saslprep.o scram-common.o string.o unicode_norm.o \
-	username.o wait_error.o
+	username.o wait_error.o guc-file.o
 
 ifeq ($(with_openssl),yes)
 OBJS_COMMON += sha2_openssl.o
@@ -72,7 +72,7 @@ GEN_KEYWORDLIST_DEPS = $(TOOLSDIR)/gen_keywordlist.pl $(TOOLSDIR)/PerfectHash.pm
 
 all: libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 
-distprep: kwlist_d.h
+distprep: kwlist_d.h guc-file.c
 
 # libpgcommon is needed by some contrib
 install: all installdirs
@@ -139,10 +139,13 @@ RYU_OBJS = $(RYU_FILES) $(RYU_FILES:%.o=%_shlib.o) $(RYU_FILES:%.o=%_srv.o)
 
 $(RYU_OBJS): CFLAGS += $(PERMIT_DECLARATION_AFTER_STATEMENT)
 
-# kwlist_d.h is in the distribution tarball, so it is not cleaned here.
+# Note: guc-file.c and kwlist_d.h are not deleted by 'make clean',
+# since we want to ship them in distribution tarballs.
 clean distclean:
 	rm -f libpgcommon.a libpgcommon_shlib.a libpgcommon_srv.a
 	rm -f $(OBJS_FRONTEND) $(OBJS_SHLIB) $(OBJS_SRV)
+	@rm -f lex.yy.c
 
 maintainer-clean: distclean
 	rm -f kwlist_d.h
+	rm -f guc-file.c
diff --git a/src/backend/utils/misc/guc-file.l b/src/common/guc-file.l
similarity index 60%
rename from src/backend/utils/misc/guc-file.l
rename to src/common/guc-file.l
index 1c8b5f7d84..175685c9b5 100644
--- a/src/backend/utils/misc/guc-file.l
+++ b/src/common/guc-file.l
@@ -4,21 +4,31 @@
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  *
- * src/backend/utils/misc/guc-file.l
+ * src/common/guc-file.l
  */
 
 %{
 
+#ifndef FRONTEND
 #include "postgres.h"
 
-#include <ctype.h>
-#include <unistd.h>
-
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
 #include "storage/fd.h"
 #include "utils/guc.h"
+#include "utils/elog.h"
+#else
+#include "postgres_fe.h"
+
+#include <dirent.h>
+#include <setjmp.h>
+#endif
+
+#include <ctype.h>
+#include <unistd.h>
+#include <sys/stat.h>
 
+#include "common/guc-file.h"
 
 /*
  * flex emits a yy_fatal_error() function that it calls in response to
@@ -48,12 +58,6 @@ static sigjmp_buf *GUC_flex_fatal_jmp;
 
 static void FreeConfigVariable(ConfigVariable *item);
 
-static void record_config_file_error(const char *errmsg,
-						 const char *config_file,
-						 int lineno,
-						 ConfigVariable **head_p,
-						 ConfigVariable **tail_p);
-
 static int	GUC_flex_fatal(const char *msg);
 static char *GUC_scanstr(const char *s);
 
@@ -111,404 +115,35 @@ STRING			\'([^'\\\n]|\\.|\'\')*\'
 
 /* LCOV_EXCL_STOP */
 
-/*
- * Exported function to read and process the configuration file. The
- * parameter indicates in what context the file is being read --- either
- * postmaster startup (including standalone-backend startup) or SIGHUP.
- * All options mentioned in the configuration file are set to new values.
- * If a hard error occurs, no values will be changed.  (There can also be
- * errors that prevent just one value from being changed.)
- */
-void
-ProcessConfigFile(GucContext context)
-{
-	int			elevel;
-	MemoryContext config_cxt;
-	MemoryContext caller_cxt;
-
-	/*
-	 * Config files are processed on startup (by the postmaster only) and on
-	 * SIGHUP (by the postmaster and its children)
-	 */
-	Assert((context == PGC_POSTMASTER && !IsUnderPostmaster) ||
-		   context == PGC_SIGHUP);
-
-	/*
-	 * To avoid cluttering the log, only the postmaster bleats loudly about
-	 * problems with the config file.
-	 */
-	elevel = IsUnderPostmaster ? DEBUG2 : LOG;
-
-	/*
-	 * This function is usually called within a process-lifespan memory
-	 * context.  To ensure that any memory leaked during GUC processing does
-	 * not accumulate across repeated SIGHUP cycles, do the work in a private
-	 * context that we can free at exit.
-	 */
-	config_cxt = AllocSetContextCreate(CurrentMemoryContext,
-									   "config file processing",
-									   ALLOCSET_DEFAULT_SIZES);
-	caller_cxt = MemoryContextSwitchTo(config_cxt);
-
-	/*
-	 * Read and apply the config file.  We don't need to examine the result.
-	 */
-	(void) ProcessConfigFileInternal(context, true, elevel);
-
-	/* Clean up */
-	MemoryContextSwitchTo(caller_cxt);
-	MemoryContextDelete(config_cxt);
-}
 
 /*
- * This function handles both actual config file (re)loads and execution of
- * show_all_file_settings() (i.e., the pg_file_settings view).  In the latter
- * case we don't apply any of the settings, but we make all the usual validity
- * checks, and we return the ConfigVariable list so that it can be printed out
- * by show_all_file_settings().
+ * The bare comparison function for GUC names.
  */
-static ConfigVariable *
-ProcessConfigFileInternal(GucContext context, bool applySettings, int elevel)
+int
+guc_name_compare(const char *namea, const char *nameb)
 {
-	bool		error = false;
-	bool		applying = false;
-	const char *ConfFileWithError;
-	ConfigVariable *item,
-			   *head,
-			   *tail;
-	int			i;
-
-	/* Parse the main config file into a list of option names and values */
-	ConfFileWithError = ConfigFileName;
-	head = tail = NULL;
-
-	if (!ParseConfigFile(ConfigFileName, true,
-						 NULL, 0, 0, elevel,
-						 &head, &tail))
-	{
-		/* Syntax error(s) detected in the file, so bail out */
-		error = true;
-		goto bail_out;
-	}
-
-	/*
-	 * Parse the PG_AUTOCONF_FILENAME file, if present, after the main file to
-	 * replace any parameters set by ALTER SYSTEM command.  Because this file
-	 * is in the data directory, we can't read it until the DataDir has been
-	 * set.
-	 */
-	if (DataDir)
-	{
-		if (!ParseConfigFile(PG_AUTOCONF_FILENAME, false,
-							 NULL, 0, 0, elevel,
-							 &head, &tail))
-		{
-			/* Syntax error(s) detected in the file, so bail out */
-			error = true;
-			ConfFileWithError = PG_AUTOCONF_FILENAME;
-			goto bail_out;
-		}
-	}
-	else
-	{
-		/*
-		 * If DataDir is not set, the PG_AUTOCONF_FILENAME file cannot be
-		 * read.  In this case, we don't want to accept any settings but
-		 * data_directory from postgresql.conf, because they might be
-		 * overwritten with settings in the PG_AUTOCONF_FILENAME file which
-		 * will be read later. OTOH, since data_directory isn't allowed in the
-		 * PG_AUTOCONF_FILENAME file, it will never be overwritten later.
-		 */
-		ConfigVariable *newlist = NULL;
-
-		/*
-		 * Prune all items except the last "data_directory" from the list.
-		 */
-		for (item = head; item; item = item->next)
-		{
-			if (!item->ignore &&
-				strcmp(item->name, "data_directory") == 0)
-				newlist = item;
-		}
-
-		if (newlist)
-			newlist->next = NULL;
-		head = tail = newlist;
-
-		/*
-		 * Quick exit if data_directory is not present in file.
-		 *
-		 * We need not do any further processing, in particular we don't set
-		 * PgReloadTime; that will be set soon by subsequent full loading of
-		 * the config file.
-		 */
-		if (head == NULL)
-			goto bail_out;
-	}
-
 	/*
-	 * Mark all extant GUC variables as not present in the config file. We
-	 * need this so that we can tell below which ones have been removed from
-	 * the file since we last processed it.
+	 * The temptation to use strcasecmp() here must be resisted, because the
+	 * array ordering has to remain stable across setlocale() calls. So, build
+	 * our own with a simple ASCII-only downcasing.
 	 */
-	for (i = 0; i < num_guc_variables; i++)
+	while (*namea && *nameb)
 	{
-		struct config_generic *gconf = guc_variables[i];
-
-		gconf->status &= ~GUC_IS_IN_FILE;
-	}
-
-	/*
-	 * Check if all the supplied option names are valid, as an additional
-	 * quasi-syntactic check on the validity of the config file.  It is
-	 * important that the postmaster and all backends agree on the results of
-	 * this phase, else we will have strange inconsistencies about which
-	 * processes accept a config file update and which don't.  Hence, unknown
-	 * custom variable names have to be accepted without complaint.  For the
-	 * same reason, we don't attempt to validate the options' values here.
-	 *
-	 * In addition, the GUC_IS_IN_FILE flag is set on each existing GUC
-	 * variable mentioned in the file; and we detect duplicate entries in the
-	 * file and mark the earlier occurrences as ignorable.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		struct config_generic *record;
-
-		/* Ignore anything already marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/*
-		 * Try to find the variable; but do not create a custom placeholder if
-		 * it's not there already.
-		 */
-		record = find_option(item->name, false, elevel);
-
-		if (record)
-		{
-			/* If it's already marked, then this is a duplicate entry */
-			if (record->status & GUC_IS_IN_FILE)
-			{
-				/*
-				 * Mark the earlier occurrence(s) as dead/ignorable.  We could
-				 * avoid the O(N^2) behavior here with some additional state,
-				 * but it seems unlikely to be worth the trouble.
-				 */
-				ConfigVariable *pitem;
-
-				for (pitem = head; pitem != item; pitem = pitem->next)
-				{
-					if (!pitem->ignore &&
-						strcmp(pitem->name, item->name) == 0)
-						pitem->ignore = true;
-				}
-			}
-			/* Now mark it as present in file */
-			record->status |= GUC_IS_IN_FILE;
-		}
-		else if (strchr(item->name, GUC_QUALIFIER_SEPARATOR) == NULL)
-		{
-			/* Invalid non-custom variable, so complain */
-			ereport(elevel,
-					(errcode(ERRCODE_UNDEFINED_OBJECT),
-					 errmsg("unrecognized configuration parameter \"%s\" in file \"%s\" line %u",
-							item->name,
-							item->filename, item->sourceline)));
-			item->errmsg = pstrdup("unrecognized configuration parameter");
-			error = true;
-			ConfFileWithError = item->filename;
-		}
+		char		cha = *namea++;
+		char		chb = *nameb++;
+
+		if (cha >= 'A' && cha <= 'Z')
+			cha += 'a' - 'A';
+		if (chb >= 'A' && chb <= 'Z')
+			chb += 'a' - 'A';
+		if (cha != chb)
+			return cha - chb;
 	}
-
-	/*
-	 * If we've detected any errors so far, we don't want to risk applying any
-	 * changes.
-	 */
-	if (error)
-		goto bail_out;
-
-	/* Otherwise, set flag that we're beginning to apply changes */
-	applying = true;
-
-	/*
-	 * Check for variables having been removed from the config file, and
-	 * revert their reset values (and perhaps also effective values) to the
-	 * boot-time defaults.  If such a variable can't be changed after startup,
-	 * report that and continue.
-	 */
-	for (i = 0; i < num_guc_variables; i++)
-	{
-		struct config_generic *gconf = guc_variables[i];
-		GucStack   *stack;
-
-		if (gconf->reset_source != PGC_S_FILE ||
-			(gconf->status & GUC_IS_IN_FILE))
-			continue;
-		if (gconf->context < PGC_SIGHUP)
-		{
-			ereport(elevel,
-					(errcode(ERRCODE_CANT_CHANGE_RUNTIME_PARAM),
-					 errmsg("parameter \"%s\" cannot be changed without restarting the server",
-							gconf->name)));
-			record_config_file_error(psprintf("parameter \"%s\" cannot be changed without restarting the server",
-											  gconf->name),
-									 NULL, 0,
-									 &head, &tail);
-			error = true;
-			continue;
-		}
-
-		/* No more to do if we're just doing show_all_file_settings() */
-		if (!applySettings)
-			continue;
-
-		/*
-		 * Reset any "file" sources to "default", else set_config_option will
-		 * not override those settings.
-		 */
-		if (gconf->reset_source == PGC_S_FILE)
-			gconf->reset_source = PGC_S_DEFAULT;
-		if (gconf->source == PGC_S_FILE)
-			gconf->source = PGC_S_DEFAULT;
-		for (stack = gconf->stack; stack; stack = stack->prev)
-		{
-			if (stack->source == PGC_S_FILE)
-				stack->source = PGC_S_DEFAULT;
-		}
-
-		/* Now we can re-apply the wired-in default (i.e., the boot_val) */
-		if (set_config_option(gconf->name, NULL,
-							  context, PGC_S_DEFAULT,
-							  GUC_ACTION_SET, true, 0, false) > 0)
-		{
-			/* Log the change if appropriate */
-			if (context == PGC_SIGHUP)
-				ereport(elevel,
-						(errmsg("parameter \"%s\" removed from configuration file, reset to default",
-								gconf->name)));
-		}
-	}
-
-	/*
-	 * Restore any variables determined by environment variables or
-	 * dynamically-computed defaults.  This is a no-op except in the case
-	 * where one of these had been in the config file and is now removed.
-	 *
-	 * In particular, we *must not* do this during the postmaster's initial
-	 * loading of the file, since the timezone functions in particular should
-	 * be run only after initialization is complete.
-	 *
-	 * XXX this is an unmaintainable crock, because we have to know how to set
-	 * (or at least what to call to set) every variable that could potentially
-	 * have PGC_S_DYNAMIC_DEFAULT or PGC_S_ENV_VAR source. However, there's no
-	 * time to redesign it for 9.1.
-	 */
-	if (context == PGC_SIGHUP && applySettings)
-	{
-		InitializeGUCOptionsFromEnvironment();
-		pg_timezone_abbrev_initialize();
-		/* this selects SQL_ASCII in processes not connected to a database */
-		SetConfigOption("client_encoding", GetDatabaseEncodingName(),
-						PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT);
-	}
-
-	/*
-	 * Now apply the values from the config file.
-	 */
-	for (item = head; item; item = item->next)
-	{
-		char	   *pre_value = NULL;
-		int			scres;
-
-		/* Ignore anything marked as ignorable */
-		if (item->ignore)
-			continue;
-
-		/* In SIGHUP cases in the postmaster, we want to report changes */
-		if (context == PGC_SIGHUP && applySettings && !IsUnderPostmaster)
-		{
-			const char *preval = GetConfigOption(item->name, true, false);
-
-			/* If option doesn't exist yet or is NULL, treat as empty string */
-			if (!preval)
-				preval = "";
-			/* must dup, else might have dangling pointer below */
-			pre_value = pstrdup(preval);
-		}
-
-		scres = set_config_option(item->name, item->value,
-								  context, PGC_S_FILE,
-								  GUC_ACTION_SET, applySettings, 0, false);
-		if (scres > 0)
-		{
-			/* variable was updated, so log the change if appropriate */
-			if (pre_value)
-			{
-				const char *post_value = GetConfigOption(item->name, true, false);
-
-				if (!post_value)
-					post_value = "";
-				if (strcmp(pre_value, post_value) != 0)
-					ereport(elevel,
-							(errmsg("parameter \"%s\" changed to \"%s\"",
-									item->name, item->value)));
-			}
-			item->applied = true;
-		}
-		else if (scres == 0)
-		{
-			error = true;
-			item->errmsg = pstrdup("setting could not be applied");
-			ConfFileWithError = item->filename;
-		}
-		else
-		{
-			/* no error, but variable's active value was not changed */
-			item->applied = true;
-		}
-
-		/*
-		 * We should update source location unless there was an error, since
-		 * even if the active value didn't change, the reset value might have.
-		 * (In the postmaster, there won't be a difference, but it does matter
-		 * in backends.)
-		 */
-		if (scres != 0 && applySettings)
-			set_config_sourcefile(item->name, item->filename,
-								  item->sourceline);
-
-		if (pre_value)
-			pfree(pre_value);
-	}
-
-	/* Remember when we last successfully loaded the config file. */
-	if (applySettings)
-		PgReloadTime = GetCurrentTimestamp();
-
-bail_out:
-	if (error && applySettings)
-	{
-		/* During postmaster startup, any error is fatal */
-		if (context == PGC_POSTMASTER)
-			ereport(ERROR,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors",
-							ConfFileWithError)));
-		else if (applying)
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; unaffected changes were applied",
-							ConfFileWithError)));
-		else
-			ereport(elevel,
-					(errcode(ERRCODE_CONFIG_FILE_ERROR),
-					 errmsg("configuration file \"%s\" contains errors; no changes were applied",
-							ConfFileWithError)));
-	}
-
-	/* Successful or otherwise, return the collected data list */
-	return head;
+	if (*namea)
+		return 1;				/* a is longer */
+	if (*nameb)
+		return -1;				/* b is longer */
+	return 0;
 }
 
 /*
@@ -525,6 +160,7 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 		return pstrdup(location);
 	else
 	{
+		#ifndef FRONTEND
 		if (calling_file != NULL)
 		{
 			strlcpy(abs_path, calling_file, sizeof(abs_path));
@@ -538,6 +174,12 @@ AbsoluteConfigLocation(const char *location, const char *calling_file)
 			join_path_components(abs_path, DataDir, location);
 			canonicalize_path(abs_path);
 		}
+		#else
+		strlcpy(abs_path, calling_file, sizeof(abs_path));
+		get_parent_directory(abs_path);
+		join_path_components(abs_path, abs_path, location);
+		canonicalize_path(abs_path);
+		#endif
 		return pstrdup(abs_path);
 	}
 }
@@ -574,10 +216,15 @@ ParseConfigFile(const char *config_file, bool strict,
 	 */
 	if (depth > 10)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
 				 errmsg("could not open configuration file \"%s\": maximum nesting depth exceeded",
 						config_file)));
+		#else
+		printf(_("could not open configuration file \"%s\": maximum nesting depth exceeded\n"),
+				config_file);
+		#endif
 		record_config_file_error("nesting depth exceeded",
 								 calling_file, calling_lineno,
 								 head_p, tail_p);
@@ -585,15 +232,23 @@ ParseConfigFile(const char *config_file, bool strict,
 	}
 
 	abs_path = AbsoluteConfigLocation(config_file, calling_file);
+	#ifndef FRONTEND
 	fp = AllocateFile(abs_path, "r");
+	#else
+	fp = fopen(abs_path, "r");
+	#endif
 	if (!fp)
 	{
 		if (strict)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not open configuration file \"%s\": %m",
 							abs_path)));
+			#else
+			printf(_("could not open configuration file \"%s\"\n"), abs_path);
+			#endif
 			record_config_file_error(psprintf("could not open file \"%s\"",
 											  abs_path),
 									 calling_file, calling_lineno,
@@ -602,9 +257,13 @@ ParseConfigFile(const char *config_file, bool strict,
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(LOG,
 					(errmsg("skipping missing configuration file \"%s\"",
 							abs_path)));
+			#else
+			printf(_("skipping missing configuration file \"%s\"\n"), abs_path);
+			#endif
 		}
 		goto cleanup;
 	}
@@ -613,7 +272,14 @@ ParseConfigFile(const char *config_file, bool strict,
 
 cleanup:
 	if (fp)
+	{
+		#ifndef FRONTEND
 		FreeFile(fp);
+		#else
+		fclose(fp);
+		#endif
+	}
+
 	pfree(abs_path);
 
 	return OK;
@@ -623,7 +289,7 @@ cleanup:
  * Capture an error message in the ConfigVariable list returned by
  * config file parsing.
  */
-static void
+void
 record_config_file_error(const char *errmsg,
 						 const char *config_file,
 						 int lineno,
@@ -715,8 +381,13 @@ ParseConfigFp(FILE *fp, const char *config_file, int depth, int elevel,
 		 * corrupted parser state.  Consequently, abandon the file, but trust
 		 * that the state remains sane enough for yy_delete_buffer().
 		 */
+		#ifndef FRONTEND
 		elog(elevel, "%s at file \"%s\" line %u",
 			 GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#else
+		printf(_("%s at file \"%s\" line %u\n"),
+				GUC_flex_fatal_errmsg, config_file, ConfigFileLineno);
+		#endif
 		record_config_file_error(GUC_flex_fatal_errmsg,
 								 config_file, ConfigFileLineno,
 								 head_p, tail_p);
@@ -855,20 +526,30 @@ parse_error:
 		/* report the error */
 		if (token == GUC_EOL || token == 0)
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			  errmsg("syntax error in file \"%s\" line %u, near end of line",
 					 config_file, ConfigFileLineno - 1)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near end of line\n"),
+											config_file, ConfigFileLineno - 1);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno - 1,
 									 head_p, tail_p);
 		}
 		else
 		{
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode(ERRCODE_SYNTAX_ERROR),
 			 errmsg("syntax error in file \"%s\" line %u, near token \"%s\"",
 					config_file, ConfigFileLineno, yytext)));
+			#else
+			printf(_("syntax error in file \"%s\" line %u, near token \"%s\"\n"),
+										config_file, ConfigFileLineno, yytext);
+			#endif
 			record_config_file_error("syntax error",
 									 config_file, ConfigFileLineno,
 									 head_p, tail_p);
@@ -883,14 +564,23 @@ parse_error:
 		 * as well give up immediately.  (This prevents postmaster children
 		 * from bloating the logs with duplicate complaints.)
 		 */
+		#ifndef FRONTEND
 		if (errorcount >= 100 || elevel <= DEBUG1)
 		{
 			ereport(elevel,
 					(errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED),
-			   errmsg("too many syntax errors found, abandoning file \"%s\"",
-					  config_file)));
+					 errmsg("too many syntax errors found, abandoning file \"%s\"",
+							config_file)));
 			break;
 		}
+		#else
+		if (errorcount >= 100)
+		{
+			printf(_("too many syntax errors found, abandoning file \"%s\"\n"),
+					config_file);
+			break;
+		}
+		#endif
 
 		/* resync to next end-of-line or EOF */
 		while (token != GUC_EOL && token != 0)
@@ -934,13 +624,21 @@ ParseConfigDirectory(const char *includedir,
 	bool		status;
 
 	directory = AbsoluteConfigLocation(includedir, calling_file);
+	#ifndef FRONTEND
 	d = AllocateDir(directory);
+	#else
+	d = opendir(directory);
+	#endif
 	if (d == NULL)
 	{
+		#ifndef FRONTEND
 		ereport(elevel,
 				(errcode_for_file_access(),
 				 errmsg("could not open configuration directory \"%s\": %m",
 						directory)));
+		#else
+		printf(_("could not open configuration directory \"%s\"\n"), directory);
+		#endif
 		record_config_file_error(psprintf("could not open directory \"%s\"",
 										  directory),
 								 calling_file, calling_lineno,
@@ -957,7 +655,11 @@ ParseConfigDirectory(const char *includedir,
 	filenames = (char **) palloc(size_filenames * sizeof(char *));
 	num_filenames = 0;
 
+	#ifndef FRONTEND
 	while ((de = ReadDir(d, directory)) != NULL)
+	#else
+	while ((de = readdir(d)) != NULL)
+	#endif
 	{
 		struct stat st;
 		char		filename[MAXPGPATH];
@@ -998,10 +700,14 @@ ParseConfigDirectory(const char *includedir,
 			 * a file can't be accessed now is if it was removed between the
 			 * directory listing and now.
 			 */
+			#ifndef FRONTEND
 			ereport(elevel,
 					(errcode_for_file_access(),
 					 errmsg("could not stat file \"%s\": %m",
 							filename)));
+			#else
+			printf(_("could not stat file \"%s\"\n"), filename);
+			#endif
 			record_config_file_error(psprintf("could not stat file \"%s\"",
 											  filename),
 									 calling_file, calling_lineno,
@@ -1032,7 +738,13 @@ ParseConfigDirectory(const char *includedir,
 
 cleanup:
 	if (d)
+	{
+		#ifndef FRONTEND
 		FreeDir(d);
+		#else
+		closedir(d);
+		#endif
+	}
 	pfree(directory);
 	return status;
 }
diff --git a/src/include/common/guc-file.h b/src/include/common/guc-file.h
new file mode 100644
index 0000000000..ca969e2aed
--- /dev/null
+++ b/src/include/common/guc-file.h
@@ -0,0 +1,50 @@
+#ifndef GUC_FILE_H
+#define GUC_FILE_H
+
+#include "c.h"
+
+/*
+ * Parsing the configuration file(s) will return a list of name-value pairs
+ * with source location info.  We also abuse this data structure to carry
+ * error reports about the config files.  An entry reporting an error will
+ * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
+ *
+ * If "ignore" is true, don't attempt to apply the item (it might be an error
+ * report, or an item we determined to be duplicate).  "applied" is set true
+ * if we successfully applied, or could have applied, the setting.
+ */
+typedef struct ConfigVariable
+{
+	char	   *name;
+	char	   *value;
+	char	   *errmsg;
+	char	   *filename;
+	int			sourceline;
+	bool		ignore;
+	bool		applied;
+	struct ConfigVariable *next;
+} ConfigVariable;
+
+extern bool ParseConfigFile(const char *config_file, bool strict,
+				const char *calling_file, int calling_lineno,
+				int depth, int elevel,
+				ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigFp(FILE *fp, const char *config_file,
+			  int depth, int elevel,
+			  ConfigVariable **head_p, ConfigVariable **tail_p);
+extern bool ParseConfigDirectory(const char *includedir,
+					 const char *calling_file, int calling_lineno,
+					 int depth, int elevel,
+					 ConfigVariable **head_p,
+					 ConfigVariable **tail_p);
+extern void FreeConfigVariables(ConfigVariable *list);
+
+extern int	guc_name_compare(const char *namea, const char *nameb);
+
+extern void record_config_file_error(const char *errmsg,
+						 const char *config_file,
+						 int lineno,
+						 ConfigVariable **head_p,
+						 ConfigVariable **tail_p);
+
+#endif							/* GUC_FILE_H */
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index c07e7b945e..0b3391004c 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -1,8 +1,7 @@
 /*--------------------------------------------------------------------
  * guc.h
  *
- * External declarations pertaining to backend/utils/misc/guc.c and
- * backend/utils/misc/guc-file.l
+ * External declarations pertaining to backend/utils/misc/guc.c
  *
  * Copyright (c) 2000-2019, PostgreSQL Global Development Group
  * Written by Peter Eisentraut <peter_e@gmx.net>.
@@ -120,42 +119,6 @@ typedef enum
 	PGC_S_SESSION				/* SET command */
 } GucSource;
 
-/*
- * Parsing the configuration file(s) will return a list of name-value pairs
- * with source location info.  We also abuse this data structure to carry
- * error reports about the config files.  An entry reporting an error will
- * have errmsg != NULL, and might have NULLs for name, value, and/or filename.
- *
- * If "ignore" is true, don't attempt to apply the item (it might be an error
- * report, or an item we determined to be duplicate).  "applied" is set true
- * if we successfully applied, or could have applied, the setting.
- */
-typedef struct ConfigVariable
-{
-	char	   *name;
-	char	   *value;
-	char	   *errmsg;
-	char	   *filename;
-	int			sourceline;
-	bool		ignore;
-	bool		applied;
-	struct ConfigVariable *next;
-} ConfigVariable;
-
-extern bool ParseConfigFile(const char *config_file, bool strict,
-				const char *calling_file, int calling_lineno,
-				int depth, int elevel,
-				ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigFp(FILE *fp, const char *config_file,
-			  int depth, int elevel,
-			  ConfigVariable **head_p, ConfigVariable **tail_p);
-extern bool ParseConfigDirectory(const char *includedir,
-					 const char *calling_file, int calling_lineno,
-					 int depth, int elevel,
-					 ConfigVariable **head_p,
-					 ConfigVariable **tail_p);
-extern void FreeConfigVariables(ConfigVariable *list);
-
 /*
  * The possible values of an enum variable are specified by an array of
  * name-value pairs.  The "hidden" flag means the value is accepted but
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index f4225030fc..3ade1d51c0 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c exec.c f2s.c file_perm.c ip.c
-	  keywords.c kwlookup.c link-canary.c md5.c
+	  base64.c config_info.c controldata_utils.c d2s.c exec.c f2s.c file_perm.c
+	  guc-file.c ip.c keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c unicode_norm.c username.c
 	  wait_error.c);
@@ -149,6 +149,7 @@ sub mkvcbuild
 
 	$libpgcommon = $solution->AddProject('libpgcommon', 'lib', 'misc');
 	$libpgcommon->AddDefine('FRONTEND');
+	$libpgcommon->AddFiles('src/common', 'guc-file.l');
 	$libpgcommon->AddFiles('src/common', @pgcommonfrontendfiles);
 
 	$libpgfeutils = $solution->AddProject('libpgfeutils', 'lib', 'misc');
@@ -165,6 +166,7 @@ sub mkvcbuild
 	$postgres->ReplaceFile('src/backend/port/pg_shmem.c',
 		'src/backend/port/win32_shmem.c');
 	$postgres->AddFiles('src/port',   @pgportfiles);
+	$postgres->AddFiles('src/common', 'guc-file.l');
 	$postgres->AddFiles('src/common', @pgcommonbkndfiles);
 	$postgres->AddDir('src/timezone');
 
@@ -174,7 +176,6 @@ sub mkvcbuild
 	$postgres->AddFiles('src/backend/parser', 'scan.l', 'gram.y');
 	$postgres->AddFiles('src/backend/bootstrap', 'bootscanner.l',
 		'bootparse.y');
-	$postgres->AddFiles('src/backend/utils/misc', 'guc-file.l');
 	$postgres->AddFiles(
 		'src/backend/replication', 'repl_scanner.l',
 		'repl_gram.y',             'syncrep_scanner.l',
diff --git a/src/tools/msvc/clean.bat b/src/tools/msvc/clean.bat
index 069d6eb569..53d77aaf0a 100755
--- a/src/tools/msvc/clean.bat
+++ b/src/tools/msvc/clean.bat
@@ -80,7 +80,7 @@ if %DIST%==1 if exist src\backend\parser\scan.c del /q src\backend\parser\scan.c
 if %DIST%==1 if exist src\backend\parser\gram.c del /q src\backend\parser\gram.c
 if %DIST%==1 if exist src\backend\bootstrap\bootscanner.c del /q src\backend\bootstrap\bootscanner.c
 if %DIST%==1 if exist src\backend\bootstrap\bootparse.c del /q src\backend\bootstrap\bootparse.c
-if %DIST%==1 if exist src\backend\utils\misc\guc-file.c del /q src\backend\utils\misc\guc-file.c
+if %DIST%==1 if exist src\common\guc-file.c del /q src\common\guc-file.c
 if %DIST%==1 if exist src\backend\replication\repl_scanner.c del /q src\backend\replication\repl_scanner.c
 if %DIST%==1 if exist src\backend\replication\repl_gram.c del /q src\backend\replication\repl_gram.c
 if %DIST%==1 if exist src\backend\replication\syncrep_scanner.c del /q src\backend\replication\syncrep_scanner.c

base-commit: 050710b36964dee7e1b2bf6b5ef00041fd5d2787
-- 
2.17.1

From 4c8f5c228e089e7e72835ae5c409a5bc8425ab15 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v4] pg_rewind: options to use restore_command from command
 line or cluster config

---
 doc/src/sgml/ref/pg_rewind.sgml       |  30 ++++-
 src/bin/pg_rewind/parsexlog.c         | 161 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         |  98 +++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h         |   7 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  84 +++++++++++++-
 8 files changed, 372 insertions(+), 20 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 53a64ee29e..0c2441afa7 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> option is specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -200,6 +202,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retreive missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index e19c265cbb..5978ec9b99 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,6 +46,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -53,6 +55,9 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,7 +65,7 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -69,6 +74,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -156,7 +162,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +187,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +298,30 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
-				   strerror(errno));
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+					   strerror(errno));
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retreive
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n",
+					   xlogfpath);
 		}
 	}
 
@@ -409,3 +437,126 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ *
+ * This is a simplified and adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used during rewind process.\n");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size,
+						(unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					printf(_("could not open restored from archive file \"%s\": %s\n"),
+							xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath, strerror(errno));
+		}
+	}
+
+	printf(_("could not restore file \"%s\" from archive: %s\n"),
+			xlogfname, strerror(errno));
+
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 7ccde5c87f..9da578ec42 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -30,6 +30,8 @@
 #include "getopt_long.h"
 #include "storage/bufpage.h"
 
+#define MAX_RESTORE_COMMAND 1024
+
 static void usage(const char *progname);
 
 static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
@@ -52,11 +54,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +79,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retreive WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,6 +101,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -129,7 +138,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +150,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +170,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +240,78 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			fprintf(stderr, _("%s: conflicting options: both -r and -R are specified\n"),
+				progname);
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf "
+							"or -R/--restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAX_RESTORE_COMMAND];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				fprintf(stderr,
+						_("the program \"postgres\" is needed by %s "
+						"but was not found in the\n"
+						"same directory as \"%s\".\n"
+						"Check your installation.\n"),
+						progname, full_path);
+			else
+				fprintf(stderr,
+						_("the program \"postgres\" was found by \"%s\"\n"
+						"but was not the same version as %s.\n"
+						"Check your installation.\n"),
+						full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s\n",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster\n");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log(PG_DEBUG, "using config variable restore_command=\'%s\'.\n", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +383,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +407,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 83b2898b8b..08a753475c 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -32,11 +32,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
+			   int tliIndex, XLogRecPtr endpoint, const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 6dc05720a1..99ea821cfe 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -62,5 +62,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 85cae7e47b..4560fe4430 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -197,6 +199,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -249,6 +283,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: 41531e42d34f4aca117d343b5e40f3f757dec5fe
-- 
2.17.1

From 9770cab4909a3cd98c2db2b8a9fa4af1fedd4614 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v5] pg_rewind: options to use restore_command from command
 line or cluster config

Previously, when pg_rewind could not find required WAL files in the
target data directory the rewind process would fail. One had to
manually figure out which of required WAL files have already moved to
the archival storage and copy them back.

This patch adds possibility to specify restore_command via command
line option or use one specified inside postgresql.conf. Specified
restore_command will be used for automatic retrieval of missing WAL
files from archival storage.
---
 doc/src/sgml/ref/pg_rewind.sgml       |  30 ++++-
 src/bin/pg_rewind/parsexlog.c         | 161 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         |  96 ++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h         |   7 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  84 +++++++++++++-
 8 files changed, 370 insertions(+), 20 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 53a64ee29e..90e3f22f97 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> option is specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -200,6 +202,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retrieve missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index e19c265cbb..6be6dab7e0 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,6 +46,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -53,6 +55,9 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,7 +65,7 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -69,6 +74,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -156,7 +162,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +187,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +298,30 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
-				   strerror(errno));
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+					   strerror(errno));
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n",
+					   xlogfpath);
 		}
 	}
 
@@ -409,3 +437,126 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ *
+ * This is a simplified and adapted to frontend version of
+ * RestoreArchivedFile function from transam/xlogarchive.c
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used during rewind process.\n");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size,
+						(unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					printf(_("could not open restored from archive file \"%s\": %s\n"),
+							xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath, strerror(errno));
+		}
+	}
+
+	printf(_("could not restore file \"%s\" from archive: %s\n"),
+			xlogfname, strerror(errno));
+
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index aa753bb315..dd26dccb07 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -52,11 +52,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +77,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retrieve WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,6 +99,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -129,7 +136,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +148,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +168,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +238,78 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			fprintf(stderr, _("%s: conflicting options: both -r and -R are specified\n"),
+				progname);
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf "
+							"or -R/--restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				fprintf(stderr,
+						_("the program \"postgres\" is needed by %s "
+						"but was not found in the\n"
+						"same directory as \"%s\".\n"
+						"Check your installation.\n"),
+						progname, full_path);
+			else
+				fprintf(stderr,
+						_("the program \"postgres\" was found by \"%s\"\n"
+						"but was not the same version as %s.\n"
+						"Check your installation.\n"),
+						full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s\n",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster\n");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log(PG_DEBUG, "using config variable restore_command=\'%s\'.\n", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +381,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +405,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 83b2898b8b..08a753475c 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -32,11 +32,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
+			   int tliIndex, XLogRecPtr endpoint, const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 6dc05720a1..99ea821cfe 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -62,5 +62,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 85cae7e47b..4560fe4430 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -197,6 +199,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -249,6 +283,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: 42210524cca3a6d3161bcef9d9e687c7c1f5f6c4
-- 
2.17.1

From 9e00f7a7696a88f350e1e328a9758ab85631c813 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v6] pg_rewind: options to use restore_command from command
 line or cluster config

Previously, when pg_rewind could not find required WAL files in the
target data directory the rewind process would fail. One had to
manually figure out which of required WAL files have already moved to
the archival storage and copy them back.

This patch adds possibility to specify restore_command via command
line option or use one specified inside postgresql.conf. Specified
restore_command will be used for automatic retrieval of missing WAL
files from archival storage.
---
 doc/src/sgml/ref/pg_rewind.sgml       |  30 ++++-
 src/bin/pg_rewind/parsexlog.c         | 167 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         |  96 ++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h         |   7 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  84 ++++++++++++-
 8 files changed, 376 insertions(+), 20 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 53a64ee29e..90e3f22f97 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> option is specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -200,6 +202,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retrieve missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index e19c265cbb..3dc110be4e 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -45,6 +46,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -53,6 +55,9 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
 				   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 				   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -60,7 +65,7 @@ static int SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -69,6 +74,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -156,7 +162,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -181,6 +187,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -291,9 +298,30 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			printf(_("could not open file \"%s\": %s\n"), xlogfpath,
-				   strerror(errno));
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				printf(_("could not open file \"%s\": %s\n"), xlogfpath,
+					   strerror(errno));
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log(PG_DEBUG, "using restored from archive version of file \"%s\"\n",
+					   xlogfpath);
 		}
 	}
 
@@ -409,3 +437,132 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.\n");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				printf(_("archive file \"%s\" has wrong size: %lu instead of %lu, %s"),
+						xlogfname, (unsigned long) stat_buf.st_size,
+						(unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					printf(_("could not open restored from archive file \"%s\": %s\n"),
+							xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			printf(_("could not stat file \"%s\": %s"),
+					xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and
+	 * propagate result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s\n",
+				 wait_result_to_str(rc));
+
+	printf(_("could not restore file \"%s\" from archive\n"),
+			xlogfname);
+
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 3dcadb9b40..344b67f99b 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -52,11 +52,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 bool		debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -75,6 +77,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"));
 	printf(_("                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retrieve WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -94,6 +99,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -129,7 +136,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -141,6 +148,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -157,6 +168,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -223,6 +238,78 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			fprintf(stderr, _("%s: conflicting options: both -r and -R are specified\n"),
+				progname);
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf "
+							"or -R/--restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log(PG_DEBUG, "using command line restore_command=\'%s\'.\n", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				fprintf(stderr,
+						_("the program \"postgres\" is needed by %s "
+						"but was not found in the\n"
+						"same directory as \"%s\".\n"
+						"Check your installation.\n"),
+						progname, full_path);
+			else
+				fprintf(stderr,
+						_("the program \"postgres\" was found by \"%s\"\n"
+						"but was not the same version as %s.\n"
+						"Check your installation.\n"),
+						full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s\n",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster\n");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log(PG_DEBUG, "using config variable restore_command=\'%s\'.\n", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -294,9 +381,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	printf(_("rewinding from last common checkpoint at %X/%X on timeline %u\n"),
 		   (uint32) (chkptrec >> 32), (uint32) chkptrec,
 		   chkpttli);
@@ -319,7 +405,7 @@ main(int argc, char **argv)
 	 */
 	pg_log(PG_PROGRESS, "reading WAL in target\n");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 83b2898b8b..08a753475c 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -32,11 +32,10 @@ extern int	targetNentries;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-			   int tliIndex, XLogRecPtr endpoint);
+			   int tliIndex, XLogRecPtr endpoint, const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
-				   int tliIndex,
-				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo);
+				   int tliIndex, XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 			  int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 0562c21549..f42fb5a068 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 900d452d8b..3a58376347 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -39,7 +39,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -199,6 +201,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -251,6 +285,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: c8c885b7a5c8c1175288de1d8aaec3b4ae9050e1
-- 
2.17.1

From f5f359274322020c2338b5b494f6327eaa61c0e1 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v7] pg_rewind: options to use restore_command from command
 line or cluster config

Previously, when pg_rewind could not find required WAL files in the
target data directory the rewind process would fail. One had to
manually figure out which of required WAL files have already moved to
the archival storage and copy them back.

This patch adds possibility to specify restore_command via command
line option or use one specified inside postgresql.conf. Specified
restore_command will be used for automatic retrieval of missing WAL
files from archival storage.
---
 doc/src/sgml/ref/pg_rewind.sgml       |  30 ++++-
 src/bin/pg_rewind/parsexlog.c         | 164 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         |  92 ++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h         |   6 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  84 ++++++++++++-
 8 files changed, 371 insertions(+), 17 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 4d91eeb0ff..746c07e4df 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -67,8 +67,10 @@ PostgreSQL documentation
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
    target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   files might no longer be present. In that case, they can be automatically
+   copied by <application>pg_rewind</application> from the WAL archive to the 
+   <filename>pg_wal</filename> directory if either <literal>-r</literal> or
+   <literal>-R</literal> option is specified, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -202,6 +204,30 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use restore_command in the <filename>postgresql.conf</filename> to
+        retrieve missing in the target <filename>pg_wal</filename> directory
+        WAL files from the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the restore_command to use for retrieval of the missing
+        in the target <filename>pg_wal</filename> directory WAL files from
+        the WAL archive.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 287af60c4e..d1de08320c 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -44,6 +45,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -52,6 +54,9 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
 							   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 							   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -59,7 +64,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -68,6 +73,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -155,7 +161,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -180,6 +186,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -290,8 +297,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using restored from archive version of file \"%s\"",
+							 xlogfpath);
 		}
 	}
 
@@ -405,3 +433,131 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open restored from archive file \"%s\": %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\": %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and
+	 * propagate result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 6e77201be6..3f9bf0d8f5 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -51,11 +51,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retrieve WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -98,6 +103,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -134,7 +141,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -146,6 +153,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -163,6 +174,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -229,6 +244,74 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			pg_log_error("conflicting options: both -r and -R are specified");
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf "
+							"or -R/--restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log_debug("using command line restore_command=\'%s\'.", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							"same directory as \"%s\".\n"
+							"Check your installation.",
+							progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							"but was not the same version as %s.\n"
+							"Check your installation.",
+							full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -300,9 +383,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -328,7 +410,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 1125c7e60f..7dc972dc39 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -40,11 +40,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index f1eb4fe1d2..69a3c69a85 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 68b6004e94..9f39224192 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -35,7 +35,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -216,6 +218,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -270,6 +304,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: 95bbe5d82e428db342fa3ec60b95f1b9873741e5
-- 
2.17.1

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 52a1caa..7e76fcc 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,9 +66,12 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-r</literal> or
+   <literal>-R</literal> option to automatically retrieve them from the WAL
+   archive, or
    fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
    <xref linkend="guc-restore-command"/>.  The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
@@ -203,6 +206,39 @@ PostgreSQL documentation
      </varlistentry>
 
      <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        This option cannot be used together with <option>--restore-command</option>.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the <varname>restore_command</varname> to use for retrieving
+        WAL files from the WAL archive if these files are no longer available
+        in the <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        If <varname>restore_command</varname> is already set in
+        <filename>postgresql.conf</filename>, you can provide the
+        <option>--use-postgresql-conf</option> option instead.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
        <para>
@@ -288,7 +324,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-r</option> or <option>-R</option> option to search
+      for the missing files in the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 287af60..5a7f759 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -44,6 +45,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -52,6 +54,9 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
 							   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 							   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -59,7 +64,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -68,6 +73,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -155,7 +161,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -180,6 +186,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -290,8 +297,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using restored from archive version of file \"%s\"",
+							 xlogfpath);
 		}
 	}
 
@@ -405,3 +433,131 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from offline archival storage.
+ * If successful, return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is
+ * unknown, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open restored from archive file \"%s\": %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\": %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and
+	 * propagate result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index d378053..8e06343 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -51,11 +51,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,10 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command set in postgresql.conf to\n"));
+	printf(_("                                 retrieve WAL files from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command to retrieve WAL files\n"));
+	printf(_("                                 from archive\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -98,6 +104,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -134,7 +142,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -146,6 +154,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -163,6 +175,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -229,6 +245,74 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			pg_log_error("conflicting options: both -r and -R are specified");
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf "
+							"or -R/--restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log_debug("using command line restore_command=\'%s\'.", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							"same directory as \"%s\".\n"
+							"Check your installation.",
+							progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							"but was not the same version as %s.\n"
+							"Check your installation.",
+							full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using configuration variable restore_command=\'%s\'.", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -300,9 +384,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -328,7 +411,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 1125c7e..7dc972d 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -40,11 +40,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 1151921..8a6fa33 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index f1eb4fe..69a3c69 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd..24cec25 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 68b6004..ff9be13 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -35,7 +35,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -216,6 +218,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to a temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -270,6 +304,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# the specified directory with target WAL archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# the specified directory with target WAL archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of the target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

From 328ed78356e2b270ffe4c84baa462eb6b8e6befb Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v9] pg_rewind: options to use restore_command from command
 line or cluster config

Previously, when pg_rewind could not find required WAL files in the
target data directory the rewind process would fail. One had to
manually figure out which of required WAL files have already moved to
the archival storage and copy them back.

This patch adds possibility to specify restore_command via command
line option or use one specified inside postgresql.conf. Specified
restore_command will be used for automatic retrieval of missing WAL
files from archival storage.
---
 doc/src/sgml/ref/pg_rewind.sgml       |  49 +++++++-
 src/bin/pg_rewind/parsexlog.c         | 164 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         |  92 ++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h         |   6 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  84 ++++++++++++-
 8 files changed, 386 insertions(+), 21 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 52a1caa246..d5a14a2e08 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,12 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-r</literal> or
+   <literal>-R</literal> option to automatically retrieve them from the WAL
+   archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -202,6 +203,39 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-r</option></term>
+      <term><option>--use-postgresql-conf</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        This option cannot be used together with <option>--restore-command</option>.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-R <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the <varname>restore_command</varname> to use for retrieving
+        WAL files from the WAL archive if these files are no longer available
+        in the <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        If <varname>restore_command</varname> is already set in
+        <filename>postgresql.conf</filename>, you can provide the
+        <option>--use-postgresql-conf</option> option instead.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -288,7 +322,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-r</option> or <option>-R</option> option to search
+      for the missing files in the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index f0439edce3..6326e9a899 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -44,6 +45,7 @@ static char xlogfpath[MAXPGPATH];
 typedef struct XLogPageReadPrivate
 {
 	const char *datadir;
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -52,6 +54,9 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
 							   int reqLen, XLogRecPtr targetRecPtr, char *readBuf,
 							   TimeLineID *pageTLI);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -59,7 +64,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -68,6 +73,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -154,7 +160,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -179,6 +185,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 
 	private.datadir = datadir;
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -289,8 +296,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(private->datadir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
@@ -404,3 +432,131 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and
+	 * propagate result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index d378053de4..1633e0271d 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -51,11 +51,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,9 @@ usage(const char *progname)
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
 	printf(_("  -P, --progress                 write progress messages\n"));
+	printf(_("  -r, --use-postgresql-conf      use restore_command in the postgresql.conf to\n"));
+	printf(_("                                 retrieve WALs from archive\n"));
+	printf(_("  -R, --restore-command=COMMAND  restore_command\n"));
 	printf(_("      --debug                    write a lot of debug messages\n"));
 	printf(_("  -V, --version                  output version information, then exit\n"));
 	printf(_("  -?, --help                     show this help, then exit\n"));
@@ -98,6 +103,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"use-postgresql-conf", no_argument, NULL, 'r'},
+		{"restore-command", required_argument, NULL, 'R'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -134,7 +141,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPR:r", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -146,6 +153,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'r':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -163,6 +174,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'R':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -229,6 +244,74 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			pg_log_error("conflicting options: both -r and -R are specified");
+			fprintf(stderr, _("You must run %s with either -r/--use-postgresql-conf "
+							"or -R/--restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log_debug("using command line restore_command=\'%s\'.", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							"same directory as \"%s\".\n"
+							"Check your installation.",
+							progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							"but was not the same version as %s.\n"
+							"Check your installation.",
+							full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -300,9 +383,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -328,7 +410,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 1125c7e60f..7dc972dc39 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -40,11 +40,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index f1eb4fe1d2..69a3c69a85 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 68b6004e94..9f39224192 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -35,7 +35,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -216,6 +218,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -270,6 +304,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-r"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: da9456d22a7697ef2c5ba9dd1402d948b2ec7f09
-- 
2.17.1

From d7e1041c756b79e6e4636be1b0337453db8a7457 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v10] pg_rewind: options to use restore_command from command
 line or cluster config

Previously, when pg_rewind could not find required WAL files in the
target data directory the rewind process would fail. One had to
manually figure out which of required WAL files have already moved to
the archival storage and copy them back.

This patch adds possibility to specify restore_command via command
line option or use one specified inside postgresql.conf. Specified
restore_command will be used for automatic retrieval of missing WAL
files from archival storage.
---
 doc/src/sgml/ref/pg_rewind.sgml       |  49 +++++++-
 src/bin/pg_rewind/parsexlog.c         | 164 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         | 112 +++++++++++++++---
 src/bin/pg_rewind/pg_rewind.h         |   6 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     |  84 ++++++++++++-
 8 files changed, 396 insertions(+), 31 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index ac142d22fc..27c662cc83 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,12 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> or
+   <literal>-C</literal> option to automatically retrieve them from the WAL
+   archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -202,6 +203,39 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        This option cannot be used together with <option>--target-restore-command</option>.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-C <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--target-restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the <varname>restore_command</varname> to use for retrieving
+        WAL files from the WAL archive if these files are no longer available
+        in the <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        If <varname>restore_command</varname> is already set in
+        <filename>postgresql.conf</filename>, you can provide the
+        <option>--restore-target-wal</option> option instead.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -288,7 +322,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> or <option>-C</option> option to search
+      for the missing files in the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 264a8f4db5..3452bf5c79 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "pg_rewind.h"
 #include "filemap.h"
@@ -43,6 +44,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -50,6 +52,9 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
 							   XLogRecPtr targetPagePtr,
 							   int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -57,7 +62,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -65,6 +70,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -150,7 +156,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -174,6 +180,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -284,8 +291,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(xlogreader->segcxt.ws_dir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
@@ -399,3 +427,131 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and
+	 * propagate result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 15e3eab550..28b3d6bcab 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -51,11 +51,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -72,16 +74,19 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
-	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
-	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
-	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
-	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
-	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
-			 "                                 safely to disk\n"));
-	printf(_("  -P, --progress                 write progress messages\n"));
-	printf(_("      --debug                    write a lot of debug messages\n"));
-	printf(_("  -V, --version                  output version information, then exit\n"));
-	printf(_("  -?, --help                     show this help, then exit\n"));
+	printf(_("  -D, --target-pgdata=DIRECTORY         existing data directory to modify\n"));
+	printf(_("      --source-pgdata=DIRECTORY         source data directory to synchronize with\n"));
+	printf(_("      --source-server=CONNSTR           source server to synchronize with\n"));
+	printf(_("  -n, --dry-run                         stop before modifying anything\n"));
+	printf(_("  -N, --no-sync                         do not wait for changes to be written\n"
+			 "                                        safely to disk\n"));
+	printf(_("  -P, --progress                        write progress messages\n"));
+	printf(_("  -c, --restore-target-wal              use restore_command in the postgresql.conf\n"));
+	printf(_("                                        to retrieve WALs from archive\n"));
+	printf(_("  -C, --target-restore-command=COMMAND  target WAL restore_command\n"));
+	printf(_("      --debug                           write a lot of debug messages\n"));
+	printf(_("  -V, --version                         output version information, then exit\n"));
+	printf(_("  -?, --help                            show this help, then exit\n"));
 	printf(_("\nReport bugs to <pgsql-bugs@lists.postgresql.org>.\n"));
 }
 
@@ -98,6 +103,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
+		{"target-restore-command", required_argument, NULL, 'C'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -134,7 +141,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNP", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPC:c", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -146,6 +153,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -163,6 +174,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'C':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -229,6 +244,74 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			pg_log_error("conflicting options: both -c and -C are specified");
+			fprintf(stderr, _("You must run %s with either -c/--restore-target-wal "
+							"or -C/--target-restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log_debug("using command line restore_command=\'%s\'.", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							"same directory as \"%s\".\n"
+							"Check your installation.",
+							progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							"but was not the same version as %s.\n"
+							"Check your installation.",
+							full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	/* Connect to remote server */
 	if (connstr_source)
 		libpqConnect(connstr_source);
@@ -300,9 +383,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -328,7 +410,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 1125c7e60f..7dc972dc39 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -40,11 +40,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 115192170e..8a6fa33016 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 10;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -106,5 +106,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index f1eb4fe1d2..69a3c69a85 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 6;
+use Test::More tests => 12;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index c4040bd562..24cec256de 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 4;
+use Test::More tests => 8;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 68b6004e94..260a58b3fa 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -35,7 +35,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -216,6 +218,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -270,6 +304,54 @@ sub run_pg_rewind
 			],
 			'pg_rewind remote');
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--target-restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: a083657896c739909a25190ebd0032c01f6c8109
-- 
2.17.1

From a05c3343e0bd6fe339c944f6b0cde64ceb46a0b3 Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Tue, 19 Feb 2019 19:14:53 +0300
Subject: [PATCH v11] pg_rewind: options to use restore_command from command
 line or cluster config

Previously, when pg_rewind could not find required WAL files in the
target data directory the rewind process would fail. One had to
manually figure out which of required WAL files have already moved to
the archival storage and copy them back.

This patch adds possibility to specify restore_command via command
line option or use one specified inside postgresql.conf. Specified
restore_command will be used for automatic retrieval of missing WAL
files from archival storage.
---
 doc/src/sgml/ref/pg_rewind.sgml       |  49 +++++++-
 src/bin/pg_rewind/parsexlog.c         | 164 +++++++++++++++++++++++++-
 src/bin/pg_rewind/pg_rewind.c         | 118 +++++++++++++++---
 src/bin/pg_rewind/pg_rewind.h         |   6 +-
 src/bin/pg_rewind/t/001_basic.pl      |   4 +-
 src/bin/pg_rewind/t/002_databases.pl  |   4 +-
 src/bin/pg_rewind/t/003_extrafiles.pl |   4 +-
 src/bin/pg_rewind/t/RewindTest.pm     | 105 ++++++++++++++++-
 8 files changed, 416 insertions(+), 38 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..b601a5c7e4 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,12 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> or
+   <literal>-C</literal> option to automatically retrieve them from the WAL
+   archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +233,39 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        This option cannot be used together with <option>--target-restore-command</option>.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-C <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--target-restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the <varname>restore_command</varname> to use for retrieving
+        WAL files from the WAL archive if these files are no longer available
+        in the <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        If <varname>restore_command</varname> is already set in
+        <filename>postgresql.conf</filename>, you can provide the
+        <option>--restore-target-wal</option> option instead.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +352,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> or <option>-C</option> option to search
+      for the missing files in the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index 1d03375a3e..fd67790ac3 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "access/rmgr.h"
 #include "access/xlog_internal.h"
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -48,6 +50,9 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
 							   XLogRecPtr targetPagePtr,
 							   int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
 
+static int RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -55,7 +60,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +68,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -148,7 +154,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -172,6 +178,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -282,8 +289,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWAL(xlogreader->segcxt.ws_dir,
+											xlogfname,
+											WalSegSz,
+											private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
@@ -397,3 +425,131 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery. If the file size is not
+ * known, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWAL(const char *path, const char *xlogfname,
+				   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy
+	 * the missing WAL file from archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and
+	 * propagate result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index e75c7eed1c..72e903912e 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wals = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,19 +76,22 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
-	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
-	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
-	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
-	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
-			 "                                 (requires --source-server)\n"));
-	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
-	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
-			 "                                 safely to disk\n"));
-	printf(_("  -P, --progress                 write progress messages\n"));
-	printf(_("      --no-ensure-shutdown       do not automatically fix unclean shutdown\n"));
-	printf(_("      --debug                    write a lot of debug messages\n"));
-	printf(_("  -V, --version                  output version information, then exit\n"));
-	printf(_("  -?, --help                     show this help, then exit\n"));
+	printf(_("  -D, --target-pgdata=DIRECTORY         existing data directory to modify\n"));
+	printf(_("      --source-pgdata=DIRECTORY         source data directory to synchronize with\n"));
+	printf(_("      --source-server=CONNSTR           source server to synchronize with\n"));
+	printf(_("  -R, --write-recovery-conf             write configuration for replication\n"
+			 "                                        (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal              use restore_command in the postgresql.conf\n"));
+	printf(_("                                        to retrieve WALs from archive\n"));
+	printf(_("  -C, --target-restore-command=COMMAND  target WAL restore_command\n"));
+	printf(_("  -n, --dry-run                         stop before modifying anything\n"));
+	printf(_("  -N, --no-sync                         do not wait for changes to be written\n"
+			 "                                        safely to disk\n"));
+	printf(_("  -P, --progress                        write progress messages\n"));
+	printf(_("      --no-ensure-shutdown              do not automatically fix unclean shutdown\n"));
+	printf(_("      --debug                           write a lot of debug messages\n"));
+	printf(_("  -V, --version                         output version information, then exit\n"));
+	printf(_("  -?, --help                            show this help, then exit\n"));
 	printf(_("\nReport bugs to <pgsql-bugs@lists.postgresql.org>.\n"));
 }
 
@@ -105,6 +110,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
+		{"target-restore-command", required_argument, NULL, 'C'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +150,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRC:c", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +162,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wals = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -176,6 +187,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'C':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -252,6 +267,74 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_command != NULL)
+	{
+		if (restore_wals)
+		{
+			pg_log_error("conflicting options: both -c and -C are specified");
+			fprintf(stderr, _("You must run %s with either -c/--restore-target-wal "
+							"or -C/--target-restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log_debug("using command line restore_command=\'%s\'.", restore_command);
+	}
+	else if (restore_wals)
+	{
+		int   rc;
+		char  postgres_exec_path[MAXPGPATH],
+			  postgres_cmd[MAXPGPATH],
+			  cmd_output[MAXPGPATH];
+		FILE *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char	full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							"same directory as \"%s\".\n"
+							"Check your installation.",
+							progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							"but was not the same version as %s.\n"
+							"Check your installation.",
+							full_path, progname);
+			exit(1);
+		}
+
+		/* Build a command to execute for restore_command GUC retrieval if set. */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +432,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +459,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index 360b2b3da8..3abe83b38c 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..73967d818d 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 25;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 1db534c0dc..d046a755e5 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 7;
+use Test::More tests => 13;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index f4710440fc..ab1fbbc125 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 5;
+use Test::More tests => 9;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..58055bb494 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -35,7 +35,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -216,6 +218,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wals
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wals_archive_dir = catdir($tmp_dir, "master_wals_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wals_archive_dir);
+	make_path($wals_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wals_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wals_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wals_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -227,10 +261,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive' || $test_mode eq 'archive_conf')
+	{
+		# We test pg_rewind with restore_command by simply moving all
+		# WAL to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +331,54 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"--target-restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WALs archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wals($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

base-commit: 88d45ac752ae49dbfafeb163b07381d3b8a6b601
-- 
2.17.1

commit fc40af46a4f42ef648fac3cb5662a4a31b562759
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date:   Sat Jan 18 18:11:49 2020 +0300

    pg_rewind: Add options to restore WAL files from archive
    
    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.
    
    This commit implements two new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage.  The first
    option let pg_rewind read restore_command from postgresql.conf, while the
    second one specifies restore_command directly.
    
    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Andrey Borodin, Alvaro Herrera, Michael Paquier
    Reviewed-by: Andres Freund, Alexander Korotkov

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e9..b601a5c7e44 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,12 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> or
+   <literal>-C</literal> option to automatically retrieve them from the WAL
+   archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +233,39 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        This option cannot be used together with <option>--target-restore-command</option>.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-C <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--target-restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the <varname>restore_command</varname> to use for retrieving
+        WAL files from the WAL archive if these files are no longer available
+        in the <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        If <varname>restore_command</varname> is already set in
+        <filename>postgresql.conf</filename>, you can provide the
+        <option>--restore-target-wal</option> option instead.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +352,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> or <option>-C</option> option to search
+      for the missing files in the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index b6429827cfb..7db7aa60e1a 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "access/rmgr.h"
 #include "access/xlog_internal.h"
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -48,6 +50,9 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
 							   XLogRecPtr targetPagePtr,
 							   int reqLen, XLogRecPtr targetRecPtr, char *readBuf);
 
+static int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
 /*
  * Read WAL from the datadir/pg_wal, starting from 'startpoint' on timeline
  * index 'tliIndex' in target timeline history, until 'endpoint'. Make note of
@@ -55,7 +60,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +68,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -148,7 +154,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -172,6 +178,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -282,8 +289,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
@@ -397,3 +425,131 @@ extractPageInfo(XLogReaderState *record)
 		process_block_change(forknum, rnode, blkno);
 	}
 }
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+static int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab7..fed70222cc6 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,19 +76,22 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
-	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
-	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
-	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
-	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
-			 "                                 (requires --source-server)\n"));
-	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
-	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
-			 "                                 safely to disk\n"));
-	printf(_("  -P, --progress                 write progress messages\n"));
-	printf(_("      --no-ensure-shutdown       do not automatically fix unclean shutdown\n"));
-	printf(_("      --debug                    write a lot of debug messages\n"));
-	printf(_("  -V, --version                  output version information, then exit\n"));
-	printf(_("  -?, --help                     show this help, then exit\n"));
+	printf(_("  -D, --target-pgdata=DIRECTORY         existing data directory to modify\n"));
+	printf(_("      --source-pgdata=DIRECTORY         source data directory to synchronize with\n"));
+	printf(_("      --source-server=CONNSTR           source server to synchronize with\n"));
+	printf(_("  -R, --write-recovery-conf             write configuration for replication\n"
+			 "                                        (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal              use restore_command in the postgresql.conf\n"));
+	printf(_("                                        to retrieve WAL files from archive\n"));
+	printf(_("  -C, --target-restore-command=COMMAND  target WAL restore_command\n"));
+	printf(_("  -n, --dry-run                         stop before modifying anything\n"));
+	printf(_("  -N, --no-sync                         do not wait for changes to be written\n"
+			 "                                        safely to disk\n"));
+	printf(_("  -P, --progress                        write progress messages\n"));
+	printf(_("      --no-ensure-shutdown              do not automatically fix unclean shutdown\n"));
+	printf(_("      --debug                           write a lot of debug messages\n"));
+	printf(_("  -V, --version                         output version information, then exit\n"));
+	printf(_("  -?, --help                            show this help, then exit\n"));
 	printf(_("\nReport bugs to <pgsql-bugs@lists.postgresql.org>.\n"));
 }
 
@@ -105,6 +110,8 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
+		{"target-restore-command", required_argument, NULL, 'C'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +150,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRC:c", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +162,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -176,6 +187,10 @@ main(int argc, char **argv)
 				datadir_target = pg_strdup(optarg);
 				break;
 
+			case 'C':
+				restore_command = pg_strdup(optarg);
+				break;
+
 			case 1:				/* --source-pgdata */
 				datadir_source = pg_strdup(optarg);
 				break;
@@ -252,6 +267,77 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_command != NULL)
+	{
+		if (restore_wal)
+		{
+			pg_log_error("conflicting options: both -c and -C are specified");
+			fprintf(stderr, _("You must run %s with either -c/--restore-target-wal "
+							  "or -C/--target-restore-command.\n"), progname);
+			exit(1);
+		}
+
+		pg_log_debug("using command line restore_command=\'%s\'.", restore_command);
+	}
+	else if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval if
+		 * set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +435,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +462,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32d..b122ae43e5a 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced1..73967d818d0 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 25;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,7 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 1db534c0dc0..d046a755e5f 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 7;
+use Test::More tests => 13;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,7 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index f4710440fc3..ab1fbbc1256 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 5;
+use Test::More tests => 9;
 
 use File::Find;
 
@@ -90,5 +90,7 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
+run_test('archive_conf');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac86..873239b9d95 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -35,7 +35,9 @@ use Carp;
 use Config;
 use Exporter 'import';
 use File::Copy;
-use File::Path qw(rmtree);
+use File::Glob ':bsd_glob';
+use File::Path qw(remove_tree make_path);
+use File::Spec::Functions qw(catdir catfile);
 use IPC::Run qw(run);
 use PostgresNode;
 use TestLib;
@@ -216,6 +218,38 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wal
+{
+	my $tmp_dir = shift;
+	my $master_pgdata = shift;
+	my $wal_archive_dir = catdir($tmp_dir, "master_wal_archive");
+	my @wal_files = bsd_glob catfile($master_pgdata, "pg_wal", "0000000*");
+	my $restore_command;
+
+	remove_tree($wal_archive_dir);
+	make_path($wal_archive_dir) or die;
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	foreach my $wal_file (@wal_files)
+	{
+		move($wal_file, "$wal_archive_dir") or die;
+	}
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wal_archive_dir\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wal_archive_dir/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -227,10 +261,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive' || $test_mode eq 'archive_conf')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +331,54 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		my $restore_command = move_wal($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"--target-restore-command=$restore_command"
+			],
+			'pg_rewind archive');
+	}
+	elsif ($test_mode eq "archive_conf")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		my $master_conf_path = catfile($master_pgdata, 'postgresql.conf');
+		my $restore_command = move_wal($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		open(my $conf_fd, ">>", $master_conf_path) or die;
+		print $conf_fd "\nrestore_command='$restore_command'";
+		close $conf_fd;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 

commit b2d59c9532f3beb3a17b8c03341aa4557809d038
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date:   Sat Jan 18 18:11:49 2020 +0300

    pg_rewind: Add options to restore WAL files from archive
    
    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.
    
    This commit implements two new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage.  The first
    option let pg_rewind read restore_command from postgresql.conf, while the
    second one specifies restore_command directly.
    
    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Andrey Borodin, Alvaro Herrera, Michael Paquier
    Reviewed-by: Andres Freund, Alexander Korotkov

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e9..b601a5c7e44 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,12 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> or
+   <literal>-C</literal> option to automatically retrieve them from the WAL
+   archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +233,39 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        This option cannot be used together with <option>--target-restore-command</option>.
+       </para>
+      </listitem>
+     </varlistentry>
+
+     <varlistentry>
+      <term><option>-C <replaceable class="parameter">restore_command</replaceable></option></term>
+      <term><option>--target-restore-command=<replaceable class="parameter">restore_command</replaceable></option></term>
+      <listitem>
+       <para>
+        Specifies the <varname>restore_command</varname> to use for retrieving
+        WAL files from the WAL archive if these files are no longer available
+        in the <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+       <para>
+        If <varname>restore_command</varname> is already set in
+        <filename>postgresql.conf</filename>, you can provide the
+        <option>--restore-target-wal</option> option instead.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +352,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> or <option>-C</option> option to search
+      for the missing files in the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index b6429827cfb..26f41581c00 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -12,6 +12,7 @@
 #include "postgres_fe.h"
 
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "access/rmgr.h"
 #include "access/xlog_internal.h"
@@ -19,6 +20,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +43,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +58,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +66,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -148,7 +152,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -172,6 +176,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -282,8 +287,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab7..33d6aada4e5 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,19 +76,21 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
-	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
-	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
-	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
-	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
-			 "                                 (requires --source-server)\n"));
-	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
-	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
-			 "                                 safely to disk\n"));
-	printf(_("  -P, --progress                 write progress messages\n"));
-	printf(_("      --no-ensure-shutdown       do not automatically fix unclean shutdown\n"));
-	printf(_("      --debug                    write a lot of debug messages\n"));
-	printf(_("  -V, --version                  output version information, then exit\n"));
-	printf(_("  -?, --help                     show this help, then exit\n"));
+	printf(_("  -D, --target-pgdata=DIRECTORY         existing data directory to modify\n"));
+	printf(_("      --source-pgdata=DIRECTORY         source data directory to synchronize with\n"));
+	printf(_("      --source-server=CONNSTR           source server to synchronize with\n"));
+	printf(_("  -R, --write-recovery-conf             write configuration for replication\n"
+			 "                                        (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal              use restore_command in target config\n"));
+	printf(_("                                        to retrieve WAL files from archive\n"));
+	printf(_("  -n, --dry-run                         stop before modifying anything\n"));
+	printf(_("  -N, --no-sync                         do not wait for changes to be written\n"
+			 "                                        safely to disk\n"));
+	printf(_("  -P, --progress                        write progress messages\n"));
+	printf(_("      --no-ensure-shutdown              do not automatically fix unclean shutdown\n"));
+	printf(_("      --debug                           write a lot of debug messages\n"));
+	printf(_("  -V, --version                         output version information, then exit\n"));
+	printf(_("  -?, --help                            show this help, then exit\n"));
 	printf(_("\nReport bugs to <pgsql-bugs@lists.postgresql.org>.\n"));
 }
 
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRC:c", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval if
+		 * set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32d..b122ae43e5a 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced1..d97e4377419 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/002_databases.pl b/src/bin/pg_rewind/t/002_databases.pl
index 1db534c0dc0..3027e09e0f4 100644
--- a/src/bin/pg_rewind/t/002_databases.pl
+++ b/src/bin/pg_rewind/t/002_databases.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 7;
+use Test::More tests => 10;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -70,5 +70,6 @@ template1
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/003_extrafiles.pl b/src/bin/pg_rewind/t/003_extrafiles.pl
index f4710440fc3..bbad5ce9c94 100644
--- a/src/bin/pg_rewind/t/003_extrafiles.pl
+++ b/src/bin/pg_rewind/t/003_extrafiles.pl
@@ -3,7 +3,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 5;
+use Test::More tests => 7;
 
 use File::Find;
 
@@ -90,5 +90,6 @@ sub run_test
 # Run the test in both modes.
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac86..14cefe4517c 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -216,6 +216,46 @@ sub promote_standby
 	return;
 }
 
+# Moves WAL files to the temporary location and returns restore_command
+# to get them back.
+sub move_wal
+{
+	my ($tmp_dir, $master_pgdata) = @_;
+	my $wal_archive_path = "$tmp_dir/master_wal_archive";
+	my $wal_path = "$master_pgdata/pg_wal";
+	my $wal_dir;
+	my $restore_command;
+
+	rmtree($wal_archive_path);
+	mkdir($wal_archive_path) or
+	  die "mkdir($wal_archive_path) failed: $!";
+
+	# Move all old master WAL files to the archive.
+	# Old master should be stopped at this point.
+	opendir($wal_dir, $wal_path) or
+	  die "opendir($wal_path) failed: $!";;
+	while (my $wal_file = readdir($wal_dir))
+	{
+		if ($wal_file =~ /^[0-9A-F]{24}$/)
+		{
+			move("$wal_path/$wal_file", "$wal_archive_path") or
+			  die "move $wal_path/$wal_file -> $wal_archive_path failed: $!";
+		}
+	}
+	closedir($wal_dir);
+
+	if ($windows_os)
+	{
+		$restore_command = "copy $wal_archive_path\\\%f \%p";
+	}
+	else
+	{
+		$restore_command = "cp $wal_archive_path/\%f \%p";
+	}
+
+	return $restore_command;
+}
+
 sub run_pg_rewind
 {
 	my $test_mode       = shift;
@@ -227,10 +267,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive' || $test_mode eq 'archive_conf')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +337,31 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		my $restore_command = move_wal($tmp_folder, $master_pgdata);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Add restore_command to postgresql.conf of target cluster.
+		$node_master->append_conf("postgresql.conf",
+								  "restore_command='$restore_command'");
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index 44ca68fa6c3..b92c03c6331 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -86,6 +86,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 00000000000..34d2be86954
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,154 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH],
+			   *dp,
+			   *endp;
+	const char *sp;
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = xlogRestoreCmd;
+	endp = xlogRestoreCmd + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					pg_fatal("restore_command with %%r cannot be used with pg_rewind.");
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 00000000000..7e9d140ea8f
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,18 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								  off_t expectedSize, const char *restoreCommand);
+
+#endif							/* ARCHIVE_H */

From 7af0b3642f6218c764eee361e013f24bfb43ffbe Mon Sep 17 00:00:00 2001
From: Alexey Kondratov <kondratov.aleksey@gmail.com>
Date: Fri, 31 Jan 2020 20:08:13 +0300
Subject: [PATCH v14] pg_rewind: Add options to restore WAL files from archive

    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.

    This commit implements two new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage.  The first
    option let pg_rewind read restore_command from postgresql.conf, while the
    second one specifies restore_command directly.

    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Andrey Borodin, Alvaro Herrera, Michael Paquier
    Reviewed-by: Andres Freund, Alexander Korotkov
---
 doc/src/sgml/ref/pg_rewind.sgml          |  28 ++++--
 src/backend/access/transam/xlogarchive.c |  58 +------------
 src/bin/pg_rewind/parsexlog.c            |  33 ++++++-
 src/bin/pg_rewind/pg_rewind.c            |  77 ++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h            |   6 +-
 src/bin/pg_rewind/t/001_basic.pl         |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm        |  64 +++++++++++++-
 src/common/Makefile                      |   2 +
 src/common/archive.c                     |  97 +++++++++++++++++++++
 src/common/fe_archive.c                  | 106 +++++++++++++++++++++++
 src/include/common/archive.h             |  21 +++++
 src/include/common/fe_archive.h          |  18 ++++
 src/tools/msvc/Mkvcbuild.pm              |   8 +-
 13 files changed, 440 insertions(+), 81 deletions(-)
 create mode 100644 src/common/archive.c
 create mode 100644 src/common/fe_archive.c
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/include/common/fe_archive.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..8fa0d5aad8 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..e71aa2edb8 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	(void) ConstructRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+								   lastRestartPointFname, xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..08a7fc3560 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab..f078cd694a 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,8 @@ usage(const char *progname)
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
 	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
 			 "                                 (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRc", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval if
+		 * set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..fd81d5684f 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,48 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories. It should
+		# be empty in this test, so it is safe.
+		rmdir($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath(
+			$node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir
+		);
+		chmod(0700, $node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index e757fb7399..43702dc309 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -47,6 +47,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -87,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..d57768a949
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,97 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+ConstructRestoreCommand(const char *restoreCommand,
+						const char *xlogpath,
+						const char *xlogfname,
+						const char *lastRestartPointFname,
+						char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..389d389d0d
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,106 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = ConstructRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+		pg_fatal("restore_command with %%r alias cannot be used.");
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..032761425b
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int ConstructRestoreCommand(const char *restoreCommand,
+								   const char *xlogpath,
+								   const char *xlogfname,
+								   const char *lastRestartPointFname,
+								   char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..a24e9f383b
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,18 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								  off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index a43e31c60e..0e298d3fdc 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -120,8 +120,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -138,8 +138,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
-- 
2.19.1

commit 9d1b38885662d40dcbcfef88e06eda7cc54225d0
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date:   Tue Feb 25 02:22:45 2020 +0300

    pg_rewind: Add options to restore WAL files from archive
    
    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.
    
    This commit implements new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage. The
    restore_command option is read from postgresql.conf.
    
    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Andrey Borodin, Alvaro Herrera, Michael Paquier
    Reviewed-by: Andres Freund, Alexander Korotkov

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e9..8fa0d5aad88 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e7526..e71aa2edb8d 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	(void) ConstructRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+								   lastRestartPointFname, xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803f..08a7fc35608 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab7..f078cd694a4 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,8 @@ usage(const char *progname)
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
 	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
 			 "                                 (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRc", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval if
+		 * set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32d..b122ae43e5a 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced1..d97e4377419 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac86..fd81d5684f0 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,48 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories. It should
+		# be empty in this test, so it is safe.
+		rmdir($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath(
+			$node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir
+		);
+		chmod(0700, $node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index ab98f4faafb..f0631da5e41 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -86,6 +87,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 00000000000..d57768a9498
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,97 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+ConstructRestoreCommand(const char *restoreCommand,
+						const char *xlogpath,
+						const char *xlogfname,
+						const char *lastRestartPointFname,
+						char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 00000000000..389d389d0dc
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,106 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = ConstructRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+		pg_fatal("restore_command with %%r alias cannot be used.");
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 00000000000..032761425bb
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int ConstructRestoreCommand(const char *restoreCommand,
+								   const char *xlogpath,
+								   const char *xlogfname,
+								   const char *lastRestartPointFname,
+								   char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 00000000000..a24e9f383b2
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,18 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								  off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 727a8fdec9b..915a2945ef0 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

commit 40f801f9b48f3cda5f8c1007439d5d90fcc0f7a1
Author: Alexander Korotkov <akorotkov@postgresql.org>
Date:   Tue Feb 25 02:22:45 2020 +0300

    pg_rewind: Add options to restore WAL files from archive
    
    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.
    
    This commit implements new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage. The
    restore_command option is read from postgresql.conf.
    
    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Michael Paquier, Andrey Borodin, Alvaro Herrera
    Reviewed-by: Andres Freund, Alexander Korotkov

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e9..8fa0d5aad88 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        <filename>postgresql.conf</filename> to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory of the target cluster.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e7526..52281e87ee6 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -65,8 +63,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	TimeLineID	restartTli;
 
 	/*
-	 * Ignore restore_command when not in archive recovery (meaning
-	 * we are in crash recovery).
+	 * Ignore restore_command when not in archive recovery (meaning we are in
+	 * crash recovery).
 	 */
 	if (!ArchiveRecoveryRequested)
 		goto not_available;
@@ -149,58 +147,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	(void) ConstructRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+								   lastRestartPointFname, xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803f..08a7fc35608 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab7..f078cd694a4 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,8 @@ usage(const char *progname)
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
 	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
 			 "                                 (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRc", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval if
+		 * set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'.", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32d..b122ae43e5a 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced1..d97e4377419 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac86..8962edd99e6 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,51 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories. It should
+		# be empty in this test, so it is safe.
+		rmdir($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath(
+			$node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir
+		);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Ensure directories have right modes. It's required by
+		# 'check PGDATA permissions' test.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index ab98f4faafb..f0631da5e41 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -86,6 +87,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 00000000000..d57768a9498
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,97 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+ConstructRestoreCommand(const char *restoreCommand,
+						const char *xlogpath,
+						const char *xlogfname,
+						const char *lastRestartPointFname,
+						char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 00000000000..389d389d0dc
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,106 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = ConstructRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+		pg_fatal("restore_command with %%r alias cannot be used.");
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels. We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 00000000000..74aa43cbaca
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int	ConstructRestoreCommand(const char *restoreCommand,
+									const char *xlogpath,
+									const char *xlogfname,
+									const char *lastRestartPointFname,
+									char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 00000000000..028e97a1dff
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,18 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 727a8fdec9b..915a2945ef0 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

From fa2fc359dd9852afc608663fa32733e800652ffa Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Tue, 25 Feb 2020 02:22:45 +0300
Subject: [PATCH v17] pg_rewind: Add options to restore WAL files from archive

    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.

    This commit implements new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage. The
    restore_command option is read from postgresql.conf.

    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Michael Paquier, Andrey Borodin, Alvaro Herrera
    Reviewed-by: Andres Freund, Alexander Korotkov
---
 doc/src/sgml/ref/pg_rewind.sgml          |  28 ++++--
 src/backend/access/transam/xlogarchive.c |  58 +------------
 src/bin/pg_rewind/parsexlog.c            |  33 ++++++-
 src/bin/pg_rewind/pg_rewind.c            |  77 ++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h            |   6 +-
 src/bin/pg_rewind/t/001_basic.pl         |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm        |  67 +++++++++++++-
 src/common/Makefile                      |   2 +
 src/common/archive.c                     |  97 +++++++++++++++++++++
 src/common/fe_archive.c                  | 106 +++++++++++++++++++++++
 src/include/common/archive.h             |  21 +++++
 src/include/common/fe_archive.h          |  18 ++++
 src/tools/msvc/Mkvcbuild.pm              |   8 +-
 13 files changed, 443 insertions(+), 81 deletions(-)
 create mode 100644 src/common/archive.c
 create mode 100644 src/common/fe_archive.c
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/include/common/fe_archive.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..64a6942031 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        the target cluster configuration to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..e71aa2edb8 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	(void) ConstructRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+								   lastRestartPointFname, xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..08a7fc3560 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab..149c0f1dc4 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,8 @@ usage(const char *progname)
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
 	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
 			 "                                 (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRc", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval if
+		 * set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "%s -D %s -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..bc761596cf 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,51 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories.
+		# It should be empty in this test, so it is safe.
+		rmdir($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath(
+			$node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir
+		);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Ensure directories have right modes.  It's required by
+		# 'check PGDATA permissions' test.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync", "--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index ab98f4faaf..f0631da5e4 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -86,6 +87,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..d57768a949
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,97 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres.h"
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+ConstructRestoreCommand(const char *restoreCommand,
+						const char *xlogpath,
+						const char *xlogfname,
+						const char *lastRestartPointFname,
+						char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..0b40fde302
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,106 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = ConstructRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+		pg_fatal("restore_command with %%r alias cannot be used.");
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels.  We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..74aa43cbac
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int	ConstructRestoreCommand(const char *restoreCommand,
+									const char *xlogpath,
+									const char *xlogfname,
+									const char *lastRestartPointFname,
+									char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..028e97a1df
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,18 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Copyright (c) 2020, PostgreSQL Global Development Group
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 727a8fdec9..915a2945ef 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

base-commit: 612a1ab76724aa1514b6509269342649f8cab375
-- 
2.19.1

From c775a2e40e405474f6ecef35843d276d43fb462f Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Tue, 25 Feb 2020 02:22:45 +0300
Subject: [PATCH v18] pg_rewind: Add options to restore WAL files from archive

    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.

    This commit implements new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage. The
    restore_command option is read from postgresql.conf.

    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Michael Paquier, Andrey Borodin, Alvaro Herrera
    Reviewed-by: Andres Freund, Alexander Korotkov
---
 doc/src/sgml/ref/pg_rewind.sgml          |  28 ++++--
 src/backend/access/transam/xlogarchive.c |  60 ++----------
 src/bin/pg_rewind/parsexlog.c            |  33 ++++++-
 src/bin/pg_rewind/pg_rewind.c            |  77 +++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h            |   6 +-
 src/bin/pg_rewind/t/001_basic.pl         |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm        |  66 +++++++++++++-
 src/common/Makefile                      |   2 +
 src/common/archive.c                     | 102 +++++++++++++++++++++
 src/common/fe_archive.c                  | 111 +++++++++++++++++++++++
 src/include/common/archive.h             |  22 +++++
 src/include/common/fe_archive.h          |  19 ++++
 src/tools/msvc/Mkvcbuild.pm              |   8 +-
 13 files changed, 457 insertions(+), 80 deletions(-)
 create mode 100644 src/common/archive.c
 create mode 100644 src/common/fe_archive.c
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/include/common/fe_archive.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..64a6942031 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        the target cluster configuration to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..f78a7e8f02 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,12 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
+	rc = BuildRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+							 lastRestartPointFname, xlogRestoreCmd);
 
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	if (rc != 0)
+		/* Sanity check, should never happen. */
+		elog(ERROR, "failed to build restore_command due to missing parameters");
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..08a7fc3560 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab..db43aada05 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,8 @@ usage(const char *progname)
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
 	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
 			 "                                 (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRc", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval
+		 * if set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "\"%s\" -D \"%s\" -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..7af8b9b347 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,50 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories.
+		# It should be empty in this test, so it is safe.
+		rmdir($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Ensure directories have right modes.  It's required by
+		# 'check PGDATA permissions' test.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index ab98f4faaf..f0631da5e4 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -86,6 +87,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..8c79044a6b
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,102 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname,
+					char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..7309983ed4
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,111 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = BuildRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+		pg_fatal("restore_command with %%r alias cannot be used.");
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels.  We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..3e6e143cd8
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,22 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int	BuildRestoreCommand(const char *restoreCommand,
+								const char *xlogpath,
+								const char *xlogfname,
+								const char *lastRestartPointFname,
+								char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..af7763ebac
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,19 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 727a8fdec9..915a2945ef 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

base-commit: 612a1ab76724aa1514b6509269342649f8cab375
-- 
2.19.1

From ea93b52b298d80aac547735c5917386b37667595 Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Tue, 25 Feb 2020 02:22:45 +0300
Subject: [PATCH v19] pg_rewind: Add options to restore WAL files from archive

    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.

    This commit implements new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage. The
    restore_command option is read from postgresql.conf.

    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Michael Paquier, Andrey Borodin, Alvaro Herrera
    Reviewed-by: Andres Freund, Alexander Korotkov
---
 doc/src/sgml/ref/pg_rewind.sgml          |  28 ++++--
 src/backend/access/transam/xlogarchive.c |  60 ++----------
 src/bin/pg_rewind/parsexlog.c            |  33 ++++++-
 src/bin/pg_rewind/pg_rewind.c            |  77 +++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h            |   6 +-
 src/bin/pg_rewind/t/001_basic.pl         |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm        |  66 +++++++++++++-
 src/common/Makefile                      |   2 +
 src/common/archive.c                     | 102 +++++++++++++++++++++
 src/common/fe_archive.c                  | 111 +++++++++++++++++++++++
 src/include/common/archive.h             |  22 +++++
 src/include/common/fe_archive.h          |  19 ++++
 src/tools/msvc/Mkvcbuild.pm              |   8 +-
 13 files changed, 457 insertions(+), 80 deletions(-)
 create mode 100644 src/common/archive.c
 create mode 100644 src/common/fe_archive.c
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/include/common/fe_archive.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..64a6942031 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        the target cluster configuration to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..f78a7e8f02 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,12 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
+	rc = BuildRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+							 lastRestartPointFname, xlogRestoreCmd);
 
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	if (rc != 0)
+		/* Sanity check, should never happen. */
+		elog(ERROR, "failed to build restore_command due to missing parameters");
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..08a7fc3560 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command to execute, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab..db43aada05 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -79,6 +81,8 @@ usage(const char *progname)
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
 	printf(_("  -R, --write-recovery-conf      write configuration for replication\n"
 			 "                                 (requires --source-server)\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -n, --dry-run                  stop before modifying anything\n"));
 	printf(_("  -N, --no-sync                  do not wait for changes to be written\n"
 			 "                                 safely to disk\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "D:nNPRc", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -155,6 +160,10 @@ main(int argc, char **argv)
 				showprogress = true;
 				break;
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'n':
 				dry_run = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval
+		 * if set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "\"%s\" -D \"%s\" -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..7af8b9b347 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,50 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories.
+		# It should be empty in this test, so it is safe.
+		rmdir($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Ensure directories have right modes.  It's required by
+		# 'check PGDATA permissions' test.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -87,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..8c79044a6b
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,102 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname,
+					char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..7309983ed4
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,111 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/* logging support */
+#define pg_fatal(...) do { pg_log_fatal(__VA_ARGS__); exit(1); } while(0)
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = BuildRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+		pg_fatal("restore_command with %%r alias cannot be used.");
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("archive file \"%s\" has wrong size: %lu instead of %lu, %s",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize, strerror(errno));
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %s\n",
+								 xlogpath, strerror(errno));
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %s",
+						 xlogpath, strerror(errno));
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels.  We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+		pg_fatal("restore_command failed due to the signal: %s",
+				 wait_result_to_str(rc));
+
+	pg_log_error("could not restore file \"%s\" from archive\n",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..3e6e143cd8
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,22 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int	BuildRestoreCommand(const char *restoreCommand,
+								const char *xlogpath,
+								const char *xlogfname,
+								const char *lastRestartPointFname,
+								char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..af7763ebac
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,19 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 834c2c39d1..25da1fa8ec 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

base-commit: c4b0edb07ed53063ea4c86cd7918ad6ea01d8979
-- 
2.19.1

From ba20808ffddf3fe2eefe96d3385697fb6583ce9a Mon Sep 17 00:00:00 2001
From: Alexander Korotkov <akorotkov@postgresql.org>
Date: Tue, 25 Feb 2020 02:22:45 +0300
Subject: [PATCH v20] pg_rewind: Add options to restore WAL files from archive

    Currently, pg_rewind fails when it could not find required WAL files in the
    target data directory.  One have to manually figure out which WAL files are
    required and copy them back from archive.

    This commit implements new pg_rewind options, which allow pg_rewind to
    automatically retrieve missing WAL files from archival storage. The
    restore_command option is read from postgresql.conf.

    Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1%40postgrespro.ru
    Author: Alexey Kondratov
    Reviewed-by: Michael Paquier, Andrey Borodin, Alvaro Herrera
    Reviewed-by: Andres Freund, Alexander Korotkov
---
 doc/src/sgml/ref/pg_rewind.sgml          |  28 ++++--
 src/backend/access/transam/xlogarchive.c |  60 ++----------
 src/bin/pg_rewind/parsexlog.c            |  33 ++++++-
 src/bin/pg_rewind/pg_rewind.c            |  77 ++++++++++++++-
 src/bin/pg_rewind/pg_rewind.h            |   6 +-
 src/bin/pg_rewind/t/001_basic.pl         |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm        |  66 ++++++++++++-
 src/common/Makefile                      |   2 +
 src/common/archive.c                     | 102 ++++++++++++++++++++
 src/common/fe_archive.c                  | 114 +++++++++++++++++++++++
 src/include/common/archive.h             |  22 +++++
 src/include/common/fe_archive.h          |  19 ++++
 src/tools/msvc/Mkvcbuild.pm              |   8 +-
 13 files changed, 460 insertions(+), 80 deletions(-)
 create mode 100644 src/common/archive.c
 create mode 100644 src/common/fe_archive.c
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/include/common/fe_archive.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..64a6942031 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use the <varname>restore_command</varname> defined in
+        the target cluster configuration to retrieve WAL files from
+        the WAL archive if these files are no longer available in the
+        <filename>pg_wal</filename> directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..f78a7e8f02 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,12 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
+	rc = BuildRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+							 lastRestartPointFname, xlogRestoreCmd);
 
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	if (rc != 0)
+		/* Sanity check, should never happen. */
+		elog(ERROR, "failed to build restore_command due to missing parameters");
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..16ae668f16 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve
+			 * missing WAL file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index c6d00bb0ab..290c71ce71 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -53,11 +53,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +76,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"));
+	printf(_("                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -105,6 +109,7 @@ main(int argc, char **argv)
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"debug", no_argument, NULL, 3},
 		{NULL, 0, NULL, 0}
 	};
@@ -143,7 +148,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -151,6 +156,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -252,6 +261,65 @@ main(int argc, char **argv)
 		exit(1);
 	}
 
+	if (restore_wal)
+	{
+		int			rc;
+		char		postgres_exec_path[MAXPGPATH],
+					postgres_cmd[MAXPGPATH],
+					cmd_output[MAXPGPATH];
+		FILE	   *output_fp;
+
+		/* Find postgres executable. */
+		rc = find_other_exec(argv[0], "postgres",
+							 PG_BACKEND_VERSIONSTR,
+							 postgres_exec_path);
+
+		if (rc < 0)
+		{
+			char		full_path[MAXPGPATH];
+
+			if (find_my_exec(argv[0], full_path) < 0)
+				strlcpy(full_path, progname, sizeof(full_path));
+
+			if (rc == -1)
+				pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+							 "same directory as \"%s\".\n"
+							 "Check your installation.",
+							 progname, full_path);
+			else
+				pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+							 "but was not the same version as %s.\n"
+							 "Check your installation.",
+							 full_path, progname);
+			exit(1);
+		}
+
+		/*
+		 * Build a command to execute for restore_command GUC retrieval
+		 * if set.
+		 */
+		snprintf(postgres_cmd, sizeof(postgres_cmd), "\"%s\" -D \"%s\" -C restore_command",
+				 postgres_exec_path, datadir_target);
+
+		if ((output_fp = popen(postgres_cmd, "r")) == NULL ||
+			fgets(cmd_output, sizeof(cmd_output), output_fp) == NULL)
+			pg_fatal("could not get restore_command using %s: %s",
+					 postgres_cmd, strerror(errno));
+
+		pclose(output_fp);
+
+		/* Remove trailing newline */
+		if (strchr(cmd_output, '\n') != NULL)
+			*strchr(cmd_output, '\n') = '\0';
+
+		if (!strcmp(cmd_output, ""))
+			pg_fatal("restore_command is not set on the target cluster");
+
+		restore_command = pg_strdup(cmd_output);
+
+		pg_log_debug("using config variable restore_command=\'%s\'", restore_command);
+	}
+
 	umask(pg_mode_mask);
 
 	atexit(disconnect_atexit);
@@ -349,9 +417,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -377,7 +444,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..842782b146 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,50 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and
+		# specified directory with target WAL archive.
+		# Old master should be stopped at this point.
+
+		# First, remove archive_dir, since RecursiveCopy::copypath
+		# does not support copying to existing directories.
+		# It should be empty in this test, so it is safe.
+		rmtree($node_master->archive_dir);
+
+		# Move all old master WAL files to the archive.
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Ensure directories have right modes.  It's required by
+		# 'check PGDATA permissions' test.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Just to append an appropriate restore_command
+		# to postgresql.conf
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"-c"
+			],
+			'pg_rewind archive_conf');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -87,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..8c79044a6b
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,102 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * Constructs restore_command from template with %p, %f and %r aliases.
+ * Returns 0 if restore_command was successfuly built.
+ *
+ * If any of the required arguments is NULL, but corresponding alias is
+ * met, then -1 code will be returned.
+ */
+int
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname,
+					char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Construct the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..ea47d86494
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,114 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc,
+				xlogfd;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = BuildRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+	{
+		pg_log_fatal("restore_command with %%r alias cannot be used.");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("unexpected WAL file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+			}
+			else
+			{
+				xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+					pg_log_error("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			/* Stat failed */
+			pg_log_error("could not stat file \"%s\" restored from archive: %m",
+						 xlogpath);
+		}
+	}
+
+	/*
+	 * If the failure was due to any sort of signal, then it will be
+	 * misleading to return message 'could not restore file...' and propagate
+	 * result to the upper levels.  We should exit right now.
+	 */
+	if (wait_result_is_any_signal(rc, false))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..3e6e143cd8
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,22 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+extern int	BuildRestoreCommand(const char *restoreCommand,
+								const char *xlogpath,
+								const char *xlogfname,
+								const char *lastRestartPointFname,
+								char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..af7763ebac
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,19 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 834c2c39d1..25da1fa8ec 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

base-commit: afb5465e0cfce7637066eaaaeecab30b0f23fbe3
-- 
2.19.1

diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..e0260dd453
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,28 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+/*
+ * Routine to build a restore command to retrieve WAL segments from a WAL
+ * archive.  This uses the arguments given by the caller to replace the
+ * corresponding alias fields as defined in the GUC parameter
+ * restore_command.
+ */
+extern int	BuildRestoreCommand(const char *restoreCommand,
+								const char *xlogpath,	/* alias %p */
+								const char *xlogfname,	/* alias %f */
+								const char *lastRestartPointFname,	/* alias %r */
+								char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..af7763ebac
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,19 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedWALFile(const char *path, const char *xlogfname,
+								   off_t expectedSize, const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/include/port.h b/src/include/port.h
index 3be994b43c..0685ce3abc 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames);
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
-/* Portable way to find binaries (in exec.c) */
+/* Portable way to find and execute binaries (in exec.c) */
 extern int	find_my_exec(const char *argv0, char *retpath);
 extern int	find_other_exec(const char *argv0, const char *target,
 							const char *versionstr, char *retpath);
+extern char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 /* Doesn't belong here, but this is used with find_other_exec(), so... */
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..b90dbd44d8 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -65,8 +63,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	TimeLineID	restartTli;
 
 	/*
-	 * Ignore restore_command when not in archive recovery (meaning
-	 * we are in crash recovery).
+	 * Ignore restore_command when not in archive recovery (meaning we are in
+	 * crash recovery).
 	 */
 	if (!ArchiveRecoveryRequested)
 		goto not_available;
@@ -149,58 +147,13 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
+	/* Build the command to execute */
+	rc = BuildRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+							 lastRestartPointFname, xlogRestoreCmd);
 
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	if (rc != 0)
+		elog(ERROR, "failed to build restore command \"%s\" due to incorrect parameters",
+			 xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
@@ -87,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..7152b96983
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,106 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * BuildRestoreCommand
+ *
+ * Builds a restore command to retrieve a WAL segment from WAL archives,
+ * replacing the supported aliases with values supplied by the caller:
+ * xlogpath for %p, xlogfname for %f and lastRestartPointFname for %r.
+ * Returns 0 if restore_command was successfully built.
+ *
+ * If any of the required arguments is NULL and that the corresponding alias
+ * is found in the command given by the caller, then -1 is returned.
+ */
+int
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname,
+					char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Build the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return -1;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return 0;
+}
diff --git a/src/common/exec.c b/src/common/exec.c
index 88400daa47..5321509b00 100644
--- a/src/common/exec.c
+++ b/src/common/exec.c
@@ -1,7 +1,7 @@
 /*-------------------------------------------------------------------------
  *
  * exec.c
- *		Functions for finding and validating executable files
+ *		Functions for finding and validating from executables files
  *
  *
  * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
@@ -51,7 +51,6 @@
 
 static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
-static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 #ifdef WIN32
 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
@@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target,
 /*
  * Execute a command in a pipe and read the first line from it.
  */
-static char *
+char *
 pipe_read_line(char *cmd, char *line, int maxsize)
 {
 	FILE	   *pgver;
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..3c688c4731
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,124 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archive from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * RestoreArchivedWALFile
+ *
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful return a file descriptor of the restored WAL file, else
+ * return -1.
+ *
+ * The caller has to pass the expected size of the file restored from
+ * the archives via "expectedSize".
+ */
+int
+RestoreArchivedWALFile(const char *path, const char *xlogfname,
+					   off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH],
+				xlogRestoreCmd[MAXPGPATH];
+	int			rc;
+	struct stat stat_buf;
+
+	Assert(expectedSize > 0);
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	rc = BuildRestoreCommand(restoreCommand, xlogpath, xlogfname, NULL, xlogRestoreCmd);
+
+	if (rc < 0)
+	{
+		pg_log_fatal("restore_command with %%r alias cannot be used.");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing WAL file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (stat_buf.st_size != expectedSize)
+			{
+				pg_log_error("unexpected WAL file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+				return -1;
+			}
+			else
+			{
+				int			xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+				{
+					pg_log_error("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+					return -1;
+				}
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			pg_log_error("could not stat file \"%s\": %m",
+						 xlogpath);
+			return -1;
+		}
+	}
+
+	/*
+	 * If the failure was due to a signal, then it would be misleading to
+	 * return with a failure at restoring the WAL file.  So just bail out and
+	 * exit.
+	 */
+	if (wait_result_is_any_signal(rc, true))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	/*
+	 * The WAL file is not available, so just let the caller decide what to do
+	 * next.
+	 */
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..d28096397c 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve missing WAL
+			 * file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedWALFile(xlogreader->segcxt.ws_dir,
+												xlogfname,
+												WalSegSz,
+												private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bf2d2983e7..aa5522e870 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
+#include "common/string.h"
 #include "fe_utils/recovery_gen.h"
 #include "fetch.h"
 #include "file_ops.h"
@@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
 static void digestControlFile(ControlFileData *ControlFile, char *source,
 							  size_t size);
 static void syncTargetDirectory(void);
+static void getRestoreCommand(const char *argv0);
 static void sanityChecks(void);
 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
 static void ensureCleanShutdown(const char *argv0);
@@ -53,11 +55,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +78,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"
+			 "                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -103,6 +109,7 @@ main(int argc, char **argv)
 		{"source-server", required_argument, NULL, 2},
 		{"no-ensure-shutdown", no_argument, NULL, 4},
 		{"version", no_argument, NULL, 'V'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
@@ -144,7 +151,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -152,6 +159,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -255,6 +266,8 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	getRestoreCommand(argv[0]);
+
 	atexit(disconnect_atexit);
 
 	/* Connect to remote server */
@@ -350,9 +363,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -378,7 +390,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
@@ -804,6 +816,67 @@ syncTargetDirectory(void)
 	fsync_pgdata(datadir_target, PG_VERSION_NUM);
 }
 
+/*
+ */
+static void
+getRestoreCommand(const char *argv0)
+{
+	int			rc;
+	char		postgres_exec_path[MAXPGPATH],
+				postgres_cmd[MAXPGPATH],
+				cmd_output[MAXPGPATH];
+
+	if (!restore_wal)
+		return;
+
+	/* find postgres executable */
+	rc = find_other_exec(argv0, "postgres",
+						 PG_BACKEND_VERSIONSTR,
+						 postgres_exec_path);
+
+	if (rc < 0)
+	{
+		char		full_path[MAXPGPATH];
+
+		if (find_my_exec(argv0, full_path) < 0)
+			strlcpy(full_path, progname, sizeof(full_path));
+
+		if (rc == -1)
+			pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+						 "same directory as \"%s\".\n"
+						 "Check your installation.",
+						 progname, full_path);
+		else
+			pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+						 "but was not the same version as %s.\n"
+						 "Check your installation.",
+						 full_path, progname);
+		exit(1);
+	}
+
+	/*
+	 * Build a command able to retrieve the value of GUC parameter
+	 * restore_command, if set.
+	 */
+	snprintf(postgres_cmd, sizeof(postgres_cmd),
+			 "\"%s\" -D \"%s\" -C restore_command",
+			 postgres_exec_path, datadir_target);
+
+	if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
+		exit(1);
+
+	(void) pg_strip_crlf(cmd_output);
+
+	if (strcmp(cmd_output, "") == 0)
+		pg_fatal("restore_command is not set on the target cluster");
+
+	restore_command = pg_strdup(cmd_output);
+
+	pg_log_debug("using for rewind restore_command = \'%s\'",
+				 restore_command);
+}
+
+
 /*
  * Ensure clean shutdown of target instance by launching single-user mode
  * postgres to do crash recovery.
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..577a4294f3 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,51 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and specified
+		# directory with target WAL archive.  The old master has
+		# to be stopped at this point.
+
+		# First, remove all the content in the archive directory,
+		# as RecursiveCopy::copypath does not support copying to
+		# existing directories.
+		rmtree($node_master->archive_dir);
+
+		# Move all WAL segments from the old master to the archives.
+		# These will be used by pg_rewind.
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Make sure that directories have the right umask as this is
+		# required by a follow-up check on permissions, and better
+		# safe than sorry.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Add appropriate restore_command to the target cluster
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"--restore-target-wal"
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 42d29edd4e..180b05ddb6 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use <varname>restore_command</varname> defined in the target cluster
+        configuration to retrieve WAL files from the WAL archive if these
+        files are no longer available in the <filename>pg_wal</filename>
+        directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 834c2c39d1..25da1fa8ec 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -119,8 +119,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
@@ -137,8 +137,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 

From bad2c04b0eb3a146f0c2719ed8360b3b255c3c47 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 9 Mar 2020 17:15:00 +0900
Subject: [PATCH] Move routine generating restore_command to src/common/

restore_command has only been used until now by the backend, but there
is a pending patch for pg_rewind to make use of that in the frontend.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/archive.h             |  28 ++++++
 src/backend/access/transam/xlogarchive.c |  61 ++-----------
 src/common/Makefile                      |   1 +
 src/common/archive.c                     | 109 +++++++++++++++++++++++
 src/tools/msvc/Mkvcbuild.pm              |   4 +-
 5 files changed, 146 insertions(+), 57 deletions(-)
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/common/archive.c

diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..bdcc49ffd3
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,28 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+/*
+ * Routine to build a restore command to retrieve WAL segments from a WAL
+ * archive.  This uses the arguments given by the caller to replace the
+ * corresponding alias fields as defined in the GUC parameter
+ * restore_command.
+ */
+extern bool BuildRestoreCommand(const char *restoreCommand,
+								const char *xlogpath,	/* %p */
+								const char *xlogfname,	/* %f */
+								const char *lastRestartPointFname,	/* %r */
+								char *result);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..6e8cd88a5e 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,11 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	/* Build the restore command to execute */
+	if (!BuildRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+							 lastRestartPointFname, xlogRestoreCmd))
+		elog(ERROR, "could not build restore command \"%s\"",
+			 xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..6939b9d087 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..574d56410d
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,109 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * BuildRestoreCommand
+ *
+ * Builds a restore command to retrieve a WAL segment from WAL archives,
+ * replacing the supported aliases with values supplied by the caller:
+ * xlogpath for %p, xlogfname for %f and lastRestartPointFname for %r.
+ * Returns true if restore_command was successfully built.
+ *
+ * If any of the required arguments is NULL and that the corresponding alias
+ * is found in the command given by the caller, then false is returned.
+ *
+ * The resulting restore command is stored in "result", which has to be
+ * a pre-allocated buffer of size MAXPGPATH.
+ */
+bool
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname,
+					char *result)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Build the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return false;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return false;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return false;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return true;
+}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index f89a8a4fdb..c648078e20 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -120,8 +120,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
-- 
2.25.1

From 4e2b5b60e003ec67a4854f2625cc610f01428fe2 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 9 Mar 2020 17:15:00 +0900
Subject: [PATCH v2] Move routine generating restore_command to src/common/

restore_command has only been used until now by the backend, but there
is a pending patch for pg_rewind to make use of that in the frontend.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/archive.h             |  29 ++++++
 src/backend/access/transam/xlogarchive.c |  62 ++-----------
 src/common/Makefile                      |   1 +
 src/common/archive.c                     | 110 +++++++++++++++++++++++
 src/tools/msvc/Mkvcbuild.pm              |   4 +-
 5 files changed, 149 insertions(+), 57 deletions(-)
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/common/archive.c

diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..805930490b
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,29 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+/*
+ * Routine to build a restore command to retrieve WAL segments from a WAL
+ * archive.  This uses the arguments given by the caller to replace the
+ * corresponding alias fields as defined in the GUC parameter
+ * restore_command.
+ */
+extern bool BuildRestoreCommand(const char *restoreCommand,
+								const char *xlogpath,	/* %p */
+								const char *xlogfname,	/* %f */
+								const char *lastRestartPointFname,	/* %r */
+								char *commandResult,
+								int commandResultLen);
+
+#endif							/* ARCHIVE_H */
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..e1d6df89e1 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -55,9 +56,6 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	char		xlogpath[MAXPGPATH];
 	char		xlogRestoreCmd[MAXPGPATH];
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,12 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	/* Build the restore command to execute */
+	if (!BuildRestoreCommand(recoveryRestoreCommand, xlogpath, xlogfname,
+							 lastRestartPointFname, xlogRestoreCmd,
+							 MAXPGPATH))
+		elog(ERROR, "could not build restore command \"%s\"",
+			 xlogRestoreCmd);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..6939b9d087 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..74c71e0f4c
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,110 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * BuildRestoreCommand
+ *
+ * Builds a restore command to retrieve a WAL segment from WAL archives,
+ * replacing the supported aliases with values supplied by the caller:
+ * xlogpath for %p, xlogfname for %f and lastRestartPointFname for %r.
+ * Returns true if restore_command was successfully built.
+ *
+ * If any of the required arguments is NULL and that the corresponding alias
+ * is found in the command given by the caller, then false is returned.
+ *
+ * The resulting restore command is stored in "commandResult", pre-allocated
+ * buffer of size "restoreCommandLen".
+ */
+bool
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname,
+					char *commandResult,
+					int commandResultLen)
+{
+	char	   *dp,
+			   *endp;
+	const char *sp;
+
+	/*
+	 * Build the command to be executed.
+	 */
+	dp = commandResult;
+	endp = commandResult + commandResultLen - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+						return false;
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+						return false;
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+						return false;
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return true;
+}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index f89a8a4fdb..c648078e20 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -120,8 +120,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
-- 
2.25.1

From 33d9a6837f2435966006947dad18c21e40e0c271 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Wed, 11 Mar 2020 12:25:18 +0900
Subject: [PATCH v3] Move routine generating restore_command to src/common/

restore_command has only been used until now by the backend, but there
is a pending patch for pg_rewind to make use of that in the frontend.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/archive.h             |  27 +++++
 src/backend/access/transam/xlogarchive.c |  66 ++-----------
 src/common/Makefile                      |   1 +
 src/common/archive.c                     | 119 +++++++++++++++++++++++
 src/tools/msvc/Mkvcbuild.pm              |   4 +-
 5 files changed, 159 insertions(+), 58 deletions(-)
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/common/archive.c

diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..8af0b4566f
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+/*
+ * Routine to build a restore command to retrieve WAL segments from a WAL
+ * archive.  This uses the arguments given by the caller to replace the
+ * corresponding alias fields as defined in the GUC parameter
+ * restore_command.
+ */
+extern char *BuildRestoreCommand(const char *restoreCommand,
+								 const char *xlogpath,	/* %p */
+								 const char *xlogfname, /* %f */
+								 const char *lastRestartPointFname);	/* %r */
+
+#endif							/* ARCHIVE_H */
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..914ad340ea 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -53,11 +54,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 					bool cleanupEnabled)
 {
 	char		xlogpath[MAXPGPATH];
-	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *xlogRestoreCmd;
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,13 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	/* Build the restore command to execute */
+	xlogRestoreCmd = BuildRestoreCommand(recoveryRestoreCommand,
+										 xlogpath, xlogfname,
+										 lastRestartPointFname);
+	if (xlogRestoreCmd == NULL)
+		elog(ERROR, "could not build restore command \"%s\"",
+			 recoveryRestoreCommand);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
@@ -217,6 +170,7 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	rc = system(xlogRestoreCmd);
 
 	PostRestoreCommand();
+	pfree(xlogRestoreCmd);
 
 	if (rc == 0)
 	{
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..6939b9d087 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..ef0ce532ed
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,119 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * BuildRestoreCommand
+ *
+ * Builds a restore command to retrieve a WAL segment from WAL archives,
+ * replacing the supported aliases with values supplied by the caller as
+ * defined by the GUC parameter restore_command: xlogpath for %p,
+ * xlogfname for %f and lastRestartPointFname for %r.
+ *
+ * The result is a palloc'd string for the restore command built.  The
+ * caller is responsible for freeing it.  If any of the required arguments
+ * is NULL and that the corresponding alias is found in the command given
+ * by the caller, then NULL is returned.
+ */
+char *
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname)
+{
+	char	   *dp;
+	char	   *endp;
+	char	   *result;
+	const char *sp;
+
+	result = palloc0(MAXPGPATH);
+
+	/*
+	 * Build the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+					{
+						pfree(result);
+						return NULL;
+					}
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+					{
+						pfree(result);
+						return NULL;
+					}
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+					{
+						pfree(result);
+						return NULL;
+					}
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return result;
+}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index f89a8a4fdb..c648078e20 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -120,8 +120,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
-- 
2.25.1

From 43ac17434f5fba9effd77c1962d46589ba693874 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 12 Mar 2020 13:22:34 +0900
Subject: [PATCH 1/2] Move routine generating restore_command to src/common/

restore_command has only been used until now by the backend, but there
is a pending patch for pg_rewind to make use of that in the frontend.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/archive.h             |  27 +++++
 src/backend/access/transam/xlogarchive.c |  66 ++-----------
 src/common/Makefile                      |   1 +
 src/common/archive.c                     | 119 +++++++++++++++++++++++
 src/tools/msvc/Mkvcbuild.pm              |   4 +-
 5 files changed, 159 insertions(+), 58 deletions(-)
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/common/archive.c

diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..8af0b4566f
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+/*
+ * Routine to build a restore command to retrieve WAL segments from a WAL
+ * archive.  This uses the arguments given by the caller to replace the
+ * corresponding alias fields as defined in the GUC parameter
+ * restore_command.
+ */
+extern char *BuildRestoreCommand(const char *restoreCommand,
+								 const char *xlogpath,	/* %p */
+								 const char *xlogfname, /* %f */
+								 const char *lastRestartPointFname);	/* %r */
+
+#endif							/* ARCHIVE_H */
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..914ad340ea 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -53,11 +54,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 					bool cleanupEnabled)
 {
 	char		xlogpath[MAXPGPATH];
-	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *xlogRestoreCmd;
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,13 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	/* Build the restore command to execute */
+	xlogRestoreCmd = BuildRestoreCommand(recoveryRestoreCommand,
+										 xlogpath, xlogfname,
+										 lastRestartPointFname);
+	if (xlogRestoreCmd == NULL)
+		elog(ERROR, "could not build restore command \"%s\"",
+			 recoveryRestoreCommand);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
@@ -217,6 +170,7 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	rc = system(xlogRestoreCmd);
 
 	PostRestoreCommand();
+	pfree(xlogRestoreCmd);
 
 	if (rc == 0)
 	{
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..6939b9d087 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..783fc3d752
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,119 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+
+/*
+ * BuildRestoreCommand
+ *
+ * Builds a restore command to retrieve a file from WAL archives, replacing
+ * the supported aliases with values supplied by the caller as defined by
+ * the GUC parameter restore_command: xlogpath for %p, xlogfname for %f and
+ * lastRestartPointFname for %r.
+ *
+ * The result is a palloc'd string for the restore command built.  The
+ * caller is responsible for freeing it.  If any of the required arguments
+ * is NULL and that the corresponding alias is found in the command given
+ * by the caller, then NULL is returned.
+ */
+char *
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname)
+{
+	char	   *dp;
+	char	   *endp;
+	char	   *result;
+	const char *sp;
+
+	result = palloc0(MAXPGPATH);
+
+	/*
+	 * Build the command to be executed.
+	 */
+	dp = result;
+	endp = result + MAXPGPATH - 1;
+	*endp = '\0';
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					/* %p: relative path of target file */
+					if (xlogpath == NULL)
+					{
+						pfree(result);
+						return NULL;
+					}
+					sp++;
+					StrNCpy(dp, xlogpath, endp - dp);
+					make_native_path(dp);
+					dp += strlen(dp);
+					break;
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+					{
+						pfree(result);
+						return NULL;
+					}
+					sp++;
+					StrNCpy(dp, xlogfname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+					{
+						pfree(result);
+						return NULL;
+					}
+					sp++;
+					StrNCpy(dp, lastRestartPointFname, endp - dp);
+					dp += strlen(dp);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					if (dp < endp)
+						*dp++ = *sp;
+					break;
+			}
+		}
+		else
+		{
+			if (dp < endp)
+				*dp++ = *sp;
+		}
+	}
+	*dp = '\0';
+
+	return result;
+}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index f89a8a4fdb..c648078e20 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -120,8 +120,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
-	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
-	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
+	  archive.c base64.c config_info.c controldata_utils.c d2s.c encnames.c
+	  exec.c f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
 	  pg_lzcompress.c pgfnames.c psprintf.c relpath.c rmtree.c
 	  saslprep.c scram-common.c string.c stringinfo.c unicode_norm.c username.c
-- 
2.25.1

From ccf64c26b425ef4d36bb409a9e6f2e70c64513e8 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Thu, 12 Mar 2020 13:03:23 +0900
Subject: [PATCH 2/2] Add -c/--restore-target-wal to pg_rewind

pg_rewind needs to copy from the source server to the target a set of
relation blocks changed from the previous checkpoint where WAL forked
between both up to the end of WAL on the target.  This may require WAL
segments that are not present anymore on the target's pg_wal, causing
pg_rewind to fail.  It is possible to fix that by copying manually the
WAL segments needed but this may lead to extra and useless work.

Instead, this commit introduces a new option allowing pg_rewind to use a
restore_command when running by grabbing it from the target
configuration.  This allows the rewind operation to be more reliable,
and only the necessary segments are fetched from the archives in this
case.

In order to do that, a new routine is added to src/common/ to allow
frontend tools to retrieve a WAL segment using an already-built restore
command.  This version is much more simple than the backend equivalent.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/fe_archive.h   |  21 +++++
 src/include/port.h                |   3 +-
 src/common/Makefile               |   1 +
 src/common/exec.c                 |   3 +-
 src/common/fe_archive.c           | 129 ++++++++++++++++++++++++++++++
 src/bin/pg_rewind/parsexlog.c     |  33 +++++++-
 src/bin/pg_rewind/pg_rewind.c     |  87 ++++++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h     |   6 +-
 src/bin/pg_rewind/t/001_basic.pl  |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm |  64 ++++++++++++++-
 doc/src/sgml/ref/pg_rewind.sgml   |  28 +++++--
 src/tools/msvc/Mkvcbuild.pm       |   4 +-
 12 files changed, 355 insertions(+), 27 deletions(-)
 create mode 100644 src/include/common/fe_archive.h
 create mode 100644 src/common/fe_archive.c

diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..13d19d11e7
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	FrontendRestoreArchivedFile(const char *path,
+										const char *xlogfname,
+										off_t expectedSize,
+										const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/include/port.h b/src/include/port.h
index 29f3e39e5b..20a5de1b7a 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames);
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
-/* Portable way to find binaries (in exec.c) */
+/* Portable way to find and execute binaries (in exec.c) */
 extern int	find_my_exec(const char *argv0, char *retpath);
 extern int	find_other_exec(const char *argv0, const char *target,
 							const char *versionstr, char *retpath);
+extern char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 /* Doesn't belong here, but this is used with find_other_exec(), so... */
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
diff --git a/src/common/Makefile b/src/common/Makefile
index 6939b9d087..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -88,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/exec.c b/src/common/exec.c
index 88400daa47..f39b0a294b 100644
--- a/src/common/exec.c
+++ b/src/common/exec.c
@@ -51,7 +51,6 @@
 
 static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
-static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 #ifdef WIN32
 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
@@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target,
 /*
  * Execute a command in a pipe and read the first line from it.
  */
-static char *
+char *
 pipe_read_line(char *cmd, char *line, int maxsize)
 {
 	FILE	   *pgver;
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..1716e754ee
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,129 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * FrontendRestoreArchivedFile
+ *
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful, return a file descriptor of the restored file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+FrontendRestoreArchivedFile(const char *path, const char *xlogfname,
+							off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char	   *xlogRestoreCmd;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
+										 xlogfname, NULL);
+	if (xlogRestoreCmd == NULL)
+	{
+		pg_log_fatal("could not use restore_command with %%r alias");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+	pfree(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+				exit(1);
+			}
+			else
+			{
+				int			xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+				{
+					pg_log_fatal("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+					exit(1);
+				}
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			if (errno != ENOENT)
+			{
+				pg_log_fatal("could not stat file \"%s\": %m",
+							 xlogpath);
+				exit(1);
+			}
+			return -1;
+		}
+	}
+
+	/*
+	 * If the failure was due to a signal, then it would be misleading to
+	 * return with a failure at restoring the file.  So just bail out and
+	 * exit.  Hard shell errors such as "command not found" are treated as
+	 * fatal too.
+	 */
+	if (wait_result_is_any_signal(rc, true))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	/*
+	 * The file is not available, so just let the caller decide what to do
+	 * next.
+	 */
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..7c8bc1dfe2 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve missing WAL
+			 * file from the archive.
+			 */
+			xlogreadfd = FrontendRestoreArchivedFile(xlogreader->segcxt.ws_dir,
+													 xlogfname,
+													 WalSegSz,
+													 private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bf2d2983e7..44eb15b269 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
+#include "common/string.h"
 #include "fe_utils/recovery_gen.h"
 #include "fetch.h"
 #include "file_ops.h"
@@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
 static void digestControlFile(ControlFileData *ControlFile, char *source,
 							  size_t size);
 static void syncTargetDirectory(void);
+static void getRestoreCommand(const char *argv0);
 static void sanityChecks(void);
 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
 static void ensureCleanShutdown(const char *argv0);
@@ -53,11 +55,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +78,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"
+			 "                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -103,6 +109,7 @@ main(int argc, char **argv)
 		{"source-server", required_argument, NULL, 2},
 		{"no-ensure-shutdown", no_argument, NULL, 4},
 		{"version", no_argument, NULL, 'V'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
@@ -144,7 +151,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -152,6 +159,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -255,6 +266,8 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	getRestoreCommand(argv[0]);
+
 	atexit(disconnect_atexit);
 
 	/* Connect to remote server */
@@ -350,9 +363,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -378,7 +390,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
@@ -804,6 +816,71 @@ syncTargetDirectory(void)
 	fsync_pgdata(datadir_target, PG_VERSION_NUM);
 }
 
+/*
+ * Get value of GUC parameter restore_command from the target cluster.
+ *
+ * This uses a logic based on "postgres -C" to get the value from
+ * from the cluster.
+ */
+static void
+getRestoreCommand(const char *argv0)
+{
+	int			rc;
+	char		postgres_exec_path[MAXPGPATH],
+				postgres_cmd[MAXPGPATH],
+				cmd_output[MAXPGPATH];
+
+	if (!restore_wal)
+		return;
+
+	/* find postgres executable */
+	rc = find_other_exec(argv0, "postgres",
+						 PG_BACKEND_VERSIONSTR,
+						 postgres_exec_path);
+
+	if (rc < 0)
+	{
+		char		full_path[MAXPGPATH];
+
+		if (find_my_exec(argv0, full_path) < 0)
+			strlcpy(full_path, progname, sizeof(full_path));
+
+		if (rc == -1)
+			pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+						 "same directory as \"%s\".\n"
+						 "Check your installation.",
+						 progname, full_path);
+		else
+			pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+						 "but was not the same version as %s.\n"
+						 "Check your installation.",
+						 full_path, progname);
+		exit(1);
+	}
+
+	/*
+	 * Build a command able to retrieve the value of GUC parameter
+	 * restore_command, if set.
+	 */
+	snprintf(postgres_cmd, sizeof(postgres_cmd),
+			 "\"%s\" -D \"%s\" -C restore_command",
+			 postgres_exec_path, datadir_target);
+
+	if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
+		exit(1);
+
+	(void) pg_strip_crlf(cmd_output);
+
+	if (strcmp(cmd_output, "") == 0)
+		pg_fatal("restore_command is not set on the target cluster");
+
+	restore_command = pg_strdup(cmd_output);
+
+	pg_log_debug("using for rewind restore_command = \'%s\'",
+				 restore_command);
+}
+
+
 /*
  * Ensure clean shutdown of target instance by launching single-user mode
  * postgres to do crash recovery.
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..349d2fa0b2 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,48 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and specified
+		# directory with target WAL archive.  The old master has
+		# to be stopped at this point.
+
+		# Remove the existing archive directory and move all WAL
+		# segments from the old master to the archives.  These
+		# will be used by pg_rewind.
+		rmtree($node_master->archive_dir);
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Make sure that directories have the right umask as this is
+		# required by a follow-up check on permissions, and better
+		# safe than sorry.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Add appropriate restore_command to the target cluster
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"--restore-target-wal"
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index f64d659522..07c49e4719 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use <varname>restore_command</varname> defined in the target cluster
+        configuration to retrieve WAL files from the WAL archive if these
+        files are no longer available in the <filename>pg_wal</filename>
+        directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index c648078e20..92df33a7e9 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -138,8 +138,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
-- 
2.25.1

From 53ef0a122eedd661a31813815563a09178dd56da Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Fri, 13 Mar 2020 09:16:44 +0900
Subject: [PATCH v3 1/2] Move routine generating restore_command to src/common/

restore_command has only been used until now by the backend, but there
is a pending patch for pg_rewind to make use of that in the frontend.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/archive.h             |  27 +++++
 src/backend/access/transam/xlogarchive.c |  66 ++-----------
 src/common/Makefile                      |   1 +
 src/common/archive.c                     | 121 +++++++++++++++++++++++
 src/tools/msvc/Mkvcbuild.pm              |   1 +
 5 files changed, 160 insertions(+), 56 deletions(-)
 create mode 100644 src/include/common/archive.h
 create mode 100644 src/common/archive.c

diff --git a/src/include/common/archive.h b/src/include/common/archive.h
new file mode 100644
index 0000000000..8af0b4566f
--- /dev/null
+++ b/src/include/common/archive.h
@@ -0,0 +1,27 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.h
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef ARCHIVE_H
+#define ARCHIVE_H
+
+/*
+ * Routine to build a restore command to retrieve WAL segments from a WAL
+ * archive.  This uses the arguments given by the caller to replace the
+ * corresponding alias fields as defined in the GUC parameter
+ * restore_command.
+ */
+extern char *BuildRestoreCommand(const char *restoreCommand,
+								 const char *xlogpath,	/* %p */
+								 const char *xlogfname, /* %f */
+								 const char *lastRestartPointFname);	/* %r */
+
+#endif							/* ARCHIVE_H */
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 188b73e752..914ad340ea 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -21,6 +21,7 @@
 
 #include "access/xlog.h"
 #include "access/xlog_internal.h"
+#include "common/archive.h"
 #include "miscadmin.h"
 #include "postmaster/startup.h"
 #include "replication/walsender.h"
@@ -53,11 +54,8 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 					bool cleanupEnabled)
 {
 	char		xlogpath[MAXPGPATH];
-	char		xlogRestoreCmd[MAXPGPATH];
+	char	   *xlogRestoreCmd;
 	char		lastRestartPointFname[MAXPGPATH];
-	char	   *dp;
-	char	   *endp;
-	const char *sp;
 	int			rc;
 	struct stat stat_buf;
 	XLogSegNo	restartSegNo;
@@ -149,58 +147,13 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	else
 		XLogFileName(lastRestartPointFname, 0, 0L, wal_segment_size);
 
-	/*
-	 * construct the command to be executed
-	 */
-	dp = xlogRestoreCmd;
-	endp = xlogRestoreCmd + MAXPGPATH - 1;
-	*endp = '\0';
-
-	for (sp = recoveryRestoreCommand; *sp; sp++)
-	{
-		if (*sp == '%')
-		{
-			switch (sp[1])
-			{
-				case 'p':
-					/* %p: relative path of target file */
-					sp++;
-					StrNCpy(dp, xlogpath, endp - dp);
-					make_native_path(dp);
-					dp += strlen(dp);
-					break;
-				case 'f':
-					/* %f: filename of desired file */
-					sp++;
-					StrNCpy(dp, xlogfname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case 'r':
-					/* %r: filename of last restartpoint */
-					sp++;
-					StrNCpy(dp, lastRestartPointFname, endp - dp);
-					dp += strlen(dp);
-					break;
-				case '%':
-					/* convert %% to a single % */
-					sp++;
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-				default:
-					/* otherwise treat the % as not special */
-					if (dp < endp)
-						*dp++ = *sp;
-					break;
-			}
-		}
-		else
-		{
-			if (dp < endp)
-				*dp++ = *sp;
-		}
-	}
-	*dp = '\0';
+	/* Build the restore command to execute */
+	xlogRestoreCmd = BuildRestoreCommand(recoveryRestoreCommand,
+										 xlogpath, xlogfname,
+										 lastRestartPointFname);
+	if (xlogRestoreCmd == NULL)
+		elog(ERROR, "could not build restore command \"%s\"",
+			 recoveryRestoreCommand);
 
 	ereport(DEBUG3,
 			(errmsg_internal("executing restore command \"%s\"",
@@ -217,6 +170,7 @@ RestoreArchivedFile(char *path, const char *xlogfname,
 	rc = system(xlogRestoreCmd);
 
 	PostRestoreCommand();
+	pfree(xlogRestoreCmd);
 
 	if (rc == 0)
 	{
diff --git a/src/common/Makefile b/src/common/Makefile
index ce01df68b9..6939b9d087 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -46,6 +46,7 @@ LIBS += $(PTHREAD_LIBS)
 # If you add objects here, see also src/tools/msvc/Mkvcbuild.pm
 
 OBJS_COMMON = \
+	archive.o \
 	base64.o \
 	config_info.o \
 	controldata_utils.o \
diff --git a/src/common/archive.c b/src/common/archive.c
new file mode 100644
index 0000000000..a94e4d0a5e
--- /dev/null
+++ b/src/common/archive.c
@@ -0,0 +1,121 @@
+/*-------------------------------------------------------------------------
+ *
+ * archive.c
+ *	  Common WAL archive routines
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#include "postgres.h"
+#else
+#include "postgres_fe.h"
+#endif
+
+#include "common/archive.h"
+#include "lib/stringinfo.h"
+
+/*
+ * BuildRestoreCommand
+ *
+ * Builds a restore command to retrieve a file from WAL archives, replacing
+ * the supported aliases with values supplied by the caller as defined by
+ * the GUC parameter restore_command: xlogpath for %p, xlogfname for %f and
+ * lastRestartPointFname for %r.
+ *
+ * The result is a palloc'd string for the restore command built.  The
+ * caller is responsible for freeing it.  If any of the required arguments
+ * is NULL and that the corresponding alias is found in the command given
+ * by the caller, then NULL is returned.
+ */
+char *
+BuildRestoreCommand(const char *restoreCommand,
+					const char *xlogpath,
+					const char *xlogfname,
+					const char *lastRestartPointFname)
+{
+	StringInfoData result;
+	const char *sp;
+
+	/*
+	 * Build the command to be executed.
+	 */
+	initStringInfo(&result);
+
+	for (sp = restoreCommand; *sp; sp++)
+	{
+		if (*sp == '%')
+		{
+			switch (sp[1])
+			{
+				case 'p':
+					{
+						char	   *nativePath;
+
+						/* %p: relative path of target file */
+						if (xlogpath == NULL)
+						{
+							pfree(result.data);
+							return NULL;
+						}
+						sp++;
+
+						/*
+						 * This needs to use a placeholder to not modify the
+						 * input with the conversion done via
+						 * make_native_path().
+						 */
+						nativePath = pstrdup(xlogpath);
+						make_native_path(nativePath);
+						appendStringInfoString(&result,
+											   nativePath);
+						pfree(nativePath);
+						break;
+					}
+				case 'f':
+					/* %f: filename of desired file */
+					if (xlogfname == NULL)
+					{
+						pfree(result.data);
+						return NULL;
+					}
+					sp++;
+					appendStringInfoString(&result, xlogfname);
+					break;
+				case 'r':
+					/* %r: filename of last restartpoint */
+					if (lastRestartPointFname == NULL)
+					{
+						pfree(result.data);
+						return NULL;
+					}
+					sp++;
+					appendStringInfoString(&result,
+										   lastRestartPointFname);
+					break;
+				case '%':
+					/* convert %% to a single % */
+					sp++;
+					appendStringInfoChar(&result, *sp);
+					break;
+				default:
+					/* otherwise treat the % as not special */
+					appendStringInfoChar(&result, *sp);
+					break;
+			}
+		}
+		else
+		{
+			appendStringInfoChar(&result, *sp);
+		}
+	}
+
+	return result.data;
+}
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index f89a8a4fdb..636428b044 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -120,6 +120,7 @@ sub mkvcbuild
 	}
 
 	our @pgcommonallfiles = qw(
+	  archive.c
 	  base64.c config_info.c controldata_utils.c d2s.c encnames.c exec.c
 	  f2s.c file_perm.c hashfn.c ip.c jsonapi.c
 	  keywords.c kwlookup.c link-canary.c md5.c
-- 
2.25.1

From 947411524c6aea85edf76e0d04ac97ddd4300a36 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Fri, 13 Mar 2020 09:17:21 +0900
Subject: [PATCH v3 2/2] Add -c/--restore-target-wal to pg_rewind

pg_rewind needs to copy from the source server to the target a set of
relation blocks changed from the previous checkpoint where WAL forked
between both up to the end of WAL on the target.  This may require WAL
segments that are not present anymore on the target's pg_wal, causing
pg_rewind to fail.  It is possible to fix that by copying manually the
WAL segments needed but this may lead to extra and useless work.

Instead, this commit introduces a new option allowing pg_rewind to use a
restore_command when running by grabbing it from the target
configuration.  This allows the rewind operation to be more reliable,
and only the necessary segments are fetched from the archives in this
case.

In order to do that, a new routine is added to src/common/ to allow
frontend tools to retrieve a WAL segment using an already-built restore
command.  This version is much more simple than the backend equivalent.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/fe_archive.h   |  21 +++++
 src/include/port.h                |   3 +-
 src/common/Makefile               |   1 +
 src/common/exec.c                 |   3 +-
 src/common/fe_archive.c           | 129 ++++++++++++++++++++++++++++++
 src/bin/pg_rewind/parsexlog.c     |  33 +++++++-
 src/bin/pg_rewind/pg_rewind.c     |  87 ++++++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h     |   6 +-
 src/bin/pg_rewind/t/001_basic.pl  |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm |  64 ++++++++++++++-
 doc/src/sgml/ref/pg_rewind.sgml   |  28 +++++--
 src/tools/msvc/Mkvcbuild.pm       |   4 +-
 12 files changed, 355 insertions(+), 27 deletions(-)
 create mode 100644 src/include/common/fe_archive.h
 create mode 100644 src/common/fe_archive.c

diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..13d19d11e7
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	FrontendRestoreArchivedFile(const char *path,
+										const char *xlogfname,
+										off_t expectedSize,
+										const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/include/port.h b/src/include/port.h
index 29f3e39e5b..20a5de1b7a 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames);
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
-/* Portable way to find binaries (in exec.c) */
+/* Portable way to find and execute binaries (in exec.c) */
 extern int	find_my_exec(const char *argv0, char *retpath);
 extern int	find_other_exec(const char *argv0, const char *target,
 							const char *versionstr, char *retpath);
+extern char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 /* Doesn't belong here, but this is used with find_other_exec(), so... */
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
diff --git a/src/common/Makefile b/src/common/Makefile
index 6939b9d087..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -88,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/exec.c b/src/common/exec.c
index 88400daa47..f39b0a294b 100644
--- a/src/common/exec.c
+++ b/src/common/exec.c
@@ -51,7 +51,6 @@
 
 static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
-static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 #ifdef WIN32
 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
@@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target,
 /*
  * Execute a command in a pipe and read the first line from it.
  */
-static char *
+char *
 pipe_read_line(char *cmd, char *line, int maxsize)
 {
 	FILE	   *pgver;
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..1716e754ee
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,129 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * FrontendRestoreArchivedFile
+ *
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful, return a file descriptor of the restored file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+FrontendRestoreArchivedFile(const char *path, const char *xlogfname,
+							off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char	   *xlogRestoreCmd;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
+										 xlogfname, NULL);
+	if (xlogRestoreCmd == NULL)
+	{
+		pg_log_fatal("could not use restore_command with %%r alias");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+	pfree(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+				exit(1);
+			}
+			else
+			{
+				int			xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+				{
+					pg_log_fatal("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+					exit(1);
+				}
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			if (errno != ENOENT)
+			{
+				pg_log_fatal("could not stat file \"%s\": %m",
+							 xlogpath);
+				exit(1);
+			}
+			return -1;
+		}
+	}
+
+	/*
+	 * If the failure was due to a signal, then it would be misleading to
+	 * return with a failure at restoring the file.  So just bail out and
+	 * exit.  Hard shell errors such as "command not found" are treated as
+	 * fatal too.
+	 */
+	if (wait_result_is_any_signal(rc, true))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	/*
+	 * The file is not available, so just let the caller decide what to do
+	 * next.
+	 */
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..7c8bc1dfe2 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve missing WAL
+			 * file from the archive.
+			 */
+			xlogreadfd = FrontendRestoreArchivedFile(xlogreader->segcxt.ws_dir,
+													 xlogfname,
+													 WalSegSz,
+													 private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bf2d2983e7..44eb15b269 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
+#include "common/string.h"
 #include "fe_utils/recovery_gen.h"
 #include "fetch.h"
 #include "file_ops.h"
@@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
 static void digestControlFile(ControlFileData *ControlFile, char *source,
 							  size_t size);
 static void syncTargetDirectory(void);
+static void getRestoreCommand(const char *argv0);
 static void sanityChecks(void);
 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
 static void ensureCleanShutdown(const char *argv0);
@@ -53,11 +55,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +78,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"
+			 "                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -103,6 +109,7 @@ main(int argc, char **argv)
 		{"source-server", required_argument, NULL, 2},
 		{"no-ensure-shutdown", no_argument, NULL, 4},
 		{"version", no_argument, NULL, 'V'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
@@ -144,7 +151,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -152,6 +159,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -255,6 +266,8 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	getRestoreCommand(argv[0]);
+
 	atexit(disconnect_atexit);
 
 	/* Connect to remote server */
@@ -350,9 +363,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -378,7 +390,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
@@ -804,6 +816,71 @@ syncTargetDirectory(void)
 	fsync_pgdata(datadir_target, PG_VERSION_NUM);
 }
 
+/*
+ * Get value of GUC parameter restore_command from the target cluster.
+ *
+ * This uses a logic based on "postgres -C" to get the value from
+ * from the cluster.
+ */
+static void
+getRestoreCommand(const char *argv0)
+{
+	int			rc;
+	char		postgres_exec_path[MAXPGPATH],
+				postgres_cmd[MAXPGPATH],
+				cmd_output[MAXPGPATH];
+
+	if (!restore_wal)
+		return;
+
+	/* find postgres executable */
+	rc = find_other_exec(argv0, "postgres",
+						 PG_BACKEND_VERSIONSTR,
+						 postgres_exec_path);
+
+	if (rc < 0)
+	{
+		char		full_path[MAXPGPATH];
+
+		if (find_my_exec(argv0, full_path) < 0)
+			strlcpy(full_path, progname, sizeof(full_path));
+
+		if (rc == -1)
+			pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+						 "same directory as \"%s\".\n"
+						 "Check your installation.",
+						 progname, full_path);
+		else
+			pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+						 "but was not the same version as %s.\n"
+						 "Check your installation.",
+						 full_path, progname);
+		exit(1);
+	}
+
+	/*
+	 * Build a command able to retrieve the value of GUC parameter
+	 * restore_command, if set.
+	 */
+	snprintf(postgres_cmd, sizeof(postgres_cmd),
+			 "\"%s\" -D \"%s\" -C restore_command",
+			 postgres_exec_path, datadir_target);
+
+	if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
+		exit(1);
+
+	(void) pg_strip_crlf(cmd_output);
+
+	if (strcmp(cmd_output, "") == 0)
+		pg_fatal("restore_command is not set on the target cluster");
+
+	restore_command = pg_strdup(cmd_output);
+
+	pg_log_debug("using for rewind restore_command = \'%s\'",
+				 restore_command);
+}
+
+
 /*
  * Ensure clean shutdown of target instance by launching single-user mode
  * postgres to do crash recovery.
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..349d2fa0b2 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,48 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and specified
+		# directory with target WAL archive.  The old master has
+		# to be stopped at this point.
+
+		# Remove the existing archive directory and move all WAL
+		# segments from the old master to the archives.  These
+		# will be used by pg_rewind.
+		rmtree($node_master->archive_dir);
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Make sure that directories have the right umask as this is
+		# required by a follow-up check on permissions, and better
+		# safe than sorry.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Add appropriate restore_command to the target cluster
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"--restore-target-wal"
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index f64d659522..07c49e4719 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use <varname>restore_command</varname> defined in the target cluster
+        configuration to retrieve WAL files from the WAL archive if these
+        files are no longer available in the <filename>pg_wal</filename>
+        directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 636428b044..4b68a5c640 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -139,8 +139,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
-- 
2.25.1

From ecb2b3d62cce7ef56aa4fdb5343c54d9ee94100b Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Fri, 13 Mar 2020 09:17:21 +0900
Subject: [PATCH v4] Add -c/--restore-target-wal to pg_rewind

pg_rewind needs to copy from the source server to the target a set of
relation blocks changed from the previous checkpoint where WAL forked
between both up to the end of WAL on the target.  This may require WAL
segments that are not present anymore on the target's pg_wal, causing
pg_rewind to fail.  It is possible to fix that by copying manually the
WAL segments needed but this may lead to extra and useless work.

Instead, this commit introduces a new option allowing pg_rewind to use a
restore_command when running by grabbing it from the target
configuration.  This allows the rewind operation to be more reliable,
and only the necessary segments are fetched from the archives in this
case.

In order to do that, a new routine is added to src/common/ to allow
frontend tools to retrieve a WAL segment using an already-built restore
command.  This version is much more simple than the backend equivalent.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/fe_archive.h   |  21 +++++
 src/include/port.h                |   3 +-
 src/common/Makefile               |   1 +
 src/common/exec.c                 |   3 +-
 src/common/fe_archive.c           | 129 ++++++++++++++++++++++++++++++
 src/bin/pg_rewind/parsexlog.c     |  33 +++++++-
 src/bin/pg_rewind/pg_rewind.c     |  87 ++++++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h     |   6 +-
 src/bin/pg_rewind/t/001_basic.pl  |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm |  64 ++++++++++++++-
 doc/src/sgml/ref/pg_rewind.sgml   |  28 +++++--
 src/tools/msvc/Mkvcbuild.pm       |   4 +-
 12 files changed, 355 insertions(+), 27 deletions(-)
 create mode 100644 src/include/common/fe_archive.h
 create mode 100644 src/common/fe_archive.c

diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..13d19d11e7
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	FrontendRestoreArchivedFile(const char *path,
+										const char *xlogfname,
+										off_t expectedSize,
+										const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/include/port.h b/src/include/port.h
index 29f3e39e5b..20a5de1b7a 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames);
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
-/* Portable way to find binaries (in exec.c) */
+/* Portable way to find and execute binaries (in exec.c) */
 extern int	find_my_exec(const char *argv0, char *retpath);
 extern int	find_other_exec(const char *argv0, const char *target,
 							const char *versionstr, char *retpath);
+extern char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 /* Doesn't belong here, but this is used with find_other_exec(), so... */
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
diff --git a/src/common/Makefile b/src/common/Makefile
index 6939b9d087..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -88,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/exec.c b/src/common/exec.c
index 88400daa47..f39b0a294b 100644
--- a/src/common/exec.c
+++ b/src/common/exec.c
@@ -51,7 +51,6 @@
 
 static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
-static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 #ifdef WIN32
 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
@@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target,
 /*
  * Execute a command in a pipe and read the first line from it.
  */
-static char *
+char *
 pipe_read_line(char *cmd, char *line, int maxsize)
 {
 	FILE	   *pgver;
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..1716e754ee
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,129 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * FrontendRestoreArchivedFile
+ *
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful, return a file descriptor of the restored file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+FrontendRestoreArchivedFile(const char *path, const char *xlogfname,
+							off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char	   *xlogRestoreCmd;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
+										 xlogfname, NULL);
+	if (xlogRestoreCmd == NULL)
+	{
+		pg_log_fatal("could not use restore_command with %%r alias");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+	pfree(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+				exit(1);
+			}
+			else
+			{
+				int			xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+				{
+					pg_log_fatal("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+					exit(1);
+				}
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			if (errno != ENOENT)
+			{
+				pg_log_fatal("could not stat file \"%s\": %m",
+							 xlogpath);
+				exit(1);
+			}
+			return -1;
+		}
+	}
+
+	/*
+	 * If the failure was due to a signal, then it would be misleading to
+	 * return with a failure at restoring the file.  So just bail out and
+	 * exit.  Hard shell errors such as "command not found" are treated as
+	 * fatal too.
+	 */
+	if (wait_result_is_any_signal(rc, true))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	/*
+	 * The file is not available, so just let the caller decide what to do
+	 * next.
+	 */
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..7c8bc1dfe2 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve missing WAL
+			 * file from the archive.
+			 */
+			xlogreadfd = FrontendRestoreArchivedFile(xlogreader->segcxt.ws_dir,
+													 xlogfname,
+													 WalSegSz,
+													 private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bf2d2983e7..44eb15b269 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
+#include "common/string.h"
 #include "fe_utils/recovery_gen.h"
 #include "fetch.h"
 #include "file_ops.h"
@@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
 static void digestControlFile(ControlFileData *ControlFile, char *source,
 							  size_t size);
 static void syncTargetDirectory(void);
+static void getRestoreCommand(const char *argv0);
 static void sanityChecks(void);
 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
 static void ensureCleanShutdown(const char *argv0);
@@ -53,11 +55,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +78,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"
+			 "                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -103,6 +109,7 @@ main(int argc, char **argv)
 		{"source-server", required_argument, NULL, 2},
 		{"no-ensure-shutdown", no_argument, NULL, 4},
 		{"version", no_argument, NULL, 'V'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
@@ -144,7 +151,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -152,6 +159,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -255,6 +266,8 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	getRestoreCommand(argv[0]);
+
 	atexit(disconnect_atexit);
 
 	/* Connect to remote server */
@@ -350,9 +363,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -378,7 +390,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
@@ -804,6 +816,71 @@ syncTargetDirectory(void)
 	fsync_pgdata(datadir_target, PG_VERSION_NUM);
 }
 
+/*
+ * Get value of GUC parameter restore_command from the target cluster.
+ *
+ * This uses a logic based on "postgres -C" to get the value from
+ * from the cluster.
+ */
+static void
+getRestoreCommand(const char *argv0)
+{
+	int			rc;
+	char		postgres_exec_path[MAXPGPATH],
+				postgres_cmd[MAXPGPATH],
+				cmd_output[MAXPGPATH];
+
+	if (!restore_wal)
+		return;
+
+	/* find postgres executable */
+	rc = find_other_exec(argv0, "postgres",
+						 PG_BACKEND_VERSIONSTR,
+						 postgres_exec_path);
+
+	if (rc < 0)
+	{
+		char		full_path[MAXPGPATH];
+
+		if (find_my_exec(argv0, full_path) < 0)
+			strlcpy(full_path, progname, sizeof(full_path));
+
+		if (rc == -1)
+			pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+						 "same directory as \"%s\".\n"
+						 "Check your installation.",
+						 progname, full_path);
+		else
+			pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+						 "but was not the same version as %s.\n"
+						 "Check your installation.",
+						 full_path, progname);
+		exit(1);
+	}
+
+	/*
+	 * Build a command able to retrieve the value of GUC parameter
+	 * restore_command, if set.
+	 */
+	snprintf(postgres_cmd, sizeof(postgres_cmd),
+			 "\"%s\" -D \"%s\" -C restore_command",
+			 postgres_exec_path, datadir_target);
+
+	if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
+		exit(1);
+
+	(void) pg_strip_crlf(cmd_output);
+
+	if (strcmp(cmd_output, "") == 0)
+		pg_fatal("restore_command is not set on the target cluster");
+
+	restore_command = pg_strdup(cmd_output);
+
+	pg_log_debug("using for rewind restore_command = \'%s\'",
+				 restore_command);
+}
+
+
 /*
  * Ensure clean shutdown of target instance by launching single-user mode
  * postgres to do crash recovery.
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..349d2fa0b2 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,23 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# We test pg_rewind with restore_command by simply moving all WAL files
+		# to another location.  It leads to failed ensureCleanShutdown
+		# execution.  Since it is difficult to emulate a situation, when
+		# keeping the last WAL segment is enough for startup recovery, but
+		# not enough for successful pg_rewind run, we run these modes with
+		# --no-ensure-shutdown.  So stop the master gracefully.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +298,48 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and specified
+		# directory with target WAL archive.  The old master has
+		# to be stopped at this point.
+
+		# Remove the existing archive directory and move all WAL
+		# segments from the old master to the archives.  These
+		# will be used by pg_rewind.
+		rmtree($node_master->archive_dir);
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Make sure that directories have the right umask as this is
+		# required by a follow-up check on permissions, and better
+		# safe than sorry.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Add appropriate restore_command to the target cluster
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"--restore-target-wal"
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index f64d659522..07c49e4719 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use <varname>restore_command</varname> defined in the target cluster
+        configuration to retrieve WAL files from the WAL archive if these
+        files are no longer available in the <filename>pg_wal</filename>
+        directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 636428b044..4b68a5c640 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -139,8 +139,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
-- 
2.25.1

diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index 860a996414..d683af377f 100644
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -36,6 +36,7 @@
 
 #include "access/timeline.h"
 #include "access/xlog.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "access/xlogdefs.h"
 #include "pgstat.h"
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 7621fc05e2..242427f815 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -32,6 +32,7 @@
 #include "access/transam.h"
 #include "access/twophase.h"
 #include "access/xact.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "access/xloginsert.h"
 #include "access/xlogreader.h"
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 914ad340ea..04104b55ea 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -20,6 +20,7 @@
 #include <unistd.h>
 
 #include "access/xlog.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "common/archive.h"
 #include "miscadmin.h"
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 25e0333c9e..cc91954ac1 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -48,6 +48,7 @@
 #include "access/htup_details.h"
 #include "access/timeline.h"
 #include "access/transam.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_type.h"
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index 27ded593ab..8e3cfcf83e 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -320,22 +320,4 @@ extern bool InArchiveRecovery;
 extern bool StandbyMode;
 extern char *recoveryRestoreCommand;
 
-/*
- * Prototypes for functions in xlogarchive.c
- */
-extern bool RestoreArchivedFile(char *path, const char *xlogfname,
-								const char *recovername, off_t expectedSize,
-								bool cleanupEnabled);
-extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
-								   bool failOnSignal);
-extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
-extern void XLogArchiveNotify(const char *xlog);
-extern void XLogArchiveNotifySeg(XLogSegNo segno);
-extern void XLogArchiveForceDone(const char *xlog);
-extern bool XLogArchiveCheckDone(const char *xlog);
-extern bool XLogArchiveIsBusy(const char *xlog);
-extern bool XLogArchiveIsReady(const char *xlog);
-extern bool XLogArchiveIsReadyOrDone(const char *xlog);
-extern void XLogArchiveCleanup(const char *xlog);
-
 #endif							/* XLOG_INTERNAL_H */
diff --git a/src/include/access/xlogarchive.h b/src/include/access/xlogarchive.h
new file mode 100644
index 0000000000..3406fb2800
--- /dev/null
+++ b/src/include/access/xlogarchive.h
@@ -0,0 +1,31 @@
+/*
+ * xlogarchive.h
+ *		Prototypes of functions for archiving WAL files and restoring
+ *		from the archive.
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/access/xlogarchive.h
+ */
+#ifndef XLOG_ARCHIVE_H
+#define XLOG_ARCHIVE_H
+
+#include "access/xlogdefs.h"
+
+extern bool RestoreArchivedFile(char *path, const char *xlogfname,
+								const char *recovername, off_t expectedSize,
+								bool cleanupEnabled);
+extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
+								   bool failOnSignal);
+extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
+extern void XLogArchiveNotify(const char *xlog);
+extern void XLogArchiveNotifySeg(XLogSegNo segno);
+extern void XLogArchiveForceDone(const char *xlog);
+extern bool XLogArchiveCheckDone(const char *xlog);
+extern bool XLogArchiveIsBusy(const char *xlog);
+extern bool XLogArchiveIsReady(const char *xlog);
+extern bool XLogArchiveIsReadyOrDone(const char *xlog);
+extern void XLogArchiveCleanup(const char *xlog);
+
+#endif							/* XLOG_ARCHIVE_H */

From 71302a709a54a88985563c38830deb784728e682 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 30 Mar 2020 10:34:17 +0900
Subject: [PATCH v5 1/2] Move routines of xlogarchive.c into their own header

The definitions of those routines have been part of xlog_internal.h,
which is included by several frontend tools.  More could be done in this
area, but that's already a nice and simple cut.
---
 src/include/access/xlog_internal.h       | 18 ------------
 src/include/access/xlogarchive.h         | 35 ++++++++++++++++++++++++
 src/backend/access/transam/timeline.c    |  1 +
 src/backend/access/transam/xlog.c        |  1 +
 src/backend/access/transam/xlogarchive.c |  1 +
 src/backend/replication/walreceiver.c    |  1 +
 6 files changed, 39 insertions(+), 18 deletions(-)
 create mode 100644 src/include/access/xlogarchive.h

diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index 27ded593ab..8e3cfcf83e 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -320,22 +320,4 @@ extern bool InArchiveRecovery;
 extern bool StandbyMode;
 extern char *recoveryRestoreCommand;
 
-/*
- * Prototypes for functions in xlogarchive.c
- */
-extern bool RestoreArchivedFile(char *path, const char *xlogfname,
-								const char *recovername, off_t expectedSize,
-								bool cleanupEnabled);
-extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
-								   bool failOnSignal);
-extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
-extern void XLogArchiveNotify(const char *xlog);
-extern void XLogArchiveNotifySeg(XLogSegNo segno);
-extern void XLogArchiveForceDone(const char *xlog);
-extern bool XLogArchiveCheckDone(const char *xlog);
-extern bool XLogArchiveIsBusy(const char *xlog);
-extern bool XLogArchiveIsReady(const char *xlog);
-extern bool XLogArchiveIsReadyOrDone(const char *xlog);
-extern void XLogArchiveCleanup(const char *xlog);
-
 #endif							/* XLOG_INTERNAL_H */
diff --git a/src/include/access/xlogarchive.h b/src/include/access/xlogarchive.h
new file mode 100644
index 0000000000..1c67de2ede
--- /dev/null
+++ b/src/include/access/xlogarchive.h
@@ -0,0 +1,35 @@
+/*------------------------------------------------------------------------
+ *
+ * xlogarchive.h
+ *		Prototypes for WAL archives in the backend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *		src/include/access/xlogarchive.h
+ *
+ *------------------------------------------------------------------------
+ */
+
+#ifndef XLOG_ARCHIVE_H
+#define XLOG_ARCHIVE_H
+
+#include "access/xlogdefs.h"
+
+extern bool RestoreArchivedFile(char *path, const char *xlogfname,
+								const char *recovername, off_t expectedSize,
+								bool cleanupEnabled);
+extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
+								   bool failOnSignal);
+extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
+extern void XLogArchiveNotify(const char *xlog);
+extern void XLogArchiveNotifySeg(XLogSegNo segno);
+extern void XLogArchiveForceDone(const char *xlog);
+extern bool XLogArchiveCheckDone(const char *xlog);
+extern bool XLogArchiveIsBusy(const char *xlog);
+extern bool XLogArchiveIsReady(const char *xlog);
+extern bool XLogArchiveIsReadyOrDone(const char *xlog);
+extern void XLogArchiveCleanup(const char *xlog);
+
+#endif							/* XLOG_ARCHIVE_H */
diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index 860a996414..d683af377f 100644
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -36,6 +36,7 @@
 
 #include "access/timeline.h"
 #include "access/xlog.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "access/xlogdefs.h"
 #include "pgstat.h"
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 8fe92962b0..03c81c0375 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -32,6 +32,7 @@
 #include "access/transam.h"
 #include "access/twophase.h"
 #include "access/xact.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "access/xloginsert.h"
 #include "access/xlogreader.h"
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 914ad340ea..04104b55ea 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -20,6 +20,7 @@
 #include <unistd.h>
 
 #include "access/xlog.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "common/archive.h"
 #include "miscadmin.h"
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 760e3c7ab0..9ecbfe336e 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -54,6 +54,7 @@
 #include "access/htup_details.h"
 #include "access/timeline.h"
 #include "access/transam.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_type.h"
-- 
2.26.0

From fb4470376ee308463648c31354942169553e0582 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 30 Mar 2020 10:51:51 +0900
Subject: [PATCH v5 2/2] Add -c/--restore-target-wal to pg_rewind

pg_rewind needs to copy from the source server to the target a set of
relation blocks changed from the previous checkpoint where WAL forked
between both up to the end of WAL on the target.  This may require WAL
segments that are not present anymore on the target's pg_wal, causing
pg_rewind to fail.  It is possible to fix that by copying manually the
WAL segments needed but this may lead to extra and useless work.

Instead, this commit introduces a new option allowing pg_rewind to use a
restore_command when running by grabbing it from the target
configuration.  This allows the rewind operation to be more reliable,
and only the necessary segments are fetched from the archives in this
case.

In order to do that, a new routine is added to src/common/ to allow
frontend tools to retrieve a WAL segment using an already-built restore
command.  This version is much more simple than the backend equivalent.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 src/include/common/fe_archive.h   |  21 +++++
 src/include/port.h                |   3 +-
 src/common/Makefile               |   1 +
 src/common/exec.c                 |   3 +-
 src/common/fe_archive.c           | 128 ++++++++++++++++++++++++++++++
 src/bin/pg_rewind/parsexlog.c     |  33 +++++++-
 src/bin/pg_rewind/pg_rewind.c     |  87 ++++++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h     |   6 +-
 src/bin/pg_rewind/t/001_basic.pl  |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm |  70 +++++++++++++++-
 doc/src/sgml/ref/pg_rewind.sgml   |  28 +++++--
 src/tools/msvc/Mkvcbuild.pm       |   4 +-
 12 files changed, 360 insertions(+), 27 deletions(-)
 create mode 100644 src/include/common/fe_archive.h
 create mode 100644 src/common/fe_archive.c

diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..96506baefb
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedFile(const char *path,
+										const char *xlogfname,
+										off_t expectedSize,
+										const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/include/port.h b/src/include/port.h
index 29f3e39e5b..20a5de1b7a 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames);
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
-/* Portable way to find binaries (in exec.c) */
+/* Portable way to find and execute binaries (in exec.c) */
 extern int	find_my_exec(const char *argv0, char *retpath);
 extern int	find_other_exec(const char *argv0, const char *target,
 							const char *versionstr, char *retpath);
+extern char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 /* Doesn't belong here, but this is used with find_other_exec(), so... */
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
diff --git a/src/common/Makefile b/src/common/Makefile
index 6939b9d087..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -88,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/exec.c b/src/common/exec.c
index 88400daa47..f39b0a294b 100644
--- a/src/common/exec.c
+++ b/src/common/exec.c
@@ -51,7 +51,6 @@
 
 static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
-static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 #ifdef WIN32
 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
@@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target,
 /*
  * Execute a command in a pipe and read the first line from it.
  */
-static char *
+char *
 pipe_read_line(char *cmd, char *line, int maxsize)
 {
 	FILE	   *pgver;
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..146bc4e048
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,128 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * RestoreArchivedFile
+ *
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful, return a file descriptor of the restored file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedFile(const char *path, const char *xlogfname,
+							off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char	   *xlogRestoreCmd;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
+										 xlogfname, NULL);
+	if (xlogRestoreCmd == NULL)
+	{
+		pg_log_fatal("could not use restore_command with %%r alias");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+	pfree(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+				exit(1);
+			}
+			else
+			{
+				int			xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+				{
+					pg_log_fatal("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+					exit(1);
+				}
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			if (errno != ENOENT)
+			{
+				pg_log_fatal("could not stat file \"%s\": %m",
+							 xlogpath);
+				exit(1);
+			}
+		}
+	}
+
+	/*
+	 * If the failure was due to a signal, then it would be misleading to
+	 * return with a failure at restoring the file.  So just bail out and
+	 * exit.  Hard shell errors such as "command not found" are treated as
+	 * fatal too.
+	 */
+	if (wait_result_is_any_signal(rc, true))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	/*
+	 * The file is not available, so just let the caller decide what to do
+	 * next.
+	 */
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..b147b7212f 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restore_command)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restore_command;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve missing WAL
+			 * file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedFile(xlogreader->segcxt.ws_dir,
+													 xlogfname,
+													 WalSegSz,
+													 private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bf2d2983e7..44eb15b269 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
+#include "common/string.h"
 #include "fe_utils/recovery_gen.h"
 #include "fetch.h"
 #include "file_ops.h"
@@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
 static void digestControlFile(ControlFileData *ControlFile, char *source,
 							  size_t size);
 static void syncTargetDirectory(void);
+static void getRestoreCommand(const char *argv0);
 static void sanityChecks(void);
 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
 static void ensureCleanShutdown(const char *argv0);
@@ -53,11 +55,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +78,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"
+			 "                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -103,6 +109,7 @@ main(int argc, char **argv)
 		{"source-server", required_argument, NULL, 2},
 		{"no-ensure-shutdown", no_argument, NULL, 4},
 		{"version", no_argument, NULL, 'V'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
@@ -144,7 +151,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -152,6 +159,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -255,6 +266,8 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	getRestoreCommand(argv[0]);
+
 	atexit(disconnect_atexit);
 
 	/* Connect to remote server */
@@ -350,9 +363,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -378,7 +390,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
@@ -804,6 +816,71 @@ syncTargetDirectory(void)
 	fsync_pgdata(datadir_target, PG_VERSION_NUM);
 }
 
+/*
+ * Get value of GUC parameter restore_command from the target cluster.
+ *
+ * This uses a logic based on "postgres -C" to get the value from
+ * from the cluster.
+ */
+static void
+getRestoreCommand(const char *argv0)
+{
+	int			rc;
+	char		postgres_exec_path[MAXPGPATH],
+				postgres_cmd[MAXPGPATH],
+				cmd_output[MAXPGPATH];
+
+	if (!restore_wal)
+		return;
+
+	/* find postgres executable */
+	rc = find_other_exec(argv0, "postgres",
+						 PG_BACKEND_VERSIONSTR,
+						 postgres_exec_path);
+
+	if (rc < 0)
+	{
+		char		full_path[MAXPGPATH];
+
+		if (find_my_exec(argv0, full_path) < 0)
+			strlcpy(full_path, progname, sizeof(full_path));
+
+		if (rc == -1)
+			pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+						 "same directory as \"%s\".\n"
+						 "Check your installation.",
+						 progname, full_path);
+		else
+			pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+						 "but was not the same version as %s.\n"
+						 "Check your installation.",
+						 full_path, progname);
+		exit(1);
+	}
+
+	/*
+	 * Build a command able to retrieve the value of GUC parameter
+	 * restore_command, if set.
+	 */
+	snprintf(postgres_cmd, sizeof(postgres_cmd),
+			 "\"%s\" -D \"%s\" -C restore_command",
+			 postgres_exec_path, datadir_target);
+
+	if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
+		exit(1);
+
+	(void) pg_strip_crlf(cmd_output);
+
+	if (strcmp(cmd_output, "") == 0)
+		pg_fatal("restore_command is not set on the target cluster");
+
+	restore_command = pg_strdup(cmd_output);
+
+	pg_log_debug("using for rewind restore_command = \'%s\'",
+				 restore_command);
+}
+
+
 /*
  * Ensure clean shutdown of target instance by launching single-user mode
  * postgres to do crash recovery.
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..7dabf395e1 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,26 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# pg_rewind is tested with --restore-target-wal by moving all
+		# WAL files to a secondary location.  Note that this leads to
+		# a failure in ensureCleanShutdown(), forcing to the use of
+		# --no-ensure-shutdown in this mode as the initial set of WAL
+		# files needed to ensure a clean restart is gone.  This could
+		# be improved by keeping around only a minimum set of WAL
+		# segments but that would just make the test more costly,
+		# without improving the coverage.  Hence, instead, stop
+		# gracefully the primary here.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +301,51 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and specified
+		# directory with target WAL archive.  The old master has
+		# to be stopped at this point.
+
+		# Remove the existing archive directory and move all WAL
+		# segments from the old master to the archives.  These
+		# will be used by pg_rewind.
+		rmtree($node_master->archive_dir);
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Make sure that directories have the right umask as this is
+		# required by a follow-up check on permissions, and better
+		# safe than sorry.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Add appropriate restore_command to the target cluster
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Note the use of --no-ensure-shutdown here.  WAL files are
+		# gone in this mode and the primary has been stopped
+		# gracefully already.
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"--restore-target-wal"
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index f64d659522..07c49e4719 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use <varname>restore_command</varname> defined in the target cluster
+        configuration to retrieve WAL files from the WAL archive if these
+        files are no longer available in the <filename>pg_wal</filename>
+        directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 39709f20e6..5c88825f49 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -139,8 +139,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
-- 
2.26.0

From f94990da84844841a35e80ca30e2b3d8c3bdaded Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 30 Mar 2020 10:51:51 +0900
Subject: [PATCH v6 2/2] Add -c/--restore-target-wal to pg_rewind

pg_rewind needs to copy from the source server to the target a set of
relation blocks changed from the previous checkpoint where WAL forked
between both up to the end of WAL on the target.  This may require WAL
segments that are not present anymore on the target's pg_wal, causing
pg_rewind to fail.  It is possible to fix that by copying manually the
WAL segments needed but this may lead to extra and useless work.

Instead, this commit introduces a new option allowing pg_rewind to use a
restore_command when running by grabbing it from the target
configuration.  This allows the rewind operation to be more reliable,
and only the necessary segments are fetched from the archives in this
case.

In order to do that, a new routine is added to src/common/ to allow
frontend tools to retrieve a WAL segment using an already-built restore
command.  This version is much more simple than the backend equivalent.

Author: Alexey Kondratov
Reviewed-by: Andrey Borodin, Andres Freund, Alvaro Herrera, Alexander
Korotkov, Michael Paquier
Discussion: https://postgr.es/m/a3acff50-5a0d-9a2c-b3b2-ee36168955c1@postgrespro.ru
---
 doc/src/sgml/ref/pg_rewind.sgml   |  28 +++++--
 src/bin/pg_rewind/parsexlog.c     |  33 +++++++-
 src/bin/pg_rewind/pg_rewind.c     |  87 ++++++++++++++++++--
 src/bin/pg_rewind/pg_rewind.h     |   6 +-
 src/bin/pg_rewind/t/001_basic.pl  |   3 +-
 src/bin/pg_rewind/t/RewindTest.pm |  70 +++++++++++++++-
 src/common/Makefile               |   1 +
 src/common/exec.c                 |   3 +-
 src/common/fe_archive.c           | 128 ++++++++++++++++++++++++++++++
 src/include/common/fe_archive.h   |  21 +++++
 src/include/port.h                |   3 +-
 src/tools/msvc/Mkvcbuild.pm       |   4 +-
 12 files changed, 360 insertions(+), 27 deletions(-)
 create mode 100644 src/common/fe_archive.c
 create mode 100644 src/include/common/fe_archive.h

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index f64d659522..07c49e4719 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -66,11 +66,11 @@ PostgreSQL documentation
    can be found either on the target timeline, the source timeline, or their common
    ancestor. In the typical failover scenario where the target cluster was
    shut down soon after the divergence, this is not a problem, but if the
-   target cluster ran for a long time after the divergence, the old WAL
-   files might no longer be present. In that case, they can be manually
-   copied from the WAL archive to the <filename>pg_wal</filename> directory, or
-   fetched on startup by configuring <xref linkend="guc-primary-conninfo"/> or
-   <xref linkend="guc-restore-command"/>.  The use of
+   target cluster ran for a long time after the divergence, its old WAL
+   files might no longer be present. In this case, you can manually copy them
+   from the WAL archive to the <filename>pg_wal</filename> directory, or run
+   <application>pg_rewind</application> with the <literal>-c</literal> option to
+   automatically retrieve them from the WAL archive. The use of
    <application>pg_rewind</application> is not limited to failover, e.g.  a standby
    server can be promoted, run some write transactions, and then rewinded
    to become a standby again.
@@ -232,6 +232,19 @@ PostgreSQL documentation
       </listitem>
      </varlistentry>
 
+     <varlistentry>
+      <term><option>-c</option></term>
+      <term><option>--restore-target-wal</option></term>
+      <listitem>
+       <para>
+        Use <varname>restore_command</varname> defined in the target cluster
+        configuration to retrieve WAL files from the WAL archive if these
+        files are no longer available in the <filename>pg_wal</filename>
+        directory.
+       </para>
+      </listitem>
+     </varlistentry>
+
      <varlistentry>
       <term><option>--debug</option></term>
       <listitem>
@@ -318,7 +331,10 @@ GRANT EXECUTE ON function pg_catalog.pg_read_binary_file(text, bigint, bigint, b
       history forked off from the target cluster. For each WAL record,
       record each data block that was touched. This yields a list of all
       the data blocks that were changed in the target cluster, after the
-      source cluster forked off.
+      source cluster forked off. If some of the WAL files are no longer
+      available, try re-running <application>pg_rewind</application> with
+      the <option>-c</option> option to search for the missing files in
+      the WAL archive.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index eb61cb8803..b7629fcc6b 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,6 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
+#include "common/fe_archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
@@ -41,6 +42,7 @@ static char xlogfpath[MAXPGPATH];
 
 typedef struct XLogPageReadPrivate
 {
+	const char *restoreCommand;
 	int			tliIndex;
 } XLogPageReadPrivate;
 
@@ -55,7 +57,7 @@ static int	SimpleXLogPageRead(XLogReaderState *xlogreader,
  */
 void
 extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
-			   XLogRecPtr endpoint)
+			   XLogRecPtr endpoint, const char *restoreCommand)
 {
 	XLogRecord *record;
 	XLogReaderState *xlogreader;
@@ -63,6 +65,7 @@ extractPageMap(const char *datadir, XLogRecPtr startpoint, int tliIndex,
 	XLogPageReadPrivate private;
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -146,7 +149,7 @@ readOneRecord(const char *datadir, XLogRecPtr ptr, int tliIndex)
 void
 findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 				   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-				   XLogRecPtr *lastchkptredo)
+				   XLogRecPtr *lastchkptredo, const char *restoreCommand)
 {
 	/* Walk backwards, starting from the given record */
 	XLogRecord *record;
@@ -170,6 +173,7 @@ findLastCheckpoint(const char *datadir, XLogRecPtr forkptr, int tliIndex,
 	}
 
 	private.tliIndex = tliIndex;
+	private.restoreCommand = restoreCommand;
 	xlogreader = XLogReaderAllocate(WalSegSz, datadir, &SimpleXLogPageRead,
 									&private);
 	if (xlogreader == NULL)
@@ -281,8 +285,29 @@ SimpleXLogPageRead(XLogReaderState *xlogreader, XLogRecPtr targetPagePtr,
 
 		if (xlogreadfd < 0)
 		{
-			pg_log_error("could not open file \"%s\": %m", xlogfpath);
-			return -1;
+			/*
+			 * If we have no restore_command to execute, then exit.
+			 */
+			if (private->restoreCommand == NULL)
+			{
+				pg_log_error("could not open file \"%s\": %m", xlogfpath);
+				return -1;
+			}
+
+			/*
+			 * Since we have restore_command, then try to retrieve missing WAL
+			 * file from the archive.
+			 */
+			xlogreadfd = RestoreArchivedFile(xlogreader->segcxt.ws_dir,
+													 xlogfname,
+													 WalSegSz,
+													 private->restoreCommand);
+
+			if (xlogreadfd < 0)
+				return -1;
+			else
+				pg_log_debug("using file \"%s\" restored from archive",
+							 xlogfpath);
 		}
 	}
 
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index bf2d2983e7..db849aa209 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -22,6 +22,7 @@
 #include "common/file_perm.h"
 #include "common/file_utils.h"
 #include "common/restricted_token.h"
+#include "common/string.h"
 #include "fe_utils/recovery_gen.h"
 #include "fetch.h"
 #include "file_ops.h"
@@ -38,6 +39,7 @@ static void createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli,
 static void digestControlFile(ControlFileData *ControlFile, char *source,
 							  size_t size);
 static void syncTargetDirectory(void);
+static void getRestoreCommand(const char *argv0);
 static void sanityChecks(void);
 static void findCommonAncestorTimeline(XLogRecPtr *recptr, int *tliIndex);
 static void ensureCleanShutdown(const char *argv0);
@@ -53,11 +55,13 @@ int			WalSegSz;
 char	   *datadir_target = NULL;
 char	   *datadir_source = NULL;
 char	   *connstr_source = NULL;
+char	   *restore_command = NULL;
 
 static bool debug = false;
 bool		showprogress = false;
 bool		dry_run = false;
 bool		do_sync = true;
+bool		restore_wal = false;
 
 /* Target history */
 TimeLineHistoryEntry *targetHistory;
@@ -74,6 +78,8 @@ usage(const char *progname)
 	printf(_("%s resynchronizes a PostgreSQL cluster with another copy of the cluster.\n\n"), progname);
 	printf(_("Usage:\n  %s [OPTION]...\n\n"), progname);
 	printf(_("Options:\n"));
+	printf(_("  -c, --restore-target-wal       use restore_command in target config\n"
+			 "                                 to retrieve WAL files from archive\n"));
 	printf(_("  -D, --target-pgdata=DIRECTORY  existing data directory to modify\n"));
 	printf(_("      --source-pgdata=DIRECTORY  source data directory to synchronize with\n"));
 	printf(_("      --source-server=CONNSTR    source server to synchronize with\n"));
@@ -103,6 +109,7 @@ main(int argc, char **argv)
 		{"source-server", required_argument, NULL, 2},
 		{"no-ensure-shutdown", no_argument, NULL, 4},
 		{"version", no_argument, NULL, 'V'},
+		{"restore-target-wal", no_argument, NULL, 'c'},
 		{"dry-run", no_argument, NULL, 'n'},
 		{"no-sync", no_argument, NULL, 'N'},
 		{"progress", no_argument, NULL, 'P'},
@@ -144,7 +151,7 @@ main(int argc, char **argv)
 		}
 	}
 
-	while ((c = getopt_long(argc, argv, "D:nNPR", long_options, &option_index)) != -1)
+	while ((c = getopt_long(argc, argv, "cD:nNPR", long_options, &option_index)) != -1)
 	{
 		switch (c)
 		{
@@ -152,6 +159,10 @@ main(int argc, char **argv)
 				fprintf(stderr, _("Try \"%s --help\" for more information.\n"), progname);
 				exit(1);
 
+			case 'c':
+				restore_wal = true;
+				break;
+
 			case 'P':
 				showprogress = true;
 				break;
@@ -255,6 +266,8 @@ main(int argc, char **argv)
 
 	umask(pg_mode_mask);
 
+	getRestoreCommand(argv[0]);
+
 	atexit(disconnect_atexit);
 
 	/* Connect to remote server */
@@ -350,9 +363,8 @@ main(int argc, char **argv)
 		exit(0);
 	}
 
-	findLastCheckpoint(datadir_target, divergerec,
-					   lastcommontliIndex,
-					   &chkptrec, &chkpttli, &chkptredo);
+	findLastCheckpoint(datadir_target, divergerec, lastcommontliIndex,
+					   &chkptrec, &chkpttli, &chkptredo, restore_command);
 	pg_log_info("rewinding from last common checkpoint at %X/%X on timeline %u",
 				(uint32) (chkptrec >> 32), (uint32) chkptrec,
 				chkpttli);
@@ -378,7 +390,7 @@ main(int argc, char **argv)
 	if (showprogress)
 		pg_log_info("reading WAL in target");
 	extractPageMap(datadir_target, chkptrec, lastcommontliIndex,
-				   ControlFile_target.checkPoint);
+				   ControlFile_target.checkPoint, restore_command);
 	filemap_finalize();
 
 	if (showprogress)
@@ -804,6 +816,71 @@ syncTargetDirectory(void)
 	fsync_pgdata(datadir_target, PG_VERSION_NUM);
 }
 
+/*
+ * Get value of GUC parameter restore_command from the target cluster.
+ *
+ * This uses a logic based on "postgres -C" to get the value
+ * from the cluster.
+ */
+static void
+getRestoreCommand(const char *argv0)
+{
+	int			rc;
+	char		postgres_exec_path[MAXPGPATH],
+				postgres_cmd[MAXPGPATH],
+				cmd_output[MAXPGPATH];
+
+	if (!restore_wal)
+		return;
+
+	/* find postgres executable */
+	rc = find_other_exec(argv0, "postgres",
+						 PG_BACKEND_VERSIONSTR,
+						 postgres_exec_path);
+
+	if (rc < 0)
+	{
+		char		full_path[MAXPGPATH];
+
+		if (find_my_exec(argv0, full_path) < 0)
+			strlcpy(full_path, progname, sizeof(full_path));
+
+		if (rc == -1)
+			pg_log_error("The program \"postgres\" is needed by %s but was not found in the\n"
+						 "same directory as \"%s\".\n"
+						 "Check your installation.",
+						 progname, full_path);
+		else
+			pg_log_error("The program \"postgres\" was found by \"%s\"\n"
+						 "but was not the same version as %s.\n"
+						 "Check your installation.",
+						 full_path, progname);
+		exit(1);
+	}
+
+	/*
+	 * Build a command able to retrieve the value of GUC parameter
+	 * restore_command, if set.
+	 */
+	snprintf(postgres_cmd, sizeof(postgres_cmd),
+			 "\"%s\" -D \"%s\" -C restore_command",
+			 postgres_exec_path, datadir_target);
+
+	if (!pipe_read_line(postgres_cmd, cmd_output, sizeof(cmd_output)))
+		exit(1);
+
+	(void) pg_strip_crlf(cmd_output);
+
+	if (strcmp(cmd_output, "") == 0)
+		pg_fatal("restore_command is not set on the target cluster");
+
+	restore_command = pg_strdup(cmd_output);
+
+	pg_log_debug("using for rewind restore_command = \'%s\'",
+				 restore_command);
+}
+
+
 /*
  * Ensure clean shutdown of target instance by launching single-user mode
  * postgres to do crash recovery.
diff --git a/src/bin/pg_rewind/pg_rewind.h b/src/bin/pg_rewind/pg_rewind.h
index e4e8d23c32..b122ae43e5 100644
--- a/src/bin/pg_rewind/pg_rewind.h
+++ b/src/bin/pg_rewind/pg_rewind.h
@@ -42,11 +42,13 @@ extern uint64 fetch_done;
 
 /* in parsexlog.c */
 extern void extractPageMap(const char *datadir, XLogRecPtr startpoint,
-						   int tliIndex, XLogRecPtr endpoint);
+						   int tliIndex, XLogRecPtr endpoint,
+						   const char *restoreCommand);
 extern void findLastCheckpoint(const char *datadir, XLogRecPtr searchptr,
 							   int tliIndex,
 							   XLogRecPtr *lastchkptrec, TimeLineID *lastchkpttli,
-							   XLogRecPtr *lastchkptredo);
+							   XLogRecPtr *lastchkptredo,
+							   const char *restoreCommand);
 extern XLogRecPtr readOneRecord(const char *datadir, XLogRecPtr ptr,
 								int tliIndex);
 
diff --git a/src/bin/pg_rewind/t/001_basic.pl b/src/bin/pg_rewind/t/001_basic.pl
index 95d8ccfced..d97e437741 100644
--- a/src/bin/pg_rewind/t/001_basic.pl
+++ b/src/bin/pg_rewind/t/001_basic.pl
@@ -1,7 +1,7 @@
 use strict;
 use warnings;
 use TestLib;
-use Test::More tests => 15;
+use Test::More tests => 20;
 
 use FindBin;
 use lib $FindBin::RealBin;
@@ -171,5 +171,6 @@ in master, before promotion
 # Run the test in both modes
 run_test('local');
 run_test('remote');
+run_test('archive');
 
 exit(0);
diff --git a/src/bin/pg_rewind/t/RewindTest.pm b/src/bin/pg_rewind/t/RewindTest.pm
index 82fa220ac8..7dabf395e1 100644
--- a/src/bin/pg_rewind/t/RewindTest.pm
+++ b/src/bin/pg_rewind/t/RewindTest.pm
@@ -38,6 +38,7 @@ use File::Copy;
 use File::Path qw(rmtree);
 use IPC::Run qw(run);
 use PostgresNode;
+use RecursiveCopy;
 use TestLib;
 use Test::More;
 
@@ -227,10 +228,26 @@ sub run_pg_rewind
 	# Append the rewind-specific role to the connection string.
 	$standby_connstr = "$standby_connstr user=rewind_user";
 
-	# Stop the master and be ready to perform the rewind.  The cluster
-	# needs recovery to finish once, and pg_rewind makes sure that it
-	# happens automatically.
-	$node_master->stop('immediate');
+	if ($test_mode eq 'archive')
+	{
+		# pg_rewind is tested with --restore-target-wal by moving all
+		# WAL files to a secondary location.  Note that this leads to
+		# a failure in ensureCleanShutdown(), forcing to the use of
+		# --no-ensure-shutdown in this mode as the initial set of WAL
+		# files needed to ensure a clean restart is gone.  This could
+		# be improved by keeping around only a minimum set of WAL
+		# segments but that would just make the test more costly,
+		# without improving the coverage.  Hence, instead, stop
+		# gracefully the primary here.
+		$node_master->stop;
+	}
+	else
+	{
+		# Stop the master and be ready to perform the rewind.  The cluster
+		# needs recovery to finish once, and pg_rewind makes sure that it
+		# happens automatically.
+		$node_master->stop('immediate');
+	}
 
 	# At this point, the rewind processing is ready to run.
 	# We now have a very simple scenario with a few diverged WAL record.
@@ -284,6 +301,51 @@ sub run_pg_rewind
 		$node_standby->safe_psql('postgres',
 			"ALTER ROLE rewind_user WITH REPLICATION;");
 	}
+	elsif ($test_mode eq "archive")
+	{
+
+		# Do rewind using a local pgdata as source and specified
+		# directory with target WAL archive.  The old master has
+		# to be stopped at this point.
+
+		# Remove the existing archive directory and move all WAL
+		# segments from the old master to the archives.  These
+		# will be used by pg_rewind.
+		rmtree($node_master->archive_dir);
+		RecursiveCopy::copypath($node_master->data_dir . "/pg_wal",
+			$node_master->archive_dir);
+
+		# Fast way to remove entire directory content
+		rmtree($node_master->data_dir . "/pg_wal");
+		mkdir($node_master->data_dir . "/pg_wal");
+
+		# Make sure that directories have the right umask as this is
+		# required by a follow-up check on permissions, and better
+		# safe than sorry.
+		chmod(0700, $node_master->archive_dir);
+		chmod(0700, $node_master->data_dir . "/pg_wal");
+
+		# Add appropriate restore_command to the target cluster
+		$node_master->enable_restoring($node_master, 0);
+
+		# Stop the new master and be ready to perform the rewind.
+		$node_standby->stop;
+
+		# Note the use of --no-ensure-shutdown here.  WAL files are
+		# gone in this mode and the primary has been stopped
+		# gracefully already.
+		command_ok(
+			[
+				'pg_rewind',
+				"--debug",
+				"--source-pgdata=$standby_pgdata",
+				"--target-pgdata=$master_pgdata",
+				"--no-sync",
+				"--no-ensure-shutdown",
+				"--restore-target-wal"
+			],
+			'pg_rewind archive');
+	}
 	else
 	{
 
diff --git a/src/common/Makefile b/src/common/Makefile
index 6939b9d087..a97c723fbd 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -88,6 +88,7 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
+	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/common/exec.c b/src/common/exec.c
index 88400daa47..f39b0a294b 100644
--- a/src/common/exec.c
+++ b/src/common/exec.c
@@ -51,7 +51,6 @@
 
 static int	validate_exec(const char *path);
 static int	resolve_symlinks(char *path);
-static char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 #ifdef WIN32
 static BOOL GetTokenUser(HANDLE hToken, PTOKEN_USER *ppTokenUser);
@@ -356,7 +355,7 @@ find_other_exec(const char *argv0, const char *target,
 /*
  * Execute a command in a pipe and read the first line from it.
  */
-static char *
+char *
 pipe_read_line(char *cmd, char *line, int maxsize)
 {
 	FILE	   *pgver;
diff --git a/src/common/fe_archive.c b/src/common/fe_archive.c
new file mode 100644
index 0000000000..b0d68870db
--- /dev/null
+++ b/src/common/fe_archive.c
@@ -0,0 +1,128 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.c
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *	  src/common/fe_archive.c
+ *
+ *-------------------------------------------------------------------------
+ */
+
+#ifndef FRONTEND
+#error "This file is not expected to be compiled for backend code"
+#endif
+
+#include "postgres_fe.h"
+
+#include <unistd.h>
+#include <sys/stat.h>
+
+#include "access/xlog_internal.h"
+#include "common/archive.h"
+#include "common/fe_archive.h"
+#include "common/logging.h"
+
+
+/*
+ * RestoreArchivedFile
+ *
+ * Attempt to retrieve the specified file from off-line archival storage.
+ * If successful, return a file descriptor of the restored file, else
+ * return -1.
+ *
+ * For fixed-size files, the caller may pass the expected size as an
+ * additional crosscheck on successful recovery.  If the file size is not
+ * known, set expectedSize = 0.
+ */
+int
+RestoreArchivedFile(const char *path, const char *xlogfname,
+					off_t expectedSize, const char *restoreCommand)
+{
+	char		xlogpath[MAXPGPATH];
+	char	   *xlogRestoreCmd;
+	int			rc;
+	struct stat stat_buf;
+
+	snprintf(xlogpath, MAXPGPATH, "%s/" XLOGDIR "/%s", path, xlogfname);
+
+	xlogRestoreCmd = BuildRestoreCommand(restoreCommand, xlogpath,
+										 xlogfname, NULL);
+	if (xlogRestoreCmd == NULL)
+	{
+		pg_log_fatal("could not use restore_command with %%r alias");
+		exit(1);
+	}
+
+	/*
+	 * Execute restore_command, which should copy the missing file from
+	 * archival storage.
+	 */
+	rc = system(xlogRestoreCmd);
+	pfree(xlogRestoreCmd);
+
+	if (rc == 0)
+	{
+		/*
+		 * Command apparently succeeded, but let's make sure the file is
+		 * really there now and has the correct size.
+		 */
+		if (stat(xlogpath, &stat_buf) == 0)
+		{
+			if (expectedSize > 0 && stat_buf.st_size != expectedSize)
+			{
+				pg_log_fatal("unexpected file size for \"%s\": %lu instead of %lu",
+							 xlogfname, (unsigned long) stat_buf.st_size,
+							 (unsigned long) expectedSize);
+				exit(1);
+			}
+			else
+			{
+				int			xlogfd = open(xlogpath, O_RDONLY | PG_BINARY, 0);
+
+				if (xlogfd < 0)
+				{
+					pg_log_fatal("could not open file \"%s\" restored from archive: %m",
+								 xlogpath);
+					exit(1);
+				}
+				else
+					return xlogfd;
+			}
+		}
+		else
+		{
+			if (errno != ENOENT)
+			{
+				pg_log_fatal("could not stat file \"%s\": %m",
+							 xlogpath);
+				exit(1);
+			}
+		}
+	}
+
+	/*
+	 * If the failure was due to a signal, then it would be misleading to
+	 * return with a failure at restoring the file.  So just bail out and
+	 * exit.  Hard shell errors such as "command not found" are treated as
+	 * fatal too.
+	 */
+	if (wait_result_is_any_signal(rc, true))
+	{
+		pg_log_fatal("restore_command failed due to the signal: %s",
+					 wait_result_to_str(rc));
+		exit(1);
+	}
+
+	/*
+	 * The file is not available, so just let the caller decide what to do
+	 * next.
+	 */
+	pg_log_error("could not restore file \"%s\" from archive",
+				 xlogfname);
+	return -1;
+}
diff --git a/src/include/common/fe_archive.h b/src/include/common/fe_archive.h
new file mode 100644
index 0000000000..495b560d24
--- /dev/null
+++ b/src/include/common/fe_archive.h
@@ -0,0 +1,21 @@
+/*-------------------------------------------------------------------------
+ *
+ * fe_archive.h
+ *	  Routines to access WAL archives from frontend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/common/fe_archive.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef FE_ARCHIVE_H
+#define FE_ARCHIVE_H
+
+extern int	RestoreArchivedFile(const char *path,
+								const char *xlogfname,
+								off_t expectedSize,
+								const char *restoreCommand);
+
+#endif							/* FE_ARCHIVE_H */
diff --git a/src/include/port.h b/src/include/port.h
index 29f3e39e5b..20a5de1b7a 100644
--- a/src/include/port.h
+++ b/src/include/port.h
@@ -102,10 +102,11 @@ extern void pgfnames_cleanup(char **filenames);
 /* Portable locale initialization (in exec.c) */
 extern void set_pglocale_pgservice(const char *argv0, const char *app);
 
-/* Portable way to find binaries (in exec.c) */
+/* Portable way to find and execute binaries (in exec.c) */
 extern int	find_my_exec(const char *argv0, char *retpath);
 extern int	find_other_exec(const char *argv0, const char *target,
 							const char *versionstr, char *retpath);
+extern char *pipe_read_line(char *cmd, char *line, int maxsize);
 
 /* Doesn't belong here, but this is used with find_other_exec(), so... */
 #define PG_BACKEND_VERSIONSTR "postgres (PostgreSQL) " PG_VERSION "\n"
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index 39709f20e6..5c88825f49 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -139,8 +139,8 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
-		  logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
+		  file_utils.c logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
-- 
2.19.1

From 4736dc52ad71f4eb9801856d0968eed9f89379ec Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 30 Mar 2020 10:34:17 +0900
Subject: [PATCH v6 1/2] Move routines of xlogarchive.c into their own header

The definitions of those routines have been part of xlog_internal.h,
which is included by several frontend tools.  More could be done in this
area, but that's already a nice and simple cut.
---
 src/backend/access/transam/timeline.c    |  1 +
 src/backend/access/transam/xlog.c        |  1 +
 src/backend/access/transam/xlogarchive.c |  1 +
 src/backend/replication/walreceiver.c    |  1 +
 src/include/access/xlog_internal.h       | 18 ------------
 src/include/access/xlogarchive.h         | 35 ++++++++++++++++++++++++
 6 files changed, 39 insertions(+), 18 deletions(-)
 create mode 100644 src/include/access/xlogarchive.h

diff --git a/src/backend/access/transam/timeline.c b/src/backend/access/transam/timeline.c
index 860a996414..d683af377f 100644
--- a/src/backend/access/transam/timeline.c
+++ b/src/backend/access/transam/timeline.c
@@ -36,6 +36,7 @@
 
 #include "access/timeline.h"
 #include "access/xlog.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "access/xlogdefs.h"
 #include "pgstat.h"
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 1951103b26..39fe801c7e 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -32,6 +32,7 @@
 #include "access/transam.h"
 #include "access/twophase.h"
 #include "access/xact.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "access/xloginsert.h"
 #include "access/xlogreader.h"
diff --git a/src/backend/access/transam/xlogarchive.c b/src/backend/access/transam/xlogarchive.c
index 914ad340ea..04104b55ea 100644
--- a/src/backend/access/transam/xlogarchive.c
+++ b/src/backend/access/transam/xlogarchive.c
@@ -20,6 +20,7 @@
 #include <unistd.h>
 
 #include "access/xlog.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "common/archive.h"
 #include "miscadmin.h"
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 760e3c7ab0..9ecbfe336e 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -54,6 +54,7 @@
 #include "access/htup_details.h"
 #include "access/timeline.h"
 #include "access/transam.h"
+#include "access/xlogarchive.h"
 #include "access/xlog_internal.h"
 #include "catalog/pg_authid.h"
 #include "catalog/pg_type.h"
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index 27ded593ab..8e3cfcf83e 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -320,22 +320,4 @@ extern bool InArchiveRecovery;
 extern bool StandbyMode;
 extern char *recoveryRestoreCommand;
 
-/*
- * Prototypes for functions in xlogarchive.c
- */
-extern bool RestoreArchivedFile(char *path, const char *xlogfname,
-								const char *recovername, off_t expectedSize,
-								bool cleanupEnabled);
-extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
-								   bool failOnSignal);
-extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
-extern void XLogArchiveNotify(const char *xlog);
-extern void XLogArchiveNotifySeg(XLogSegNo segno);
-extern void XLogArchiveForceDone(const char *xlog);
-extern bool XLogArchiveCheckDone(const char *xlog);
-extern bool XLogArchiveIsBusy(const char *xlog);
-extern bool XLogArchiveIsReady(const char *xlog);
-extern bool XLogArchiveIsReadyOrDone(const char *xlog);
-extern void XLogArchiveCleanup(const char *xlog);
-
 #endif							/* XLOG_INTERNAL_H */
diff --git a/src/include/access/xlogarchive.h b/src/include/access/xlogarchive.h
new file mode 100644
index 0000000000..1c67de2ede
--- /dev/null
+++ b/src/include/access/xlogarchive.h
@@ -0,0 +1,35 @@
+/*------------------------------------------------------------------------
+ *
+ * xlogarchive.h
+ *		Prototypes for WAL archives in the backend
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * IDENTIFICATION
+ *		src/include/access/xlogarchive.h
+ *
+ *------------------------------------------------------------------------
+ */
+
+#ifndef XLOG_ARCHIVE_H
+#define XLOG_ARCHIVE_H
+
+#include "access/xlogdefs.h"
+
+extern bool RestoreArchivedFile(char *path, const char *xlogfname,
+								const char *recovername, off_t expectedSize,
+								bool cleanupEnabled);
+extern void ExecuteRecoveryCommand(const char *command, const char *commandName,
+								   bool failOnSignal);
+extern void KeepFileRestoredFromArchive(const char *path, const char *xlogfname);
+extern void XLogArchiveNotify(const char *xlog);
+extern void XLogArchiveNotifySeg(XLogSegNo segno);
+extern void XLogArchiveForceDone(const char *xlog);
+extern bool XLogArchiveCheckDone(const char *xlog);
+extern bool XLogArchiveIsBusy(const char *xlog);
+extern bool XLogArchiveIsReady(const char *xlog);
+extern bool XLogArchiveIsReadyOrDone(const char *xlog);
+extern void XLogArchiveCleanup(const char *xlog);
+
+#endif							/* XLOG_ARCHIVE_H */

base-commit: 24566b359d095c3800c2a326d88a595722813f58
-- 
2.19.1

From ca75b91498c71b6558bd6befa3ad1510e00cf5fa Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 8 Jun 2020 15:06:02 +0900
Subject: [PATCH] Move frontend-side archive APIs to src/fe_utils/

---
 .../{common/fe_archive.h => fe_utils/archive.h}        |  4 ++--
 src/common/Makefile                                    |  1 -
 src/fe_utils/Makefile                                  |  1 +
 src/{common/fe_archive.c => fe_utils/archive.c}        | 10 +++-------
 src/bin/pg_rewind/parsexlog.c                          |  2 +-
 src/tools/msvc/Mkvcbuild.pm                            |  8 ++++----
 6 files changed, 11 insertions(+), 15 deletions(-)
 rename src/include/{common/fe_archive.h => fe_utils/archive.h} (91%)
 rename src/{common/fe_archive.c => fe_utils/archive.c} (94%)

diff --git a/src/include/common/fe_archive.h b/src/include/fe_utils/archive.h
similarity index 91%
rename from src/include/common/fe_archive.h
rename to src/include/fe_utils/archive.h
index 495b560d24..a6beaf04ea 100644
--- a/src/include/common/fe_archive.h
+++ b/src/include/fe_utils/archive.h
@@ -1,12 +1,12 @@
 /*-------------------------------------------------------------------------
  *
- * fe_archive.h
+ * archive.h
  *	  Routines to access WAL archives from frontend
  *
  * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * src/include/common/fe_archive.h
+ * src/include/fe_utils/archive.h
  *
  *-------------------------------------------------------------------------
  */
diff --git a/src/common/Makefile b/src/common/Makefile
index d0be882cca..16619e4ba8 100644
--- a/src/common/Makefile
+++ b/src/common/Makefile
@@ -89,7 +89,6 @@ endif
 # (Mkvcbuild.pm has a copy of this list, too)
 OBJS_FRONTEND = \
 	$(OBJS_COMMON) \
-	fe_archive.o \
 	fe_memutils.o \
 	file_utils.o \
 	logging.o \
diff --git a/src/fe_utils/Makefile b/src/fe_utils/Makefile
index 9eb4417690..dd20663604 100644
--- a/src/fe_utils/Makefile
+++ b/src/fe_utils/Makefile
@@ -20,6 +20,7 @@ include $(top_builddir)/src/Makefile.global
 override CPPFLAGS := -DFRONTEND -I$(libpq_srcdir) $(CPPFLAGS)
 
 OBJS = \
+	archive.o \
 	cancel.o \
 	conditional.o \
 	mbprint.o \
diff --git a/src/common/fe_archive.c b/src/fe_utils/archive.c
similarity index 94%
rename from src/common/fe_archive.c
rename to src/fe_utils/archive.c
index b0d68870db..c4cb213198 100644
--- a/src/common/fe_archive.c
+++ b/src/fe_utils/archive.c
@@ -1,6 +1,6 @@
 /*-------------------------------------------------------------------------
  *
- * fe_archive.c
+ * archive.c
  *	  Routines to access WAL archives from frontend
  *
  * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
@@ -8,15 +8,11 @@
  *
  *
  * IDENTIFICATION
- *	  src/common/fe_archive.c
+ *	  src/fe_utils/archive.c
  *
  *-------------------------------------------------------------------------
  */
 
-#ifndef FRONTEND
-#error "This file is not expected to be compiled for backend code"
-#endif
-
 #include "postgres_fe.h"
 
 #include <unistd.h>
@@ -24,8 +20,8 @@
 
 #include "access/xlog_internal.h"
 #include "common/archive.h"
-#include "common/fe_archive.h"
 #include "common/logging.h"
+#include "fe_utils/archive.h"
 
 
 /*
diff --git a/src/bin/pg_rewind/parsexlog.c b/src/bin/pg_rewind/parsexlog.c
index d637f5eb77..bc6f976994 100644
--- a/src/bin/pg_rewind/parsexlog.c
+++ b/src/bin/pg_rewind/parsexlog.c
@@ -19,7 +19,7 @@
 #include "catalog/pg_control.h"
 #include "catalog/storage_xlog.h"
 #include "commands/dbcommands_xlog.h"
-#include "common/fe_archive.h"
+#include "fe_utils/archive.h"
 #include "filemap.h"
 #include "pg_rewind.h"
 
diff --git a/src/tools/msvc/Mkvcbuild.pm b/src/tools/msvc/Mkvcbuild.pm
index c21c94dc1f..82d7d2c0e8 100644
--- a/src/tools/msvc/Mkvcbuild.pm
+++ b/src/tools/msvc/Mkvcbuild.pm
@@ -138,14 +138,14 @@ sub mkvcbuild
 	}
 
 	our @pgcommonfrontendfiles = (
-		@pgcommonallfiles, qw(fe_archive.c fe_memutils.c
-		  file_utils.c logging.c restricted_token.c));
+		@pgcommonallfiles, qw(fe_memutils.c file_utils.c
+			logging.c restricted_token.c));
 
 	our @pgcommonbkndfiles = @pgcommonallfiles;
 
 	our @pgfeutilsfiles = qw(
-	  cancel.c conditional.c mbprint.c print.c psqlscan.l psqlscan.c
-	  simple_list.c string_utils.c recovery_gen.c);
+	  archive.c cancel.c conditional.c mbprint.c print.c psqlscan.l
+	  psqlscan.c simple_list.c string_utils.c recovery_gen.c);
 
 	$libpgport = $solution->AddProject('libpgport', 'lib', 'misc');
 	$libpgport->AddDefine('FRONTEND');
-- 
2.27.0.rc0