pg_resetwal tests, logging, and docs update

From 0922727410313e37c1ffaad4f6fbf90f9990923b Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 15:54:37 +0200
Subject: [PATCH v2 1/7] pg_resetwal: Update an obsolete comment

---
 src/bin/pg_resetwal/pg_resetwal.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 25ecdaaa15..b7885e34f3 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -6,8 +6,7 @@
  *
  * The theory of operation is fairly simple:
  *	  1. Read the existing pg_control (which will include the last
- *		 checkpoint record).  If it is an old format then update to
- *		 current format.
+ *		 checkpoint record).
  *	  2. If pg_control is corrupt, attempt to intuit reasonable values,
  *		 by scanning the old xlog if necessary.
  *	  3. Modify pg_control to reflect a "shutdown" state with a checkpoint

base-commit: bf094372d14bf00f1c04f70f6ec5790f8b2c8801
-- 
2.42.0

From 8fee9806bfa94fc999e730d3fb55946c656e6c64 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 15:58:49 +0200
Subject: [PATCH v2 2/7] pg_resetwal: Improve error with wrong/missing data
 directory

Run chdir() before permission check to get a less confusing error
message if the specified data directory does not exist.
---
 src/bin/pg_resetwal/pg_resetwal.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index b7885e34f3..e344c9284d 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -345,6 +345,10 @@ main(int argc, char *argv[])
 
 	get_restricted_token();
 
+	if (chdir(DataDir) < 0)
+		pg_fatal("could not change directory to \"%s\": %m",
+				 DataDir);
+
 	/* Set mask based on PGDATA permissions */
 	if (!GetDataDirectoryCreatePerm(DataDir))
 		pg_fatal("could not read permissions of directory \"%s\": %m",
@@ -352,10 +356,6 @@ main(int argc, char *argv[])
 
 	umask(pg_mode_mask);
 
-	if (chdir(DataDir) < 0)
-		pg_fatal("could not change directory to \"%s\": %m",
-				 DataDir);
-
 	/* Check that data directory matches our server version */
 	CheckDataVersion();
 
-- 
2.42.0

From 241dc252f314ee32ebf853f236a17029ec477d50 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 16:02:35 +0200
Subject: [PATCH v2 3/7] pg_resetwal: Regroup --help output

Put the options to modify the control values into a separate group.
This matches the outline of the man page.
---
 src/bin/pg_resetwal/pg_resetwal.c | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index e344c9284d..12e0869251 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -1128,24 +1128,29 @@ static void
 usage(void)
 {
 	printf(_("%s resets the PostgreSQL write-ahead log.\n\n"), progname);
-	printf(_("Usage:\n  %s [OPTION]... DATADIR\n\n"), progname);
-	printf(_("Options:\n"));
+	printf(_("Usage:\n"));
+	printf(_("  %s [OPTION]... DATADIR\n"), progname);
+
+	printf(_("\nOptions:\n"));
+	printf(_(" [-D, --pgdata=]DATADIR  data directory\n"));
+	printf(_("  -f, --force            force update to be done\n"));
+	printf(_("  -n, --dry-run          no update, just show what would be done\n"));
+	printf(_("  -V, --version          output version information, then exit\n"));
+	printf(_("  -?, --help             show this help, then exit\n"));
+
+	printf(_("\nOptions to override control file values:\n"));
 	printf(_("  -c, --commit-timestamp-ids=XID,XID\n"
 			 "                                   set oldest and newest transactions bearing\n"
 			 "                                   commit timestamp (zero means no change)\n"));
-	printf(_(" [-D, --pgdata=]DATADIR            data directory\n"));
 	printf(_("  -e, --epoch=XIDEPOCH             set next transaction ID epoch\n"));
-	printf(_("  -f, --force                      force update to be done\n"));
 	printf(_("  -l, --next-wal-file=WALFILE      set minimum starting location for new WAL\n"));
 	printf(_("  -m, --multixact-ids=MXID,MXID    set next and oldest multitransaction ID\n"));
-	printf(_("  -n, --dry-run                    no update, just show what would be done\n"));
 	printf(_("  -o, --next-oid=OID               set next OID\n"));
 	printf(_("  -O, --multixact-offset=OFFSET    set next multitransaction offset\n"));
 	printf(_("  -u, --oldest-transaction-id=XID  set oldest transaction ID\n"));
-	printf(_("  -V, --version                    output version information, then exit\n"));
 	printf(_("  -x, --next-transaction-id=XID    set next transaction ID\n"));
 	printf(_("      --wal-segsize=SIZE           size of WAL segments, in megabytes\n"));
-	printf(_("  -?, --help                       show this help, then exit\n"));
+
 	printf(_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
 	printf(_("%s home page: <%s>\n"), PACKAGE_NAME, PACKAGE_URL);
 }
-- 
2.42.0

From ff81acdd646c64efcae8b6cf083daff0494f6f82 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 16:06:22 +0200
Subject: [PATCH v2 4/7] pg_resetwal: Use frontend logging API

This now causes error messages related to the lack of the -f option to
appear on standard error rather than standard output.
---
 src/bin/pg_resetwal/pg_resetwal.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 12e0869251..35876e1c95 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -458,20 +458,22 @@ main(int argc, char *argv[])
 	if (minXlogSegNo > newXlogSegNo)
 		newXlogSegNo = minXlogSegNo;
 
+	if (noupdate)
+	{
+		PrintNewControlValues();
+		exit(0);
+	}
+
 	/*
 	 * If we had to guess anything, and -f was not given, just print the
-	 * guessed values and exit.  Also print if -n is given.
+	 * guessed values and exit.
 	 */
-	if ((guessed && !force) || noupdate)
+	if (guessed && !force)
 	{
 		PrintNewControlValues();
-		if (!noupdate)
-		{
-			printf(_("\nIf these values seem acceptable, use -f to force reset.\n"));
-			exit(1);
-		}
-		else
-			exit(0);
+		pg_log_error("not proceeding because control file values were guessed");
+		pg_log_error_hint("If these values seem acceptable, use -f to force reset.");
+		exit(1);
 	}
 
 	/*
@@ -479,9 +481,9 @@ main(int argc, char *argv[])
 	 */
 	if (ControlFile.state != DB_SHUTDOWNED && !force)
 	{
-		printf(_("The database server was not shut down cleanly.\n"
-				 "Resetting the write-ahead log might cause data to be lost.\n"
-				 "If you want to proceed anyway, use -f to force reset.\n"));
+		pg_log_error("database server was not shut down cleanly");
+		pg_log_error_detail("Resetting the write-ahead log might cause data to be lost.");
+		pg_log_error_hint("If you want to proceed anyway, use -f to force reset.");
 		exit(1);
 	}
 
-- 
2.42.0

From fda162ae9864b121c386e07fabed520de089a3f5 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 16:09:32 +0200
Subject: [PATCH v2 5/7] doc: Improve documentation about pg_resetwal -f option

---
 doc/src/sgml/ref/pg_resetwal.sgml | 62 +++++++++++++++++++++++++------
 src/bin/pg_resetwal/pg_resetwal.c |  3 +-
 2 files changed, 53 insertions(+), 12 deletions(-)

diff --git a/doc/src/sgml/ref/pg_resetwal.sgml b/doc/src/sgml/ref/pg_resetwal.sgml
index fd539f5604..1f9c4b69dd 100644
--- a/doc/src/sgml/ref/pg_resetwal.sgml
+++ b/doc/src/sgml/ref/pg_resetwal.sgml
@@ -52,21 +52,33 @@ <title>Description</title>
   </para>
 
   <para>
-   After running this command, it should be possible to start the server,
+   Some options, such as <option>--wal-segsize</option> (see below), can also
+   be used to modify certain global settings of a database cluster without the
+   need to rerun <command>initdb</command>.  This can be done safely on an
+   otherwise sound database cluster, if none of the dangerous modes mentioned
+   below are used.
+  </para>
+
+  <para>
+   If <command>pg_resetwal</command> is used on a data directory where the
+   server has been cleanly shut down and the control file is sound, then it
+   will have no effect on the contents of the database system, except that no
+   longer used WAL files are cleared away.  Any other use is potentially
+   dangerous and must be done with great care.  <command>pg_resetwal</command>
+   will require the <option>-f</option> (force) option to be specified before
+   working on a data directory in an unclean shutdown state or with a
+   corrupted control file.
+  </para>
+
+  <para>
+   After running this command on a data directory with corrupted WAL or a
+   corrupted control file, it should be possible to start the server,
    but bear in mind that the database might contain inconsistent data due to
    partially-committed transactions.  You should immediately dump your data,
    run <command>initdb</command>, and restore.  After restore, check for
    inconsistencies and repair as needed.
   </para>
 
-  <para>
-   This utility can only be run by the user who installed the server, because
-   it requires read/write access to the data directory.
-   For safety reasons, you must specify the data directory on the command line.
-   <command>pg_resetwal</command> does not use the environment variable
-   <envar>PGDATA</envar>.
-  </para>
-
   <para>
    If <command>pg_resetwal</command> complains that it cannot determine
    valid data for <filename>pg_control</filename>, you can force it to proceed anyway
@@ -82,19 +94,41 @@ <title>Description</title>
    execute any data-modifying operations in the database before you dump,
    as any such action is likely to make the corruption worse.
   </para>
+
+  <para>
+   This utility can only be run by the user who installed the server, because
+   it requires read/write access to the data directory.
+  </para>
  </refsect1>
 
  <refsect1>
   <title>Options</title>
 
   <variablelist>
+   <varlistentry>
+    <term><replaceable class="parameter">datadir</replaceable></term>
+    <term><option>-D <replaceable class="parameter">datadir</replaceable></option></term>
+    <term><option>--pgdata=<replaceable class="parameter">datadir</replaceable></option></term>
+    <listitem>
+     <para>
+      Specifies the location of the database directory.
+      For safety reasons, you must specify the data directory on the command
+      line.  <command>pg_resetwal</command> does not use the environment
+      variable <envar>PGDATA</envar>.
+     </para>
+    </listitem>
+   </varlistentry>
+
    <varlistentry>
     <term><option>-f</option></term>
     <term><option>--force</option></term>
     <listitem>
      <para>
-      Force <command>pg_resetwal</command> to proceed even if it cannot determine
-      valid data for <filename>pg_control</filename>, as explained above.
+      Force <command>pg_resetwal</command> to proceed even in situations where
+      it could be dangerous, as explained above.  Specifically, this option is
+      required to proceed if the server had not been cleanly shut down, or if
+      <command>pg_resetwal</command> cannot determine valid data for
+      <filename>pg_control</filename>.
      </para>
     </listitem>
    </varlistentry>
@@ -284,6 +318,12 @@ <title>Options</title>
       linkend="app-initdb"/> for more information.
      </para>
 
+     <para>
+      This option can also be used to change the WAL segment size of an
+      existing database cluster, avoiding the need to
+      re-<command>initdb</command>.
+     </para>
+
      <note>
       <para>
        While <command>pg_resetwal</command> will set the WAL starting address
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 35876e1c95..47e05bd2c9 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -1135,7 +1135,8 @@ usage(void)
 
 	printf(_("\nOptions:\n"));
 	printf(_(" [-D, --pgdata=]DATADIR  data directory\n"));
-	printf(_("  -f, --force            force update to be done\n"));
+	printf(_("  -f, --force            force update to be done even after unclean shutdown or\n"
+			 "                         if pg_control values had to be guessed\n"));
 	printf(_("  -n, --dry-run          no update, just show what would be done\n"));
 	printf(_("  -V, --version          output version information, then exit\n"));
 	printf(_("  -?, --help             show this help, then exit\n"));
-- 
2.42.0

From bc62da6173e029e1fd25d13bbbe648f008be6b68 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 16:11:38 +0200
Subject: [PATCH v2 6/7] doc: pg_resetwal: Add comments how the multipliers are
 derived

---
 doc/src/sgml/ref/pg_resetwal.sgml | 8 +++++++-
 src/bin/pg_resetwal/pg_resetwal.c | 1 +
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/pg_resetwal.sgml b/doc/src/sgml/ref/pg_resetwal.sgml
index 1f9c4b69dd..8380f97c04 100644
--- a/doc/src/sgml/ref/pg_resetwal.sgml
+++ b/doc/src/sgml/ref/pg_resetwal.sgml
@@ -166,7 +166,8 @@ <title>Options</title>
    <command>pg_resetwal</command> is unable to determine appropriate values
    by reading <filename>pg_control</filename>.  Safe values can be determined as
    described below.  For values that take numeric arguments, hexadecimal
-   values can be specified by using the prefix <literal>0x</literal>.
+   values can be specified by using the prefix <literal>0x</literal>.  Note
+   that these instructions only apply with the standard block size of 8 kB.
   </para>
 
   <variablelist>
@@ -189,6 +190,7 @@ <title>Options</title>
       greatest file name in the same directory.  The file names are in
       hexadecimal.
      </para>
+      <!-- FIXME: multiplier? -->
     </listitem>
    </varlistentry>
 
@@ -272,6 +274,7 @@ <title>Options</title>
       names are in hexadecimal, so the easiest way to do this is to specify
       the option value in hexadecimal and append four zeroes.
      </para>
+     <!-- 65536 = SLRU_PAGES_PER_SEGMENT * BLCKSZ / sizeof(MultiXactOffset) -->
     </listitem>
    </varlistentry>
 
@@ -306,6 +309,7 @@ <title>Options</title>
       The file names are in hexadecimal.  There is no simple recipe such as
       the ones for other options of appending zeroes.
      </para>
+     <!-- 52352 = SLRU_PAGES_PER_SEGMENT * floor(BLCKSZ/20) * 4; see multixact.c -->
     </listitem>
    </varlistentry>
 
@@ -354,6 +358,7 @@ <title>Options</title>
       in <filename>pg_xact</filename>, <literal>-u 0x700000</literal> will work (five
       trailing zeroes provide the proper multiplier).
      </para>
+     <!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
     </listitem>
    </varlistentry>
 
@@ -375,6 +380,7 @@ <title>Options</title>
       in <filename>pg_xact</filename>, <literal>-x 0x1200000</literal> will work (five
       trailing zeroes provide the proper multiplier).
      </para>
+     <!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
     </listitem>
    </varlistentry>
   </variablelist>
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index 47e05bd2c9..89b35c2748 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -211,6 +211,7 @@ main(int argc, char *argv[])
 					exit(1);
 				}
 
+				// FIXME: why 2?
 				if (set_oldest_commit_ts_xid < 2 &&
 					set_oldest_commit_ts_xid != 0)
 					pg_fatal("transaction ID (-c) must be either 0 or greater than or equal to 2");
-- 
2.42.0

From e3874416d63113668ac67cffd92765531a5df697 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 19 Sep 2023 16:12:52 +0200
Subject: [PATCH v2 7/7] pg_resetwal: Add more tests and test coverage

---
 src/bin/pg_resetwal/t/001_basic.pl     | 114 +++++++++++++++++++++++++
 src/bin/pg_resetwal/t/002_corrupted.pl |   4 +
 2 files changed, 118 insertions(+)

diff --git a/src/bin/pg_resetwal/t/001_basic.pl b/src/bin/pg_resetwal/t/001_basic.pl
index 7e5efbf56b..001bb455ef 100644
--- a/src/bin/pg_resetwal/t/001_basic.pl
+++ b/src/bin/pg_resetwal/t/001_basic.pl
@@ -14,6 +14,7 @@
 
 my $node = PostgreSQL::Test::Cluster->new('main');
 $node->init;
+$node->append_conf('postgresql.conf', 'track_commit_timestamp = on');
 
 command_like([ 'pg_resetwal', '-n', $node->data_dir ],
 	qr/checkpoint/, 'pg_resetwal -n produces output');
@@ -29,4 +30,117 @@
 		'check PGDATA permissions');
 }
 
+command_ok([ 'pg_resetwal', '-D', $node->data_dir ], 'pg_resetwal runs');
+$node->start;
+is($node->safe_psql("postgres", "SELECT 1;"), 1, 'server running and working after reset');
+
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/lock file .* exists/, 'fails if server running');
+
+$node->stop('immediate');
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/database server was not shut down cleanly/, 'does not run after immediate shutdown');
+command_ok([ 'pg_resetwal', '-f', $node->data_dir ], 'runs after immediate shutdown with force');
+$node->start;
+is($node->safe_psql("postgres", "SELECT 1;"), 1, 'server running and working after forced reset');
+
+$node->stop;
+
+# check various command-line handling
+
+command_fails_like([ 'pg_resetwal', 'foo' ], qr/error: could not change directory/, 'fails with nonexistent data directory');
+command_fails_like([ 'pg_resetwal', 'foo', 'bar'], qr/too many command-line arguments/, 'fails with too many command-line arguments');
+
+$ENV{PGDATA} = $node->data_dir;  # not used
+command_fails_like([ 'pg_resetwal' ], qr/no data directory specified/, 'fails with too few command-line arguments');
+
+# error cases
+# -c
+command_fails_like([ 'pg_resetwal', '-c', 'foo', $node->data_dir], qr/error: invalid argument for option -c/, 'fails with incorrect -c option');
+command_fails_like([ 'pg_resetwal', '-c', '10,bar', $node->data_dir], qr/error: invalid argument for option -c/, 'fails with incorrect -c option part 2');
+command_fails_like([ 'pg_resetwal', '-c', '1,10', $node->data_dir], qr/greater than/, 'fails with -c value 1 part 1');
+command_fails_like([ 'pg_resetwal', '-c', '10,1', $node->data_dir], qr/greater than/, 'fails with -c value 1 part 2');
+# -e
+command_fails_like([ 'pg_resetwal', '-e', 'foo', $node->data_dir], qr/error: invalid argument for option -e/, 'fails with incorrect -e option');
+command_fails_like([ 'pg_resetwal', '-e', '-1', $node->data_dir], qr/must not be -1/, 'fails with -e value -1');
+# -l
+command_fails_like([ 'pg_resetwal', '-l', 'foo', $node->data_dir], qr/error: invalid argument for option -l/, 'fails with incorrect -l option');
+# -m
+command_fails_like([ 'pg_resetwal', '-m', 'foo', $node->data_dir], qr/error: invalid argument for option -m/, 'fails with incorrect -m option');
+command_fails_like([ 'pg_resetwal', '-m', '10,bar', $node->data_dir], qr/error: invalid argument for option -m/, 'fails with incorrect -m option part 2');
+command_fails_like([ 'pg_resetwal', '-m', '0,10', $node->data_dir], qr/must not be 0/, 'fails with -m value 0 part 1');
+command_fails_like([ 'pg_resetwal', '-m', '10,0', $node->data_dir], qr/must not be 0/, 'fails with -m value 0 part 2');
+# -o
+command_fails_like([ 'pg_resetwal', '-o', 'foo', $node->data_dir], qr/error: invalid argument for option -o/, 'fails with incorrect -o option');
+command_fails_like([ 'pg_resetwal', '-o', '0', $node->data_dir], qr/must not be 0/, 'fails with -o value 0');
+# -O
+command_fails_like([ 'pg_resetwal', '-O', 'foo', $node->data_dir], qr/error: invalid argument for option -O/, 'fails with incorrect -O option');
+command_fails_like([ 'pg_resetwal', '-O', '-1', $node->data_dir], qr/must not be -1/, 'fails with -O value -1');
+# --wal-segsize
+command_fails_like([ 'pg_resetwal', '--wal-segsize', 'foo', $node->data_dir], qr/error: invalid value/, 'fails with incorrect --wal-segsize option');
+command_fails_like([ 'pg_resetwal', '--wal-segsize', '13', $node->data_dir], qr/must be a power/, 'fails with invalid --wal-segsize value');
+# -u
+command_fails_like([ 'pg_resetwal', '-u', 'foo', $node->data_dir], qr/error: invalid argument for option -u/, 'fails with incorrect -u option');
+command_fails_like([ 'pg_resetwal', '-u', '1', $node->data_dir], qr/must be greater than/, 'fails with -u value too small');
+# -x
+command_fails_like([ 'pg_resetwal', '-x', 'foo', $node->data_dir], qr/error: invalid argument for option -x/, 'fails with incorrect -x option');
+command_fails_like([ 'pg_resetwal', '-x', '1', $node->data_dir], qr/must be greater than/, 'fails with -x value too small');
+
+# run with control override options
+
+my $out = (run_command([ 'pg_resetwal', '-n', $node->data_dir ]))[0];
+$out =~ /^Database block size: *(\d+)$/m or die;
+my $blcksz = $1;
+
+my @cmd = ('pg_resetwal', '-D', $node->data_dir);
+
+# some not-so-critical hardcoded values
+push @cmd, '-e', 1;
+push @cmd, '-l', '00000001000000320000004B';
+push @cmd, '-o', 100_000;
+push @cmd, '--wal-segsize', 1;
+
+# these use the guidance from the documentation
+
+sub get_slru_files
+{
+	opendir(my $dh, $node->data_dir . '/' . $_[0]) or die $!;
+	my @files = sort grep { /[0-9A-F]+/ } readdir $dh;
+	closedir $dh;
+	return @files;
+}
+
+my (@files, $mult);
+
+@files = get_slru_files('pg_commit_ts');
+$mult = 32 * $blcksz * 4; # FIXME
+# -c argument is "old,new"
+push @cmd,
+  '-c', sprintf("%d,%d",
+	  hex($files[0]) == 0 ? 2 : hex($files[0]), hex($files[-1]));
+
+@files = get_slru_files('pg_multixact/offsets');
+$mult = 32 * $blcksz / 4;
+# -m argument is "new,old"
+push @cmd,
+  '-m', sprintf("%d,%d",
+	  (hex($files[-1]) + 1) * $mult,
+	  hex($files[0]) == 0 ? 1 : hex($files[0] * $mult));
+
+@files = get_slru_files('pg_multixact/members');
+$mult = 32 * int($blcksz/20) * 4;
+push @cmd,
+  '-O', (hex($files[-1]) + 1) * $mult;
+
+@files = get_slru_files('pg_xact');
+$mult = 32 * $blcksz * 4;
+push @cmd,
+  '-u', (hex($files[0]) == 0 ? 3 : hex($files[0]) * $mult),
+  '-x', ((hex($files[-1]) + 1) * $mult);
+
+command_ok([@cmd, '-n'], 'runs with control override options, dry run');
+command_ok(\@cmd, 'runs with control override options');
+command_like([ 'pg_resetwal', '-n', $node->data_dir ], qr/^Latest checkpoint's NextOID: *100000$/m, 'spot check that control changes were applied');
+
+$node->start;
+ok(1, 'server started after reset');
+
 done_testing();
diff --git a/src/bin/pg_resetwal/t/002_corrupted.pl b/src/bin/pg_resetwal/t/002_corrupted.pl
index 6d19a1efd5..ddbd0556bb 100644
--- a/src/bin/pg_resetwal/t/002_corrupted.pl
+++ b/src/bin/pg_resetwal/t/002_corrupted.pl
@@ -55,4 +55,8 @@
 	],
 	'processes zero WAL segment size');
 
+# now try to run it
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/not proceeding because control file values were guessed/, 'does not run when control file values were guessed');
+command_ok([ 'pg_resetwal', '-f', $node->data_dir ], 'runs with force when control file values were guessed');
+
 done_testing();
-- 
2.42.0

From 16affb34b3f53b4639a136f9eb1d927c89780ec1 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Sun, 29 Oct 2023 16:48:16 +0100
Subject: [PATCH v3 1/2] doc: pg_resetwal: Add comments how the multipliers are
 derived

Discussion: https://www.postgresql.org/message-id/flat/0f3ab4a1-ae80-56e8-3426-6b4a02507687@eisentraut.org
---
 doc/src/sgml/ref/pg_resetwal.sgml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/pg_resetwal.sgml b/doc/src/sgml/ref/pg_resetwal.sgml
index 08cd3ce5fc2..cf9c7e70f27 100644
--- a/doc/src/sgml/ref/pg_resetwal.sgml
+++ b/doc/src/sgml/ref/pg_resetwal.sgml
@@ -166,7 +166,8 @@ <title>Options</title>
    <command>pg_resetwal</command> is unable to determine appropriate values
    by reading <filename>pg_control</filename>.  Safe values can be determined as
    described below.  For values that take numeric arguments, hexadecimal
-   values can be specified by using the prefix <literal>0x</literal>.
+   values can be specified by using the prefix <literal>0x</literal>.  Note
+   that these instructions only apply with the standard block size of 8 kB.
   </para>
 
   <variablelist>
@@ -189,6 +190,7 @@ <title>Options</title>
       greatest file name in the same directory.  The file names are in
       hexadecimal.
      </para>
+      <!-- XXX: Should there be a multiplier, similar to the other options? -->
     </listitem>
    </varlistentry>
 
@@ -272,6 +274,7 @@ <title>Options</title>
       names are in hexadecimal, so the easiest way to do this is to specify
       the option value in hexadecimal and append four zeroes.
      </para>
+     <!-- 65536 = SLRU_PAGES_PER_SEGMENT * BLCKSZ / sizeof(MultiXactOffset) -->
     </listitem>
    </varlistentry>
 
@@ -306,6 +309,7 @@ <title>Options</title>
       The file names are in hexadecimal.  There is no simple recipe such as
       the ones for other options of appending zeroes.
      </para>
+     <!-- 52352 = SLRU_PAGES_PER_SEGMENT * floor(BLCKSZ/20) * 4; see multixact.c -->
     </listitem>
    </varlistentry>
 
@@ -354,6 +358,7 @@ <title>Options</title>
       in <filename>pg_xact</filename>, <literal>-u 0x700000</literal> will work (five
       trailing zeroes provide the proper multiplier).
      </para>
+     <!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
     </listitem>
    </varlistentry>
 
@@ -375,6 +380,7 @@ <title>Options</title>
       in <filename>pg_xact</filename>, <literal>-x 0x1200000</literal> will work (five
       trailing zeroes provide the proper multiplier).
      </para>
+     <!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
     </listitem>
    </varlistentry>
   </variablelist>

base-commit: 237f8765dfd9149471d37f3754d15cef888338a8
-- 
2.42.0

From 3b5c60dc87f4440aa81d50d0c6363aea7a970347 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Sun, 29 Oct 2023 16:48:16 +0100
Subject: [PATCH v3 2/2] pg_resetwal: Add more tests and test coverage

Discussion: https://www.postgresql.org/message-id/flat/0f3ab4a1-ae80-56e8-3426-6b4a02507687@eisentraut.org
---
 src/bin/pg_resetwal/t/001_basic.pl     | 120 +++++++++++++++++++++++++
 src/bin/pg_resetwal/t/002_corrupted.pl |   4 +
 2 files changed, 124 insertions(+)

diff --git a/src/bin/pg_resetwal/t/001_basic.pl b/src/bin/pg_resetwal/t/001_basic.pl
index 7e5efbf56b5..6c02c4ae74a 100644
--- a/src/bin/pg_resetwal/t/001_basic.pl
+++ b/src/bin/pg_resetwal/t/001_basic.pl
@@ -14,6 +14,7 @@
 
 my $node = PostgreSQL::Test::Cluster->new('main');
 $node->init;
+$node->append_conf('postgresql.conf', 'track_commit_timestamp = on');
 
 command_like([ 'pg_resetwal', '-n', $node->data_dir ],
 	qr/checkpoint/, 'pg_resetwal -n produces output');
@@ -29,4 +30,123 @@
 		'check PGDATA permissions');
 }
 
+command_ok([ 'pg_resetwal', '-D', $node->data_dir ], 'pg_resetwal runs');
+$node->start;
+is($node->safe_psql("postgres", "SELECT 1;"), 1, 'server running and working after reset');
+
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/lock file .* exists/, 'fails if server running');
+
+$node->stop('immediate');
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/database server was not shut down cleanly/, 'does not run after immediate shutdown');
+command_ok([ 'pg_resetwal', '-f', $node->data_dir ], 'runs after immediate shutdown with force');
+$node->start;
+is($node->safe_psql("postgres", "SELECT 1;"), 1, 'server running and working after forced reset');
+
+$node->stop;
+
+# check various command-line handling
+
+# Note: This test intends to check that a nonexistent data directory
+# gives a reasonable error message.  Because of the way the code is
+# currently structured, you get an error about readings permissions,
+# which is perhaps suboptimal, so feel free to update this test if
+# this gets improved.
+command_fails_like([ 'pg_resetwal', 'foo' ], qr/error: could not read permissions of directory/, 'fails with nonexistent data directory');
+
+command_fails_like([ 'pg_resetwal', 'foo', 'bar'], qr/too many command-line arguments/, 'fails with too many command-line arguments');
+
+$ENV{PGDATA} = $node->data_dir;  # not used
+command_fails_like([ 'pg_resetwal' ], qr/no data directory specified/, 'fails with too few command-line arguments');
+
+# error cases
+# -c
+command_fails_like([ 'pg_resetwal', '-c', 'foo', $node->data_dir], qr/error: invalid argument for option -c/, 'fails with incorrect -c option');
+command_fails_like([ 'pg_resetwal', '-c', '10,bar', $node->data_dir], qr/error: invalid argument for option -c/, 'fails with incorrect -c option part 2');
+command_fails_like([ 'pg_resetwal', '-c', '1,10', $node->data_dir], qr/greater than/, 'fails with -c value 1 part 1');
+command_fails_like([ 'pg_resetwal', '-c', '10,1', $node->data_dir], qr/greater than/, 'fails with -c value 1 part 2');
+# -e
+command_fails_like([ 'pg_resetwal', '-e', 'foo', $node->data_dir], qr/error: invalid argument for option -e/, 'fails with incorrect -e option');
+command_fails_like([ 'pg_resetwal', '-e', '-1', $node->data_dir], qr/must not be -1/, 'fails with -e value -1');
+# -l
+command_fails_like([ 'pg_resetwal', '-l', 'foo', $node->data_dir], qr/error: invalid argument for option -l/, 'fails with incorrect -l option');
+# -m
+command_fails_like([ 'pg_resetwal', '-m', 'foo', $node->data_dir], qr/error: invalid argument for option -m/, 'fails with incorrect -m option');
+command_fails_like([ 'pg_resetwal', '-m', '10,bar', $node->data_dir], qr/error: invalid argument for option -m/, 'fails with incorrect -m option part 2');
+command_fails_like([ 'pg_resetwal', '-m', '0,10', $node->data_dir], qr/must not be 0/, 'fails with -m value 0 part 1');
+command_fails_like([ 'pg_resetwal', '-m', '10,0', $node->data_dir], qr/must not be 0/, 'fails with -m value 0 part 2');
+# -o
+command_fails_like([ 'pg_resetwal', '-o', 'foo', $node->data_dir], qr/error: invalid argument for option -o/, 'fails with incorrect -o option');
+command_fails_like([ 'pg_resetwal', '-o', '0', $node->data_dir], qr/must not be 0/, 'fails with -o value 0');
+# -O
+command_fails_like([ 'pg_resetwal', '-O', 'foo', $node->data_dir], qr/error: invalid argument for option -O/, 'fails with incorrect -O option');
+command_fails_like([ 'pg_resetwal', '-O', '-1', $node->data_dir], qr/must not be -1/, 'fails with -O value -1');
+# --wal-segsize
+command_fails_like([ 'pg_resetwal', '--wal-segsize', 'foo', $node->data_dir], qr/error: invalid value/, 'fails with incorrect --wal-segsize option');
+command_fails_like([ 'pg_resetwal', '--wal-segsize', '13', $node->data_dir], qr/must be a power/, 'fails with invalid --wal-segsize value');
+# -u
+command_fails_like([ 'pg_resetwal', '-u', 'foo', $node->data_dir], qr/error: invalid argument for option -u/, 'fails with incorrect -u option');
+command_fails_like([ 'pg_resetwal', '-u', '1', $node->data_dir], qr/must be greater than/, 'fails with -u value too small');
+# -x
+command_fails_like([ 'pg_resetwal', '-x', 'foo', $node->data_dir], qr/error: invalid argument for option -x/, 'fails with incorrect -x option');
+command_fails_like([ 'pg_resetwal', '-x', '1', $node->data_dir], qr/must be greater than/, 'fails with -x value too small');
+
+# run with control override options
+
+my $out = (run_command([ 'pg_resetwal', '-n', $node->data_dir ]))[0];
+$out =~ /^Database block size: *(\d+)$/m or die;
+my $blcksz = $1;
+
+my @cmd = ('pg_resetwal', '-D', $node->data_dir);
+
+# some not-so-critical hardcoded values
+push @cmd, '-e', 1;
+push @cmd, '-l', '00000001000000320000004B';
+push @cmd, '-o', 100_000;
+push @cmd, '--wal-segsize', 1;
+
+# these use the guidance from the documentation
+
+sub get_slru_files
+{
+	opendir(my $dh, $node->data_dir . '/' . $_[0]) or die $!;
+	my @files = sort grep { /[0-9A-F]+/ } readdir $dh;
+	closedir $dh;
+	return @files;
+}
+
+my (@files, $mult);
+
+@files = get_slru_files('pg_commit_ts');
+# XXX: Should there be a multiplier, similar to the other options?
+# -c argument is "old,new"
+push @cmd,
+  '-c', sprintf("%d,%d",
+	  hex($files[0]) == 0 ? 3 : hex($files[0]), hex($files[-1]));
+
+@files = get_slru_files('pg_multixact/offsets');
+$mult = 32 * $blcksz / 4;
+# -m argument is "new,old"
+push @cmd,
+  '-m', sprintf("%d,%d",
+	  (hex($files[-1]) + 1) * $mult,
+	  hex($files[0]) == 0 ? 1 : hex($files[0] * $mult));
+
+@files = get_slru_files('pg_multixact/members');
+$mult = 32 * int($blcksz/20) * 4;
+push @cmd,
+  '-O', (hex($files[-1]) + 1) * $mult;
+
+@files = get_slru_files('pg_xact');
+$mult = 32 * $blcksz * 4;
+push @cmd,
+  '-u', (hex($files[0]) == 0 ? 3 : hex($files[0]) * $mult),
+  '-x', ((hex($files[-1]) + 1) * $mult);
+
+command_ok([@cmd, '-n'], 'runs with control override options, dry run');
+command_ok(\@cmd, 'runs with control override options');
+command_like([ 'pg_resetwal', '-n', $node->data_dir ], qr/^Latest checkpoint's NextOID: *100000$/m, 'spot check that control changes were applied');
+
+$node->start;
+ok(1, 'server started after reset');
+
 done_testing();
diff --git a/src/bin/pg_resetwal/t/002_corrupted.pl b/src/bin/pg_resetwal/t/002_corrupted.pl
index b3a37728a42..ee888504730 100644
--- a/src/bin/pg_resetwal/t/002_corrupted.pl
+++ b/src/bin/pg_resetwal/t/002_corrupted.pl
@@ -55,4 +55,8 @@
 	],
 	'processes zero WAL segment size');
 
+# now try to run it
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/not proceeding because control file values were guessed/, 'does not run when control file values were guessed');
+command_ok([ 'pg_resetwal', '-f', $node->data_dir ], 'runs with force when control file values were guessed');
+
 done_testing();
-- 
2.42.0

From ff3a5ef09ea7f6f54262986e234ec919d53821ac Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 31 Oct 2023 07:42:17 -0400
Subject: [PATCH] More consistent behavior of GetDataDirectoryCreatePerm on
 Windows

On Windows, GetDataDirectoryCreatePerm() just did nothing.  The way
the code in some callers is structured, this is the first function
that tries to address the data directory.  So it also ends up the
place that is responsible for reporting that a data directory does not
exist or similar.  Therefore, on Windows, these scenarios end up on a
potentially completely different code paths.

To unify this, to make testing more consistent across platforms, have
GetDataDirectoryCreatePerm() run the stat() call on Windows as well,
even though it won't do anything with the result.  That way, file
system errors are reporting to callers in the same way as on
non-Windows.
---
 src/common/file_perm.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/src/common/file_perm.c b/src/common/file_perm.c
index 60f88d2caf1..81464f939ca 100644
--- a/src/common/file_perm.c
+++ b/src/common/file_perm.c
@@ -59,12 +59,12 @@ SetDataDirectoryCreatePerm(int dataDirMode)
  * false is returned.
  *
  * Suppress when on Windows, because there may not be proper support for Unix-y
- * file permissions.
+ * file permissions.  But we still run stat() on the directory so that callers
+ * get consistent behavior for example if the directory does not exist.
  */
 bool
 GetDataDirectoryCreatePerm(const char *dataDir)
 {
-#if !defined(WIN32) && !defined(__CYGWIN__)
 	struct stat statBuf;
 
 	/*
@@ -75,16 +75,12 @@ GetDataDirectoryCreatePerm(const char *dataDir)
 	if (stat(dataDir, &statBuf) == -1)
 		return false;
 
+#if !defined(WIN32) && !defined(__CYGWIN__)
 	/* Set permissions */
 	SetDataDirectoryCreatePerm(statBuf.st_mode);
-	return true;
-#else							/* !defined(WIN32) && !defined(__CYGWIN__) */
-	/*
-	 * On Windows, we don't have anything to do here since they don't have
-	 * Unix-y permissions.
-	 */
-	return true;
 #endif
+
+	return true;
 }
 
 
-- 
2.42.0

From 66362ceec2359db43e42251787e233c384078483 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Sun, 29 Oct 2023 16:48:16 +0100
Subject: [PATCH v4 3/3] pg_resetwal: Add more tests and test coverage

Discussion: https://www.postgresql.org/message-id/flat/0f3ab4a1-ae80-56e8-3426-6b4a02507687@eisentraut.org
---
 src/bin/pg_resetwal/t/001_basic.pl     | 120 +++++++++++++++++++++++++
 src/bin/pg_resetwal/t/002_corrupted.pl |   4 +
 2 files changed, 124 insertions(+)

diff --git a/src/bin/pg_resetwal/t/001_basic.pl b/src/bin/pg_resetwal/t/001_basic.pl
index 7e5efbf56b..6c02c4ae74 100644
--- a/src/bin/pg_resetwal/t/001_basic.pl
+++ b/src/bin/pg_resetwal/t/001_basic.pl
@@ -14,6 +14,7 @@ program_options_handling_ok('pg_resetwal');
 
 my $node = PostgreSQL::Test::Cluster->new('main');
 $node->init;
+$node->append_conf('postgresql.conf', 'track_commit_timestamp = on');
 
 command_like([ 'pg_resetwal', '-n', $node->data_dir ],
 	qr/checkpoint/, 'pg_resetwal -n produces output');
@@ -29,4 +30,123 @@ SKIP:
 		'check PGDATA permissions');
 }
 
+command_ok([ 'pg_resetwal', '-D', $node->data_dir ], 'pg_resetwal runs');
+$node->start;
+is($node->safe_psql("postgres", "SELECT 1;"), 1, 'server running and working after reset');
+
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/lock file .* exists/, 'fails if server running');
+
+$node->stop('immediate');
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/database server was not shut down cleanly/, 'does not run after immediate shutdown');
+command_ok([ 'pg_resetwal', '-f', $node->data_dir ], 'runs after immediate shutdown with force');
+$node->start;
+is($node->safe_psql("postgres", "SELECT 1;"), 1, 'server running and working after forced reset');
+
+$node->stop;
+
+# check various command-line handling
+
+# Note: This test intends to check that a nonexistent data directory
+# gives a reasonable error message.  Because of the way the code is
+# currently structured, you get an error about readings permissions,
+# which is perhaps suboptimal, so feel free to update this test if
+# this gets improved.
+command_fails_like([ 'pg_resetwal', 'foo' ], qr/error: could not read permissions of directory/, 'fails with nonexistent data directory');
+
+command_fails_like([ 'pg_resetwal', 'foo', 'bar'], qr/too many command-line arguments/, 'fails with too many command-line arguments');
+
+$ENV{PGDATA} = $node->data_dir;  # not used
+command_fails_like([ 'pg_resetwal' ], qr/no data directory specified/, 'fails with too few command-line arguments');
+
+# error cases
+# -c
+command_fails_like([ 'pg_resetwal', '-c', 'foo', $node->data_dir], qr/error: invalid argument for option -c/, 'fails with incorrect -c option');
+command_fails_like([ 'pg_resetwal', '-c', '10,bar', $node->data_dir], qr/error: invalid argument for option -c/, 'fails with incorrect -c option part 2');
+command_fails_like([ 'pg_resetwal', '-c', '1,10', $node->data_dir], qr/greater than/, 'fails with -c value 1 part 1');
+command_fails_like([ 'pg_resetwal', '-c', '10,1', $node->data_dir], qr/greater than/, 'fails with -c value 1 part 2');
+# -e
+command_fails_like([ 'pg_resetwal', '-e', 'foo', $node->data_dir], qr/error: invalid argument for option -e/, 'fails with incorrect -e option');
+command_fails_like([ 'pg_resetwal', '-e', '-1', $node->data_dir], qr/must not be -1/, 'fails with -e value -1');
+# -l
+command_fails_like([ 'pg_resetwal', '-l', 'foo', $node->data_dir], qr/error: invalid argument for option -l/, 'fails with incorrect -l option');
+# -m
+command_fails_like([ 'pg_resetwal', '-m', 'foo', $node->data_dir], qr/error: invalid argument for option -m/, 'fails with incorrect -m option');
+command_fails_like([ 'pg_resetwal', '-m', '10,bar', $node->data_dir], qr/error: invalid argument for option -m/, 'fails with incorrect -m option part 2');
+command_fails_like([ 'pg_resetwal', '-m', '0,10', $node->data_dir], qr/must not be 0/, 'fails with -m value 0 part 1');
+command_fails_like([ 'pg_resetwal', '-m', '10,0', $node->data_dir], qr/must not be 0/, 'fails with -m value 0 part 2');
+# -o
+command_fails_like([ 'pg_resetwal', '-o', 'foo', $node->data_dir], qr/error: invalid argument for option -o/, 'fails with incorrect -o option');
+command_fails_like([ 'pg_resetwal', '-o', '0', $node->data_dir], qr/must not be 0/, 'fails with -o value 0');
+# -O
+command_fails_like([ 'pg_resetwal', '-O', 'foo', $node->data_dir], qr/error: invalid argument for option -O/, 'fails with incorrect -O option');
+command_fails_like([ 'pg_resetwal', '-O', '-1', $node->data_dir], qr/must not be -1/, 'fails with -O value -1');
+# --wal-segsize
+command_fails_like([ 'pg_resetwal', '--wal-segsize', 'foo', $node->data_dir], qr/error: invalid value/, 'fails with incorrect --wal-segsize option');
+command_fails_like([ 'pg_resetwal', '--wal-segsize', '13', $node->data_dir], qr/must be a power/, 'fails with invalid --wal-segsize value');
+# -u
+command_fails_like([ 'pg_resetwal', '-u', 'foo', $node->data_dir], qr/error: invalid argument for option -u/, 'fails with incorrect -u option');
+command_fails_like([ 'pg_resetwal', '-u', '1', $node->data_dir], qr/must be greater than/, 'fails with -u value too small');
+# -x
+command_fails_like([ 'pg_resetwal', '-x', 'foo', $node->data_dir], qr/error: invalid argument for option -x/, 'fails with incorrect -x option');
+command_fails_like([ 'pg_resetwal', '-x', '1', $node->data_dir], qr/must be greater than/, 'fails with -x value too small');
+
+# run with control override options
+
+my $out = (run_command([ 'pg_resetwal', '-n', $node->data_dir ]))[0];
+$out =~ /^Database block size: *(\d+)$/m or die;
+my $blcksz = $1;
+
+my @cmd = ('pg_resetwal', '-D', $node->data_dir);
+
+# some not-so-critical hardcoded values
+push @cmd, '-e', 1;
+push @cmd, '-l', '00000001000000320000004B';
+push @cmd, '-o', 100_000;
+push @cmd, '--wal-segsize', 1;
+
+# these use the guidance from the documentation
+
+sub get_slru_files
+{
+	opendir(my $dh, $node->data_dir . '/' . $_[0]) or die $!;
+	my @files = sort grep { /[0-9A-F]+/ } readdir $dh;
+	closedir $dh;
+	return @files;
+}
+
+my (@files, $mult);
+
+@files = get_slru_files('pg_commit_ts');
+# XXX: Should there be a multiplier, similar to the other options?
+# -c argument is "old,new"
+push @cmd,
+  '-c', sprintf("%d,%d",
+	  hex($files[0]) == 0 ? 3 : hex($files[0]), hex($files[-1]));
+
+@files = get_slru_files('pg_multixact/offsets');
+$mult = 32 * $blcksz / 4;
+# -m argument is "new,old"
+push @cmd,
+  '-m', sprintf("%d,%d",
+	  (hex($files[-1]) + 1) * $mult,
+	  hex($files[0]) == 0 ? 1 : hex($files[0] * $mult));
+
+@files = get_slru_files('pg_multixact/members');
+$mult = 32 * int($blcksz/20) * 4;
+push @cmd,
+  '-O', (hex($files[-1]) + 1) * $mult;
+
+@files = get_slru_files('pg_xact');
+$mult = 32 * $blcksz * 4;
+push @cmd,
+  '-u', (hex($files[0]) == 0 ? 3 : hex($files[0]) * $mult),
+  '-x', ((hex($files[-1]) + 1) * $mult);
+
+command_ok([@cmd, '-n'], 'runs with control override options, dry run');
+command_ok(\@cmd, 'runs with control override options');
+command_like([ 'pg_resetwal', '-n', $node->data_dir ], qr/^Latest checkpoint's NextOID: *100000$/m, 'spot check that control changes were applied');
+
+$node->start;
+ok(1, 'server started after reset');
+
 done_testing();
diff --git a/src/bin/pg_resetwal/t/002_corrupted.pl b/src/bin/pg_resetwal/t/002_corrupted.pl
index b3a37728a4..ee88850473 100644
--- a/src/bin/pg_resetwal/t/002_corrupted.pl
+++ b/src/bin/pg_resetwal/t/002_corrupted.pl
@@ -55,4 +55,8 @@ command_checks_all(
 	],
 	'processes zero WAL segment size');
 
+# now try to run it
+command_fails_like([ 'pg_resetwal', $node->data_dir ], qr/not proceeding because control file values were guessed/, 'does not run when control file values were guessed');
+command_ok([ 'pg_resetwal', '-f', $node->data_dir ], 'runs with force when control file values were guessed');
+
 done_testing();
-- 
2.42.0

From 51f5c777afdec1701ad25d6f8ecf06a5114a6836 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Tue, 31 Oct 2023 07:42:17 -0400
Subject: [PATCH v4 1/3] More consistent behavior of GetDataDirectoryCreatePerm
 on Windows

On Windows, GetDataDirectoryCreatePerm() just did nothing.  The way
the code in some callers is structured, this is the first function
that tries to address the data directory.  So it also ends up the
place that is responsible for reporting that a data directory does not
exist or similar.  Therefore, on Windows, these scenarios end up on a
potentially completely different code paths.

To unify this, to make testing more consistent across platforms, have
GetDataDirectoryCreatePerm() run the stat() call on Windows as well,
even though it won't do anything with the result.  That way, file
system errors are reporting to callers in the same way as on
non-Windows.
---
 src/common/file_perm.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/src/common/file_perm.c b/src/common/file_perm.c
index 60f88d2caf..81464f939c 100644
--- a/src/common/file_perm.c
+++ b/src/common/file_perm.c
@@ -59,12 +59,12 @@ SetDataDirectoryCreatePerm(int dataDirMode)
  * false is returned.
  *
  * Suppress when on Windows, because there may not be proper support for Unix-y
- * file permissions.
+ * file permissions.  But we still run stat() on the directory so that callers
+ * get consistent behavior for example if the directory does not exist.
  */
 bool
 GetDataDirectoryCreatePerm(const char *dataDir)
 {
-#if !defined(WIN32) && !defined(__CYGWIN__)
 	struct stat statBuf;
 
 	/*
@@ -75,16 +75,12 @@ GetDataDirectoryCreatePerm(const char *dataDir)
 	if (stat(dataDir, &statBuf) == -1)
 		return false;
 
+#if !defined(WIN32) && !defined(__CYGWIN__)
 	/* Set permissions */
 	SetDataDirectoryCreatePerm(statBuf.st_mode);
-	return true;
-#else							/* !defined(WIN32) && !defined(__CYGWIN__) */
-	/*
-	 * On Windows, we don't have anything to do here since they don't have
-	 * Unix-y permissions.
-	 */
-	return true;
 #endif
+
+	return true;
 }
 
 
-- 
2.42.0

From e481925f79fd51149acee628511b1837c199fdeb Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Sun, 29 Oct 2023 16:48:16 +0100
Subject: [PATCH v4 2/3] doc: pg_resetwal: Add comments how the multipliers are
 derived

Discussion: https://www.postgresql.org/message-id/flat/0f3ab4a1-ae80-56e8-3426-6b4a02507687@eisentraut.org
---
 doc/src/sgml/ref/pg_resetwal.sgml | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/doc/src/sgml/ref/pg_resetwal.sgml b/doc/src/sgml/ref/pg_resetwal.sgml
index 08cd3ce5fc..cf9c7e70f2 100644
--- a/doc/src/sgml/ref/pg_resetwal.sgml
+++ b/doc/src/sgml/ref/pg_resetwal.sgml
@@ -166,7 +166,8 @@ PostgreSQL documentation
    <command>pg_resetwal</command> is unable to determine appropriate values
    by reading <filename>pg_control</filename>.  Safe values can be determined as
    described below.  For values that take numeric arguments, hexadecimal
-   values can be specified by using the prefix <literal>0x</literal>.
+   values can be specified by using the prefix <literal>0x</literal>.  Note
+   that these instructions only apply with the standard block size of 8 kB.
   </para>
 
   <variablelist>
@@ -189,6 +190,7 @@ PostgreSQL documentation
       greatest file name in the same directory.  The file names are in
       hexadecimal.
      </para>
+      <!-- XXX: Should there be a multiplier, similar to the other options? -->
     </listitem>
    </varlistentry>
 
@@ -272,6 +274,7 @@ PostgreSQL documentation
       names are in hexadecimal, so the easiest way to do this is to specify
       the option value in hexadecimal and append four zeroes.
      </para>
+     <!-- 65536 = SLRU_PAGES_PER_SEGMENT * BLCKSZ / sizeof(MultiXactOffset) -->
     </listitem>
    </varlistentry>
 
@@ -306,6 +309,7 @@ PostgreSQL documentation
       The file names are in hexadecimal.  There is no simple recipe such as
       the ones for other options of appending zeroes.
      </para>
+     <!-- 52352 = SLRU_PAGES_PER_SEGMENT * floor(BLCKSZ/20) * 4; see multixact.c -->
     </listitem>
    </varlistentry>
 
@@ -354,6 +358,7 @@ PostgreSQL documentation
       in <filename>pg_xact</filename>, <literal>-u 0x700000</literal> will work (five
       trailing zeroes provide the proper multiplier).
      </para>
+     <!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
     </listitem>
    </varlistentry>
 
@@ -375,6 +380,7 @@ PostgreSQL documentation
       in <filename>pg_xact</filename>, <literal>-x 0x1200000</literal> will work (five
       trailing zeroes provide the proper multiplier).
      </para>
+     <!-- 1048576 = SLRU_PAGES_PER_SEGMENT * BLCKSZ * CLOG_XACTS_PER_BYTE -->
     </listitem>
    </varlistentry>
   </variablelist>
-- 
2.42.0