From 57bcaf49bd10ec3e6afb14f3ec384cb88a65efe6 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Tue, 28 Sep 2021 12:28:21 +0900
Subject: [PATCH v7 1/2] Refactor fd handling when forking syslogger in
 EXEC_BACKEND build

---
 src/backend/postmaster/syslogger.c | 122 +++++++++++++++--------------
 1 file changed, 62 insertions(+), 60 deletions(-)

diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index bca3883572..ddb47e3cb0 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -130,6 +130,8 @@ static volatile sig_atomic_t rotation_requested = false;
 
 /* Local subroutines */
 #ifdef EXEC_BACKEND
+static long syslogger_fdget(FILE *file);
+static FILE *syslogger_fdopen(int fd);
 static pid_t syslogger_forkexec(void);
 static void syslogger_parseArgs(int argc, char *argv[]);
 #endif
@@ -733,6 +735,60 @@ SysLogger_Start(void)
 
 #ifdef EXEC_BACKEND
 
+/*
+ * syslogger_fdget() -
+ *
+ * Utility wrapper to grab the file descriptor of an opened error output
+ * file.  Used when building the command to fork the logging collector.
+ */
+static long
+syslogger_fdget(FILE *file)
+{
+#ifndef WIN32
+	if (file != NULL)
+		return (long) fileno(file);
+	else
+		return -1;
+#else							/* WIN32 */
+	if (file != NULL)
+		return (long) _get_osfhandle(_fileno(file));
+	else
+		return 0;
+#endif							/* WIN32 */
+}
+
+/*
+ * syslogger_fdopen() -
+ *
+ * Utility wrapper to re-open an error output file, using the given file
+ * descriptor.  Used when parsing arguments in a forked logging collector.
+ */
+static FILE *
+syslogger_fdopen(int fd)
+{
+	FILE	   *file = NULL;
+
+#ifndef WIN32
+	if (fd != -1)
+	{
+		file = fdopen(fd, "a");
+		setvbuf(file, NULL, PG_IOLBF, 0);
+	}
+#else							/* WIN32 */
+	if (fd != 0)
+	{
+		fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
+		if (fd > 0)
+		{
+			file = fdopen(fd, "a");
+			setvbuf(file, NULL, PG_IOLBF, 0);
+		}
+	}
+#endif							/* WIN32 */
+
+	return file;
+}
+
 /*
  * syslogger_forkexec() -
  *
@@ -751,34 +807,11 @@ syslogger_forkexec(void)
 	av[ac++] = NULL;			/* filled in by postmaster_forkexec */
 
 	/* static variables (those not passed by write_backend_variables) */
-#ifndef WIN32
-	if (syslogFile != NULL)
-		snprintf(filenobuf, sizeof(filenobuf), "%d",
-				 fileno(syslogFile));
-	else
-		strcpy(filenobuf, "-1");
-#else							/* WIN32 */
-	if (syslogFile != NULL)
-		snprintf(filenobuf, sizeof(filenobuf), "%ld",
-				 (long) _get_osfhandle(_fileno(syslogFile)));
-	else
-		strcpy(filenobuf, "0");
-#endif							/* WIN32 */
+	snprintf(filenobuf, sizeof(filenobuf), "%ld",
+			 syslogger_fdget(syslogFile));
 	av[ac++] = filenobuf;
-
-#ifndef WIN32
-	if (csvlogFile != NULL)
-		snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%d",
-				 fileno(csvlogFile));
-	else
-		strcpy(csvfilenobuf, "-1");
-#else							/* WIN32 */
-	if (csvlogFile != NULL)
-		snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%ld",
-				 (long) _get_osfhandle(_fileno(csvlogFile)));
-	else
-		strcpy(csvfilenobuf, "0");
-#endif							/* WIN32 */
+	snprintf(csvfilenobuf, sizeof(csvfilenobuf), "%ld",
+			 syslogger_fdget(csvlogFile));
 	av[ac++] = csvfilenobuf;
 
 	av[ac] = NULL;
@@ -807,41 +840,10 @@ syslogger_parseArgs(int argc, char *argv[])
 	 * fails there's not a lot we can do to report the problem anyway.  As
 	 * coded, we'll just crash on a null pointer dereference after failure...
 	 */
-#ifndef WIN32
 	fd = atoi(*argv++);
-	if (fd != -1)
-	{
-		syslogFile = fdopen(fd, "a");
-		setvbuf(syslogFile, NULL, PG_IOLBF, 0);
-	}
+	syslogFile = syslogger_fdopen(fd);
 	fd = atoi(*argv++);
-	if (fd != -1)
-	{
-		csvlogFile = fdopen(fd, "a");
-		setvbuf(csvlogFile, NULL, PG_IOLBF, 0);
-	}
-#else							/* WIN32 */
-	fd = atoi(*argv++);
-	if (fd != 0)
-	{
-		fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
-		if (fd > 0)
-		{
-			syslogFile = fdopen(fd, "a");
-			setvbuf(syslogFile, NULL, PG_IOLBF, 0);
-		}
-	}
-	fd = atoi(*argv++);
-	if (fd != 0)
-	{
-		fd = _open_osfhandle(fd, _O_APPEND | _O_TEXT);
-		if (fd > 0)
-		{
-			csvlogFile = fdopen(fd, "a");
-			setvbuf(csvlogFile, NULL, PG_IOLBF, 0);
-		}
-	}
-#endif							/* WIN32 */
+	csvlogFile = syslogger_fdopen(fd);
 }
 #endif							/* EXEC_BACKEND */
 
-- 
2.33.0