From f91530c7bb1590530f9174a62c4c73cf1544aca9 Mon Sep 17 00:00:00 2001
From: Nathan Bossart <nathan@postgresql.org>
Date: Tue, 28 Nov 2023 15:25:03 -0600
Subject: [PATCH v5 3/3] Revert "Avoid calling proc_exit() in processes forked
 by system()."

Thanks to commit XXXXXXXXXX, this check in the SIGTERM handler for
the startup process is now obsolete and can be removed.  Instead of
leaving around the dead function write_stderr_signal_safe(), I've
opted to just remove it for now.  Thanks to modern version control
software, it will be trivial to dig it up if it is ever needed in
the future.

This partially reverts commit 97550c0711.

Reviewed-by: Andres Freund
Discussion: https://postgr.es/m/20231121212008.GA3742740%40nathanxps13
---
 src/backend/postmaster/startup.c | 17 +----------------
 src/backend/utils/error/elog.c   | 28 ----------------------------
 src/include/utils/elog.h         |  6 ------
 3 files changed, 1 insertion(+), 50 deletions(-)

diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index 234817cd54..dfdbb56adb 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -19,8 +19,6 @@
  */
 #include "postgres.h"
 
-#include <unistd.h>
-
 #include "access/xlog.h"
 #include "access/xlogrecovery.h"
 #include "access/xlogutils.h"
@@ -112,20 +110,7 @@ static void
 StartupProcShutdownHandler(SIGNAL_ARGS)
 {
 	if (in_restore_command)
-	{
-		/*
-		 * If we are in a child process (e.g., forked by system() in
-		 * RestoreArchivedFile()), we don't want to call any exit callbacks.
-		 * The parent will take care of that.
-		 */
-		if (MyProcPid == (int) getpid())
-			proc_exit(1);
-		else
-		{
-			write_stderr_signal_safe("StartupProcShutdownHandler() called in child process\n");
-			_exit(1);
-		}
-	}
+		proc_exit(1);
 	else
 		shutdown_requested = true;
 	WakeupRecovery();
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index 6ea575a53b..2e86dd44d9 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -3731,31 +3731,3 @@ write_stderr(const char *fmt,...)
 #endif
 	va_end(ap);
 }
-
-
-/*
- * Write a message to STDERR using only async-signal-safe functions.  This can
- * be used to safely emit a message from a signal handler.
- *
- * TODO: It is likely possible to safely do a limited amount of string
- * interpolation (e.g., %s and %d), but that is not presently supported.
- */
-void
-write_stderr_signal_safe(const char *str)
-{
-	int			nwritten = 0;
-	int			ntotal = strlen(str);
-
-	while (nwritten < ntotal)
-	{
-		int			rc;
-
-		rc = write(STDERR_FILENO, str + nwritten, ntotal - nwritten);
-
-		/* Just give up on error.  There isn't much else we can do. */
-		if (rc == -1)
-			return;
-
-		nwritten += rc;
-	}
-}
diff --git a/src/include/utils/elog.h b/src/include/utils/elog.h
index 0971d5ce33..b25ea65dff 100644
--- a/src/include/utils/elog.h
+++ b/src/include/utils/elog.h
@@ -536,10 +536,4 @@ extern void write_jsonlog(ErrorData *edata);
  */
 extern void write_stderr(const char *fmt,...) pg_attribute_printf(1, 2);
 
-/*
- * Write a message to STDERR using only async-signal-safe functions.  This can
- * be used to safely emit a message from a signal handler.
- */
-extern void write_stderr_signal_safe(const char *fmt);
-
 #endif							/* ELOG_H */
-- 
2.25.1