errdetail-pid-fix2.patch

diff --git a/src/backend/replication/syncrep.c b/src/backend/replication/syncrep.c
index 46a778f0917..896ba45412d 100644
--- a/src/backend/replication/syncrep.c
+++ b/src/backend/replication/syncrep.c
@@ -300,22 +300,18 @@ SyncRepWaitForLSN(XLogRecPtr lsn, bool commit)
 		 */
 		if (ProcDiePending)
 		{
-			/*
-			 * ProcDieSenderPid/Uid are read directly from the globals here
-			 * rather than copied to locals first; a second SIGTERM could
-			 * change them between reads, but that is harmless because the
-			 * process is about to die anyway.  The signal sender detail is
-			 * inlined rather than using a separate errdetail() call because
-			 * it must be appended to the existing detail message.
-			 */
-			ereport(WARNING,
-					(errcode(ERRCODE_ADMIN_SHUTDOWN),
-					 errmsg("canceling the wait for synchronous replication and terminating connection due to administrator command"),
-					 errdetail("The transaction has already committed locally, but might not have been replicated to the standby.%s",
-							   ProcDieSenderPid == 0 ? "" :
-							   psprintf("\nSignal sent by PID %d, UID %d.",
-										(int) ProcDieSenderPid,
-										(int) ProcDieSenderUid))));
+			if (ProcDieSenderPid != 0)
+				ereport(WARNING,
+						(errcode(ERRCODE_ADMIN_SHUTDOWN),
+						 errmsg("canceling the wait for synchronous replication and terminating connection due to administrator command"),
+						 errdetail("The transaction has already committed locally, but might not have been replicated to the standby. Signal sent by PID %d, UID %d.",
+								   (int) ProcDieSenderPid,
+								   (int) ProcDieSenderUid)));
+			else
+				ereport(WARNING,
+						(errcode(ERRCODE_ADMIN_SHUTDOWN),
+						 errmsg("canceling the wait for synchronous replication and terminating connection due to administrator command"),
+						 errdetail("The transaction has already committed locally, but might not have been replicated to the standby.")));
 			whereToSendOutput = DestNone;
 			SyncRepCancelWait();
 			break;
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 4fb18741dc5..df336e3f194 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -3023,8 +3023,16 @@ die(SIGNAL_ARGS)
 	/* Don't joggle the elbow of proc_exit */
 	if (!proc_exit_inprogress)
 	{
+		int			sender_pid = 0;
+		int			sender_uid = 0;
+
 		InterruptPending = true;
 		ProcDiePending = true;
+#ifdef HAVE_SA_SIGINFO
+		pqsignal_get_sender(&sender_pid, &sender_uid);
+#endif
+		ProcDieSenderPid = sender_pid;
+		ProcDieSenderUid = sender_uid;
 	}
 
 	/* for the cumulative stats system */
diff --git a/src/bin/psql/t/001_basic.pl b/src/bin/psql/t/001_basic.pl
index 7c21204c1f2..9d966c7bece 100644
--- a/src/bin/psql/t/001_basic.pl
+++ b/src/bin/psql/t/001_basic.pl
@@ -142,8 +142,11 @@ my ($ret, $out, $err) = $node->psql('postgres',
 is($ret, 2, 'server crash: psql exit code');
 like($out, qr/before/, 'server crash: output before crash');
 unlike($out, qr/AFTER/, 'server crash: no output after crash');
+my $detail_re = check_pg_config("#define HAVE_SA_SIGINFO 1")
+	? qr/DETAIL:  Signal sent by PID \d+, UID \d+\.\n/
+	: qr//;
 like( $err, qr/psql:<stdin>:2: FATAL:  terminating connection due to administrator command
-(?:DETAIL:  Signal sent by PID \d+, UID \d+\.\n)?psql:<stdin>:2: server closed the connection unexpectedly
+${detail_re}psql:<stdin>:2: server closed the connection unexpectedly
 	This probably means the server terminated abnormally
 	before or while processing the request.
 psql:<stdin>:2: error: connection to server was lost/,
diff --git a/src/include/libpq/pqsignal.h b/src/include/libpq/pqsignal.h
index 9f494a1fdf9..40ed553cdf6 100644
--- a/src/include/libpq/pqsignal.h
+++ b/src/include/libpq/pqsignal.h
@@ -51,4 +51,8 @@ extern PGDLLIMPORT sigset_t StartupBlockSig;
 
 extern void pqinitmask(void);
 
+#ifdef HAVE_SA_SIGINFO
+extern void pqsignal_get_sender(int *sender_pid, int *sender_uid);
+#endif
+
 #endif							/* PQSIGNAL_H */
diff --git a/src/port/pqsignal.c b/src/port/pqsignal.c
index 8841464b5cb..7ee101517aa 100644
--- a/src/port/pqsignal.c
+++ b/src/port/pqsignal.c
@@ -71,6 +71,16 @@ StaticAssertDecl(SIGALRM < PG_NSIG, "SIGALRM >= PG_NSIG");
 
 static volatile pqsigfunc pqsignal_handlers[PG_NSIG];
 
+#if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
+/*
+ * Pointer to the siginfo_t for the signal currently being handled.  This
+ * lives on wrapper_handler's stack frame and is saved/restored around the
+ * call to the real handler, so nested signals each see their own siginfo.
+ * Signal handlers can call pqsignal_get_sender() to retrieve it.
+ */
+static volatile siginfo_t *current_siginfo;
+#endif
+
 /*
  * Except when called with SIG_IGN or SIG_DFL, pqsignal() sets up this function
  * as the handler for all signals.  This wrapper handler function checks that
@@ -84,7 +94,7 @@ static volatile pqsigfunc pqsignal_handlers[PG_NSIG];
  */
 #if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
 static void
-wrapper_handler(int signo, siginfo_t * info, void *context)
+wrapper_handler(int postgres_signal_arg, siginfo_t *info, void *context)
 #else
 static void
 wrapper_handler(SIGNAL_ARGS)
@@ -92,8 +102,7 @@ wrapper_handler(SIGNAL_ARGS)
 {
 	int			save_errno = errno;
 #if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
-	/* SA_SIGINFO signature uses signo, not SIGNAL_ARGS macro */
-	int			postgres_signal_arg = signo;
+	volatile siginfo_t *saved_siginfo = current_siginfo;
 #endif
 
 	Assert(postgres_signal_arg > 0);
@@ -116,19 +125,50 @@ wrapper_handler(SIGNAL_ARGS)
 	}
 
 #ifdef HAVE_SA_SIGINFO
-	if (signo == SIGTERM && info)
-	{
-		ProcDieSenderPid = info->si_pid;
-		ProcDieSenderUid = info->si_uid;
-	}
-#endif
+	current_siginfo = info;
+	(*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg);
+	current_siginfo = saved_siginfo;
+#else
+	(*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg);
 #endif
 
+#else							/* FRONTEND */
 	(*pqsignal_handlers[postgres_signal_arg]) (postgres_signal_arg);
+#endif
 
 	errno = save_errno;
 }
 
+#if !defined(FRONTEND) && defined(HAVE_SA_SIGINFO)
+/*
+ * pqsignal_get_sender - retrieve the PID and UID of the current signal sender
+ *
+ * This may only be called from within a signal handler.  The values come from
+ * the siginfo_t passed by the kernel to wrapper_handler, which is on the
+ * stack and thus safe against nesting: if a different signal interrupts, its
+ * wrapper_handler invocation saves and restores the pointer, so the outer
+ * handler still sees the correct siginfo after the nested handler returns.
+ *
+ * If siginfo is not available (e.g. info was NULL), returns zeros.
+ */
+void
+pqsignal_get_sender(int *sender_pid, int *sender_uid)
+{
+	volatile siginfo_t *info = current_siginfo;
+
+	if (info)
+	{
+		*sender_pid = info->si_pid;
+		*sender_uid = info->si_uid;
+	}
+	else
+	{
+		*sender_pid = 0;
+		*sender_uid = 0;
+	}
+}
+#endif
+
 /*
  * Set up a signal handler, with SA_RESTART, for signal "signo"
  *