From 81256cd05f0745353c6572362155b57250a0d2a0 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 21 May 2018 00:32:28 -0400
Subject: [PATCH] Fix unsafe usage of strerror(errno) within ereport().
This is the converse of the unsafe-usage-of-%m problem: the reason
ereport/elog provide that format code is mainly to dodge the hazard
of errno getting changed before control reaches functions within the
arguments of the macro. I only found one instance of this hazard,
but it's been there since 9.4 :-(.
---
src/backend/libpq/auth.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/src/backend/libpq/auth.c b/src/backend/libpq/auth.c
index 3014b17a7c..63f37902e6 100644
--- a/src/backend/libpq/auth.c
+++ b/src/backend/libpq/auth.c
@@ -2041,10 +2041,12 @@ auth_peer(hbaPort *port)
pw = getpwuid(uid);
if (!pw)
{
+ int save_errno = errno;
+
ereport(LOG,
(errmsg("could not look up local user ID %ld: %s",
(long) uid,
- errno ? strerror(errno) : _("user does not exist"))));
+ save_errno ? strerror(save_errno) : _("user does not exist"))));
return STATUS_ERROR;
}
--
2.50.1