From 1545ca9a7463f4ae8451a845774a107ad0757a9f Mon Sep 17 00:00:00 2001 From: Tom Lane 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 be8c477685..9c77701785 100644 --- a/src/backend/libpq/auth.c +++ b/src/backend/libpq/auth.c @@ -1752,10 +1752,12 @@ 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; }