From d8e1de899c8ec480af6696350957b13a2cc3ff0b Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Thu, 6 Dec 2018 15:08:44 -0500 Subject: [PATCH] Improve our response to invalid format strings, and detect more cases. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Places that are testing for *printf failure ought to include the format string in their error reports, since bad-format-string is one of the more likely causes of such failure. This both makes it easier to find and repair the mistake, and provides at least some useful info to the user who stumbles across such a problem. Also, tighten snprintf.c to report EINVAL for an invalid flag or final character in a format %-spec (including the case where the %-spec is missing a final character altogether). This seems like better project policy, and it also allows removing an instruction or two from the hot code path. Back-patch the error reporting change in pvsnprintf, since it should be harmless and may be helpful; but not the snprintf.c change. Per discussion of bug #15511 from Ertuğrul Kahveci, which reported an invalid translated format string. These changes don't fix that error, but they should improve matters next time we make such a mistake. Discussion: https://postgr.es/m/15511-1d8b6a0bc874112f@postgresql.org --- src/common/psprintf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/common/psprintf.c b/src/common/psprintf.c index b974a99be1..1254a9ed4d 100644 --- a/src/common/psprintf.c +++ b/src/common/psprintf.c @@ -129,9 +129,9 @@ pvsnprintf(char *buf, size_t len, const char *fmt, va_list args) if (nprinted < 0 && errno != 0 && errno != ENOMEM) { #ifndef FRONTEND - elog(ERROR, "vsnprintf failed: %m"); + elog(ERROR, "vsnprintf failed: %m with format string \"%s\"", fmt); #else - fprintf(stderr, "vsnprintf failed: %s\n", strerror(errno)); + fprintf(stderr, "vsnprintf failed: %m with format string \"%s\"\n", fmt); exit(EXIT_FAILURE); #endif }