Fix unsafe assumption that struct timeval.tv_sec is a "long".

tglsfdc · tglsfdc · commit 0645dacc371d · 2016-12-06T19:52:34.000-05:00
It typically is a "long", but it seems possible that on some platforms it wouldn't be. In any case, this silences a compiler warning on OpenBSD (cf buildfarm member curculio). While at it, use snprintf not sprintf. This format string couldn't possibly overrun the supplied buffer, but that doesn't seem like a good reason not to use the safer style. Oversight in commit f828654. Back-patch to 9.6 where that came in.
diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
@@ -2484,8 +2484,9 @@ log_line_prefix(StringInfo buf, ErrorData *edata)
 						saved_timeval_set = true;
 					}
 
-					sprintf(strfbuf, "%ld.%03d", saved_timeval.tv_sec,
-							(int) (saved_timeval.tv_usec / 1000));
+					snprintf(strfbuf, sizeof(strfbuf), "%ld.%03d",
+							 (long) saved_timeval.tv_sec,
+							 (int) (saved_timeval.tv_usec / 1000));
 
 					if (padding != 0)
 						appendStringInfo(buf, "%*s", padding, strfbuf);
