From: Michal Schmidt <mschmidt@redhat.com>
Date: Mon, 29 Oct 2012 20:04:47 +0000 (+0100)
Subject: util: improve overflow checks
X-Git-Tag: v196~179
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=fd09c93de9337c3df566180d04368353bb3662e7

util: improve overflow checks

commit 49371bb fixed the observed division by zero, but missed another
occurrence of the same bug. It was also not the optimal fix. We can
simply make the divisor a constant by swapping it with the compared
value.
---

diff --git a/src/shared/util.c b/src/shared/util.c
index 9a45e6058..8ec83e49a 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -148,8 +148,7 @@ usec_t timespec_load(const struct timespec *ts) {
             ts->tv_nsec == (long) -1)
                 return (usec_t) -1;
 
-        if (ts->tv_sec > 0 &&
-            USEC_PER_SEC > ((UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / (usec_t) ts->tv_sec))
+        if ((usec_t) ts->tv_sec > (UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / USEC_PER_SEC)
                 return (usec_t) -1;
 
         return
@@ -179,7 +178,7 @@ usec_t timeval_load(const struct timeval *tv) {
             tv->tv_usec == (suseconds_t) -1)
                 return (usec_t) -1;
 
-        if (USEC_PER_SEC > (UINT64_MAX - tv->tv_usec) / (usec_t) tv->tv_sec)
+        if ((usec_t) tv->tv_sec > (UINT64_MAX - tv->tv_usec) / USEC_PER_SEC)
                 return (usec_t) -1;
 
         return