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 9a45e6058e200813fed1bae7ff9d27f0ebb164a5..8ec83e49a8c0342539e712eb2b012b32cb75651c 100644 (file)
--- 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