From: Lennart Poettering <lennart@poettering.net>
Date: Thu, 2 Feb 2017 17:25:33 +0000 (+0100)
Subject: time: time_t is signed, and mktime() is happy to return negative time
X-Git-Tag: v233.3~81
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=commitdiff_plain;h=6357ed92bd48120109f246b34e0fa8977a2caedc;hp=0a1154544763e1e1ceec84b21ee87a101fbfb19a;p=elogind.git

time: time_t is signed, and mktime() is happy to return negative time

Passing a year such as 1960 to mktime() will result in a negative return
value. This is quite confusing, as the man page claims that on failure
the call will return -1...

Given that our own usec_t type is unsigned, and we can't express times
before 1970 hence, let's consider all negative times returned by
mktime() as invalid, regardless if just -1, or anything else negative.
---

diff --git a/src/basic/time-util.c b/src/basic/time-util.c
index ecb621ec4..2333f6a66 100644
--- a/src/basic/time-util.c
+++ b/src/basic/time-util.c
@@ -189,7 +189,7 @@ usec_t triple_timestamp_by_clock(triple_timestamp *ts, clockid_t clock) {
 usec_t timespec_load(const struct timespec *ts) {
         assert(ts);
 
-        if (ts->tv_sec == (time_t) -1 && ts->tv_nsec == (long) -1)
+        if (ts->tv_sec < 0 || ts->tv_nsec < 0)
                 return USEC_INFINITY;
 
         if ((usec_t) ts->tv_sec > (UINT64_MAX - (ts->tv_nsec / NSEC_PER_USEC)) / USEC_PER_SEC)
@@ -204,7 +204,7 @@ usec_t timespec_load(const struct timespec *ts) {
 nsec_t timespec_load_nsec(const struct timespec *ts) {
         assert(ts);
 
-        if (ts->tv_sec == (time_t) -1 && ts->tv_nsec == (long) -1)
+        if (ts->tv_sec < 0 || ts->tv_nsec < 0)
                 return NSEC_INFINITY;
 
         if ((nsec_t) ts->tv_sec >= (UINT64_MAX - ts->tv_nsec) / NSEC_PER_SEC)
@@ -232,8 +232,7 @@ struct timespec *timespec_store(struct timespec *ts, usec_t u)  {
 usec_t timeval_load(const struct timeval *tv) {
         assert(tv);
 
-        if (tv->tv_sec == (time_t) -1 &&
-            tv->tv_usec == (suseconds_t) -1)
+        if (tv->tv_sec < 0 || tv->tv_usec < 0)
                 return USEC_INFINITY;
 
         if ((usec_t) tv->tv_sec > (UINT64_MAX - tv->tv_usec) / USEC_PER_SEC)
@@ -843,7 +842,7 @@ parse_usec:
 
 from_tm:
         x = mktime_or_timegm(&tm, utc);
-        if (x == (time_t) -1)
+        if (x < 0)
                 return -EINVAL;
 
         if (weekday >= 0 && tm.tm_wday != weekday)