From b0652d95f2e824c3ed5a4fcacaab907d0b5de3ba Mon Sep 17 00:00:00 2001
From: Milan Crha <mcrha@redhat.com>
Date: Mon, 9 May 2016 08:50:18 +0200
Subject: [PATCH] Check return value of gmtime_r()

When it returns NULL, the output variable is not set.
---
 src/libical/icaltime.c     | 3 ++-
 src/libical/icaltimezone.c | 4 +++-
 src/libicalvcal/icalvcal.c | 5 ++++-
 src/test/timezones.c       | 4 +++-
 4 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/src/libical/icaltime.c b/src/libical/icaltime.c
index c0ad168..2921903 100644
--- a/src/libical/icaltime.c
+++ b/src/libical/icaltime.c
@@ -236,7 +236,8 @@ struct icaltimetype icaltime_from_timet_with_zone(const time_t tm, const int is_
     utc_zone = icaltimezone_get_utc_timezone();
 
     /* Convert the time_t to a struct tm in UTC time. We can trust gmtime for this. */
-    gmtime_r(&tm, &t);
+    if (!gmtime_r(&tm, &t))
+        return is_date ? icaltime_null_date () : icaltime_null_time ();
 
     tt.year = t.tm_year + 1900;
     tt.month = t.tm_mon + 1;
diff --git a/src/libical/icaltimezone.c b/src/libical/icaltimezone.c
index 65c6441..b180d32 100644
--- a/src/libical/icaltimezone.c
+++ b/src/libical/icaltimezone.c
@@ -1363,7 +1363,9 @@ static int get_offset(icaltimezone *zone)
     int offset;
     const time_t now = time(NULL);
 
-    gmtime_r(&now, &local);
+    if (!gmtime_r(&now, &local))
+        return 0;
+
     tt = tm_to_icaltimetype(&local);
     offset = icaltimezone_get_utc_offset(zone, &tt, NULL);
 
diff --git a/src/libicalvcal/icalvcal.c b/src/libicalvcal/icalvcal.c
index 325a6d5..c6f428c 100644
--- a/src/libicalvcal/icalvcal.c
+++ b/src/libicalvcal/icalvcal.c
@@ -134,7 +134,10 @@ static void convert_floating_time_to_utc(struct icaltimetype *itt)
     t = mktime(&tmp_tm);
 
     /* Now convert back to a struct tm, but with a UTC time. */
-    gmtime_r(&t, &utc_tm);
+    if (!gmtime_r(&t, &utc_tm)) {
+        *itt = itt->is_date ? icaltime_null_date () : icaltime_null_time ();
+        return;
+    }
 
     /* Now put it back into the icaltime. */
     itt->year = utc_tm.tm_year + 1900;
diff --git a/src/test/timezones.c b/src/test/timezones.c
index b936242..3648307 100644
--- a/src/test/timezones.c
+++ b/src/test/timezones.c
@@ -106,7 +106,9 @@ int main()
             if (verbose || curr_failed != failed) {
                 struct tm utc_tm;
 
-                gmtime_r(&curr_time, &utc_tm);
+                if (!gmtime_r(&curr_time, &utc_tm))
+                    memset(&utc_tm, 0, sizeof(utc_tm));
+
                 printf(
                     "%s: day %03d: %s: %04d-%02d-%02d %02d:%02d:%02d UTC = "
                     "libc %04d-%02d-%02d %02d:%02d:%02d dst %d",
-- 
2.5.0