fallback to gettimeofday when monotonic clock is unavailable at run-time

1 files changed, 18 insertions, 3 deletions

diff --git a/ares/ares__timeval.c b/ares/ares__timeval.c
index c3f39f523..7437b5a18 100644
--- a/ares/ares__timeval.c
+++ b/ares/ares__timeval.c
@@ -46,9 +46,24 @@ struct timeval ares__tvnow(void)
   */
   struct timeval now;
   struct timespec tsnow;
-  (void)clock_gettime(CLOCK_MONOTONIC, &tsnow);
-  now.tv_sec = tsnow.tv_sec;
-  now.tv_usec = tsnow.tv_nsec / 1000;
+  if(0 == clock_gettime(CLOCK_MONOTONIC, &tsnow)) {
+    now.tv_sec = tsnow.tv_sec;
+    now.tv_usec = tsnow.tv_nsec / 1000;
+  }
+  /*
+  ** Even when the configure process has truly detected monotonic clock
+  ** availability, it might happen that it is not actually available at
+  ** run-time. When this occurs simply fallback to other time source.
+  */
+#ifdef HAVE_GETTIMEOFDAY
+  else
+    (void)gettimeofday(&now, NULL);
+#else
+  else {
+    now.tv_sec = (long)time(NULL);
+    now.tv_usec = 0;
+  }
+#endif
   return now;
 }