toplev.c (init_local_tick): Process the failure when read fails for random_seed.

	* toplev.c (init_local_tick): Process the failure when read
	fails for random_seed.

From-SVN: r220006

gcc/ChangeLog

 2015-01-23  Chen Gang  <gang.chen.5i5j@gmail.com>
 
+	* toplev.c (init_local_tick): Process the failure when read
+	fails for random_seed.
+
 	* ubsan.c (ubsan_type_descriptor): Use 'pretty_print' for
 	'pretty_name' to avoid memory overflow.
 

gcc/toplev.c

@@ -295,7 +295,9 @@ init_local_tick (void)
       int fd = open ("/dev/urandom", O_RDONLY);
       if (fd >= 0)
         {
-          read (fd, &random_seed, sizeof (random_seed));
+          if (read (fd, &random_seed, sizeof (random_seed))
+              != sizeof (random_seed))
+            random_seed = 0;
           close (fd);
         }