Merge from emacs--rel--22

[bpt/emacs.git] / lib-src / b2m.c

diff --git a/lib-src/b2m.c b/lib-src/b2m.c
index 5bebe56..a3ab9a5 100644 (file)
--- a/lib-src/b2m.c
+++ b/lib-src/b2m.c
@@ -44,6 +44,15 @@
 
 typedef int logical;
 
+#define TM_YEAR_BASE 1900
+
+/* Nonzero if TM_YEAR is a struct tm's tm_year value that causes
+   asctime to have well-defined behavior.  */
+#ifndef TM_YEAR_IN_ASCTIME_RANGE
+# define TM_YEAR_IN_ASCTIME_RANGE(tm_year) \
+    (1000 - TM_YEAR_BASE <= (tm_year) && (tm_year) <= 9999 - TM_YEAR_BASE)
+#endif
+
 /*
  * A `struct linebuffer' is a structure which holds a line of text.
  * `readline' reads a line from a stream into a linebuffer and works
@@ -87,6 +96,7 @@ main (argc, argv)
 {
   logical labels_saved, printing, header;
   time_t ltoday;
+  struct tm *tm;
   char *labels, *p, *today;
   struct linebuffer data;
 
@@ -131,7 +141,13 @@ main (argc, argv)
 
   labels_saved = printing = header = FALSE;
   ltoday = time (0);
-  today = ctime (&ltoday);
+  /* Convert to a string, checking for out-of-range time stamps.
+     Don't use 'ctime', as that might dump core if the hardware clock
+     is set to a bizarre value.  */
+  tm = localtime (&ltoday);
+  if (! (tm && TM_YEAR_IN_ASCTIME_RANGE (tm->tm_year)
+        && (today = asctime (tm))))
+    fatal ("current time is out of range");
   data.size = 200;
   data.buffer = xnew (200, char);