2.5-18.1

1 files changed, 48 insertions, 18 deletions

diff --git a/time/asctime.c b/time/asctime.c
index f20b311bb5..dc4fd54f4e 100644
--- a/time/asctime.c
+++ b/time/asctime.c
@@ -1,4 +1,5 @@
-/* Copyright (C) 1991,1993,1995-1997,2000,2002 Free Software Foundation, Inc.
+/* Copyright (C) 1991,1993,1995-1997,2000,2002,2005
+   Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
    The GNU C Library is free software; you can redistribute it and/or
@@ -18,6 +19,7 @@
 
 #include "../locale/localeinfo.h"
 #include <errno.h>
+#include <limits.h>
 #include <stdio.h>
 #include <time.h>
 
@@ -29,17 +31,9 @@ extern const struct locale_data _nl_C_LC_TIME attribute_hidden;
 static const char format[] = "%.3s %.3s%3d %.2d:%.2d:%.2d %d\n";
 static char result[	         3+1+ 3+1+20+1+20+1+20+1+20+1+20+1 + 1];
 
-/* Returns a string of the form "Day Mon dd hh:mm:ss yyyy\n"
-   which is the representation of TP in that form.  */
-char *
-asctime (const struct tm *tp)
-{
-  return __asctime_r (tp, result);
-}
-libc_hidden_def (asctime)
 
-char *
-__asctime_r (const struct tm *tp, char *buf)
+static char *
+asctime_internal (const struct tm *tp, char *buf, size_t buflen)
 {
   if (tp == NULL)
     {
@@ -47,15 +41,51 @@ __asctime_r (const struct tm *tp, char *buf)
       return NULL;
     }
 
-  if (sprintf (buf, format,
-	       (tp->tm_wday < 0 || tp->tm_wday >= 7 ?
-		"???" : ab_day_name (tp->tm_wday)),
-	       (tp->tm_mon < 0 || tp->tm_mon >= 12 ?
-		"???" : ab_month_name (tp->tm_mon)),
-	       tp->tm_mday, tp->tm_hour, tp->tm_min,
-	       tp->tm_sec, 1900 + tp->tm_year) < 0)
+  /* We limit the size of the year which can be printed.  Using the %d
+     format specifier used the addition of 1900 would overflow the
+     number and a negative vaue is printed.  For some architectures we
+     could in theory use %ld or an evern larger integer format but
+     this would mean the output needs more space.  This would not be a
+     problem if the 'asctime_r' interface would be defined sanely and
+     a buffer size would be passed.  */
+  if (__builtin_expect (tp->tm_year > INT_MAX - 1900, 0))
+    {
+    eoverflow:
+      __set_errno (EOVERFLOW);
+      return NULL;
+    }
+
+  int n = __snprintf (buf, buflen, format,
+		      (tp->tm_wday < 0 || tp->tm_wday >= 7 ?
+		       "???" : ab_day_name (tp->tm_wday)),
+		      (tp->tm_mon < 0 || tp->tm_mon >= 12 ?
+		       "???" : ab_month_name (tp->tm_mon)),
+		      tp->tm_mday, tp->tm_hour, tp->tm_min,
+		      tp->tm_sec, 1900 + tp->tm_year);
+  if (n < 0)
     return NULL;
+  if (n >= buflen)
+    goto eoverflow;
 
   return buf;
 }
+
+
+/* Like asctime, but write result to the user supplied buffer.  The
+   buffer is only guaranteed to be 26 bytes in length.  */
+char *
+__asctime_r (const struct tm *tp, char *buf)
+{
+  return asctime_internal (tp, buf, 26);
+}
 weak_alias (__asctime_r, asctime_r)
+
+
+/* Returns a string of the form "Day Mon dd hh:mm:ss yyyy\n"
+   which is the representation of TP in that form.  */
+char *
+asctime (const struct tm *tp)
+{
+  return asctime_internal (tp, result, sizeof (result));
+}
+libc_hidden_def (asctime)