Always fill output buffer in XPG strerror function

3 files changed, 15 insertions, 10 deletions

diff --git a/ChangeLog b/ChangeLog
index fc2b7a8..bc73ba3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2011-05-21  Ulrich Drepper  <drepper@gmail.com>
 
+	[BZ #12782]
+	* string/xpg-strerror.c (__xpg_strerror_r): Fill buffer even if error
+	is returned.
+
 	* string/_strerror.c (__strerror_r): Print negative errors as signed
 	numbers.
 
diff --git a/NEWS b/NEWS
index a99c74a..90ccee7 100644
--- a/NEWS
+++ b/NEWS
@@ -16,8 +16,8 @@ Version 2.14
   12454, 12460, 12469, 12489, 12509, 12510, 12511, 12518, 12527, 12541,
   12545, 12551, 12582, 12583, 12587, 12597, 12601, 12611, 12625, 12626,
   12631, 12650, 12653, 12655, 12660, 12681, 12685, 12711, 12713, 12714,
-  12717, 12723, 12724, 12734, 12738, 12746, 12766, 12775, 12777, 12788,
-  12792
+  12717, 12723, 12724, 12734, 12738, 12746, 12766, 12775, 12777, 12782,
+  12788, 12792
 
 * The RPC implementation in libc is obsoleted.  Old programs keep working
   but new programs cannot be linked with the routines in libc anymore.
diff --git a/string/xpg-strerror.c b/string/xpg-strerror.c
index 8d89812..00256c3 100644
--- a/string/xpg-strerror.c
+++ b/string/xpg-strerror.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 1991, 1993, 1995, 1996, 1997, 1998, 2000, 2002, 2004, 2010
+/* Copyright (C) 1991, 1993, 1995-1998, 2000, 2002, 2004, 2010, 2011
    Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -17,6 +17,7 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
+#include <assert.h>
 #include <errno.h>
 #include <libintl.h>
 #include <stdio.h>
@@ -37,16 +38,16 @@
 int
 __xpg_strerror_r (int errnum, char *buf, size_t buflen)
 {
+  const char *estr = __strerror_r (errnum, buf, buflen);
+  size_t estrlen = strlen (estr);
+
   if (errnum < 0 || errnum >= _sys_nerr_internal
       || _sys_errlist_internal[errnum] == NULL)
     return EINVAL;
 
-  const char *estr = (const char *) _(_sys_errlist_internal[errnum]);
-  size_t estrlen = strlen (estr) + 1;
-
-  if (buflen < estrlen)
-    return ERANGE;
+  assert (estr != buf);
+/* Terminate the string in any case.  */
+  *((char *) __mempcpy (buf, estr, MIN (buflen - 1, estrlen))) = '\0';
 
-  memcpy (buf, estr, estrlen);
-  return 0;
+  return buflen <= estrlen ? ERANGE : 0;
 }