string/strerror.c

   1 /* Copyright (C) 1991, 93, 94, 95, 96, 98, 2002 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <libintl.h>
  20 #include <stdio.h>
  21 #include <string.h>
  22 #include <errno.h>
  23
  24 /* Return a string describing the errno code in ERRNUM.
  25    The storage is good only until the next call to strerror.
  26    Writing to the storage causes undefined behavior.  */
  27 libc_freeres_ptr (static char *buf);
  28
  29 char *
  30 strerror (errnum)
  31      int errnum;
  32 {
  33   char *ret = __strerror_r (errnum, NULL, 0);
  34   int saved_errno;
  35
  36   if (__builtin_expect (ret != NULL, 1))
  37     return ret;
  38   saved_errno = errno;
  39   if (buf == NULL)
  40     buf = malloc (1024);
  41   __set_errno (saved_errno);
  42   if (buf == NULL)
  43     return _("Unknown error");
  44   return __strerror_r (errnum, buf, 1024);
  45 }