/* xreadlink.c -- readlink wrapper to return the link name in malloc'd storage
- Copyright 2001 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2003-2007, 2009-2010 Free Software Foundation, Inc.
- This program is free software; you can redistribute it and/or modify
+ This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2, or (at your option)
- any later version.
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; see the file COPYING.
- If not, write to the Free Software Foundation,
- 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
-/* Written by Jim Meyering <jim@meyering.net> */
+/* Written by Jim Meyering <jim@meyering.net>
+ and Bruno Haible <bruno@clisp.org>. */
-#if HAVE_CONFIG_H
-# include <config.h>
-#endif
+#include <config.h>
-#include <stdio.h>
-#include <errno.h>
-#ifndef errno
-extern int errno;
-#endif
-
-#if HAVE_LIMITS_H
-# include <limits.h>
-#endif
-#if HAVE_SYS_TYPES_H
-# include <sys/types.h>
-#endif
-#if HAVE_STDLIB_H
-# include <stdlib.h>
-#endif
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
+/* Specification. */
+#include "xreadlink.h"
-#ifndef SIZE_MAX
-# define SIZE_MAX ((size_t) -1)
-#endif
-#ifndef SSIZE_MAX
-# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
-#endif
+#include <errno.h>
+#include "areadlink.h"
#include "xalloc.h"
-#include "xreadlink.h"
/* Call readlink to get the symbolic link value of FILENAME.
Return a pointer to that NUL-terminated string in malloc'd storage.
- If readlink fails, return NULL (caller may use errno to diagnose).
+ If readlink fails, return NULL and set errno.
If realloc fails, or if the link value is longer than SIZE_MAX :-),
give a diagnostic and exit. */
char *
xreadlink (char const *filename)
{
- /* The initial buffer size for the link value. A power of 2
- detects arithmetic overflow earlier, but is not required. */
- size_t buf_size = 128;
-
- while (1)
- {
- char *buffer = xmalloc (buf_size);
- ssize_t link_length = readlink (filename, buffer, buf_size);
-
- if (link_length < 0)
- {
- int saved_errno = errno;
- free (buffer);
- errno = saved_errno;
- return NULL;
- }
-
- if (link_length < buf_size)
- {
- buffer[link_length] = 0;
- return buffer;
- }
-
- free (buffer);
- buf_size *= 2;
- if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
- xalloc_die ();
- }
+ char *result = areadlink (filename);
+ if (result == NULL && errno == ENOMEM)
+ xalloc_die ();
+ return result;
}