/* xreadlink.c -- readlink wrapper to return the link name in malloc'd storage
- Copyright (C) 2001, 2003-2007 Free Software Foundation, Inc.
+ Copyright (C) 2001, 2003-2007, 2009-2013 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,
- 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
/* Written by Jim Meyering <jim@meyering.net>
and Bruno Haible <bruno@clisp.org>. */
/* Specification. */
#include "xreadlink.h"
-#include <stdio.h>
-#include <string.h>
#include <errno.h>
-#include <limits.h>
-#include <sys/types.h>
-#include <stdlib.h>
-#if HAVE_UNISTD_H
-# include <unistd.h>
-#endif
-#ifndef SIZE_MAX
-# define SIZE_MAX ((size_t) -1)
-#endif
-#ifndef SSIZE_MAX
-# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2))
-#endif
-
-#ifdef NO_XMALLOC
-# define xmalloc malloc
-#else
-# include "xalloc.h"
-#endif
+#include "areadlink.h"
+#include "xalloc.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. */
-#define INITIAL_BUF_SIZE 1024
-
- /* Allocate the initial buffer on the stack. This way, in the common
- case of a symlink of small size, we get away with a single small malloc()
- instead of a big malloc() followed by a shrinking realloc(). */
- char initial_buf[INITIAL_BUF_SIZE];
-
- char *buffer = initial_buf;
- size_t buf_size = sizeof (initial_buf);
-
- while (1)
- {
- /* Attempt to read the link into the current buffer. */
- ssize_t link_length = readlink (filename, buffer, buf_size);
-
- /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1
- with errno == ERANGE if the buffer is too small. */
- if (link_length < 0 && errno != ERANGE)
- {
- if (buffer != initial_buf)
- {
- int saved_errno = errno;
- free (buffer);
- errno = saved_errno;
- }
- return NULL;
- }
-
- if ((size_t) link_length < buf_size)
- {
- buffer[link_length++] = '\0';
-
- /* Return it in a chunk of memory as small as possible. */
- if (buffer == initial_buf)
- {
- buffer = (char *) xmalloc (link_length);
-#ifdef NO_XMALLOC
- if (buffer == NULL)
- return NULL;
-#endif
- memcpy (buffer, initial_buf, link_length);
- }
- else
- {
- /* Shrink buffer before returning it. */
- if ((size_t) link_length < buf_size)
- {
- char *smaller_buffer = (char *) realloc (buffer, link_length);
-
- if (smaller_buffer != NULL)
- buffer = smaller_buffer;
- }
- }
- return buffer;
- }
-
- if (buffer != initial_buf)
- free (buffer);
- buf_size *= 2;
- if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0))
-#ifdef NO_XMALLOC
- return NULL;
-#else
- xalloc_die ();
-#endif
- buffer = (char *) xmalloc (buf_size);
-#ifdef NO_XMALLOC
- if (buffer == NULL)
- return NULL;
-#endif
- }
+ char *result = areadlink (filename);
+ if (result == NULL && errno == ENOMEM)
+ xalloc_die ();
+ return result;
}
projects / gnulib.git / blobdiff