1/* areadlink.c -- readlink wrapper to return the link name in malloc'd storage
2 Unlike xreadlink and xreadlink_with_size, don't ever call exit.
3
4 Copyright (C) 2001, 2003-2007, 2009-2019 Free Software Foundation, Inc.
5
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>. */
18
19/* Written by Jim Meyering <jim@meyering.net>
20 and Bruno Haible <bruno@clisp.org>. */
21
22#include <config.h>
23
24/* Specification. */
25#include "areadlink.h"
26
27#include "careadlinkat.h"
28
29#include <stdlib.h>
30#include <unistd.h>
31
32/* Get the symbolic link value of FILENAME and put it into BUFFER, with
33 size BUFFER_SIZE. This function acts like readlink but has
34 readlinkat's signature. */
35static ssize_t
36careadlinkatcwd (int fd, char const *filename, char *buffer,
37 size_t buffer_size)
38{
39 /* FD must be AT_FDCWD here, otherwise the caller is using this
40 function in contexts it was not meant for. */
41 if (fd != AT_FDCWD)
42 abort ();
43 return readlink (filename, buffer, buffer_size);
44}
45
46/* Call readlink to get the symbolic link value of FILENAME.
47 Return a pointer to that NUL-terminated string in malloc'd storage.
48 If readlink fails, return NULL and set errno.
49 If allocation fails, or if the link value is longer than SIZE_MAX :-),
50 return NULL and set errno to ENOMEM. */
51
52char *
53areadlink (char const *filename)
54{
55 return careadlinkat (AT_FDCWD, filename, NULL, 0, NULL, careadlinkatcwd);
56}
57