rm_/lib/areadlink.c

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2020-09-02 16:47:03 +08:00
/* areadlink.c -- readlink wrapper to return the link name in malloc'd storage
Unlike xreadlink and xreadlink_with_size, don't ever call exit.
Copyright (C) 2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.
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 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
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
/* Written by Jim Meyering <jim@meyering.net>
and Bruno Haible <bruno@clisp.org>. */
#include <config.h>
/* Specification. */
#include "areadlink.h"
#include "careadlinkat.h"
#include <stdlib.h>
#include <unistd.h>
/* Get the symbolic link value of FILENAME and put it into BUFFER, with
size BUFFER_SIZE. This function acts like readlink but has
readlinkat's signature. */
static ssize_t
careadlinkatcwd (int fd, char const *filename, char *buffer,
size_t buffer_size)
{
/* FD must be AT_FDCWD here, otherwise the caller is using this
function in contexts it was not meant for. */
if (fd != AT_FDCWD)
abort ();
return readlink (filename, buffer, buffer_size);
}
/* 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 and set errno.
If allocation fails, or if the link value is longer than SIZE_MAX :-),
return NULL and set errno to ENOMEM. */
char *
areadlink (char const *filename)
{
return careadlinkat (AT_FDCWD, filename, NULL, 0, NULL, careadlinkatcwd);
}