mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-16 01:50:11 +00:00
96 lines
2.5 KiB
C
96 lines
2.5 KiB
C
/* Copyright (C) 2005-2014 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library 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
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library; if not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <stddef.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sysdep.h>
|
|
#include <unistd.h>
|
|
#include <kernel-features.h>
|
|
|
|
|
|
/* Read the contents of the symbolic link PATH relative to FD into no
|
|
more than LEN bytes of BUF. */
|
|
ssize_t
|
|
readlinkat (fd, path, buf, len)
|
|
int fd;
|
|
const char *path;
|
|
char *buf;
|
|
size_t len;
|
|
{
|
|
int result;
|
|
|
|
#ifdef __NR_readlinkat
|
|
# ifndef __ASSUME_ATFCTS
|
|
if (__have_atfcts >= 0)
|
|
# endif
|
|
{
|
|
result = INLINE_SYSCALL (readlinkat, 4, fd, path, buf, len);
|
|
# ifndef __ASSUME_ATFCTS
|
|
if (result == -1 && errno == ENOSYS)
|
|
__have_atfcts = -1;
|
|
else
|
|
# endif
|
|
return result;
|
|
}
|
|
#endif
|
|
|
|
#ifndef __ASSUME_ATFCTS
|
|
char *pathbuf = NULL;
|
|
|
|
if (fd != AT_FDCWD && path[0] != '/')
|
|
{
|
|
size_t pathlen = strlen (path);
|
|
if (__glibc_unlikely (pathlen == 0))
|
|
{
|
|
__set_errno (ENOENT);
|
|
return -1;
|
|
}
|
|
|
|
static const char procfd[] = "/proc/self/fd/%d/%s";
|
|
/* Buffer for the path name we are going to use. It consists of
|
|
- the string /proc/self/fd/
|
|
- the file descriptor number
|
|
- the file name provided.
|
|
The final NUL is included in the sizeof. A bit of overhead
|
|
due to the format elements compensates for possible negative
|
|
numbers. */
|
|
size_t buflen = sizeof (procfd) + sizeof (int) * 3 + pathlen;
|
|
pathbuf = __alloca (buflen);
|
|
|
|
__snprintf (pathbuf, buflen, procfd, fd, path);
|
|
path = pathbuf;
|
|
}
|
|
|
|
INTERNAL_SYSCALL_DECL (err);
|
|
|
|
result = INTERNAL_SYSCALL (readlink, err, 3, path, buf, len);
|
|
|
|
if (__glibc_unlikely (INTERNAL_SYSCALL_ERROR_P (result, err)))
|
|
{
|
|
__atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, pathbuf);
|
|
result = -1;
|
|
}
|
|
|
|
return result;
|
|
#endif
|
|
}
|
|
libc_hidden_def (readlinkat)
|