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/* 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 <string.h>
#include <stdio.h>
#include <sysdep.h>
#include <unistd.h>
#include <kernel-features.h>
/* Make a link to FROM named TO but relative paths in TO and FROM are
interpreted relative to FROMFD and TOFD respectively. */
int
linkat (fromfd, from, tofd, to, flags)
int fromfd;
const char *from;
int tofd;
const char *to;
int flags;
{
int result;
#ifdef __NR_linkat
# ifndef __ASSUME_ATFCTS
if (__have_atfcts >= 0)
# endif
{
result = INLINE_SYSCALL (linkat, 5, fromfd, from, tofd, to, flags);
# ifndef __ASSUME_ATFCTS
if (result == -1 && errno == ENOSYS)
__have_atfcts = -1;
else
# endif
return result;
}
#endif
#ifndef __ASSUME_ATFCTS
/* Without kernel support we cannot handle AT_SYMLINK_FOLLOW. */
if (flags != 0)
{
__set_errno (EINVAL);
return -1;
}
static const char procfd[] = "/proc/self/fd/%d/%s";
char *buffrom = NULL;
if (fromfd != AT_FDCWD && from[0] != '/')
{
size_t filelen = strlen (from);
if (__builtin_expect (filelen == 0, 0))
{
__set_errno (ENOENT);
return -1;
}
/* 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 + filelen;
buffrom = alloca (buflen);
__snprintf (buffrom, buflen, procfd, fromfd, from);
from = buffrom;
}
char *bufto = NULL;
if (tofd != AT_FDCWD && to[0] != '/')
{
size_t filelen = strlen (to);
/* 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 + filelen;
bufto = alloca (buflen);
__snprintf (bufto, buflen, procfd, tofd, to);
to = bufto;
}
INTERNAL_SYSCALL_DECL (err);
result = INTERNAL_SYSCALL (link, err, 2, from, to);
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
{
__atfct_seterrno_2 (INTERNAL_SYSCALL_ERRNO (result, err), tofd, bufto,
fromfd, buffrom);
result = -1;
}
return result;
#endif
}
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