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/* Copyright (C) 2005, 2006 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, write to the Free
Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA. */
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <sysdep.h>
#include <sys/syscall.h>
#include <shlib-compat.h>
#include <bp-checks.h>
#include <linux/posix_types.h>
#include <kernel-features.h>
/*
In Linux 2.1.x the chown functions have been changed. A new function lchown
was introduced. The new chown now follows symlinks - the old chown and the
new lchown do not follow symlinks.
The new lchown function has the same number as the old chown had and the
new chown has a new number. When compiling with headers from Linux > 2.1.8x
it's impossible to run this libc with older kernels. In these cases libc
has therefore to route calls to chown to the old chown function.
*/
/* Running under Linux > 2.1.80. */
#ifdef __NR_chown32
# if __ASSUME_32BITUIDS == 0
/* This variable is shared with all files that need to check for 32bit
uids. */
extern int __libc_missing_32bit_uids;
# endif
#endif /* __NR_chown32 */
int
fchownat (int fd, const char *file, uid_t owner, gid_t group, int flag)
{
if (flag & ~AT_SYMLINK_NOFOLLOW)
{
__set_errno (EINVAL);
return -1;
}
char *buf = NULL;
if (fd != AT_FDCWD && file[0] != '/')
{
size_t filelen = strlen (file);
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 + filelen;
buf = alloca (buflen);
__snprintf (buf, buflen, procfd, fd, file);
file = buf;
}
int result;
INTERNAL_SYSCALL_DECL (err);
#if __ASSUME_32BITUIDS > 0
result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file), owner,
group);
#else
static int __libc_old_chown;
# ifdef __NR_chown32
if (__libc_missing_32bit_uids <= 0)
{
if (flag & AT_SYMLINK_NOFOLLOW)
result = INTERNAL_SYSCALL (lchown32, err, 3, CHECK_STRING (file),
owner, group);
else
result = INTERNAL_SYSCALL (chown32, err, 3, CHECK_STRING (file),
owner, group);
if (__builtin_expect (!INTERNAL_SYSCALL_ERROR_P (result, err), 1))
return result;
if (INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
goto fail;
__libc_missing_32bit_uids = 1;
}
# endif /* __NR_chown32 */
if (((owner + 1) > (uid_t) ((__kernel_uid_t) -1U))
|| ((group + 1) > (gid_t) ((__kernel_gid_t) -1U)))
{
__set_errno (EINVAL);
return -1;
}
if (!__libc_old_chown && (flag & AT_SYMLINK_NOFOLLOW) == 0)
{
result = INTERNAL_SYSCALL (chown, err, 3, CHECK_STRING (file), owner,
group);
if (!INTERNAL_SYSCALL_ERROR_P (result, err))
return result;
if (INTERNAL_SYSCALL_ERRNO (result, err) != ENOSYS)
goto fail;
__libc_old_chown = 1;
}
result = INTERNAL_SYSCALL (lchown, err, 3, CHECK_STRING (file), owner,
group);
#endif
if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (result, err), 0))
{
fail:
__atfct_seterrno (INTERNAL_SYSCALL_ERRNO (result, err), fd, buf);
result = -1;
}
return result;
}
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