mirror of
https://sourceware.org/git/glibc.git
synced 2025-10-28 23:34:53 +03:00
e5244cd88a
fstatat64 depends on inlining to produce the desired __fxstatat64 call, which does not happen with -Os, leading to a link failure with an undefined reference to fstatat64. __fxstatat64 has a macro definition in include/sys/stat.h and thus avoids the problem.
99 lines
3.3 KiB
C
99 lines
3.3 KiB
C
/* Change the protections of file relative to open directory. Linux version.
|
|
Copyright (C) 2006-2020 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
|
|
<https://www.gnu.org/licenses/>. */
|
|
|
|
#include <errno.h>
|
|
#include <fcntl.h>
|
|
#include <not-cancel.h>
|
|
#include <stdio.h>
|
|
#include <sys/stat.h>
|
|
#include <sys/types.h>
|
|
#include <sysdep.h>
|
|
#include <unistd.h>
|
|
|
|
int
|
|
fchmodat (int fd, const char *file, mode_t mode, int flag)
|
|
{
|
|
if (flag == 0)
|
|
return INLINE_SYSCALL (fchmodat, 3, fd, file, mode);
|
|
else if (flag != AT_SYMLINK_NOFOLLOW)
|
|
return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL);
|
|
else
|
|
{
|
|
/* The kernel system call does not have a mode argument.
|
|
However, we can create an O_PATH descriptor and change that
|
|
via /proc (which does not resolve symbolic links). */
|
|
|
|
int pathfd = __openat_nocancel (fd, file,
|
|
O_PATH | O_NOFOLLOW | O_CLOEXEC);
|
|
if (pathfd < 0)
|
|
/* This may report errors such as ENFILE and EMFILE. The
|
|
caller can treat them as temporary if necessary. */
|
|
return pathfd;
|
|
|
|
/* Use fstatat because fstat does not work on O_PATH descriptors
|
|
before Linux 3.6. */
|
|
struct stat64 st;
|
|
if (__fstatat64 (pathfd, "", &st, AT_EMPTY_PATH) != 0)
|
|
{
|
|
__close_nocancel (pathfd);
|
|
return -1;
|
|
}
|
|
|
|
/* Some Linux versions with some file systems can actually
|
|
change symbolic link permissions via /proc, but this is not
|
|
intentional, and it gives inconsistent results (e.g., error
|
|
return despite mode change). The expected behavior is that
|
|
symbolic link modes cannot be changed at all, and this check
|
|
enforces that. */
|
|
if (S_ISLNK (st.st_mode))
|
|
{
|
|
__close_nocancel (pathfd);
|
|
__set_errno (EOPNOTSUPP);
|
|
return -1;
|
|
}
|
|
|
|
/* For most file systems, fchmod does not operate on O_PATH
|
|
descriptors, so go through /proc. */
|
|
char buf[32];
|
|
if (__snprintf (buf, sizeof (buf), "/proc/self/fd/%d", pathfd) < 0)
|
|
{
|
|
/* This also may report strange error codes to the caller
|
|
(although snprintf really should not fail). */
|
|
__close_nocancel (pathfd);
|
|
return -1;
|
|
}
|
|
|
|
int ret = __chmod (buf, mode);
|
|
if (ret != 0)
|
|
{
|
|
if (errno == ENOENT)
|
|
/* /proc has not been mounted. Without /proc, there is no
|
|
way to upgrade the O_PATH descriptor to a full
|
|
descriptor. It is also not possible to re-open the
|
|
file without O_PATH because the file name may refer to
|
|
another file, and opening that without O_PATH may have
|
|
side effects (such as blocking, device rewinding, or
|
|
releasing POSIX locks). */
|
|
__set_errno (EOPNOTSUPP);
|
|
}
|
|
__close_nocancel (pathfd);
|
|
return ret;
|
|
}
|
|
}
|
|
libc_hidden_def (fchmodat)
|