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/*
* Copyright (C) 2015 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <errno.h>
#include <unistd.h>
#include "private/ErrnoRestorer.h"
extern "C" int ___fchmodat(int, const char*, mode_t);
int fchmodat(int dirfd, const char* pathname, mode_t mode, int flags) {
if ((flags & ~AT_SYMLINK_NOFOLLOW) != 0) {
errno = EINVAL;
return -1;
}
if (flags & AT_SYMLINK_NOFOLLOW) {
// Emulate AT_SYMLINK_NOFOLLOW using the mechanism described
// at https://sourceware.org/bugzilla/show_bug.cgi?id=14578
// comment #10
int fd = openat(dirfd, pathname, O_PATH | O_NOFOLLOW | O_CLOEXEC);
if (fd == -1) {
return -1; // returns errno from openat
}
// POSIX requires that ENOTSUP be returned when the system
// doesn't support setting the mode of a symbolic link.
// This is true for all Linux kernels.
// We rely on the O_PATH compatibility layer added in the
// fchmod() function to get errno correct.
int result = fchmod(fd, mode);
ErrnoRestorer errno_restorer; // don't let close() clobber errno
close(fd);
return result;
}
return ___fchmodat(dirfd, pathname, mode);
}
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