platform_bionic/libc/bionic/fchmodat.cpp
Elliott Hughes 6cb70ad776 Add the ScopedFd that we've never quite gotten around to.
This is actually for the new change I'm working on, but let's retrofit
it first to separate any bugs in these changes from those in the new
change...

Test: treehugger
Change-Id: I890aeb61f9792810a77ad0da3f9674c9cc5db7bb
2019-10-31 21:16:18 -07:00

62 lines
2.3 KiB
C++

/*
* 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/ScopedFd.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
ScopedFd fd(openat(dirfd, pathname, O_PATH | O_NOFOLLOW | O_CLOEXEC));
if (fd.get() == -1) return -1;
// 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.
return fchmod(fd.get(), mode);
}
return __fchmodat(dirfd, pathname, mode);
}