00490ae3f3
In https://android-review.googlesource.com/#/c/127908/5/libc/SYSCALLS.TXT@116 Elliott said: for LP64 these will be hidden. for LP32 we were cowards and left them all public for compatibility (though i don't think we ever dremeled to see whether it was needed). we don't have an easy way to recognize additions, though, so we can't prevent adding new turds. Add a mechanism to prevent the adding of new turds, and use that mechanism on the fchmod/fchmodat system calls. Bug: 19233951 Change-Id: I98f98345970b631a379f348df57858f9fc3d57c0
67 lines
2.5 KiB
C++
67 lines
2.5 KiB
C++
/*
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* Copyright (C) 2015 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <fcntl.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#include <errno.h>
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#include <unistd.h>
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#include "private/ErrnoRestorer.h"
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extern "C" int ___fchmodat(int, const char*, mode_t);
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int fchmodat(int dirfd, const char* pathname, mode_t mode, int flags) {
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if ((flags & ~AT_SYMLINK_NOFOLLOW) != 0) {
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errno = EINVAL;
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return -1;
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}
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if (flags & AT_SYMLINK_NOFOLLOW) {
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// Emulate AT_SYMLINK_NOFOLLOW using the mechanism described
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// at https://sourceware.org/bugzilla/show_bug.cgi?id=14578
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// comment #10
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int fd = openat(dirfd, pathname, O_PATH | O_NOFOLLOW | O_CLOEXEC);
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if (fd == -1) {
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return -1; // returns errno from openat
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}
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// POSIX requires that ENOTSUP be returned when the system
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// doesn't support setting the mode of a symbolic link.
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// This is true for all Linux kernels.
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// We rely on the O_PATH compatibility layer added in the
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// fchmod() function to get errno correct.
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int result = fchmod(fd, mode);
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ErrnoRestorer errno_restorer; // don't let close() clobber errno
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close(fd);
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return result;
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}
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return ___fchmodat(dirfd, pathname, mode);
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}
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