1 /* 2 * Copyright (C) 2015 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <fcntl.h> 30 #include <sys/stat.h> 31 #include <sys/types.h> 32 #include <errno.h> 33 #include <unistd.h> 34 35 #include "private/ErrnoRestorer.h" 36 37 extern "C" int ___fchmodat(int, const char*, mode_t); 38 39 int fchmodat(int dirfd, const char* pathname, mode_t mode, int flags) { 40 if ((flags & ~AT_SYMLINK_NOFOLLOW) != 0) { 41 errno = EINVAL; 42 return -1; 43 } 44 45 if (flags & AT_SYMLINK_NOFOLLOW) { 46 // Emulate AT_SYMLINK_NOFOLLOW using the mechanism described 47 // at https://sourceware.org/bugzilla/show_bug.cgi?id=14578 48 // comment #10 49 50 int fd = openat(dirfd, pathname, O_PATH | O_NOFOLLOW | O_CLOEXEC); 51 if (fd == -1) { 52 return -1; // returns errno from openat 53 } 54 55 // POSIX requires that ENOTSUP be returned when the system 56 // doesn't support setting the mode of a symbolic link. 57 // This is true for all Linux kernels. 58 // We rely on the O_PATH compatibility layer added in the 59 // fchmod() function to get errno correct. 60 int result = fchmod(fd, mode); 61 ErrnoRestorer errno_restorer; // don't let close() clobber errno 62 close(fd); 63 return result; 64 } 65 66 return ___fchmodat(dirfd, pathname, mode); 67 } 68
