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 <unistd.h> 31 #include <errno.h> 32 33 extern "C" int ___faccessat(int, const char*, int); 34 35 int faccessat(int dirfd, const char* pathname, int mode, int flags) { 36 // "The mode specifies the accessibility check(s) to be performed, 37 // and is either the value F_OK, or a mask consisting of the 38 // bitwise OR of one or more of R_OK, W_OK, and X_OK." 39 if ((mode != F_OK) && ((mode & ~(R_OK | W_OK | X_OK)) != 0) && 40 ((mode & (R_OK | W_OK | X_OK)) == 0)) { 41 errno = EINVAL; 42 return -1; 43 } 44 45 if (flags != 0) { 46 // We deliberately don't support AT_SYMLINK_NOFOLLOW, a glibc 47 // only feature which is error prone and dangerous. 48 // More details at http://permalink.gmane.org/gmane.linux.lib.musl.general/6952 49 // 50 // AT_EACCESS isn't supported either. Android doesn't have setuid 51 // programs, and never runs code with euid!=uid. It could be 52 // implemented in an expensive way, following the model at 53 // https://gitlab.com/bminor/musl/commit/0a05eace163cee9b08571d2ff9d90f5e82d9c228 54 // but not worth it. 55 errno = EINVAL; 56 return -1; 57 } 58 59 return ___faccessat(dirfd, pathname, mode); 60 } 61
