| /* Test for access to file, relative to open directory. Linux version. |
| Copyright (C) 2006-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <stddef.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <unistd.h> |
| #include <sys/types.h> |
| #include <alloca.h> |
| #include <sysdep.h> |
| |
| |
| int |
| faccessat (int fd, const char *file, int mode, int flag) |
| { |
| if (flag & ~(AT_SYMLINK_NOFOLLOW | AT_EACCESS)) |
| return INLINE_SYSCALL_ERROR_RETURN_VALUE (EINVAL); |
| |
| if ((flag == 0 || ((flag & ~AT_EACCESS) == 0 && ! __libc_enable_secure))) |
| return INLINE_SYSCALL (faccessat, 3, fd, file, mode); |
| |
| struct stat64 stats; |
| if (__fxstatat64 (_STAT_VER, fd, file, &stats, flag & AT_SYMLINK_NOFOLLOW)) |
| return -1; |
| |
| mode &= (X_OK | W_OK | R_OK); /* Clear any bogus bits. */ |
| #if R_OK != S_IROTH || W_OK != S_IWOTH || X_OK != S_IXOTH |
| # error Oops, portability assumptions incorrect. |
| #endif |
| |
| if (mode == F_OK) |
| return 0; /* The file exists. */ |
| |
| uid_t uid = (flag & AT_EACCESS) ? __geteuid () : __getuid (); |
| |
| /* The super-user can read and write any file, and execute any file |
| that anyone can execute. */ |
| if (uid == 0 && ((mode & X_OK) == 0 |
| || (stats.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH)))) |
| return 0; |
| |
| int granted = (uid == stats.st_uid |
| ? (unsigned int) (stats.st_mode & (mode << 6)) >> 6 |
| : (stats.st_gid == ((flag & AT_EACCESS) |
| ? __getegid () : __getgid ()) |
| || __group_member (stats.st_gid)) |
| ? (unsigned int) (stats.st_mode & (mode << 3)) >> 3 |
| : (stats.st_mode & mode)); |
| |
| if (granted == mode) |
| return 0; |
| |
| return INLINE_SYSCALL_ERROR_RETURN_VALUE (EACCES); |
| } |