1 /* Open a directory relative to another directory. 2 3 Copyright 2006-2020 Free Software Foundation, Inc. 4 5 This program is free software: you can redistribute it and/or modify 6 it under the terms of the GNU General Public License as published by 7 the Free Software Foundation; either version 3 of the License, or 8 (at your option) any later version. 9 10 This program is distributed in the hope that it will be useful, 11 but WITHOUT ANY WARRANTY; without even the implied warranty of 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 GNU General Public License for more details. 14 15 You should have received a copy of the GNU General Public License 16 along with this program. If not, see <https://www.gnu.org/licenses/>. 17 18 Written by Jim Meyering and Paul Eggert. */ 19 20 #include <config.h> 21 22 #include <opendirat.h> 23 24 #include <errno.h> 25 #include <fcntl--.h> 26 #include <unistd.h> 27 28 /* Relative to DIR_FD, open the directory DIR, passing EXTRA_FLAGS to 29 the underlying openat call. On success, store into *PNEW_FD the 30 underlying file descriptor of the newly opened directory and return 31 the directory stream. On failure, return NULL and set errno. 32 33 On success, *PNEW_FD is at least 3, so this is a "safer" function. */ 34 35 DIR * 36 opendirat (int dir_fd, char const *dir, int extra_flags, int *pnew_fd) 37 { 38 int open_flags = (O_RDONLY | O_CLOEXEC | O_DIRECTORY | O_NOCTTY 39 | O_NONBLOCK | extra_flags); 40 int new_fd = openat (dir_fd, dir, open_flags); 41 42 if (new_fd < 0) 43 return NULL; 44 DIR *dirp = fdopendir (new_fd); 45 if (dirp) 46 *pnew_fd = new_fd; 47 else 48 { 49 int fdopendir_errno = errno; 50 close (new_fd); 51 errno = fdopendir_errno; 52 } 53 return dirp; 54 } 55