| xf.li | bdd93d5 | 2023-05-12 07:10:14 -0700 | [diff] [blame] | 1 | /* Copyright (C) 1992-2016 Free Software Foundation, Inc. |
| 2 | This file is part of the GNU C Library. |
| 3 | |
| 4 | The GNU C Library is free software; you can redistribute it and/or |
| 5 | modify it under the terms of the GNU Lesser General Public |
| 6 | License as published by the Free Software Foundation; either |
| 7 | version 2.1 of the License, or (at your option) any later version. |
| 8 | |
| 9 | The GNU C Library is distributed in the hope that it will be useful, |
| 10 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | Lesser General Public License for more details. |
| 13 | |
| 14 | You should have received a copy of the GNU Lesser General Public |
| 15 | License along with the GNU C Library; if not, see |
| 16 | <http://www.gnu.org/licenses/>. */ |
| 17 | |
| 18 | /* This file implements the `flock' function in terms of the POSIX.1 `fcntl' |
| 19 | locking mechanism. In 4BSD, these are two incompatible locking mechanisms, |
| 20 | perhaps with different semantics? */ |
| 21 | |
| 22 | #include <errno.h> |
| 23 | #include <unistd.h> |
| 24 | #include <fcntl.h> |
| 25 | #include <sys/file.h> |
| 26 | |
| 27 | /* Apply or remove an advisory lock, according to OPERATION, |
| 28 | on the file FD refers to. */ |
| 29 | int |
| 30 | __flock (int fd, int operation) |
| 31 | { |
| 32 | struct flock lbuf; |
| 33 | |
| 34 | switch (operation & ~LOCK_NB) |
| 35 | { |
| 36 | case LOCK_SH: |
| 37 | lbuf.l_type = F_RDLCK; |
| 38 | break; |
| 39 | case LOCK_EX: |
| 40 | lbuf.l_type = F_WRLCK; |
| 41 | break; |
| 42 | case LOCK_UN: |
| 43 | lbuf.l_type = F_UNLCK; |
| 44 | break; |
| 45 | default: |
| 46 | __set_errno (EINVAL); |
| 47 | return -1; |
| 48 | } |
| 49 | |
| 50 | lbuf.l_whence = SEEK_SET; |
| 51 | lbuf.l_start = lbuf.l_len = 0L; /* Lock the whole file. */ |
| 52 | |
| 53 | return __fcntl (fd, (operation & LOCK_NB) ? F_SETLK : F_SETLKW, &lbuf); |
| 54 | } |
| 55 | |
| 56 | weak_alias (__flock, flock) |