1 | /* Copyright (C) 1994-2019 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 | #ifndef __OFF_T_MATCHES_OFF64_T |
19 | |
20 | #include <unistd.h> |
21 | #include <fcntl.h> |
22 | #include <errno.h> |
23 | |
24 | /* lockf is a simplified interface to fcntl's locking facilities. */ |
25 | int |
26 | lockf (int fd, int cmd, off_t len) |
27 | { |
28 | /* lockf is always relative to the current file position. */ |
29 | struct flock fl = { |
30 | .l_type = F_WRLCK, |
31 | .l_whence = SEEK_CUR, |
32 | .l_len = len |
33 | }; |
34 | |
35 | /* lockf() is a cancellation point but so is fcntl() if F_SETLKW is |
36 | used. Therefore we don't have to care about cancellation here, |
37 | the fcntl() function will take care of it. */ |
38 | switch (cmd) |
39 | { |
40 | case F_TEST: |
41 | /* Test the lock: return 0 if FD is unlocked or locked by this process; |
42 | return -1, set errno to EACCES, if another process holds the lock. */ |
43 | fl.l_type = F_RDLCK; |
44 | if (__fcntl (fd, F_GETLK, &fl) < 0) |
45 | return -1; |
46 | if (fl.l_type == F_UNLCK || fl.l_pid == __getpid ()) |
47 | return 0; |
48 | __set_errno (EACCES); |
49 | return -1; |
50 | case F_ULOCK: |
51 | fl.l_type = F_UNLCK; |
52 | return __fcntl (fd, F_SETLK, &fl); |
53 | case F_LOCK: |
54 | return __fcntl (fd, F_SETLKW, &fl); |
55 | case F_TLOCK: |
56 | return __fcntl (fd, F_SETLK, &fl); |
57 | } |
58 | __set_errno (EINVAL); |
59 | return -1; |
60 | } |
61 | #endif |
62 | |