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b168057a | 1 | /* Copyright (C) 1994-2015 Free Software Foundation, Inc. |
c84142e8 | 2 | This file is part of the GNU C Library. |
28f540f4 | 3 | |
c84142e8 | 4 | The GNU C Library is free software; you can redistribute it and/or |
41bdb6e2 AJ |
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. | |
28f540f4 | 8 | |
c84142e8 UD |
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 | |
41bdb6e2 | 12 | Lesser General Public License for more details. |
28f540f4 | 13 | |
41bdb6e2 | 14 | You should have received a copy of the GNU Lesser General Public |
59ba27a6 PE |
15 | License along with the GNU C Library; if not, see |
16 | <http://www.gnu.org/licenses/>. */ | |
28f540f4 | 17 | |
03af9520 RM |
18 | /* We need to avoid the header declaration of lockf64, because |
19 | the types don't match lockf and then the compiler will | |
20 | complain about the mismatch when we do the alias below. */ | |
21 | #define lockf64 __renamed_lockf64 | |
22 | ||
23 | #include <fcntl.h> | |
24 | ||
25 | #undef lockf64 | |
26 | ||
28f540f4 RM |
27 | #include <sys/types.h> |
28 | #include <unistd.h> | |
28f540f4 | 29 | #include <errno.h> |
9c2322bc | 30 | #include <string.h> |
28f540f4 RM |
31 | |
32 | /* lockf is a simplified interface to fcntl's locking facilities. */ | |
33 | ||
34 | int | |
35 | lockf (int fd, int cmd, off_t len) | |
36 | { | |
37 | struct flock fl; | |
38 | ||
9c2322bc UD |
39 | memset ((char *) &fl, '\0', sizeof (fl)); |
40 | ||
bfce746a UD |
41 | /* lockf is always relative to the current file position. */ |
42 | fl.l_whence = SEEK_CUR; | |
43 | fl.l_start = 0; | |
44 | fl.l_len = len; | |
45 | ||
28f540f4 RM |
46 | switch (cmd) |
47 | { | |
48 | case F_TEST: | |
49 | /* Test the lock: return 0 if FD is unlocked or locked by this process; | |
50 | return -1, set errno to EACCES, if another process holds the lock. */ | |
9c3b1ceb | 51 | fl.l_type = F_RDLCK; |
50304ef0 | 52 | if (__fcntl (fd, F_GETLK, &fl) < 0) |
28f540f4 | 53 | return -1; |
50304ef0 | 54 | if (fl.l_type == F_UNLCK || fl.l_pid == __getpid ()) |
28f540f4 | 55 | return 0; |
c4029823 | 56 | __set_errno (EACCES); |
28f540f4 RM |
57 | return -1; |
58 | ||
59 | case F_ULOCK: | |
60 | fl.l_type = F_UNLCK; | |
61 | cmd = F_SETLK; | |
62 | break; | |
63 | case F_LOCK: | |
64 | fl.l_type = F_WRLCK; | |
65 | cmd = F_SETLKW; | |
66 | break; | |
67 | case F_TLOCK: | |
68 | fl.l_type = F_WRLCK; | |
69 | cmd = F_SETLK; | |
70 | break; | |
71 | ||
72 | default: | |
c4029823 | 73 | __set_errno (EINVAL); |
28f540f4 RM |
74 | return -1; |
75 | } | |
76 | ||
7a114794 UD |
77 | /* lockf() is a cancellation point but so is fcntl() if F_SETLKW is |
78 | used. Therefore we don't have to care about cancellation here, | |
79 | the fcntl() function will take care of it. */ | |
50304ef0 | 80 | return __fcntl (fd, cmd, &fl); |
28f540f4 | 81 | } |
03af9520 RM |
82 | |
83 | #ifdef __OFF_T_MATCHES_OFF64_T | |
84 | weak_alias (lockf, lockf64) | |
85 | #endif |