1 /*
2 * Copyright (C) 2008 The Android Open Source Project
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * * Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * * Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in
12 * the documentation and/or other materials provided with the
13 * distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 /* implement flockfile(), ftrylockfile() and funlockfile()
30 *
31 * we can't use the OpenBSD implementation which uses kernel-specific
32 * APIs not available on Linux.
33 *
34 * Instead, we use a pthread_mutex_t within the FILE* internal state.
35 * See fileext.h for details.
36 *
37 * the behaviour, if fclose() is called while the corresponding
38 * file is locked is totally undefined.
39 */
40 #include <stdio.h>
41 #include <string.h>
42 #include <errno.h>
43 #include "fileext.h"
44
45
46 void
flockfile(FILE * fp)47 flockfile(FILE * fp)
48 {
49 if (fp != NULL) {
50 _FLOCK_LOCK(fp);
51 }
52 }
53
54
55 int
ftrylockfile(FILE * fp)56 ftrylockfile(FILE *fp)
57 {
58 /* The specification for ftrylockfile() says it returns 0 on success,
59 * or non-zero on error. So return an errno code directly on error.
60 */
61 int ret = EINVAL;
62
63 if (fp != NULL) {
64 ret = _FLOCK_TRYLOCK(fp);
65 }
66 return ret;
67 }
68
69 void
funlockfile(FILE * fp)70 funlockfile(FILE * fp)
71 {
72 if (fp != NULL) {
73 _FLOCK_UNLOCK(fp);
74 }
75 }
76