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#include <errno.h>
30#include <stdio.h>
31
32#include "local.h"
33
34// We can't use the OpenBSD implementation which uses kernel-specific
35// APIs not available on Linux. Instead we use a pthread_mutex_t within
36// struct __sfileext (see fileext.h).
37
38void flockfile(FILE* fp) {
39  if (fp != nullptr) {
40    pthread_mutex_lock(&_FLOCK(fp));
41  }
42}
43
44int ftrylockfile(FILE* fp) {
45  // The specification for ftrylockfile() says it returns 0 on success,
46  // or non-zero on error. So return an errno code directly on error.
47  if (fp == nullptr) {
48    return EINVAL;
49  }
50
51  return pthread_mutex_trylock(&_FLOCK(fp));
52}
53
54void funlockfile(FILE* fp) {
55  if (fp != nullptr) {
56    pthread_mutex_unlock(&_FLOCK(fp));
57  }
58}
59