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 
flockfile(FILE * fp)38 void flockfile(FILE* fp) {
39   if (fp != nullptr) {
40     pthread_mutex_lock(&_FLOCK(fp));
41   }
42 }
43 
ftrylockfile(FILE * fp)44 int 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 
funlockfile(FILE * fp)54 void funlockfile(FILE* fp) {
55   if (fp != nullptr) {
56     pthread_mutex_unlock(&_FLOCK(fp));
57   }
58 }
59