2 * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
13 * 3. Neither the name of the author nor the names of any co-contributors
14 * may be used to endorse or promote products derived from this software
15 * without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * POSIX stdio FILE locking functions. These assume that the locking
32 * is only required at FILE structure level, not at file descriptor
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD$");
40 #include "namespace.h"
45 #include "un-namespace.h"
51 * Weak symbols for externally visible functions in this file:
53 __weak_reference(_flockfile, flockfile);
54 __weak_reference(_flockfile_debug_stub, _flockfile_debug);
55 __weak_reference(_ftrylockfile, ftrylockfile);
56 __weak_reference(_funlockfile, funlockfile);
59 * We need to retain binary compatibility for a while. So pretend
60 * that _lock is part of FILE * even though it is dereferenced off
61 * _extra now. When we stop encoding the size of FILE into binaries
62 * this can be changed in stdio.h. This will reduce the amount of
63 * code that has to change in the future (just remove this comment
71 pthread_t curthread = _pthread_self();
73 if (fp->_lock->fl_owner == curthread)
74 fp->_lock->fl_count++;
77 * Make sure this mutex is treated as a private
80 _pthread_mutex_lock(&fp->_lock->fl_mutex);
81 fp->_lock->fl_owner = curthread;
82 fp->_lock->fl_count = 1;
87 * This can be overriden by the threads library if it is linked in.
90 _flockfile_debug_stub(FILE *fp, char *fname, int lineno)
96 _ftrylockfile(FILE *fp)
98 pthread_t curthread = _pthread_self();
101 if (fp->_lock->fl_owner == curthread)
102 fp->_lock->fl_count++;
104 * Make sure this mutex is treated as a private
107 else if (_pthread_mutex_trylock(&fp->_lock->fl_mutex) == 0) {
108 fp->_lock->fl_owner = curthread;
109 fp->_lock->fl_count = 1;
117 _funlockfile(FILE *fp)
119 pthread_t curthread = _pthread_self();
122 * Check if this file is owned by the current thread:
124 if (fp->_lock->fl_owner == curthread) {
126 * Check if this thread has locked the FILE
129 if (fp->_lock->fl_count > 1)
131 * Decrement the count of the number of
132 * times the running thread has locked this
135 fp->_lock->fl_count--;
138 * The running thread will release the
141 fp->_lock->fl_count = 0;
142 fp->_lock->fl_owner = NULL;
143 _pthread_mutex_unlock(&fp->_lock->fl_mutex);