1 /* 2 * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>. 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 * 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. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by John Birrell. 16 * 4. Neither the name of the author nor the names of any co-contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 * $FreeBSD: src/lib/libc/stdio/_flock_stub.c,v 1.3 1999/08/28 00:00:55 peter Exp $ 33 * $DragonFly: src/lib/libc/stdio/_flock_stub.c,v 1.8 2005/05/11 12:45:57 davidxu Exp $ 34 * 35 */ 36 37 #include "namespace.h" 38 #include <stdio.h> 39 #include <pthread.h> 40 #include "un-namespace.h" 41 42 #include "local.h" 43 44 void __flockfile(FILE *fp); 45 void __flockfile_debug(FILE *fp, char *fname, int lineno); 46 int __ftrylockfile(FILE *fp); 47 void __funlockfile(FILE *fp); 48 49 /* 50 * Externally visible weak symbols. 51 */ 52 __weak_reference(__flockfile, flockfile); 53 __weak_reference(__flockfile, _flockfile); 54 __weak_reference(__flockfile_debug, _flockfile_debug); 55 __weak_reference(__ftrylockfile, ftrylockfile); 56 __weak_reference(__ftrylockfile, _ftrylockfile); 57 __weak_reference(__funlockfile, funlockfile); 58 __weak_reference(__funlockfile, _funlockfile); 59 60 #define _lock _extra 61 62 void 63 __flockfile(FILE *fp) 64 { 65 pthread_t curthread = _pthread_self(); 66 67 if (fp->_lock->fl_owner == curthread) 68 fp->_lock->fl_count++; 69 else { 70 /* 71 * Make sure this mutex is treated as a private 72 * internal mutex: 73 */ 74 _pthread_mutex_lock(&fp->_lock->fl_mutex); 75 fp->_lock->fl_owner = curthread; 76 fp->_lock->fl_count = 1; 77 } 78 } 79 80 void 81 __flockfile_debug(FILE *fp, char *fname __unused, int lineno __unused) 82 { 83 _flockfile(fp); 84 } 85 86 int 87 __ftrylockfile(FILE *fp) 88 { 89 pthread_t curthread = _pthread_self(); 90 int ret = 0; 91 92 if (fp->_lock->fl_owner == curthread) 93 fp->_lock->fl_count++; 94 /* 95 * Make sure this mutex is treated as a private 96 * internal mutex: 97 */ 98 else if (_pthread_mutex_trylock(&fp->_lock->fl_mutex) == 0) { 99 fp->_lock->fl_owner = curthread; 100 fp->_lock->fl_count = 1; 101 } 102 else 103 ret = -1; 104 return (ret); 105 } 106 107 void 108 __funlockfile(FILE *fp) 109 { 110 pthread_t curthread = _pthread_self(); 111 112 /* 113 * Check if this file is owned by the current thread: 114 */ 115 if (fp->_lock->fl_owner == curthread) { 116 /* 117 * Check if this thread has locked the FILE 118 * more than once: 119 */ 120 if (fp->_lock->fl_count > 1) 121 /* 122 * Decrement the count of the number of 123 * times the running thread has locked this 124 * file: 125 */ 126 fp->_lock->fl_count--; 127 else { 128 /* 129 * The running thread will release the 130 * lock now: 131 */ 132 fp->_lock->fl_count = 0; 133 fp->_lock->fl_owner = NULL; 134 _pthread_mutex_unlock(&fp->_lock->fl_mutex); 135 } 136 } 137 } 138