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 1.10 2005/07/23 23:14:44 joerg 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 #include "priv_stdio.h" 44 45 void __flockfile(FILE *fp); 46 void __flockfile_debug(FILE *fp, char *fname, int lineno); 47 int __ftrylockfile(FILE *fp); 48 void __funlockfile(FILE *fp); 49 50 /* 51 * Externally visible weak symbols. 52 */ 53 __weak_reference(__flockfile, flockfile); 54 __weak_reference(__flockfile, _flockfile); 55 __weak_reference(__flockfile_debug, _flockfile_debug); 56 __weak_reference(__ftrylockfile, ftrylockfile); 57 __weak_reference(__ftrylockfile, _ftrylockfile); 58 __weak_reference(__funlockfile, funlockfile); 59 __weak_reference(__funlockfile, _funlockfile); 60 61 void 62 __flockfile(FILE *fp) 63 { 64 pthread_t curthread = _pthread_self(); 65 66 if (fp->fl_owner == curthread) 67 fp->fl_count++; 68 else { 69 /* 70 * Make sure this mutex is treated as a private 71 * internal mutex: 72 */ 73 _pthread_mutex_lock(&fp->fl_mutex); 74 fp->fl_owner = curthread; 75 fp->fl_count = 1; 76 } 77 } 78 79 void 80 __flockfile_debug(FILE *fp, char *fname __unused, int lineno __unused) 81 { 82 _flockfile(fp); 83 } 84 85 int 86 __ftrylockfile(FILE *fp) 87 { 88 pthread_t curthread = _pthread_self(); 89 int ret = 0; 90 91 if (fp->fl_owner == curthread) 92 fp->fl_count++; 93 /* 94 * Make sure this mutex is treated as a private 95 * internal mutex: 96 */ 97 else if (_pthread_mutex_trylock(&fp->fl_mutex) == 0) { 98 fp->fl_owner = curthread; 99 fp->fl_count = 1; 100 } 101 else 102 ret = -1; 103 return (ret); 104 } 105 106 void 107 __funlockfile(FILE *fp) 108 { 109 pthread_t curthread = _pthread_self(); 110 111 /* 112 * Check if this file is owned by the current thread: 113 */ 114 if (fp->fl_owner == curthread) { 115 /* 116 * Check if this thread has locked the FILE 117 * more than once: 118 */ 119 if (fp->fl_count > 1) 120 /* 121 * Decrement the count of the number of 122 * times the running thread has locked this 123 * file: 124 */ 125 fp->fl_count--; 126 else { 127 /* 128 * The running thread will release the 129 * lock now: 130 */ 131 fp->fl_count = 0; 132 fp->fl_owner = NULL; 133 _pthread_mutex_unlock(&fp->fl_mutex); 134 } 135 } 136 } 137