1 /* $NetBSD: flockfile.c,v 1.4 2003/02/01 03:25:00 nathanw Exp $ */ 2 3 /*- 4 * Copyright (c) 2002 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Nathan J. Williams. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 #if defined(LIBC_SCCS) && !defined(lint) 41 __RCSID("$NetBSD: flockfile.c,v 1.4 2003/02/01 03:25:00 nathanw Exp $"); 42 #endif /* LIBC_SCCS and not lint */ 43 44 #include "namespace.h" 45 46 #include <assert.h> 47 #include <errno.h> 48 #include <stdio.h> 49 #include <string.h> 50 #include "reentrant.h" 51 #include "local.h" 52 53 #ifdef __weak_alias 54 __weak_alias(flockfile,_flockfile) 55 __weak_alias(ftrylockfile,_ftrylockfile) 56 __weak_alias(funlockfile,_funlockfile) 57 #endif 58 59 #ifdef _REENTRANT 60 /* 61 * XXX This code makes the assumption that a thr_t (pthread_t) is a 62 * XXX pointer. 63 */ 64 65 extern int __isthreaded; 66 67 void 68 flockfile(FILE *fp) 69 { 70 71 if (__isthreaded == 0) 72 return; 73 74 mutex_lock(&_LOCK(fp)); 75 76 if (_LOCKOWNER(fp) == thr_self()) { 77 _LOCKCOUNT(fp)++; 78 } else { 79 while (_LOCKOWNER(fp) != NULL) 80 cond_wait(&_LOCKCOND(fp), &_LOCK(fp)); 81 _LOCKOWNER(fp) = thr_self(); 82 _LOCKCOUNT(fp) = 1; 83 } 84 85 mutex_unlock(&_LOCK(fp)); 86 } 87 88 int 89 ftrylockfile(FILE *fp) 90 { 91 int retval; 92 93 if (__isthreaded == 0) 94 return 0; 95 96 retval = 0; 97 mutex_lock(&_LOCK(fp)); 98 99 if (_LOCKOWNER(fp) == thr_self()) { 100 _LOCKCOUNT(fp)++; 101 } else if (_LOCKOWNER(fp) == NULL) { 102 _LOCKOWNER(fp) = thr_self(); 103 _LOCKCOUNT(fp) = 1; 104 } else 105 retval = -1; 106 107 mutex_unlock(&_LOCK(fp)); 108 109 return retval; 110 } 111 112 void 113 funlockfile(FILE *fp) 114 { 115 116 if (__isthreaded == 0) 117 return; 118 119 mutex_lock(&_LOCK(fp)); 120 121 _LOCKCOUNT(fp)--; 122 if (_LOCKCOUNT(fp) == 0) { 123 _LOCKOWNER(fp) = NULL; 124 cond_signal(&_LOCKCOND(fp)); 125 } 126 127 mutex_unlock(&_LOCK(fp)); 128 } 129 130 #else /* _REENTRANT */ 131 132 void 133 flockfile(FILE *fp) 134 { 135 /* LINTED deliberate lack of effect */ 136 (void)fp; 137 138 return; 139 } 140 141 int 142 ftrylockfile(FILE *fp) 143 { 144 /* LINTED deliberate lack of effect */ 145 (void)fp; 146 147 return (0); 148 } 149 150 void 151 funlockfile(FILE *fp) 152 { 153 /* LINTED deliberate lack of effect */ 154 (void)fp; 155 156 return; 157 } 158 159 #endif /* _REENTRANT */ 160