1 /* $NetBSD: flockfile.c,v 1.8 2003/07/22 00:56:25 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 1.8 2003/07/22 00:56:25 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 __flockfile_internal(fp, 0); 72 } 73 74 int 75 ftrylockfile(FILE *fp) 76 { 77 int retval; 78 79 if (__isthreaded == 0) 80 return 0; 81 82 retval = 0; 83 mutex_lock(&_LOCK(fp)); 84 85 if (_LOCKOWNER(fp) == thr_self()) { 86 _LOCKCOUNT(fp)++; 87 } else if (_LOCKOWNER(fp) == NULL) { 88 _LOCKOWNER(fp) = thr_self(); 89 _LOCKCOUNT(fp) = 1; 90 } else 91 retval = -1; 92 93 mutex_unlock(&_LOCK(fp)); 94 95 return retval; 96 } 97 98 void 99 funlockfile(FILE *fp) 100 { 101 102 __funlockfile_internal(fp, 0); 103 } 104 105 void 106 __flockfile_internal(FILE *fp, int internal) 107 { 108 109 if (__isthreaded == 0) 110 return; 111 112 mutex_lock(&_LOCK(fp)); 113 114 if (_LOCKOWNER(fp) == thr_self()) { 115 _LOCKCOUNT(fp)++; 116 if (internal) 117 _LOCKINTERNAL(fp)++; 118 } else { 119 /* danger! cond_wait() is a cancellation point. */ 120 int oldstate; 121 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); 122 while (_LOCKOWNER(fp) != NULL) 123 cond_wait(&_LOCKCOND(fp), &_LOCK(fp)); 124 thr_setcancelstate(oldstate, NULL); 125 _LOCKOWNER(fp) = thr_self(); 126 _LOCKCOUNT(fp) = 1; 127 if (internal) 128 _LOCKINTERNAL(fp) = 1; 129 } 130 131 if (_LOCKINTERNAL(fp) == 1) 132 /* stash cancellation state and disable */ 133 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, 134 &_LOCKCANCELSTATE(fp)); 135 136 mutex_unlock(&_LOCK(fp)); 137 } 138 139 void 140 __funlockfile_internal(FILE *fp, int internal) 141 { 142 143 if (__isthreaded == 0) 144 return; 145 146 mutex_lock(&_LOCK(fp)); 147 148 if (internal) { 149 _LOCKINTERNAL(fp)--; 150 if (_LOCKINTERNAL(fp) == 0) 151 thr_setcancelstate(_LOCKCANCELSTATE(fp), NULL); 152 } 153 154 _LOCKCOUNT(fp)--; 155 if (_LOCKCOUNT(fp) == 0) { 156 _LOCKOWNER(fp) = NULL; 157 cond_signal(&_LOCKCOND(fp)); 158 } 159 160 mutex_unlock(&_LOCK(fp)); 161 } 162 163 #else /* _REENTRANT */ 164 165 void 166 flockfile(FILE *fp) 167 { 168 /* LINTED deliberate lack of effect */ 169 (void)fp; 170 171 return; 172 } 173 174 int 175 ftrylockfile(FILE *fp) 176 { 177 /* LINTED deliberate lack of effect */ 178 (void)fp; 179 180 return (0); 181 } 182 183 void 184 funlockfile(FILE *fp) 185 { 186 /* LINTED deliberate lack of effect */ 187 (void)fp; 188 189 return; 190 } 191 192 #endif /* _REENTRANT */ 193