1 /* $NetBSD: flockfile.c,v 1.9 2008/04/28 20:23:00 martin 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 #include <sys/cdefs.h> 33 #if defined(LIBC_SCCS) && !defined(lint) 34 __RCSID("$NetBSD: flockfile.c,v 1.9 2008/04/28 20:23:00 martin Exp $"); 35 #endif /* LIBC_SCCS and not lint */ 36 37 #include "namespace.h" 38 39 #include <assert.h> 40 #include <errno.h> 41 #include <stdio.h> 42 #include <string.h> 43 #include "reentrant.h" 44 #include "local.h" 45 46 #ifdef __weak_alias 47 __weak_alias(flockfile,_flockfile) 48 __weak_alias(ftrylockfile,_ftrylockfile) 49 __weak_alias(funlockfile,_funlockfile) 50 #endif 51 52 #ifdef _REENTRANT 53 /* 54 * XXX This code makes the assumption that a thr_t (pthread_t) is a 55 * XXX pointer. 56 */ 57 58 extern int __isthreaded; 59 60 void 61 flockfile(FILE *fp) 62 { 63 64 __flockfile_internal(fp, 0); 65 } 66 67 int 68 ftrylockfile(FILE *fp) 69 { 70 int retval; 71 72 if (__isthreaded == 0) 73 return 0; 74 75 retval = 0; 76 mutex_lock(&_LOCK(fp)); 77 78 if (_LOCKOWNER(fp) == thr_self()) { 79 _LOCKCOUNT(fp)++; 80 } else if (_LOCKOWNER(fp) == NULL) { 81 _LOCKOWNER(fp) = thr_self(); 82 _LOCKCOUNT(fp) = 1; 83 } else 84 retval = -1; 85 86 mutex_unlock(&_LOCK(fp)); 87 88 return retval; 89 } 90 91 void 92 funlockfile(FILE *fp) 93 { 94 95 __funlockfile_internal(fp, 0); 96 } 97 98 void 99 __flockfile_internal(FILE *fp, int internal) 100 { 101 102 if (__isthreaded == 0) 103 return; 104 105 mutex_lock(&_LOCK(fp)); 106 107 if (_LOCKOWNER(fp) == thr_self()) { 108 _LOCKCOUNT(fp)++; 109 if (internal) 110 _LOCKINTERNAL(fp)++; 111 } else { 112 /* danger! cond_wait() is a cancellation point. */ 113 int oldstate; 114 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); 115 while (_LOCKOWNER(fp) != NULL) 116 cond_wait(&_LOCKCOND(fp), &_LOCK(fp)); 117 thr_setcancelstate(oldstate, NULL); 118 _LOCKOWNER(fp) = thr_self(); 119 _LOCKCOUNT(fp) = 1; 120 if (internal) 121 _LOCKINTERNAL(fp) = 1; 122 } 123 124 if (_LOCKINTERNAL(fp) == 1) 125 /* stash cancellation state and disable */ 126 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, 127 &_LOCKCANCELSTATE(fp)); 128 129 mutex_unlock(&_LOCK(fp)); 130 } 131 132 void 133 __funlockfile_internal(FILE *fp, int internal) 134 { 135 136 if (__isthreaded == 0) 137 return; 138 139 mutex_lock(&_LOCK(fp)); 140 141 if (internal) { 142 _LOCKINTERNAL(fp)--; 143 if (_LOCKINTERNAL(fp) == 0) 144 thr_setcancelstate(_LOCKCANCELSTATE(fp), NULL); 145 } 146 147 _LOCKCOUNT(fp)--; 148 if (_LOCKCOUNT(fp) == 0) { 149 _LOCKOWNER(fp) = NULL; 150 cond_signal(&_LOCKCOND(fp)); 151 } 152 153 mutex_unlock(&_LOCK(fp)); 154 } 155 156 #else /* _REENTRANT */ 157 158 void 159 flockfile(FILE *fp) 160 { 161 /* LINTED deliberate lack of effect */ 162 (void)fp; 163 164 return; 165 } 166 167 int 168 ftrylockfile(FILE *fp) 169 { 170 /* LINTED deliberate lack of effect */ 171 (void)fp; 172 173 return (0); 174 } 175 176 void 177 funlockfile(FILE *fp) 178 { 179 /* LINTED deliberate lack of effect */ 180 (void)fp; 181 182 return; 183 } 184 185 #endif /* _REENTRANT */ 186