1 /* $NetBSD: flockfile.c,v 1.10 2010/12/08 02:07:03 joerg 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 1.10 2010/12/08 02:07:03 joerg 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 void 59 flockfile(FILE *fp) 60 { 61 62 __flockfile_internal(fp, 0); 63 } 64 65 int 66 ftrylockfile(FILE *fp) 67 { 68 int retval; 69 70 if (__isthreaded == 0) 71 return 0; 72 73 retval = 0; 74 mutex_lock(&_LOCK(fp)); 75 76 if (_LOCKOWNER(fp) == thr_self()) { 77 _LOCKCOUNT(fp)++; 78 } else if (_LOCKOWNER(fp) == NULL) { 79 _LOCKOWNER(fp) = thr_self(); 80 _LOCKCOUNT(fp) = 1; 81 } else 82 retval = -1; 83 84 mutex_unlock(&_LOCK(fp)); 85 86 return retval; 87 } 88 89 void 90 funlockfile(FILE *fp) 91 { 92 93 __funlockfile_internal(fp, 0); 94 } 95 96 void 97 __flockfile_internal(FILE *fp, int internal) 98 { 99 100 if (__isthreaded == 0) 101 return; 102 103 mutex_lock(&_LOCK(fp)); 104 105 if (_LOCKOWNER(fp) == thr_self()) { 106 _LOCKCOUNT(fp)++; 107 if (internal) 108 _LOCKINTERNAL(fp)++; 109 } else { 110 /* danger! cond_wait() is a cancellation point. */ 111 int oldstate; 112 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate); 113 while (_LOCKOWNER(fp) != NULL) 114 cond_wait(&_LOCKCOND(fp), &_LOCK(fp)); 115 thr_setcancelstate(oldstate, NULL); 116 _LOCKOWNER(fp) = thr_self(); 117 _LOCKCOUNT(fp) = 1; 118 if (internal) 119 _LOCKINTERNAL(fp) = 1; 120 } 121 122 if (_LOCKINTERNAL(fp) == 1) 123 /* stash cancellation state and disable */ 124 thr_setcancelstate(PTHREAD_CANCEL_DISABLE, 125 &_LOCKCANCELSTATE(fp)); 126 127 mutex_unlock(&_LOCK(fp)); 128 } 129 130 void 131 __funlockfile_internal(FILE *fp, int internal) 132 { 133 134 if (__isthreaded == 0) 135 return; 136 137 mutex_lock(&_LOCK(fp)); 138 139 if (internal) { 140 _LOCKINTERNAL(fp)--; 141 if (_LOCKINTERNAL(fp) == 0) 142 thr_setcancelstate(_LOCKCANCELSTATE(fp), NULL); 143 } 144 145 _LOCKCOUNT(fp)--; 146 if (_LOCKCOUNT(fp) == 0) { 147 _LOCKOWNER(fp) = NULL; 148 cond_signal(&_LOCKCOND(fp)); 149 } 150 151 mutex_unlock(&_LOCK(fp)); 152 } 153 154 #else /* _REENTRANT */ 155 156 void 157 flockfile(FILE *fp) 158 { 159 /* LINTED deliberate lack of effect */ 160 (void)fp; 161 162 return; 163 } 164 165 int 166 ftrylockfile(FILE *fp) 167 { 168 /* LINTED deliberate lack of effect */ 169 (void)fp; 170 171 return (0); 172 } 173 174 void 175 funlockfile(FILE *fp) 176 { 177 /* LINTED deliberate lack of effect */ 178 (void)fp; 179 180 return; 181 } 182 183 #endif /* _REENTRANT */ 184