StdLib/LibC/Stdio/flockfile.c

   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 #include  <LibConfig.h>
  39 #include <sys/EfiCdefs.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 */