6d30f1a3db
recursive locks (Duh). Disable cancellation around the cond_wait() call, since that's also a cancellation point. Arguably, that would be better handled with pthread_cleanup_*(), but stubbing those for libc is difficult, and the current non-exception-based implementation of cleanup handlers is probably no faster than disabling and reenabling cancellation. Finally, it only happens in the slow path where the thread is going to sleep anyway...
193 lines
4.4 KiB
C
193 lines
4.4 KiB
C
/* $NetBSD: flockfile.c,v 1.8 2003/07/22 00:56:25 nathanw Exp $ */
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/*-
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* Copyright (c) 2002 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Nathan J. Williams.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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__RCSID("$NetBSD: flockfile.c,v 1.8 2003/07/22 00:56:25 nathanw Exp $");
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#endif /* LIBC_SCCS and not lint */
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#include "namespace.h"
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#include <assert.h>
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#include <errno.h>
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#include <stdio.h>
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#include <string.h>
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#include "reentrant.h"
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#include "local.h"
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#ifdef __weak_alias
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__weak_alias(flockfile,_flockfile)
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__weak_alias(ftrylockfile,_ftrylockfile)
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__weak_alias(funlockfile,_funlockfile)
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#endif
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#ifdef _REENTRANT
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/*
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* XXX This code makes the assumption that a thr_t (pthread_t) is a
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* XXX pointer.
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*/
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extern int __isthreaded;
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void
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flockfile(FILE *fp)
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{
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__flockfile_internal(fp, 0);
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}
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int
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ftrylockfile(FILE *fp)
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{
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int retval;
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if (__isthreaded == 0)
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return 0;
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retval = 0;
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mutex_lock(&_LOCK(fp));
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if (_LOCKOWNER(fp) == thr_self()) {
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_LOCKCOUNT(fp)++;
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} else if (_LOCKOWNER(fp) == NULL) {
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_LOCKOWNER(fp) = thr_self();
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_LOCKCOUNT(fp) = 1;
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} else
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retval = -1;
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mutex_unlock(&_LOCK(fp));
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return retval;
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}
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void
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funlockfile(FILE *fp)
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{
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__funlockfile_internal(fp, 0);
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}
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void
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__flockfile_internal(FILE *fp, int internal)
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{
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if (__isthreaded == 0)
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return;
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mutex_lock(&_LOCK(fp));
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if (_LOCKOWNER(fp) == thr_self()) {
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_LOCKCOUNT(fp)++;
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if (internal)
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_LOCKINTERNAL(fp)++;
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} else {
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/* danger! cond_wait() is a cancellation point. */
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int oldstate;
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thr_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
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while (_LOCKOWNER(fp) != NULL)
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cond_wait(&_LOCKCOND(fp), &_LOCK(fp));
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thr_setcancelstate(oldstate, NULL);
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_LOCKOWNER(fp) = thr_self();
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_LOCKCOUNT(fp) = 1;
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if (internal)
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_LOCKINTERNAL(fp) = 1;
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}
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if (_LOCKINTERNAL(fp) == 1)
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/* stash cancellation state and disable */
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thr_setcancelstate(PTHREAD_CANCEL_DISABLE,
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&_LOCKCANCELSTATE(fp));
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mutex_unlock(&_LOCK(fp));
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}
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void
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__funlockfile_internal(FILE *fp, int internal)
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{
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if (__isthreaded == 0)
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return;
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mutex_lock(&_LOCK(fp));
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if (internal) {
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_LOCKINTERNAL(fp)--;
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if (_LOCKINTERNAL(fp) == 0)
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thr_setcancelstate(_LOCKCANCELSTATE(fp), NULL);
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}
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_LOCKCOUNT(fp)--;
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if (_LOCKCOUNT(fp) == 0) {
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_LOCKOWNER(fp) = NULL;
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cond_signal(&_LOCKCOND(fp));
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}
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mutex_unlock(&_LOCK(fp));
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}
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#else /* _REENTRANT */
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void
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flockfile(FILE *fp)
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{
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/* LINTED deliberate lack of effect */
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(void)fp;
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return;
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}
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int
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ftrylockfile(FILE *fp)
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{
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/* LINTED deliberate lack of effect */
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(void)fp;
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return (0);
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}
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void
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funlockfile(FILE *fp)
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{
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/* LINTED deliberate lack of effect */
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(void)fp;
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return;
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}
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#endif /* _REENTRANT */
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