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150 lines
4.2 KiB
C
150 lines
4.2 KiB
C
/*
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* Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
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* All rights reserved.
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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 John Birrell.
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* 4. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* POSIX stdio FILE locking functions. These assume that the locking
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* is only required at FILE structure level, not at file descriptor
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* level too.
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*
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "namespace.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <pthread.h>
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#include "un-namespace.h"
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#include "local.h"
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/*
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* Weak symbols for externally visible functions in this file:
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*/
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__weak_reference(_flockfile, flockfile);
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__weak_reference(_flockfile_debug_stub, _flockfile_debug);
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__weak_reference(_ftrylockfile, ftrylockfile);
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__weak_reference(_funlockfile, funlockfile);
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/*
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* We need to retain binary compatibility for a while. So pretend
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* that _lock is part of FILE * even though it is dereferenced off
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* _extra now. When we stop encoding the size of FILE into binaries
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* this can be changed in stdio.h. This will reduce the amount of
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* code that has to change in the future (just remove this comment
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* and #define).
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*/
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#define _lock _extra
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void
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_flockfile(FILE *fp)
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{
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pthread_t curthread = _pthread_self();
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if (fp->_lock->fl_owner == curthread)
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fp->_lock->fl_count++;
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else {
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/*
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* Make sure this mutex is treated as a private
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* internal mutex:
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*/
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_pthread_mutex_lock(&fp->_lock->fl_mutex);
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fp->_lock->fl_owner = curthread;
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fp->_lock->fl_count = 1;
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}
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}
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/*
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* This can be overriden by the threads library if it is linked in.
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*/
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void
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_flockfile_debug_stub(FILE *fp, char *fname, int lineno)
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{
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_flockfile(fp);
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}
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int
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_ftrylockfile(FILE *fp)
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{
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pthread_t curthread = _pthread_self();
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int ret = 0;
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if (fp->_lock->fl_owner == curthread)
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fp->_lock->fl_count++;
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/*
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* Make sure this mutex is treated as a private
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* internal mutex:
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*/
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else if (_pthread_mutex_trylock(&fp->_lock->fl_mutex) == 0) {
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fp->_lock->fl_owner = curthread;
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fp->_lock->fl_count = 1;
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}
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else
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ret = -1;
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return (ret);
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}
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void
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_funlockfile(FILE *fp)
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{
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pthread_t curthread = _pthread_self();
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/*
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* Check if this file is owned by the current thread:
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*/
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if (fp->_lock->fl_owner == curthread) {
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/*
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* Check if this thread has locked the FILE
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* more than once:
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*/
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if (fp->_lock->fl_count > 1)
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/*
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* Decrement the count of the number of
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* times the running thread has locked this
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* file:
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*/
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fp->_lock->fl_count--;
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else {
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/*
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* The running thread will release the
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* lock now:
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*/
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fp->_lock->fl_count = 0;
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fp->_lock->fl_owner = NULL;
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_pthread_mutex_unlock(&fp->_lock->fl_mutex);
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}
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}
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}
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