[apple/libc.git] / stdio / FreeBSD / _flock_stub.c

/*
 * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by John Birrell.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

/*
 * POSIX stdio FILE locking functions. These assume that the locking
 * is only required at FILE structure level, not at file descriptor
 * level too.
 *
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD: src/lib/libc/stdio/_flock_stub.c,v 1.14 2004/03/09 04:51:58 jb Exp $");

#include "namespace.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include "un-namespace.h"

#include "local.h"


/*
 * Weak symbols for externally visible functions in this file:
 */
__weak_reference(_flockfile, flockfile);
__weak_reference(_flockfile_debug_stub, _flockfile_debug);
__weak_reference(_ftrylockfile, ftrylockfile);
__weak_reference(_funlockfile, funlockfile);

/*
 * We need to retain binary compatibility for a while.  So pretend
 * that _lock is part of FILE * even though it is dereferenced off
 * _extra now.  When we stop encoding the size of FILE into binaries
 * this can be changed in stdio.h.  This will reduce the amount of
 * code that has to change in the future (just remove this comment
 * and #define).
 */
#define _lock _extra

void
_flockfile(FILE *fp)
{
	pthread_t curthread = _pthread_self();

	if (fp->_lock->fl_owner == curthread)
		fp->_lock->fl_count++;
	else {
		/*
		 * Make sure this mutex is treated as a private
		 * internal mutex:
		 */
		_pthread_mutex_lock(&fp->_lock->fl_mutex);
		fp->_lock->fl_owner = curthread;
		fp->_lock->fl_count = 1;
	}
}

/*
 * This can be overriden by the threads library if it is linked in.
 */
void
_flockfile_debug_stub(FILE *fp, char *fname, int lineno)
{
	_flockfile(fp);
}

int
_ftrylockfile(FILE *fp)
{
	pthread_t curthread = _pthread_self();
	int	ret = 0;

	if (fp->_lock->fl_owner == curthread)
		fp->_lock->fl_count++;
	/*
	 * Make sure this mutex is treated as a private
	 * internal mutex:
	 */
	else if (_pthread_mutex_trylock(&fp->_lock->fl_mutex) == 0) {
		fp->_lock->fl_owner = curthread;
		fp->_lock->fl_count = 1;
	}
	else
		ret = -1;
	return (ret);
}

void 
_funlockfile(FILE *fp)
{
	pthread_t	curthread = _pthread_self();

	/*
	 * Check if this file is owned by the current thread:
	 */
	if (fp->_lock->fl_owner == curthread) {
		/*
		 * Check if this thread has locked the FILE
		 * more than once:
		 */
		if (fp->_lock->fl_count > 1)
			/*
			 * Decrement the count of the number of
			 * times the running thread has locked this
			 * file:
			 */
			fp->_lock->fl_count--;
		else {
			/*
			 * The running thread will release the
			 * lock now:
			 */
			fp->_lock->fl_count = 0;
			fp->_lock->fl_owner = NULL;
			_pthread_mutex_unlock(&fp->_lock->fl_mutex);
		}
	}
}
Commit	Line	Data
9385eb3d A	1	/*
	2	* Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
	3	* All rights reserved.
	4	*
	5	* Redistribution and use in source and binary forms, with or without
	6	* modification, are permitted provided that the following conditions
	7	* are met:
	8	* 1. Redistributions of source code must retain the above copyright
	9	* notice, this list of conditions and the following disclaimer.
	10	* 2. Redistributions in binary form must reproduce the above copyright
	11	* notice, this list of conditions and the following disclaimer in the
	12	* documentation and/or other materials provided with the distribution.
	13	* 3. All advertising materials mentioning features or use of this software
	14	* must display the following acknowledgement:
	15	* This product includes software developed by John Birrell.
	16	* 4. Neither the name of the author nor the names of any co-contributors
	17	* may be used to endorse or promote products derived from this software
	18	* without specific prior written permission.
	19	*
	20	* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
	21	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	* SUCH DAMAGE.
	31	*/
	32
	33	/*
	34	* POSIX stdio FILE locking functions. These assume that the locking
	35	* is only required at FILE structure level, not at file descriptor
	36	* level too.
	37	*
	38	*/
	39
	40	#include <sys/cdefs.h>
3d9156a7	41	__FBSDID("$FreeBSD: src/lib/libc/stdio/_flock_stub.c,v 1.14 2004/03/09 04:51:58 jb Exp $");
9385eb3d A	42
	43	#include "namespace.h"
	44	#include <stdio.h>
	45	#include <stdlib.h>
	46	#include <string.h>
	47	#include <pthread.h>
	48	#include "un-namespace.h"
	49
	50	#include "local.h"
	51
	52
	53	/*
	54	* Weak symbols for externally visible functions in this file:
	55	*/
	56	__weak_reference(_flockfile, flockfile);
	57	__weak_reference(_flockfile_debug_stub, _flockfile_debug);
	58	__weak_reference(_ftrylockfile, ftrylockfile);
	59	__weak_reference(_funlockfile, funlockfile);
	60
	61	/*
	62	* We need to retain binary compatibility for a while. So pretend
	63	* that _lock is part of FILE * even though it is dereferenced off
	64	* _extra now. When we stop encoding the size of FILE into binaries
	65	* this can be changed in stdio.h. This will reduce the amount of
	66	* code that has to change in the future (just remove this comment
	67	* and #define).
	68	*/
	69	#define _lock _extra
	70
	71	void
	72	_flockfile(FILE *fp)
	73	{
	74	pthread_t curthread = _pthread_self();
	75
	76	if (fp->_lock->fl_owner == curthread)
	77	fp->_lock->fl_count++;
	78	else {
	79	/*
	80	* Make sure this mutex is treated as a private
	81	* internal mutex:
	82	*/
	83	_pthread_mutex_lock(&fp->_lock->fl_mutex);
	84	fp->_lock->fl_owner = curthread;
	85	fp->_lock->fl_count = 1;
	86	}
	87	}
	88
	89	/*
	90	* This can be overriden by the threads library if it is linked in.
	91	*/
	92	void
	93	_flockfile_debug_stub(FILE fp, char fname, int lineno)
	94	{
	95	_flockfile(fp);
	96	}
	97
	98	int
	99	_ftrylockfile(FILE *fp)
	100	{
	101	pthread_t curthread = _pthread_self();
	102	int ret = 0;
	103
	104	if (fp->_lock->fl_owner == curthread)
	105	fp->_lock->fl_count++;
106	/*
107	* Make sure this mutex is treated as a private
108	* internal mutex:
109	*/
110	else if (_pthread_mutex_trylock(&fp->_lock->fl_mutex) == 0) {
111	fp->_lock->fl_owner = curthread;
112	fp->_lock->fl_count = 1;
113	}
114	else
115	ret = -1;
116	return (ret);
117	}
118
119	void
120	_funlockfile(FILE *fp)
121	{
122	pthread_t curthread = _pthread_self();
123
124	/*
125	* Check if this file is owned by the current thread:
126	*/
127	if (fp->_lock->fl_owner == curthread) {
128	/*
129	* Check if this thread has locked the FILE
130	* more than once:
131	*/
132	if (fp->_lock->fl_count > 1)
133	/*
134	* Decrement the count of the number of
135	* times the running thread has locked this
136	* file:
137	*/
138	fp->_lock->fl_count--;
139	else {
140	/*
141	* The running thread will release the
142	* lock now:
143	*/
144	fp->_lock->fl_count = 0;
145	fp->_lock->fl_owner = NULL;
146	_pthread_mutex_unlock(&fp->_lock->fl_mutex);
147	}
148	}
149	}