[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. 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 1.16 2008/04/17 22:17:53 jhb 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);

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

	if (fp->_fl_owner == curthread)
		fp->_fl_count++;
	else {
		/*
		 * Make sure this mutex is treated as a private
		 * internal mutex:
		 */
		_pthread_mutex_lock(&fp->_fl_mutex);
		fp->_fl_owner = curthread;
		fp->_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->_fl_owner == curthread)
		fp->_fl_count++;
	/*
	 * Make sure this mutex is treated as a private
	 * internal mutex:
	 */
	else if (_pthread_mutex_trylock(&fp->_fl_mutex) == 0) {
		fp->_fl_owner = curthread;
		fp->_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->_fl_owner == curthread) {
		/*
		 * Check if this thread has locked the FILE
		 * more than once:
		 */
		if (fp->_fl_count > 1)
			/*
			 * Decrement the count of the number of
			 * times the running thread has locked this
			 * file:
			 */
			fp->_fl_count--;
		else {
			/*
			 * The running thread will release the
			 * lock now:
			 */
			fp->_fl_count = 0;
			fp->_fl_owner = NULL;
			_pthread_mutex_unlock(&fp->_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.
1f2f436a	13	* 3. Neither the name of the author nor the names of any co-contributors
9385eb3d A	14	* may be used to endorse or promote products derived from this software
	15	* without specific prior written permission.
	16	*
	17	* THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``AS IS'' AND
	18	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	19	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	20	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	21	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	22	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	23	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	24	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	25	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	26	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	27	* SUCH DAMAGE.
	28	*/
	29
	30	/*
	31	* POSIX stdio FILE locking functions. These assume that the locking
	32	* is only required at FILE structure level, not at file descriptor
	33	* level too.
	34	*
	35	*/
	36
	37	#include <sys/cdefs.h>
1f2f436a	38	__FBSDID("$FreeBSD: src/lib/libc/stdio/_flock_stub.c,v 1.16 2008/04/17 22:17:53 jhb Exp $");
9385eb3d A	39
	40	#include "namespace.h"
	41	#include <stdio.h>
	42	#include <stdlib.h>
	43	#include <string.h>
	44	#include <pthread.h>
	45	#include "un-namespace.h"
	46
	47	#include "local.h"
	48
	49
	50	/*
	51	* Weak symbols for externally visible functions in this file:
	52	*/
	53	__weak_reference(_flockfile, flockfile);
	54	__weak_reference(_flockfile_debug_stub, _flockfile_debug);
	55	__weak_reference(_ftrylockfile, ftrylockfile);
	56	__weak_reference(_funlockfile, funlockfile);
	57
9385eb3d A	58	void
	59	_flockfile(FILE *fp)
	60	{
	61	pthread_t curthread = _pthread_self();
	62
1f2f436a A	63	if (fp->_fl_owner == curthread)
1f2f436a A	64	fp->_fl_count++;
9385eb3d A	65	else {
	66	/*
	67	* Make sure this mutex is treated as a private
	68	* internal mutex:
	69	*/
1f2f436a A	70	_pthread_mutex_lock(&fp->_fl_mutex);
	71	fp->_fl_owner = curthread;
	72	fp->_fl_count = 1;
9385eb3d A	73	}
	74	}
	75
	76	/*
	77	* This can be overriden by the threads library if it is linked in.
	78	*/
	79	void
	80	_flockfile_debug_stub(FILE fp, char fname, int lineno)
	81	{
	82	_flockfile(fp);
	83	}
	84
	85	int
	86	_ftrylockfile(FILE *fp)
	87	{
	88	pthread_t curthread = _pthread_self();
	89	int ret = 0;
	90
1f2f436a A	91	if (fp->_fl_owner == curthread)
1f2f436a A	92	fp->_fl_count++;
9385eb3d A	93	/*
	94	* Make sure this mutex is treated as a private
	95	* internal mutex:
	96	*/
1f2f436a A	97	else if (_pthread_mutex_trylock(&fp->_fl_mutex) == 0) {
	98	fp->_fl_owner = curthread;
	99	fp->_fl_count = 1;
9385eb3d A	100	}
	101	else
	102	ret = -1;
	103	return (ret);
	104	}
	105
	106	void
	107	_funlockfile(FILE *fp)
	108	{
	109	pthread_t curthread = _pthread_self();
	110
	111	/*
	112	* Check if this file is owned by the current thread:
	113	*/
1f2f436a	114	if (fp->_fl_owner == curthread) {
9385eb3d A	115	/*
	116	* Check if this thread has locked the FILE
	117	* more than once:
	118	*/
1f2f436a	119	if (fp->_fl_count > 1)
9385eb3d A	120	/*
	121	* Decrement the count of the number of
	122	* times the running thread has locked this
	123	* file:
	124	*/
1f2f436a	125	fp->_fl_count--;
9385eb3d A	126	else {
	127	/*
	128	* The running thread will release the
	129	* lock now:
	130	*/
1f2f436a A	131	fp->_fl_count = 0;
	132	fp->_fl_owner = NULL;
	133	_pthread_mutex_unlock(&fp->_fl_mutex);
9385eb3d A	134	}
	135	}
	136	}