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/* ==== file.c ============================================================
* Copyright (c) 1993, 1994 by Chris Provenzano, proven@mit.edu
* 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 Chris Provenzano.
* 4. The name of Chris Provenzano may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``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 CHRIS PROVENZANO 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.
*
* Description : The locking functions for stdio.
*
* 1.00 93/09/04 proven
* -Started coding this file.
*/
#ifndef lint
static const char rcsid[] = "$Id: file.c,v 1.1 1995/10/18 08:43:05 deraadt Exp $ $provenid: file.c,v 1.16 1994/02/07 02:18:55 proven Exp $";
#endif
#include <pthread.h>
#include <stdio.h>
/* ==========================================================================
* flockfile()
*/
void flockfile(FILE *fp)
{
semaphore *lock;
int fd;
fd = fileno(fp);
lock = &(fd_table[fd]->lock);
while (SEMAPHORE_TEST_AND_SET(lock)) {
pthread_yield();
}
if (fd_table[fd]->r_owner != pthread_run) {
/* This might fail but POSIX doesn't give a damn. */
fd_basic_lock(fd, FD_RDWR, lock);
}
fd_table[fd]->lockcount++;
SEMAPHORE_RESET(lock);
}
/* ==========================================================================
* ftrylockfile()
*/
int ftrylockfile(FILE *fp)
{
semaphore *lock;
int fd;
fd = fileno(fp);
lock = &(fd_table[fd]->lock);
while (SEMAPHORE_TEST_AND_SET(lock)) {
pthread_yield();
}
if (fd_table[fd]->r_owner != pthread_run) {
if (!(fd_table[fd]->r_owner && fd_table[fd]->w_owner)) {
fd_basic_lock(fd, FD_RDWR, lock);
fd = OK;
} else {
fd = NOTOK;
}
} else {
fd_table[fd]->lockcount++;
fd = OK;
}
SEMAPHORE_RESET(lock);
return(fd);
}
/* ==========================================================================
* funlockfile()
*/
void funlockfile(FILE *fp)
{
semaphore *lock;
int fd;
fd = fileno(fp);
lock = &(fd_table[fd]->lock);
while (SEMAPHORE_TEST_AND_SET(lock)) {
pthread_yield();
}
if (fd_table[fd]->r_owner == pthread_run) {
if (--fd_table[fd]->lockcount == 0) {
fd_basic_unlock(fd, FD_RDWR);
}
}
SEMAPHORE_RESET(lock);
}
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