lib/libpthread/pthreads/file.c

/* ==== file.c ============================================================
 * Copyright (c) 1993 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 : All the new stdio functions.
 *
 *  1.00 93/09/04 proven
 *      -Started coding this file.
 */

#include "pthread.h"
#include <stdio.h> /* Remove this when the stdio library is done. */

/* ==========================================================================
 * 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) {
                fd_basic_lock(fd, FD_RDWR, lock);
        }
        fd_table[fd]->lockcount++;
        SEMAPHORE_RESET(lock);
}

/* ==========================================================================
 * 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);
}