/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2002 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*
 * xsem.c: to provide a semaphore system (used by the smq routines)
 *
 * these routines come from the libxposix library.
 */

#include <pthread.h>
#include <time.h>

#include "xsem.h"


int
xsem_init(xsem_t *sem, int pshared, unsigned int value)
{
        if (pshared != 0)
                return (-1);

        pthread_mutex_init(&sem->semMutex, NULL);
        pthread_cond_init(&sem->semCV, NULL);
        sem->semaphore = value;

        return (0);
}

void
xsem_destroy(xsem_t *sem)
{
        pthread_mutex_destroy(&sem->semMutex);
        pthread_cond_destroy(&sem->semCV);
        sem->semaphore = 0;
}

int
xsem_wait(xsem_t *sem)
{
        pthread_mutex_lock(&sem->semMutex);

        if (sem->semaphore < 0) {
                sem->semaphore = 0;
                pthread_mutex_unlock(&sem->semMutex);
                return (XSEM_ERROR);
        }

        if (sem->semaphore > 0) {
                sem->semaphore--;
        } else {
                while (sem->semaphore == 0)
                        pthread_cond_wait(&sem->semCV, &sem->semMutex);

                if (sem->semaphore != 0) {
                        sem->semaphore--;
                } else {
                        pthread_mutex_unlock(&sem->semMutex);
                        return (XSEM_ERROR);
                }
        }

        pthread_mutex_unlock(&sem->semMutex);
        return (0);
}


int
xsem_trywait(xsem_t *sem)
{
        pthread_mutex_lock(&sem->semMutex);

        if (sem->semaphore < 0) {
                sem->semaphore = 0;
                pthread_mutex_unlock(&sem->semMutex);
                return (XSEM_ERROR);
        }

        if (sem->semaphore == 0) {
                pthread_mutex_unlock(&sem->semMutex);
                return (XSEM_EBUSY);
        } else {
                sem->semaphore--;
        }

        pthread_mutex_unlock(&sem->semMutex);
        return (0);
}


int
xsem_post(xsem_t *sem)
{
        pthread_mutex_lock(&sem->semMutex);
        sem->semaphore++;
        pthread_cond_signal(&sem->semCV);
        pthread_mutex_unlock(&sem->semMutex);

        return (0);
}


void
xsem_getvalue(xsem_t *sem, int *sval)
{
        *sval = sem->semaphore;
}



int
xsem_xwait(xsem_t *sem, int timeout, timestruc_t *mytime)
{
        int             status;
        timestruc_t     delay;

        if (timeout == 0)
                return (xsem_wait(sem));
        else {
                pthread_mutex_lock(&sem->semMutex);

                if (sem->semaphore < 0) {
                        sem->semaphore = 0;
                        pthread_mutex_unlock(&sem->semMutex);
                        return (XSEM_ERROR);
                }

                if (sem->semaphore > 0) {
                        sem->semaphore--;
                } else {
                        status = 0;

                        delay  = *mytime;
                        delay.tv_sec = delay.tv_sec + time(NULL);
                        while ((sem->semaphore == 0) && (status == 0)) {
                                status = pthread_cond_timedwait(&sem->semCV,
                                    &sem->semMutex, &delay);
                        }

                        /*
                         * Check one more time in case thread didn't have a
                         * chance to check before timeout ??? TBD
                         */

                        if (status != 0) {
                                pthread_mutex_unlock(&sem->semMutex);
                                return (XSEM_ETIME);
                        } else if (sem->semaphore != 0) {
                                sem->semaphore--;
                        } else {
                                pthread_mutex_unlock(&sem->semMutex);
                                return (XSEM_ERROR);
                        }
                }

                pthread_mutex_unlock(&sem->semMutex);
        }

        return (0);
}