/*
* 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.
*/
#pragma ident "%Z%%M% %I% %E% SMI"
/*
* 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);
}