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|
/* $OpenBSD: uthread_sem.c,v 1.3 2008/06/20 02:58:00 kurt Exp $ */
/*
* Copyright (C) 2000 Jason Evans <jasone@freebsd.org>.
* 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(s), this list of conditions and the following disclaimer as
* the first lines of this file unmodified other than the possible
* addition of one or more copyright notices.
* 2. Redistributions in binary form must reproduce the above copyright
* notice(s), this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``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 COPYRIGHT HOLDER(S) 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.
*
* $FreeBSD: uthread_sem.c,v 1.10 2001/05/18 00:36:05 jasone Exp $
*/
#include <stdlib.h>
#include <errno.h>
#include <semaphore.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"
#define _SEM_CHECK_VALIDITY(sem) \
if ((sem) == NULL || \
*(sem) == NULL || \
(*(sem))->magic != SEM_MAGIC) { \
errno = EINVAL; \
retval = -1; \
goto RETURN; \
}
int
sem_init(sem_t *sem, int pshared, unsigned int value)
{
int retval;
/*
* Range check the arguments.
*/
if (pshared != 0) {
/*
* The user wants a semaphore that can be shared among
* processes, which this implementation can't do. Sounds like a
* permissions problem to me (yeah right).
*/
errno = EPERM;
retval = -1;
goto RETURN;
}
if (value > SEM_VALUE_MAX) {
errno = EINVAL;
retval = -1;
goto RETURN;
}
*sem = (sem_t)malloc(sizeof(struct sem));
if (*sem == NULL) {
errno = ENOSPC;
retval = -1;
goto RETURN;
}
/*
* Initialize the semaphore.
*/
if (pthread_mutex_init(&(*sem)->lock, NULL) != 0) {
free(*sem);
errno = ENOSPC;
retval = -1;
goto RETURN;
}
if (pthread_cond_init(&(*sem)->gtzero, NULL) != 0) {
pthread_mutex_destroy(&(*sem)->lock);
free(*sem);
errno = ENOSPC;
retval = -1;
goto RETURN;
}
(*sem)->count = (u_int32_t)value;
(*sem)->nwaiters = 0;
(*sem)->magic = SEM_MAGIC;
retval = 0;
RETURN:
return retval;
}
int
sem_destroy(sem_t *sem)
{
int retval;
_SEM_CHECK_VALIDITY(sem);
/* Make sure there are no waiters. */
pthread_mutex_lock(&(*sem)->lock);
if ((*sem)->nwaiters > 0) {
pthread_mutex_unlock(&(*sem)->lock);
errno = EBUSY;
retval = -1;
goto RETURN;
}
pthread_mutex_unlock(&(*sem)->lock);
pthread_mutex_destroy(&(*sem)->lock);
pthread_cond_destroy(&(*sem)->gtzero);
(*sem)->magic = 0;
free(*sem);
retval = 0;
RETURN:
return retval;
}
/* ARGSUSED */
sem_t *
sem_open(const char *name, int oflag, ...)
{
errno = ENOSYS;
return SEM_FAILED;
}
/* ARGSUSED */
int
sem_close(sem_t *sem)
{
errno = ENOSYS;
return -1;
}
/* ARGSUSED */
int
sem_unlink(const char *name)
{
errno = ENOSYS;
return -1;
}
int
sem_wait(sem_t *sem)
{
int retval;
_thread_enter_cancellation_point();
_SEM_CHECK_VALIDITY(sem);
pthread_mutex_lock(&(*sem)->lock);
while ((*sem)->count == 0) {
(*sem)->nwaiters++;
pthread_cond_wait(&(*sem)->gtzero, &(*sem)->lock);
(*sem)->nwaiters--;
}
(*sem)->count--;
pthread_mutex_unlock(&(*sem)->lock);
retval = 0;
RETURN:
_thread_leave_cancellation_point();
return retval;
}
int
sem_trywait(sem_t *sem)
{
int retval;
_SEM_CHECK_VALIDITY(sem);
pthread_mutex_lock(&(*sem)->lock);
if ((*sem)->count > 0) {
(*sem)->count--;
retval = 0;
} else {
errno = EAGAIN;
retval = -1;
}
pthread_mutex_unlock(&(*sem)->lock);
RETURN:
return retval;
}
int
sem_post(sem_t *sem)
{
int retval;
_SEM_CHECK_VALIDITY(sem);
/*
* sem_post() is required to be safe to call from within signal
* handlers. Thus, we must defer signals.
*/
_thread_kern_sig_defer();
pthread_mutex_lock(&(*sem)->lock);
(*sem)->count++;
if ((*sem)->nwaiters > 0)
pthread_cond_signal(&(*sem)->gtzero);
pthread_mutex_unlock(&(*sem)->lock);
_thread_kern_sig_undefer();
retval = 0;
RETURN:
return retval;
}
int
sem_getvalue(sem_t *sem, int *sval)
{
int retval;
_SEM_CHECK_VALIDITY(sem);
pthread_mutex_lock(&(*sem)->lock);
*sval = (int)(*sem)->count;
pthread_mutex_unlock(&(*sem)->lock);
retval = 0;
RETURN:
return retval;
}
#endif
|
