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/*
* Asterisk -- An open source telephony toolkit.
*
* Copyright (C) 2013, Digium, Inc.
*
* David M. Lee, II <dlee@digium.com>
*
* See http://www.asterisk.org for more information about
* the Asterisk project. Please do not directly contact
* any of the maintainers of this project for assistance;
* the project provides a web site, mailing lists and IRC
* channels for your use.
*
* This program is free software, distributed under the terms of
* the GNU General Public License Version 2. See the LICENSE file
* at the top of the source tree.
*/
/*! \file
*
* \brief Asterisk semaphore support.
*/
#include "asterisk.h"
ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
#include "asterisk/sem.h"
#include "asterisk/utils.h"
#ifndef HAS_WORKING_SEMAPHORE
/* DIY semaphores! */
int ast_sem_init(struct ast_sem *sem, int pshared, unsigned int value)
{
if (pshared) {
/* Don't need it... yet */
errno = ENOSYS;
return -1;
}
/* Since value is unsigned, this will also catch attempts to init with
* a negative value */
if (value > AST_SEM_VALUE_MAX) {
errno = EINVAL;
return -1;
}
sem->count = value;
sem->waiters = 0;
ast_mutex_init(&sem->mutex);
ast_cond_init(&sem->cond, NULL);
return 0;
}
int ast_sem_destroy(struct ast_sem *sem)
{
ast_mutex_destroy(&sem->mutex);
ast_cond_destroy(&sem->cond);
return 0;
}
int ast_sem_post(struct ast_sem *sem)
{
SCOPED_MUTEX(lock, &sem->mutex);
ast_assert(sem->count >= 0);
if (sem->count == AST_SEM_VALUE_MAX) {
errno = EOVERFLOW;
return -1;
}
/* Give it up! */
++sem->count;
/* Release a waiter, if needed */
if (sem->waiters) {
ast_cond_signal(&sem->cond);
}
return 0;
}
int ast_sem_wait(struct ast_sem *sem)
{
SCOPED_MUTEX(lock, &sem->mutex);
ast_assert(sem->count >= 0);
/* Wait for a non-zero count */
++sem->waiters;
while (sem->count == 0) {
ast_cond_wait(&sem->cond, &sem->mutex);
}
--sem->waiters;
/* Take it! */
--sem->count;
return 0;
}
int ast_sem_getvalue(struct ast_sem *sem, int *sval)
{
SCOPED_MUTEX(lock, &sem->mutex);
ast_assert(sem->count >= 0);
*sval = sem->count;
return 0;
}
#endif
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