/*
* -------------------------------------------------------------
*
* Module: sem_post.c
*
* Purpose:
* Semaphores aren't actually part of the PThreads standard.
* They are defined by the POSIX Standard:
*
* POSIX 1003.1b-1993 (POSIX.1b)
*
* -------------------------------------------------------------
*
* --------------------------------------------------------------------------
*
* Pthreads-win32 - POSIX Threads Library for Win32
* Copyright(C) 1998 John E. Bossom
* Copyright(C) 1999,2005 Pthreads-win32 contributors
*
* Contact Email: [email protected]
*
* The current list of contributors is contained
* in the file CONTRIBUTORS included with the source
* code distribution. The list can also be seen at the
* following World Wide Web location:
* http://sources.redhat.com/pthreads-win32/contributors.html
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library in the file COPYING.LIB;
* if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include "pthread.h"
#include "semaphore.h"
#include "implement.h"
int
sem_post (sem_t * sem)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function posts a wakeup to a semaphore.
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* DESCRIPTION
* This function posts a wakeup to a semaphore. If there
* are waiting threads (or processes), one is awakened;
* otherwise, the semaphore value is incremented by one.
*
* RESULTS
* 0 successfully posted semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore,
* ENOSYS semaphores are not supported,
* ERANGE semaphore count is too big
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = *sem;
if (s == NULL)
{
result = EINVAL;
}
else if ((result = pthread_mutex_lock (&s->lock)) == 0)
{
/* See sem_destroy.c
*/
if (*sem == NULL)
{
(void) pthread_mutex_unlock (&s->lock);
result = EINVAL;
return -1;
}
if (s->value < SEM_VALUE_MAX)
{
#if defined(NEED_SEM)
if (++s->value <= 0
&& !SetEvent(s->sem))
{
s->value--;
result = EINVAL;
}
#else
if (++s->value <= 0
&& !ReleaseSemaphore (s->sem, 1, NULL))
{
s->value--;
result = EINVAL;
}
#endif /* NEED_SEM */
}
else
{
result = ERANGE;
}
(void) pthread_mutex_unlock (&s->lock);
}
if (result != 0)
{
errno = result;
return -1;
}
return 0;
} /* sem_post */
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