129 lines
3.5 KiB
C
129 lines
3.5 KiB
C
|
/*
|
||
|
|
* -------------------------------------------------------------
|
||
|
|
*
|
||
|
|
* 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: rpj@callisto.canberra.edu.au
|
||
|
|
*
|
||
|
|
* 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.,
|
||
|
|
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 */
|