/*
* -------------------------------------------------------------
*
* Module: sem_init.c
*
* Purpose:
* Semaphores aren't actually part of PThreads.
* They are defined by the POSIX Standard:
*
* POSIX 1003.1-2001
*
* -------------------------------------------------------------
*
* 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_init (sem_t * sem, int pshared, unsigned int value)
/*
* ------------------------------------------------------
* DOCPUBLIC
* This function initializes a semaphore. The
* initial value of the semaphore is 'value'
*
* PARAMETERS
* sem
* pointer to an instance of sem_t
*
* pshared
* if zero, this semaphore may only be shared between
* threads in the same process.
* if nonzero, the semaphore can be shared between
* processes
*
* value
* initial value of the semaphore counter
*
* DESCRIPTION
* This function initializes a semaphore. The
* initial value of the semaphore is set to 'value'.
*
* RESULTS
* 0 successfully created semaphore,
* -1 failed, error in errno
* ERRNO
* EINVAL 'sem' is not a valid semaphore, or
* 'value' >= SEM_VALUE_MAX
* ENOMEM out of memory,
* ENOSPC a required resource has been exhausted,
* ENOSYS semaphores are not supported,
* EPERM the process lacks appropriate privilege
*
* ------------------------------------------------------
*/
{
int result = 0;
sem_t s = NULL;
if (pshared != 0)
{
/*
* Creating a semaphore that can be shared between
* processes
*/
result = EPERM;
}
else if (value > (unsigned int)SEM_VALUE_MAX)
{
result = EINVAL;
}
else
{
s = (sem_t) calloc (1, sizeof (*s));
if (NULL == s)
{
result = ENOMEM;
}
else
{
s->value = value;
if (pthread_mutex_init(&s->lock, NULL) == 0)
{
#if defined(NEED_SEM)
s->sem = CreateEvent (NULL,
PTW32_FALSE, /* auto (not manual) reset */
PTW32_FALSE, /* initial state is unset */
NULL);
if (0 == s->sem)
{
free (s);
(void) pthread_mutex_destroy(&s->lock);
result = ENOSPC;
}
else
{
s->leftToUnblock = 0;
}
#else /* NEED_SEM */
if ((s->sem = CreateSemaphore (NULL, /* Always NULL */
(long) 0, /* Force threads to wait */
(long) SEM_VALUE_MAX, /* Maximum value */
NULL)) == 0) /* Name */
{
(void) pthread_mutex_destroy(&s->lock);
result = ENOSPC;
}
#endif /* NEED_SEM */
}
else
{
result = ENOSPC;
}
if (result != 0)
{
free(s);
}
}
}
if (result != 0)
{
errno = result;
return -1;
}
*sem = s;
return 0;
} /* sem_init */
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