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/*
* COPYRIGHT (c) 1989-2007.
* On-Line Applications Research Corporation (OAR).
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* $Id$
*/
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdarg.h>
#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <semaphore.h>
#include <limits.h>
#include <rtems/system.h>
#include <rtems/score/object.h>
#include <rtems/posix/semaphore.h>
#include <rtems/posix/time.h>
#include <rtems/seterr.h>
/*PAGE
*
* sem_open
*
* Opens a named semaphore. Used in conjunction with the sem_close
* and sem_unlink commands.
*
* 11.2.3 Initialize/Open a Named Semaphore, P1003.1b-1993, p.221
*
* NOTE: When oflag is O_CREAT, then optional third and fourth
* parameters must be present.
*/
sem_t *sem_open(
const char *name,
int oflag,
...
/* mode_t mode, */
/* unsigned int value */
)
{
va_list arg;
mode_t mode;
unsigned int value = 0;
int status;
sem_t the_semaphore_id;
sem_t *id;
POSIX_Semaphore_Control *the_semaphore;
Objects_Locations location;
_Thread_Disable_dispatch();
if ( oflag & O_CREAT ) {
va_start(arg, oflag);
mode = (mode_t) va_arg( arg, unsigned int );
value = va_arg( arg, unsigned int );
va_end(arg);
}
status = _POSIX_Semaphore_Name_to_id( name, &the_semaphore_id );
/*
* If the name to id translation worked, then the semaphore exists
* and we can just return a pointer to the id. Otherwise we may
* need to check to see if this is a "semaphore does not exist"
* or some other miscellaneous error on the name.
*/
if ( status ) {
/*
* Unless provided a valid name that did not already exist
* and we are willing to create then it is an error.
*/
if ( !( status == ENOENT && (oflag & O_CREAT) ) ) {
_Thread_Enable_dispatch();
rtems_set_errno_and_return_minus_one_cast( status, sem_t * );
}
} else {
/*
* Check for existence with creation.
*/
if ( (oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL) ) {
_Thread_Enable_dispatch();
rtems_set_errno_and_return_minus_one_cast( EEXIST, sem_t * );
}
the_semaphore = _POSIX_Semaphore_Get( &the_semaphore_id, &location );
the_semaphore->open_count += 1;
_Thread_Enable_dispatch();
_Thread_Enable_dispatch();
goto return_id;
}
/*
* At this point, the semaphore does not exist and everything has been
* checked. We should go ahead and create a semaphore.
*/
status =_POSIX_Semaphore_Create_support(
name,
false, /* not shared across processes */
value,
&the_semaphore
);
/*
* errno was set by Create_support, so don't set it again.
*/
_Thread_Enable_dispatch();
if ( status == -1 )
return SEM_FAILED;
return_id:
#if defined(RTEMS_USE_16_BIT_OBJECT)
the_semaphore->Semaphore_id = the_semaphore->Object.id;
id = &the_semaphore->Semaphore_id;
#else
id = (sem_t *)&the_semaphore->Object.id;
#endif
return id;
}
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