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/*

 *  semopen.c,v 1.8 2002/01/04 18:28:24 joel Exp

 */

#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;

  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();

    return (sem_t *)&the_semaphore->Object.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 (sem_t *) &the_semaphore->Object.id;

}