path: root/cpukit/posix/src/semgetvalue.c

/**
 * @file
 *
 * @brief Get the Value of a Semaphore
 * @ingroup POSIX_SEMAPHORE
 */

/*
 *  COPYRIGHT (c) 1989-2014.
 *  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.org/license/LICENSE.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#include <semaphore.h>

#include <rtems/posix/semaphoreimpl.h>

int sem_getvalue(
  sem_t  *__restrict sem,
  int    *__restrict sval
)
{
  POSIX_Semaphore_Control *the_semaphore;
  Thread_queue_Context     queue_context;

  the_semaphore = _POSIX_Semaphore_Get( sem, &queue_context );

  if ( the_semaphore == NULL ) {
    rtems_set_errno_and_return_minus_one( EINVAL );
  }

  _CORE_semaphore_Acquire_critical(
    &the_semaphore->Semaphore,
    &queue_context
  );

  *sval = _CORE_semaphore_Get_count( &the_semaphore->Semaphore );

  _CORE_semaphore_Release( &the_semaphore->Semaphore, &queue_context );
  return 0;
}