Implementation of pthread_rwlock_clockrdlock

pwrlockclockrdlock.c

/**
 * @file
 *
 * @ingroup POSIXAPI
 *
 * @brief Attempt to Obtain a Read Lock on a RWLock Instance
 */

/*
 *  POSIX RWLock Manager -- Attempt to Obtain a Read Lock on a RWLock Instance.
 *  The timeout is specified by abstime on the clock specified by clock_id.
 */

/* 
* Copyright (C) 2021 Matthew Joyce
* COPYRIGHT (c) 1989-2008
* On-Line Applications Research Corporation (OAR)
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

/* Defining to have access to function prototype in libc/include/pthread.h */
#define _GNU_SOURCE

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

#include <rtems/posix/rwlockimpl.h>
#include <rtems/posix/posixapi.h>
#include <stdio.h>

/* The POSIX Issue 8 Standard adds pthread_rwlock_clockrdlock */
int pthread_rwlock_clockrdlock(
  pthread_rwlock_t      *rwlock,
  clockid_t             clock_id,
  const struct timespec *abstime
)
{
  POSIX_RWLock_Control  *the_rwlock;
  Thread_queue_Context  queue_context;
  Status_Control        status;

  the_rwlock = _POSIX_RWLock_Get( rwlock );
  POSIX_RWLOCK_VALIDATE_OBJECT( the_rwlock );

  _Thread_queue_Context_initialize( &queue_context );

  /* 
   * The POSIX Issue 8 Standard specifies a return value of EINVAL if
   * the abstime nsec value is less than zero or greater than or equal to
   * 1 billion.  
   */
  if ( abstime->tv_nsec < 0 ) {
    return EINVAL; 
  }
	
  if ( abstime->tv_nsec >= 1000000000 ) {
    return EINVAL; 
  }

  if ( clock_id == CLOCK_REALTIME ) {
    _Thread_queue_Context_set_enqueue_timeout_realtime_timespec(
      &queue_context,
      abstime,
      true
    );
  }
  
  else if ( clock_id == CLOCK_MONOTONIC ) {
    _Thread_queue_Context_set_enqueue_timeout_monotonic_timespec(
      &queue_context,
      abstime,
      true
    );
  }

  /* 
   * The POSIX Issue 8 Standard specifies a return value of EINVAL if
   * the clock_id parameter is not CLOCK_REALTIME or CLOCK_MONOTONIC 
   */
  else {
    return EINVAL;
  }

  status = _CORE_RWLock_Seize_for_reading(
    &the_rwlock->RWLock,
    true,
    &queue_context
  );
  return _POSIX_Get_error( status );
}