posix/src/prwlockrdlock.c

0001 /* SPDX-License-Identifier: BSD-2-Clause */
0002
0003 /**
0004  * @file
0005  *
0006  * @ingroup POSIXAPI
0007  *
0008  * @brief Obtain a Read Lock on a RWLock Instance
0009  */
0010
0011 /*
0012  *  COPYRIGHT (c) 1989-2007.
0013  *  On-Line Applications Research Corporation (OAR).
0014  *
0015  * Redistribution and use in source and binary forms, with or without
0016  * modification, are permitted provided that the following conditions
0017  * are met:
0018  * 1. Redistributions of source code must retain the above copyright
0019  *    notice, this list of conditions and the following disclaimer.
0020  * 2. Redistributions in binary form must reproduce the above copyright
0021  *    notice, this list of conditions and the following disclaimer in the
0022  *    documentation and/or other materials provided with the distribution.
0023  *
0024  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
0025  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
0026  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
0027  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
0028  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
0029  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
0030  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
0031  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
0032  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
0033  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
0034  * POSSIBILITY OF SUCH DAMAGE.
0035  */
0036
0037 #ifdef HAVE_CONFIG_H
0038 #include "config.h"
0039 #endif
0040
0041 #include <rtems/posix/rwlockimpl.h>
0042 #include <rtems/posix/posixapi.h>
0043
0044 int pthread_rwlock_rdlock(
0045   pthread_rwlock_t  *rwlock
0046 )
0047 {
0048   POSIX_RWLock_Control *the_rwlock;
0049   Thread_queue_Context  queue_context;
0050   Status_Control        status;
0051
0052   the_rwlock = _POSIX_RWLock_Get( rwlock );
0053   POSIX_RWLOCK_VALIDATE_OBJECT( the_rwlock );
0054
0055   _Thread_queue_Context_initialize( &queue_context );
0056   _Thread_queue_Context_set_enqueue_do_nothing_extra( &queue_context );
0057   status = _CORE_RWLock_Seize_for_reading(
0058     &the_rwlock->RWLock,
0059     true,                 /* we are willing to wait forever */
0060     &queue_context
0061   );
0062   return _POSIX_Get_error( status );
0063 }