text: /*
   * Copyright (c) 2002, Intel Corporation. All rights reserved.
   * This file is licensed under the GPL license.  For the full content
   * of this license, see the COPYING file at the top level of this
   * source tree.
  
   * Test that pthread_rwlock_rdlock(pthread_rwlock_t *rwlock)
   *
   * pthread_rwlock_rdlock() function shall apply a read lock to the
   * read-write lock referenced by rwlock. The calling thread acquires
   * the read lock if a writer does not hold the lock and there are
   * no writers blocked on the lock.
   *
   * NOTE: This case will not test whether a thread can get the read lock if
   * there are writers blocked on the lock -- it is implementation dependant.
   *
   * Steps:
   * 1.  Initialize a pthread_rwlock_t object 'rwlock' with pthread_rwlock_init()
   * 2.  Main thread read lock 'rwlock'
   * 3.  Create a child thread. The thread read lock 'rwlock', should not block. Then unlock it.
   * 4.  Main thread unlock 'rwlock'
   * 5.  Main thread write lock 'rwlock'
   * 6.  Create child thread to read lock 'rwlock', should block
   * 7.  Main thread unlock 'rwlock'
   */
  #include <pthread.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <unistd.h>
  #include "posixtest.h"
  
  static pthread_rwlock_t rwlock;
  static int thread_state;
  
  /* thread_state indicates child thread state:
  	1: not in child thread yet;
  	2: just enter child thread ;
  	3: just before child thread exit;
  */
  
  #define NOT_CREATED_THREAD 1
  #define ENTERED_THREAD 2
  #define EXITING_THREAD 3
  
  static void *fn_rd(void *arg LTP_ATTRIBUTE_UNUSED)
  {
  	int rc = 0;
  	thread_state = ENTERED_THREAD;
  	printf("rd_thread: attempt read lock\n");
  	rc = pthread_rwlock_rdlock(&rwlock);
  	if (rc != 0) {
  		printf
  		    ("Test FAILED: rd_thread failed to get read lock, Error code:%d\n",
  		     rc);
  		exit(PTS_FAIL);
  	} else
  		printf("rd_thread: acquired read lock\n");
  
  	sleep(1);
  
  	printf("rd_thread: unlock read lock\n");
  	if (pthread_rwlock_unlock(&rwlock) != 0) {
  		printf("rd_thread: Error at pthread_rwlock_unlock()\n");
  		exit(PTS_UNRESOLVED);
  	}
  	thread_state = EXITING_THREAD;
  	pthread_exit(0);
  	return NULL;
  }
  
  int main(void)
  {
  	int cnt = 0;
  	pthread_t rd_thread1, rd_thread2;
  
  	if (pthread_rwlock_init(&rwlock, NULL) != 0) {
  		printf("main: Error at pthread_rwlock_init()\n");
  		return PTS_UNRESOLVED;
  	}
  
  	printf("main: attempt read lock\n");
  
  	/* We have no lock, this read lock should succeed */
  	if (pthread_rwlock_rdlock(&rwlock) != 0) {
  		printf
  		    ("Test FAILED: main cannot get read lock when no one owns the lock\n");
  		return PTS_FAIL;
  	} else
  		printf("main: acquired read lock\n");
  
  	thread_state = NOT_CREATED_THREAD;
  
  	printf("main: create rd_thread1\n");
  	if (pthread_create(&rd_thread1, NULL, fn_rd, NULL) != 0) {
  		printf("main: Error at 1st pthread_create()\n");
  		return PTS_UNRESOLVED;
  	}
  
  	/* If the shared data is not altered by child after 3 seconds,
  	   we regard it as blocked */
  	cnt = 0;
  	do {
  		sleep(1);
  	} while (thread_state != EXITING_THREAD && cnt++ < 3);
  
  	if (thread_state == ENTERED_THREAD) {
  		/* the child thread started but blocked */
  		printf
  		    ("Test FAILED: thread blocked on read lock, when a reader owns the lock\n");
  		exit(PTS_FAIL);
  	} else if (thread_state != EXITING_THREAD) {
  		printf("Unexpected thread state\n");
  		exit(PTS_UNRESOLVED);
  	}
  
  	printf("main: unlock read lock\n");
  	if (pthread_rwlock_unlock(&rwlock) != 0) {
  		printf("main: failed to release read lock\n");
  		exit(PTS_UNRESOLVED);
  	}
  
  	if (pthread_join(rd_thread1, NULL) != 0) {
  		printf("main: Error at 1st pthread_join()\n");
  		exit(PTS_UNRESOLVED);
  	}
  
  	/* Passed first part of the test, now for the second part. */
  
  	printf("main: attempt write lock\n");
  	if (pthread_rwlock_wrlock(&rwlock) != 0) {
  		printf("main: failed to get write lock\n");
  		return PTS_UNRESOLVED;
  	} else
  		printf("main: acquired write lock\n");
  
  	thread_state = NOT_CREATED_THREAD;
  	printf("main: create rd_thread2\n");
  	if (pthread_create(&rd_thread2, NULL, fn_rd, NULL) != 0) {
  		printf("main: failed at 2nd pthread_create()\n");
  		return PTS_UNRESOLVED;
  	}
  
  	cnt = 0;
  	/* Expect the child thread block on read lock */
  	do {
  		sleep(1);
  	} while (thread_state != EXITING_THREAD && cnt++ < 3);
  
  	if (thread_state == EXITING_THREAD) {
  		printf
  		    ("Test FAILED: thread did not block on read lock when a writer holds the lock\n");
  		return PTS_FAIL;
  	} else if (thread_state != ENTERED_THREAD) {
  		printf("main: Unexpected thread state\n");
  		return PTS_UNRESOLVED;
  	}
  
  	printf("main: unlock write lock\n");
  	if (pthread_rwlock_unlock(&rwlock) != 0) {
  		printf("main: failed to release write lock\n");
  		return PTS_UNRESOLVED;
  	}
  
  	/* We expected the child get the read lock and exit */
  	cnt = 1;
  	do {
  		sleep(1);
  	} while (thread_state != EXITING_THREAD && cnt++ < 3);
  
  	if (thread_state == ENTERED_THREAD) {
  		printf
  		    ("Test FAILED: thread blocked on read lock after the writer released the lock\n");
  		return PTS_FAIL;
  	} else if (thread_state != EXITING_THREAD) {
  		printf("main: Unexpected thread state\n");
  		return PTS_UNRESOLVED;
  	}
  
  	if (pthread_rwlock_destroy(&rwlock) != 0) {
  		printf("Error at pthread_rwlockattr_destroy()");
  		return PTS_UNRESOLVED;
  	}
  
  	printf("Test PASSED\n");
  	return PTS_PASS;
  }
  