#include <pthread.h>
#include <stdio.h>
#include <errno.h>

int ret;

void check_ret(void)
{
    switch (ret) {
	case 0:
	    puts("  OK");
	    break;
	case EDEADLK:
	    puts("  deadlock");
	    break;
	case ETIMEDOUT:
	    puts("  timed out");
	    break;
	case EINVAL:
	    puts("  invalid");
	    break;
	case EBUSY:
	    puts("  busy");
	    break;
	default:
	    printf("  unhandled error %d\n", ret);
	    break;
    }
}

int main(void)
{
    struct timespec wait;
    wait.tv_sec = time(NULL) + 5;
    wait.tv_nsec = 0;

    pthread_rwlock_t rwlock;
    ret = pthread_rwlock_init(&rwlock, NULL);

    /* Trying while holding write lock */
    printf("Acquiring write lock...\n");
    ret = pthread_rwlock_wrlock(&rwlock);
    check_ret();

    printf("Trying to acquire write lock...\n");
    ret = pthread_rwlock_trywrlock(&rwlock);
    check_ret();

    printf("Acquiring timed write lock...\n");
    ret = pthread_rwlock_timedwrlock(&rwlock, &wait);
    check_ret();

    printf("Trying to acquire read lock...\n");
    ret = pthread_rwlock_tryrdlock(&rwlock);
    check_ret();

    printf("Acquiring timed read lock...\n");
    ret = pthread_rwlock_timedrdlock(&rwlock, &wait);
    check_ret();

    printf("Acquiring read lock...\n");
    ret = pthread_rwlock_rdlock(&rwlock);
    check_ret();

    printf("Releasing write lock.\n");
    pthread_rwlock_unlock(&rwlock);

    /* Trying while holding read lock */
    printf("Acquiring read lock...\n");
    ret = pthread_rwlock_rdlock(&rwlock);
    check_ret();

    printf("Trying to acquire write lock...\n");
    ret = pthread_rwlock_trywrlock(&rwlock);
    check_ret();

    printf("Acquiring timed write lock...\n");
    ret = pthread_rwlock_timedwrlock(&rwlock, &wait);
    check_ret();

    printf("Trying to acquire read lock...\n");
    ret = pthread_rwlock_tryrdlock(&rwlock);
    check_ret();

    printf("Acquiring timed read lock...\n");
    ret = pthread_rwlock_timedrdlock(&rwlock, &wait);
    check_ret();

    printf("Acquiring read lock...\n");
    ret = pthread_rwlock_rdlock(&rwlock);
    check_ret();

    printf("Releasing read lock.\n");
    pthread_rwlock_unlock(&rwlock);

    pthread_rwlock_destroy(&rwlock);

    return (0);

}