/*
 * This program is used to verify that when the owner of a non-robust lock exit
 * prematurely without unlocking the mutex, the next owner will be block
 * indefintely.
 */

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

pthread_mutex_t lock;

void *original_owner_thread(void *ptr)
{
    printf("[original owner] Setting lock...\n");
    pthread_mutex_lock(&lock);
    printf("[original owner] Locked. Now exiting without unlocking.\n");
    pthread_exit(NULL);
}

int main(int argc, char *argv[]) 
{
    pthread_t lock_getter;
    pthread_mutexattr_t attr;
    pthread_mutexattr_init(&attr);   /* initialize the attribute object */
    /* the following line can be commented out because PTHREAD_MUTEX_STALLED is
     * the default value for a mutex attribute object */
    pthread_mutexattr_setrobust(&attr, PTHREAD_MUTEX_STALLED);

    pthread_mutex_init(&lock, &attr);   /* initialize the lock */

    pthread_create(&lock_getter, NULL, original_owner_thread, NULL);
    sleep(2);   /* original_owner_thread should have exited now */

    printf("Attempting to acquire unlock robust mutex.\n");
    int ret_code = pthread_mutex_lock(&lock);
    if(EOWNERDEAD == ret_code) {
        printf("EOWNERDEAD returned. Make the mutex consistent now\n");
        pthread_mutex_consistent(&lock);
    }

    pthread_mutex_unlock(&lock);

    return 0;
}