struct RecMutex {
    pthread_mutex_t mutex;
    pthread_cond_t locked;
    int lock;
    int owner; 
};

int rec_mutex_lock(RecMutex *rmutex) {        
    
    //CurrentThread is owner, increment lock
    if (rmutex->owner == CurrentThread()) {
        rmutex->lock++;
        return 0;
    } else {
        //Lock the mutex
        pthread_mutex_lock(&(rmutex->mutex));
        
        //Wait until the lock is free     
        while (rmutex->lock != 0) {
            pthread_cond_wait( &(rmutex->locked), &(rmutex->mutex) );
        }
        
        //Set structure paramaters
        rmutex->owner = CurrentThread();
        rmutex->lock = 1;
        pthread_mutex_unlock(&(rmutex->mutex));
        
        return 0; //Everything is A-OK
    }
}

int rec_mutex_unlock(RecMutex *rmutex) {
    if (rmutex->owner == CurrentThread()) {
        rmutex->lock--;   
    } else {
        return -2; //called without reason = error
    }
    
    if (rmutex->lock == 0) {
        rmutex->owner = -1;
        pthread_cond_signal(&(rmutex->locked));
    } else if (rmutex->lock < 0) {
        return -1; //lock is broken = error
    }
    
    return 0; //everything is A-OK       
}

int rec_mutex_init(RecMutex *rmutex) {
    pthread_mutex_init(&(rmutex->mutex), NULL);
    pthread_cond_init(&(rmutex->locked),NULL);
    rmutex->lock = 0;
    rmutex->owner = -1;
    
    return 0;
}