/* Contributed by: Vladimír Štill, https://divine.fi.muni.cz
   Description: A test of spurious wakeup of pthread_cond_wait.
*/

#include <pthread.h>
#include "svc.h"

pthread_mutex_t lock;
pthread_cond_t cond;

// only accessed in critical section guarded by mutex, so there is no need to
// make this variable atomic or volatile
int x;

void *thread( void *arg ) {
    (void)arg;
    pthread_mutex_lock( &lock );
    // BUG: cond.wait can be waken up spuriously (see man pthread_cond_wait)
    pthread_cond_wait( &cond, &lock );
    assert( x == 42 );
    pthread_mutex_unlock( &lock );
    return NULL;
}

int main() {
    pthread_t t;
    pthread_mutex_init(&lock,0);
    pthread_cond_init(&cond,0);
    pthread_create( &t, NULL, thread, NULL );
    for ( int i = 0; i <= 42; i++ )
        x = i;
    pthread_cond_broadcast( &cond );
    pthread_join( t, NULL );
}