helgrind/tests/tc09_bad_unlock.c

/* Check that an error is reported for various kinds of bogus
   pthread_mutex_unlock calls. */

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

void* child_fn ( void* arg )
{
   pthread_mutex_unlock( (pthread_mutex_t*)arg ); /* ERROR */
   return NULL;
}

void nearly_main ( void )
{
   pthread_t child;
   pthread_mutex_t mx1, mx2;
   int bogus[100], i;
   /* fill bogus with values which will cause glibc's pth_mx_unlock to fail */
   for (i = 0; i < 100; i++) bogus[i] = 0xFFFFFFFF;
   /* Unlocking a lock that is already unlocked */
   pthread_mutex_init( &mx1, NULL );
   pthread_mutex_lock( &mx1 );
   pthread_mutex_unlock( &mx1 );

   pthread_mutex_unlock( &mx1 ); /* ERROR */

   /* Unlocking a lock that is held by a different thread */

   pthread_mutex_init( &mx2, NULL );
   pthread_mutex_lock( &mx2 );
   // start child and get it to unlock this lock

   pthread_create( &child, NULL, child_fn, (void*)&mx2 );
      /* child runs and attempts to unlock our lock.  Error 
         is reported in child_fn. */
   pthread_join(child, NULL );

   /* Unlocking a totally bogus lock. */
   pthread_mutex_unlock( (pthread_mutex_t*) &bogus[50] ); /* ERROR */

   /* Now we get a freeing-locked-lock error, since the stack
      frame is removed whilst mx2 is still locked. */
}

int main ( void )
{
   nearly_main();
   nearly_main();
   return 0;
}