Kód: Vybrať všetko

int main(int argc, char *argv[]) {
int value;
pid_t child;
child = fork();
sem_t semafor;
sem_t mutex;
sem_init(&semafor,0,0);
sem_init(&mutex,0,0);
int *counter;
key_t key1 = ftok(argv[0], 98); //vytvo�en� kl��e
int shmid1 = shmget(key1, sizeof(int), IPC_CREAT | 0666);
counter= shmat(shmid1, NULL, 0);
(*counter)=1;
setbuf(stdout,NULL);
if(child == 0)
  { //cast kodu vykonavana prvym procesom
      while(1)
        {
         fprintf(stdout,"tohle je if\n");
         sem_getvalue(&semafor, &value);
         fprintf(stdout,"The value of the semaphors is %d\n", value);
         sem_wait(&mutex); 
         sem_wait(&semafor);
         fprintf(stdout,"odemknul jsem semafor\n");
         if (*counter==0)   break;
        } //koniec
  } else
      {//cast kodu vykonavana druhym procesom
        fprintf(stdout,"odemknuto\n");
        sem_post(&semafor);
       *counter=0;
        sem_getvalue(&semafor, &value);
        sem_post(&mutex);
      }//koniec
}

Kód: Vybrať všetko

Mutexs work with multiple threads or multiple processes. What you describe is not a problem if there are no other threads or processes that want access to the mutex at the same time. Add a Sleep() before the WaitForSingleObject() to allow time for other threads to gain access to the mutex and see if the wait function blocks until the other thread(s) have released the mutex.