Hi, I try to code a simple program that starts and waits on the system semaphore until it gets terminated by signal.

union semun {
   int val;
   struct semid_ds *buf;
   unsigned short int *array;
   struct seminfo *__buf;
};


int main(){
    int semaphores = semget(IPC_PRIVATE,1,IPC_CREAT | 0666);
    union semun arg;
    arg.val = 0;
    semctl(semaphores,0,SETVAL,arg);
    struct sembuf operations[1];
    operations[0].sem_num = 0; 
    operations[0].sem_op = -1;
    operations[0].sem_flg = 0;
    semop(semaphores,operations,1); 
    fprintf(stderr,"Why?\n");
    return 0;
}

I expect, that everytime this program gets executed, nothing actually happens and it waits on the semaphore, but everytime it goes through the semaphore and writes Why?. Why?