// tester

if (signal(SIGINT, sig_handler) == SIG_ERR)
                fprintf(stderr, "\ncan't catch SIGINT\n");

void sig_handler(int signo) {
    if (signo == SIGINT) {
        send_end_signal();
    }
}


// validator

if (kill(sender_pid, SIGINT) == -1)
            syserr("validator child SIGINT error kill");