Let dumpstate die a normal death when receiving a singal

    ShowUsageAndExit();

}

static void sig_handler(int) {

    _exit(EXIT_FAILURE);

}

static void register_sig_handler() {

    struct sigaction sa;

    sigemptyset(&sa.sa_mask);

    sa.sa_flags = 0;

    sa.sa_handler = sig_handler;

    sigaction(SIGPIPE, &sa, NULL); // broken pipe

    sigaction(SIGSEGV, &sa, NULL); // segment fault

    sigaction(SIGINT, &sa, NULL); // ctrl-c

    sigaction(SIGTERM, &sa, NULL); // killed

    sigaction(SIGQUIT, &sa, NULL); // quit

    signal(SIGPIPE, SIG_IGN);

}

bool Dumpstate::FinishZipFile() {