if (signal_pipe[READ_END] >= 0)
close(signal_pipe[READ_END]);
if (signal_pipe[WRITE_END] >= 0)
close(signal_pipe[WRITE_END]);
if (signal_pipe[READ_END] >= 0)
close(signal_pipe[READ_END]);
if (signal_pipe[WRITE_END] >= 0)
close(signal_pipe[WRITE_END]);