int wait_and_forward_signal(sigset_t const* const parent_sigset_ptr, pid_t const child_pid) {
	siginfo_t sig;

	if (sigtimedwait(parent_sigset_ptr, &sig, &ts) == -1) {
		switch (errno) {
			case EAGAIN:
				break;
			case EINTR:
				break;
			default:
				PRINT_FATAL("Unexpected error in sigtimedwait: '%s'", strerror(errno));
				return 1;
		}
	} else {
		/* There is a signal to handle here */
		switch (sig.si_signo) {
			case SIGCHLD:
				/* Special-cased, as we don't forward SIGCHLD. Instead, we'll
				 * fallthrough to reaping processes.
				 */
				PRINT_DEBUG("Received SIGCHLD");
				break;
			default:
				PRINT_DEBUG("Passing signal: '%s'", strsignal(sig.si_signo));
				/* Forward anything else */
				if (kill(kill_process_group ? -child_pid : child_pid, sig.si_signo)) {
					if (errno == ESRCH) {
						PRINT_WARNING("Child was dead when forwarding signal");
					} else {
						PRINT_FATAL("Unexpected error when forwarding signal: '%s'", strerror(errno));
						return 1;
					}
				}
				break;
		}
	}

	return 0;
}
…
	while (1) {
		/* Wait for one signal, and forward it */
		if (wait_and_forward_signal(&parent_sigset, child_pid)) {
			return 1;
		}

		/* Now, reap zombies */
		if (reap_zombies(child_pid, &child_exitcode)) {
			return 1;
		}

		if (child_exitcode != -1) {
			PRINT_TRACE("Exiting: child has exited");
			return child_exitcode;
		}
	}
}

Warm-up