module os

#include <signal.h>

fn C.signal(signal int, handlercb SignalHandler) voidptr

// signal will assign `handler` callback to be called when `signum` signal is received.
pub fn signal_opt(signum Signal, handler SignalHandler) ?SignalHandler {
	C.errno = 0
	prev_handler := C.signal(int(signum), handler)
	if prev_handler == C.SIG_ERR {
		// errno isn't correctly set on Windows, but EINVAL is this only possible value it can take anyway
		return error_with_code(posix_get_error_msg(C.EINVAL), C.EINVAL)
	}
	return SignalHandler(prev_handler)
}