correctly report timeout on select timeout

input.c

@@ -274,7 +274,9 @@ static int waitForInput(lua_State *L) {
 	 * timeout at all.
 	 */
 	num = select(nfds, &fds, NULL, NULL, (usecs < 0) ? NULL : &timeout);
-	if(num <= 0) {
+	if (num == 0) {
+		return luaL_error(L, "Waiting for input failed: timeout\n");
+	} else if (num < 0) {
 		return luaL_error(L, "Waiting for input failed: %d\n", errno);
 	}