clear(memSlice)
		state = (*_C_struct___res_state)(unsafe.Pointer(&memSlice[0]))
	}
	if err := _C_res_ninit(state); err != nil {
		return nil, errors.New("res_ninit failure: " + err.Error())
	}
	defer _C_res_nclose(state)

	// Some res_nsearch implementations (like macOS) do not set errno.
	// They set h_errno, which is not per-thread and useless to us.
	// res_nsearch returns the size of the DNS response packet.