28 struct ControlMessage {  struct
30   static ControlMessage FromRaw(const cmsghdr*);
31   static Result<ControlMessage> FromFileDescriptors(
34   static ControlMessage FromCredentials(const ucred&);
36   ControlMessage(const ControlMessage&) = delete;
37   ControlMessage(ControlMessage&&);
38   ~ControlMessage();
39   ControlMessage& operator=(const ControlMessage&) = delete;  argument
40   ControlMessage& operator=(ControlMessage&&);  argument
54   ControlMessage() = default;
63   std::vector<ControlMessage> control;  argument