Add support for Unix fd D-Bus type

include/sdbus-c++/Message.h

@@ -43,6 +43,7 @@ namespace sdbus {
     class ObjectPath;
     class Signature;
     template <typename... _ValueTypes> class Struct;
+    struct UnixFd;
     class MethodReply;
     namespace internal {
         class ISdBus;
@@ -100,6 +101,7 @@ namespace sdbus {
         Message& operator<<(const Variant &item);
         Message& operator<<(const ObjectPath &item);
         Message& operator<<(const Signature &item);
+        Message& operator<<(const UnixFd &item);
 
         Message& operator>>(bool& item);
         Message& operator>>(int16_t& item);
@@ -115,6 +117,7 @@ namespace sdbus {
         Message& operator>>(Variant &item);
         Message& operator>>(ObjectPath &item);
         Message& operator>>(Signature &item);
+        Message& operator>>(UnixFd &item);
 
         Message& openContainer(const std::string& signature);
         Message& closeContainer();

include/sdbus-c++/TypeTraits.h

@@ -40,6 +40,7 @@ namespace sdbus {
     template <typename... _ValueTypes> class Struct;
     class ObjectPath;
     class Signature;
+    struct UnixFd;
     class Message;
     class MethodCall;
     class MethodReply;
@@ -285,6 +286,17 @@ namespace sdbus {
         }
     };
 
+    template <>
+    struct signature_of<UnixFd>
+    {
+        static constexpr bool is_valid = true;
+
+        static const std::string str()
+        {
+            return "h";
+        }
+    };
+
     template <typename _Element>
     struct signature_of<std::vector<_Element>>
     {

include/sdbus-c++/Types.h

@@ -97,6 +97,12 @@ namespace sdbus {
         mutable Message msg_{};
     };
 
+    /********************************************//**
+     * @class Struct
+     *
+     * Representation of struct D-Bus type
+     *
+     ***********************************************/
     template <typename... _ValueTypes>
     class Struct
         : public std::tuple<_ValueTypes...>
@@ -135,6 +141,12 @@ namespace sdbus {
         return result_type(std::forward<_Elements>(args)...);
     }
 
+    /********************************************//**
+     * @class ObjectPath
+     *
+     * Representation of object path D-Bus type
+     *
+     ***********************************************/
     class ObjectPath : public std::string
     {
     public:
@@ -146,6 +158,12 @@ namespace sdbus {
         using std::string::operator=;
     };
 
+    /********************************************//**
+     * @class Signature
+     *
+     * Representation of Signature D-Bus type
+     *
+     ***********************************************/
     class Signature : public std::string
     {
     public:
@@ -157,6 +175,27 @@ namespace sdbus {
         using std::string::operator=;
     };
 
+    /********************************************//**
+     * @struct UnixFd
+     *
+     * Representation of Unix file descriptor D-Bus type
+     *
+     ***********************************************/
+    struct UnixFd
+    {
+        int fd_ = -1;
+
+        UnixFd() = default;
+        UnixFd(int fd)
+            : fd_(fd)
+        {}
+
+        operator int() const
+        {
+            return fd_;
+        }
+    };
+
 }
 
 #endif /* SDBUS_CXX_TYPES_H_ */