Pass through host provided IBStream objects

So if the host supports IStreamAttributes, we can also provide objects
that support the same itnerface to the plugin.

src/common/serialization/vst3/bstream.cpp

@@ -30,25 +30,25 @@ YaBStream::YaBStream(Steinberg::IBStream* stream) {
         throw std::runtime_error("Null pointer passed to YaBStream()");
     }
 
-    if (stream->seek(0, Steinberg::IBStream::IStreamSeekMode::kIBSeekEnd) !=
+    // Copy any existing contents, used for `IComponent::setState` and similar
+    // methods
+    if (stream->seek(0, Steinberg::IBStream::IStreamSeekMode::kIBSeekEnd) ==
         Steinberg::kResultOk) {
-        throw std::runtime_error(
-            "IBStream passed to YaBStream() does not suport seeking to end");
+        // Now that we're at the end of the stream we know how large the buffer
+        // should be
+        int64 size;
+        assert(stream->tell(&size) == Steinberg::kResultOk);
+
+        int32 num_bytes_read = 0;
+        buffer.resize(size);
+        assert(
+            stream->seek(0, Steinberg::IBStream::IStreamSeekMode::kIBSeekSet) ==
+            Steinberg::kResultOk);
+        assert(stream->read(buffer.data(), size, &num_bytes_read) ==
+               Steinberg::kResultOk);
+        assert(num_bytes_read == 0 || num_bytes_read == size);
     }
 
-    // Now that we're at the end of the stream we know how large the buffer
-    // should be
-    int64 size;
-    assert(stream->tell(&size) == Steinberg::kResultOk);
-
-    int32 num_bytes_read = 0;
-    buffer.resize(size);
-    assert(stream->seek(0, Steinberg::IBStream::IStreamSeekMode::kIBSeekSet) ==
-           Steinberg::kResultOk);
-    assert(stream->read(buffer.data(), size, &num_bytes_read) ==
-           Steinberg::kResultOk);
-    assert(num_bytes_read == 0 || num_bytes_read == size);
-
     // Starting at VST 3.6.0 streams provided by the host may contain context
     // based meta data
     if (Steinberg::FUnknownPtr<Steinberg::Vst::IStreamAttributes>

src/common/serialization/vst3/bstream.h

@@ -39,6 +39,11 @@ class YaBStream : public Steinberg::IBStream,
                   public Steinberg::ISizeableStream,
                   public Steinberg::Vst::IStreamAttributes {
    public:
+    /**
+     * This constructor should only be used by bitsery for serialization. The
+     * other constructor will check whether the `IBstream*` provided by the host
+     * supports stream attributes and configures the object accordingly.
+     */
     YaBStream();
 
     /**

src/common/serialization/vst3/plugin-proxy.h

@@ -225,31 +225,34 @@ class Vst3PluginProxy : public YaAudioPresentationLatency,
 
     /**
      * The response code and written state for a call to
-     * `{IComponent,IEditController}::getState(state)`.
+     * `{IComponent,IEditController}::getState(&state)`.
      */
     struct GetStateResponse {
         UniversalTResult result;
-        YaBStream updated_state;
+        YaBStream state;
 
         template <typename S>
         void serialize(S& s) {
             s.object(result);
-            s.object(updated_state);
+            s.object(state);
         }
     };
 
     /**
      * Message to pass through a call to
-     * `{IComponent,IEditController}::getState(state)` to the Wine plugin host.
+     * `{IComponent,IEditController}::getState(&state)` to the Wine plugin host.
      */
     struct GetState {
         using Response = GetStateResponse;
 
         native_size_t instance_id;
 
+        YaBStream state;
+
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
+            s.object(state);
         }
     };
 

src/common/serialization/vst3/plugin/program-list-data.h

@@ -111,12 +111,14 @@ class YaProgramListData : public Steinberg::Vst::IProgramListData {
 
         Steinberg::Vst::ProgramListID list_id;
         int32 program_index;
+        YaBStream data;
 
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
             s.value4b(list_id);
             s.value4b(program_index);
+            s.object(data);
         }
     };
 

src/common/serialization/vst3/plugin/unit-data.h

@@ -108,11 +108,13 @@ class YaUnitData : public Steinberg::Vst::IUnitData {
         native_size_t instance_id;
 
         Steinberg::Vst::UnitID unit_id;
+        YaBStream data;
 
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
             s.value4b(unit_id);
+            s.object(data);
         }
     };
 

src/common/serialization/vst3/plugin/xml-representation-controller.h

@@ -96,11 +96,13 @@ class YaXmlRepresentationController
         native_size_t instance_id;
 
         Steinberg::Vst::RepresentationInfo info;
+        YaBStream stream;
 
         template <typename S>
         void serialize(S& s) {
             s.value8b(instance_id);
             s.object(info);
+            s.object(stream);
         }
     };