Properly handle effGet{Input,Output}Properties

Apparently the plugin needs the actual contents of the struct for this
to work.

src/common/events.h

@@ -135,6 +135,7 @@ intptr_t send_event(boost::asio::local::stream_protocol::socket& socket,
     const std::optional<EventPayload> payload =
         data_converter.read(opcode, index, value, data);
     if (!payload.has_value()) {
+        // A 1 usually means that the event was processed succesfully
         return 1;
     }
 
@@ -217,7 +218,8 @@ void passthrough_event(boost::asio::local::stream_protocol::socket& socket,
                 return &events.as_c_events();
             },
             [&](WantsChunkBuffer&) -> void* { return string_buffer.data(); },
-            [&](const WantsVstRect&) -> void* { return string_buffer.data(); },
+            [&](VstIOProperties& props) -> void* { return &props; },
+            [&](WantsVstRect&) -> void* { return string_buffer.data(); },
             [&](const WantsVstTimeInfo&) -> void* { return nullptr; },
             [&](WantsString&) -> void* { return string_buffer.data(); }},
         event.payload);
@@ -265,6 +267,11 @@ void passthrough_event(boost::asio::local::stream_protocol::socket& socket,
                      return std::string(*static_cast<char**>(data),
                                         return_value);
                  },
+                 [&](VstIOProperties& props) -> EventResposnePayload {
+                     // The plugin has written a pointer to a VstRect struct
+                     // into the data poitner
+                     return props;
+                 },
                  [&](WantsVstRect&) -> EventResposnePayload {
                      // The plugin has written a pointer to a VstRect struct
                      // into the data poitner

src/common/logging.cpp

@@ -177,6 +177,7 @@ void Logger::log_event(bool is_dispatch,
                 [&](const WantsChunkBuffer&) {
                     message << "<writable_buffer>";
                 },
+                [&](const VstIOProperties&) { message << "<io_properties>"; },
                 [&](const WantsVstRect&) { message << "<writable_buffer>"; },
                 [&](const WantsVstTimeInfo&) { message << "<nullptr>"; },
                 [&](const WantsString&) { message << "<writable_string>"; }},
@@ -202,23 +203,25 @@ void Logger::log_event_response(bool is_dispatch,
         message << return_value;
 
         std::visit(
-            overload{[&](const std::monostate&) {},
-                     [&](const std::string& s) {
-                         if (s.size() < 32) {
-                             message << ", \"" << s << "\"";
-                         } else {
-                             // Long strings contain binary data that we
-                             // probably don't want to print
-                             message << ", <" << s.size() << " bytes>";
-                         }
-                     },
-                     [&](const AEffect&) { message << ", <AEffect_object>"; },
-                     [&](const VstRect& rect) {
-                         message << ", {l: " << rect.left << ", t: " << rect.top
-                                 << ", r: " << rect.right
-                                 << ", b: " << rect.bottom << "}";
-                     },
-                     [&](const VstTimeInfo&) { message << ", <time_info>"; }},
+            overload{
+                [&](const std::monostate&) {},
+                [&](const std::string& s) {
+                    if (s.size() < 32) {
+                        message << ", \"" << s << "\"";
+                    } else {
+                        // Long strings contain binary data that we probably
+                        // don't want to print
+                        message << ", <" << s.size() << " bytes>";
+                    }
+                },
+                [&](const AEffect&) { message << ", <AEffect_object>"; },
+                [&](const VstIOProperties&) { message << ", <io_properties>"; },
+                [&](const VstRect& rect) {
+                    message << ", {l: " << rect.left << ", t: " << rect.top
+                            << ", r: " << rect.right << ", b: " << rect.bottom
+                            << "}";
+                },
+                [&](const VstTimeInfo&) { message << ", <time_info>"; }},
             payload);
 
         log(message.str());

src/common/serialization.h

@@ -27,6 +27,8 @@
 
 #include <variant>
 
+#include "vst24.h"
+
 // These constants are limits used by bitsery
 
 /**
@@ -83,6 +85,11 @@ void serialize(S& s, AEffect& plugin) {
     s.value4b(plugin.version);
 }
 
+template <typename S>
+void serialize(S& s, VstIOProperties& props) {
+    s.container1b(props.data);
+}
+
 template <typename S>
 void serialize(S& s, VstRect& rect) {
     s.value2b(rect.top);
@@ -212,6 +219,7 @@ using EventPayload = std::variant<std::nullptr_t,
                                   AEffect,
                                   DynamicVstEvents,
                                   WantsChunkBuffer,
+                                  VstIOProperties,
                                   WantsVstRect,
                                   WantsVstTimeInfo,
                                   WantsString>;
@@ -233,6 +241,7 @@ void serialize(S& s, EventPayload& payload) {
                       events.events, max_midi_events,
                       [](S& s, VstEvent& event) { s.container1b(event.dump); });
               },
+              [](S& s, VstIOProperties& props) { s.object(props); },
               [](S&, WantsChunkBuffer&) {}, [](S&, WantsVstRect&) {},
               [](S&, WantsVstTimeInfo&) {}, [](S&, WantsString&) {}});
 }
@@ -289,8 +298,12 @@ struct Event {
  *   `audioMasterIOChanged`.
  * - An X11 window pointer for the editor window.
  */
-using EventResposnePayload =
-    std::variant<std::monostate, std::string, AEffect, VstRect, VstTimeInfo>;
+using EventResposnePayload = std::variant<std::monostate,
+                                          std::string,
+                                          AEffect,
+                                          VstIOProperties,
+                                          VstRect,
+                                          VstTimeInfo>;
 
 template <typename S>
 void serialize(S& s, EventResposnePayload& payload) {
@@ -304,6 +317,7 @@ void serialize(S& s, EventResposnePayload& payload) {
                   s.text1b(string, binary_buffer_size);
               },
               [](S& s, AEffect& effect) { s.object(effect); },
+              [](S& s, VstIOProperties& props) { s.object(props); },
               [](S& s, VstRect& rect) { s.object(rect); },
               [](S& s, VstTimeInfo& time_info) { s.object(time_info); }});
 }

src/plugin/host-bridge.cpp

@@ -206,6 +206,13 @@ class DispatchDataConverter : DefaultDataConverter {
             case effProcessEvents:
                 return DynamicVstEvents(*static_cast<const VstEvents*>(data));
                 break;
+            case effGetInputProperties:
+            case effGetOutputProperties:
+                // In this case we can't simply pass an empty marker struct
+                // because the host can have already populated this field with
+                // data (or at least Bitwig does this)
+                return *static_cast<const VstIOProperties*>(data);
+                break;
             default:
                 return DefaultDataConverter::read(opcode, index, value, data);
                 break;
@@ -232,11 +239,21 @@ class DispatchDataConverter : DefaultDataConverter {
                 // `HostBridge` and write a pointer to that struct to the data
                 // pointer
 
-                std::string buffer = std::get<std::string>(response.payload);
+                const auto buffer = std::get<std::string>(response.payload);
                 chunk.assign(buffer.begin(), buffer.end());
 
                 *static_cast<void**>(data) = chunk.data();
             } break;
+            case effGetInputProperties:
+            case effGetOutputProperties: {
+                // These opcodes pass the plugin some empty struct through the
+                // data parameter that the plugin then fills with flags and
+                // other data to describe an input or output channel.
+                const auto properties =
+                    std::get<VstIOProperties>(response.payload);
+
+                *static_cast<VstIOProperties*>(data) = properties;
+            } break;
             default:
                 DefaultDataConverter::write(opcode, data, response);
                 break;