From e89ddfe7b1bc3653ceac09c941e21bb8af538de0 Mon Sep 17 00:00:00 2001
From: Robbert van der Helm <mail@robbertvanderhelm.nl>
Date: Tue, 10 Mar 2020 00:36:29 +0100
Subject: [PATCH] Correct reading chunks

They're not actually stored in `data`, but in `*data`.
---
 src/common/communication.h | 37 ++++++++++++++++---------------------
 src/common/logging.cpp     |  2 +-
 src/common/serialization.h | 12 ++++++------
 src/plugin/host-bridge.cpp |  2 +-
 4 files changed, 24 insertions(+), 29 deletions(-)

diff --git a/src/common/communication.h b/src/common/communication.h
index 5ca4813e..4d331088 100644
--- a/src/common/communication.h
+++ b/src/common/communication.h
@@ -225,25 +225,18 @@ void passthrough_event(boost::asio::local::stream_protocol::socket& socket,
                          event.payload, event.option);
     }
 
-    // Some buffer for the event to write to if needed. We only pass around a
-    // marker struct to indicate that this is indeed the case.
-    std::vector<char> binary_buffer;
     std::array<char, max_string_length> string_buffer;
     void* data = std::visit(
-        overload{[&](const std::nullptr_t&) -> void* { return nullptr; },
-                 [&](const std::string& s) -> void* {
-                     return const_cast<char*>(s.c_str());
-                 },
-                 [&](DynamicVstEvents& events) -> void* {
-                     return &events.as_c_events();
-                 },
-                 [&](WantsBinaryBuffer&) -> void* {
-                     // Only allocate when we actually need this, i.e. when
-                     // we're getting a chunk from the plugin
-                     binary_buffer.resize(binary_buffer_size);
-                     return binary_buffer.data();
-                 },
-                 [&](WantsString&) -> void* { return string_buffer.data(); }},
+        overload{
+            [&](const std::nullptr_t&) -> void* { return nullptr; },
+            [&](const std::string& s) -> void* {
+                return const_cast<char*>(s.c_str());
+            },
+            [&](DynamicVstEvents& events) -> void* {
+                return &events.as_c_events();
+            },
+            [&](WantsChunkBuffer&) -> void* { return string_buffer.data(); },
+            [&](WantsString&) -> void* { return string_buffer.data(); }},
         event.payload);
 
     const intptr_t return_value = callback(plugin, event.opcode, event.index,
@@ -255,10 +248,12 @@ void passthrough_event(boost::asio::local::stream_protocol::socket& socket,
     //      report some data back?
     const auto response_data = std::visit(
         overload{
-            [&](WantsBinaryBuffer&) -> std::optional<std::string> {
-                // In this case the return value from the event determines how
-                // much data the plugin has written
-                return std::string(static_cast<char*>(data), return_value);
+            [&](WantsChunkBuffer&) -> std::optional<std::string> {
+                // In this case the plugin will have written its data stored in
+                // an array to which a pointer is stored in `data`, with the
+                // return value from the event determines how much data the
+                // plugin has written
+                return std::string(*static_cast<char**>(data), return_value);
             },
             [&](WantsString&) -> std::optional<std::string> {
                 return std::string(static_cast<char*>(data));
diff --git a/src/common/logging.cpp b/src/common/logging.cpp
index fff8fb38..fbade8cf 100644
--- a/src/common/logging.cpp
+++ b/src/common/logging.cpp
@@ -164,7 +164,7 @@ void Logger::log_event(bool is_dispatch,
                 [&](const DynamicVstEvents& events) {
                     message << "<" << events.events.size() << " midi_events>";
                 },
-                [&](const WantsBinaryBuffer&) {
+                [&](const WantsChunkBuffer&) {
                     message << "<writable_buffer>";
                 },
                 [&](const WantsString&) { message << "<writable_string>"; }},
diff --git a/src/common/serialization.h b/src/common/serialization.h
index 92b9ffcb..e13e81dd 100644
--- a/src/common/serialization.h
+++ b/src/common/serialization.h
@@ -111,11 +111,11 @@ class alignas(16) DynamicVstEvents {
 };
 
 /**
- * Marker struct to indicate that that the event needs to write arbitrary data
- * to the void pointer, with the return value indicating the amount of data
- * actually written.
+ * Marker struct to indicate that that the event writes arbitrary data into one
+ * of its own buffers and uses the void pointer to store start of that data,
+ * with the return value indicating the size of the array.
  */
-struct WantsBinaryBuffer {};
+struct WantsChunkBuffer {};
 
 /**
  * Marker struct to indicate that that the event requires some buffer to write
@@ -154,7 +154,7 @@ struct WantsString {};
 using EventPayload = std::variant<std::nullptr_t,
                                   std::string,
                                   DynamicVstEvents,
-                                  WantsBinaryBuffer,
+                                  WantsChunkBuffer,
                                   WantsString>;
 
 template <typename S>
@@ -170,7 +170,7 @@ void serialize(S& s, EventPayload& payload) {
                                            s.container1b(event.dump);
                                        });
                        },
-                       [](S&, WantsBinaryBuffer&) {}, [](S&, WantsString&) {}});
+                       [](S&, WantsChunkBuffer&) {}, [](S&, WantsString&) {}});
 }
 
 /**
diff --git a/src/plugin/host-bridge.cpp b/src/plugin/host-bridge.cpp
index 9464f23f..3c7e9305 100644
--- a/src/plugin/host-bridge.cpp
+++ b/src/plugin/host-bridge.cpp
@@ -148,7 +148,7 @@ class DispatchDataConverter : DefaultDataConverter {
         // TODO: More of these structs
         switch (opcode) {
             case effGetChunk:
-                return WantsBinaryBuffer();
+                return WantsChunkBuffer();
             case effProcessEvents:
                 return DynamicVstEvents(*static_cast<const VstEvents*>(data));
                 break;