Add universal way to shutdown sockets on Wine side

src/wine-host/bridges/common.h

@@ -102,6 +102,14 @@ class HostBridge {
     const boost::filesystem::path plugin_path;
 
    protected:
+    /**
+     * Used as part of the watchdog that shuts down a plugin when the remote
+     * native host process dies. This is used to prevent plugins from hanging
+     * indefinitely on a `recv()`. This function should just call
+     * `sockets.close()`.
+     */
+    virtual void close_sockets() = 0;
+
     /**
      * The IO context used for event handling so that all events and window
      * message handling can be performed from a single thread, even when hosting

src/wine-host/bridges/vst2.cpp

@@ -425,6 +425,10 @@ void Vst2Bridge::handle_x11_events() {
     }
 }
 
+void Vst2Bridge::close_sockets() {
+    sockets.close();
+}
+
 intptr_t Vst2Bridge::dispatch_wrapper(AEffect* plugin,
                                       int opcode,
                                       int index,

src/wine-host/bridges/vst2.h

@@ -68,6 +68,10 @@ class Vst2Bridge : public HostBridge {
 
     void handle_x11_events() override;
 
+   protected:
+    void close_sockets() override;
+
+   public:
     /**
      * Forward the host callback made by the plugin to the host and return the
      * results.

src/wine-host/bridges/vst3.cpp

@@ -1133,6 +1133,10 @@ void Vst3Bridge::handle_x11_events() {
     }
 }
 
+void Vst3Bridge::close_sockets() {
+    sockets.close();
+}
+
 void Vst3Bridge::register_context_menu(Vst3ContextMenuProxyImpl& context_menu) {
     std::lock_guard lock(object_instances[context_menu.owner_instance_id()]
                              .registered_context_menus_mutex);

src/wine-host/bridges/vst3.h

@@ -233,6 +233,10 @@ class Vst3Bridge : public HostBridge {
 
     void handle_x11_events() override;
 
+   protected:
+    void close_sockets() override;
+
+   public:
     /**
      * Send a callback message to the host return the response. This is a
      * shorthand for `sockets.vst_host_callback.send_message` for use in VST3