Add runtime checker for gsignal callback arguments.

src/CMakeLists.txt

@@ -101,6 +101,7 @@ set(SOURCES
   core/qxtglobalshortcutbackend.cpp
   core/scopedtransaction.cpp
   core/settingsprovider.cpp
+  core/signalchecker.cpp
   core/song.cpp
   core/songloader.cpp
   core/stylesheetloader.cpp

src/core/signalchecker.cpp

@@ -0,0 +1,48 @@
+/* This file is part of Clementine.
+   Copyright 2012, David Sansome <me@davidsansome.com>
+
+   Clementine is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   Clementine is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with Clementine.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "signalchecker.h"
+
+#include "core/logging.h"
+
+bool CheckedGConnect(
+    gpointer source,
+    const char* signal,
+    GCallback callback,
+    gpointer data,
+    const int callback_param_count) {
+  guint signal_id = g_signal_lookup(signal, G_OBJECT_TYPE(source));
+  if (signal_id == 0) {
+    qLog(Error) << "Connecting to invalid signal:" << signal;
+    Q_ASSERT(0);
+    return false;
+  }
+
+  GSignalQuery query;
+  g_signal_query(signal_id, &query);
+  // The signature for a signal callback is always:
+  // return_type callback(gpointer data1, params..., gpointer data2);
+  int signal_params = query.n_params + 2;
+  if (signal_params != callback_param_count) {
+    qLog(Error) << "Connecting callback to signal with different parameters counts";
+    Q_ASSERT(0);
+    return false;
+  }
+
+  g_signal_connect(source, signal, G_CALLBACK(callback), data);
+  return true;
+}

src/core/signalchecker.h

@@ -0,0 +1,83 @@
+/* This file is part of Clementine.
+   Copyright 2012, David Sansome <me@davidsansome.com>
+
+   Clementine is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   Clementine is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with Clementine.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef SIGNALCHECKER_H
+#define SIGNALCHECKER_H
+
+#include <glib-object.h>
+
+#include <boost/config.hpp>
+
+#ifdef BOOST_NO_VARIADIC_TEMPLATES
+
+template <typename R>
+int GetFunctionParamCount(R (*func)()) {
+  return 0;
+}
+
+template <typename R, typename P0>
+int GetFunctionParamCount(R (*func)(P0)) {
+  return 1;
+}
+
+template <typename R, typename P0, typename P1>
+int GetFunctionParamCount(R (*func)(P0, P1)) {
+  return 2;
+}
+
+template <typename R, typename P0, typename P1, typename P2>
+int GetFunctionParamCount(R (*func)(P0, P1, P2)) {
+  return 3;
+}
+
+#else  // BOOST_NO_VARIADIC_TEMPLATES
+
+template <typename R, typename... Params>
+int GetFunctionParamCount(R (*func)(Params...)) {
+  return sizeof...(Params);
+}
+
+#endif  // BOOST_NO_VARIADIC_TEMPLATES
+
+bool CheckedGConnect(
+    gpointer source,
+    const char* signal,
+    GCallback callback,
+    gpointer data,
+    const int callback_param_count);
+
+#ifdef BOOST_NO_VARIADIC_TEMPLATES
+
+template <typename R, typename P0, typename P1, typename P2>
+bool CheckedGConnect(
+    gpointer source, const char* signal, R (*callback)(P0, P1, P2), gpointer data) {
+  return CheckedGConnect(
+      source, signal, G_CALLBACK(callback), data, GetFunctionParamCount(callback));
+}
+
+#else
+
+template <typename R, typename... Params>
+bool CheckedGConnect(
+    gpointer source, const char* signal, R (*callback)(Params...), gpointer data) {
+  return CheckedGConnect(
+      source, signal, G_CALLBACK(callback), data, GetFunctionParamCount(callback));
+}
+
+#endif  // BOOST_NO_VARIADIC_TEMPLATES
+
+#endif  // SIGNALCHECKER_H

src/moodbar/moodbarpipeline.cpp

@@ -16,12 +16,14 @@
 */
 
 #include "moodbarpipeline.h"
-#include "core/logging.h"
 
 #include <QCoreApplication>
 #include <QThread>
 #include <QUrl>
 
+#include "core/logging.h"
+#include "core/signalchecker.h"
+
 bool MoodbarPipeline::sIsAvailable = false;
 
 MoodbarPipeline::MoodbarPipeline(const QUrl& local_filename)
@@ -102,7 +104,8 @@ void MoodbarPipeline::Start() {
                         "max-width", 1000, NULL);
 
   // Connect signals
-  g_signal_connect(decodebin, "pad-added", G_CALLBACK(NewPadCallback), this);
+  CheckedGConnect(
+      decodebin, "pad-added", &NewPadCallback, this);
   gst_bus_set_sync_handler(gst_pipeline_get_bus(GST_PIPELINE(pipeline_)), BusCallbackSync, this);
 
   // Set appsink callbacks