Add better error handling for CDDA loader

src/device/cddasongloader.cpp

@@ -67,6 +67,7 @@ void CddaSongLoader::LoadSongs() {
   QMutexLocker locker(&mutex_load_);
   cdio_ = cdio_open(url_.path().toLocal8Bit().constData(), DRIVER_DEVICE);
   if (cdio_ == nullptr) {
+    Error("Unable to open CDIO device.");
     return;
   }
 
@@ -74,7 +75,7 @@ void CddaSongLoader::LoadSongs() {
   GError *error = nullptr;
   cdda_ = gst_element_make_from_uri(GST_URI_SRC, "cdda://", nullptr, &error);
   if (error) {
-    qLog(Error) << error->code << error->message;
+    Error(QString("%1: %2").arg(error->code).arg(error->message));
   }
   if (cdda_ == nullptr) {
     return;
@@ -84,13 +85,23 @@ void CddaSongLoader::LoadSongs() {
     g_object_set(cdda_, "device", g_strdup(url_.path().toLocal8Bit().constData()), nullptr);
   }
   if (g_object_class_find_property (G_OBJECT_GET_CLASS (cdda_), "paranoia-mode")) {
-    g_object_set (cdda_, "paranoia-mode", 0, nullptr);
+    g_object_set(cdda_, "paranoia-mode", 0, nullptr);
   }
 
   // Change the element's state to ready and paused, to be able to query it
-  if (gst_element_set_state(cdda_, GST_STATE_READY) == GST_STATE_CHANGE_FAILURE || gst_element_set_state(cdda_, GST_STATE_PAUSED) == GST_STATE_CHANGE_FAILURE) {
+  if (gst_element_set_state(cdda_, GST_STATE_READY) == GST_STATE_CHANGE_FAILURE) {
     gst_element_set_state(cdda_, GST_STATE_NULL);
     gst_object_unref(GST_OBJECT(cdda_));
+    cdda_ = nullptr;
+    Error(tr("Error while setting CDDA device to ready state."));
+    return;
+  }
+
+  if (gst_element_set_state(cdda_, GST_STATE_PAUSED) == GST_STATE_CHANGE_FAILURE) {
+    gst_element_set_state(cdda_, GST_STATE_NULL);
+    gst_object_unref(GST_OBJECT(cdda_));
+    cdda_ = nullptr;
+    Error(tr("Error while setting CDDA device to pause state."));
     return;
   }
 
@@ -98,9 +109,20 @@ void CddaSongLoader::LoadSongs() {
   GstFormat fmt = gst_format_get_by_nick("track");
   GstFormat out_fmt = fmt;
   gint64 num_tracks = 0;
-  if (!gst_element_query_duration(cdda_, out_fmt, &num_tracks) || out_fmt != fmt) {
-    qLog(Error) << "Error while querying cdda GstElement";
+  if (!gst_element_query_duration(cdda_, out_fmt, &num_tracks)) {
+    gst_element_set_state(cdda_, GST_STATE_NULL);
     gst_object_unref(GST_OBJECT(cdda_));
+    cdda_ = nullptr;
+    Error(tr("Error while querying CDDA tracks."));
+    return;
+  }
+
+  if (out_fmt != fmt) {
+    qLog(Error) << "Error while querying cdda GstElement (2).";
+    gst_element_set_state(cdda_, GST_STATE_NULL);
+    gst_object_unref(GST_OBJECT(cdda_));
+    cdda_ = nullptr;
+    Error(tr("Error while querying CDDA tracks."));
     return;
   }
 
@@ -232,3 +254,9 @@ bool CddaSongLoader::HasChanged() {
 
 }
 
+void CddaSongLoader::Error(const QString &error) {
+
+  qLog(Error) << error;
+  emit SongsDurationLoaded(SongList(), error);
+
+}

src/device/cddasongloader.h

@@ -44,19 +44,21 @@ class CddaSongLoader : public QObject {
   Q_OBJECT
 
  public:
-  CddaSongLoader(
-      // Url of the CD device. Will use the default device if empty
-      const QUrl &url = QUrl(),
-      QObject *parent = nullptr);
+  explicit CddaSongLoader(const QUrl &url = QUrl(), QObject *parent = nullptr);
   ~CddaSongLoader();
 
   // Load songs. Signals declared below will be emitted anytime new information will be available.
   void LoadSongs();
   bool HasChanged();
 
+ private:
+  void Error(const QString &error);
+  QUrl GetUrlFromTrack(const int track_number) const;
+
  signals:
+  void SongsLoadError(const QString &error);
   void SongsLoaded(const SongList &songs);
-  void SongsDurationLoaded(const SongList &songs);
+  void SongsDurationLoaded(const SongList &songs, const QString &error = QString());
   void SongsMetadataLoaded(const SongList &songs);
 
  private slots:
@@ -65,8 +67,6 @@ class CddaSongLoader : public QObject {
 #endif
 
  private:
-  QUrl GetUrlFromTrack(int track_number) const;
-
   QUrl url_;
   GstElement *cdda_;
   CdIo_t *cdio_;
@@ -74,4 +74,3 @@ class CddaSongLoader : public QObject {
 };
 
 #endif // CDDASONGLOADER_H
-