Cope with removable media changing mount point

src/devices/connecteddevice.cpp

@@ -46,7 +46,6 @@ ConnectedDevice::ConnectedDevice(DeviceLister* lister, const QString& unique_id,
 
   // Create the model
   model_ = new LibraryModel(backend_, this);
-  model_->Init();
 }
 
 ConnectedDevice::~ConnectedDevice() {

src/devices/filesystemdevice.cpp

@@ -58,8 +58,26 @@ FilesystemDevice::FilesystemDevice(
 
   if (first_time)
     backend_->AddDirectory(mount_point);
-  else
+  else {
+    // This is a bit of a hack.  The device might not be mounted at the same
+    // path each time, so if it's different we have to munge all the paths in
+    // the database to fix it.  This can be done entirely in sqlite so it's
+    // relatively fast...
+
+    // Get the directory it was mounted at last time.  Devices only have one
+    // directory (the root).
+    Directory dir = backend_->GetAllDirectories()[0];
+    if (dir.path != mount_point) {
+      // The directory is different, commence the munging.
+      qDebug() << "Changing path from" << dir.path << "to" << mount_point;
+      backend_->ChangeDirPath(dir.id, mount_point);
+    }
+
+    // Load the directory properly now, this signals the watcher as well.
     backend_->LoadDirectoriesAsync();
+  }
+
+  model_->Init();
 }
 
 FilesystemDevice::~FilesystemDevice() {

src/library/librarybackend.cpp

@@ -49,20 +49,67 @@ void LibraryBackend::UpdateTotalSongCountAsync() {
 }
 
 void LibraryBackend::LoadDirectories() {
+  DirectoryList dirs = GetAllDirectories();
+
   QMutexLocker l(db_->Mutex());
   QSqlDatabase db(db_->Connect());
 
-  QSqlQuery q(QString("SELECT ROWID, path FROM %1").arg(dirs_table_), db);
+  foreach (const Directory& dir, dirs) {
+    emit DirectoryDiscovered(dir, SubdirsInDirectory(dir.id, db));
+  }
+}
+
+void LibraryBackend::ChangeDirPath(int id, const QString &new_path) {
+  QMutexLocker l(db_->Mutex());
+  QSqlDatabase db(db_->Connect());
+  ScopedTransaction t(&db);
+
+  // Do the dirs table
+  QSqlQuery q(QString("UPDATE %1 SET path=:path WHERE ROWID=:id").arg(dirs_table_), db);
+  q.bindValue(":path", new_path);
+  q.bindValue(":id", id);
   q.exec();
   if (db_->CheckErrors(q.lastError())) return;
 
+  const int path_len = new_path.length();
+
+  // Do the subdirs table
+  q = QSqlQuery(QString("UPDATE %1 SET path=:path || substr(path, %2)"
+                        " WHERE directory=:id").arg(subdirs_table_).arg(path_len), db);
+  q.bindValue(":path", new_path);
+  q.bindValue(":id", id);
+  q.exec();
+  if (db_->CheckErrors(q.lastError())) return;
+
+  // Do the songs table
+  q = QSqlQuery(QString("UPDATE %1 SET filename=:path || substr(filename, %2)"
+                        " WHERE directory=:id").arg(songs_table_).arg(path_len), db);
+  q.bindValue(":path", new_path);
+  q.bindValue(":id", id);
+  q.exec();
+  if (db_->CheckErrors(q.lastError())) return;
+
+  t.Commit();
+}
+
+DirectoryList LibraryBackend::GetAllDirectories() {
+  QMutexLocker l(db_->Mutex());
+  QSqlDatabase db(db_->Connect());
+
+  DirectoryList ret;
+
+  QSqlQuery q(QString("SELECT ROWID, path FROM %1").arg(dirs_table_), db);
+  q.exec();
+  if (db_->CheckErrors(q.lastError())) return ret;
+
   while (q.next()) {
     Directory dir;
     dir.id = q.value(0).toInt();
     dir.path = q.value(1).toString();
 
-    emit DirectoryDiscovered(dir, SubdirsInDirectory(dir.id, db));
+    ret << dir;
   }
+  return ret;
 }
 
 SubdirectoryList LibraryBackend::SubdirsInDirectory(int id) {

src/library/librarybackend.h

@@ -66,6 +66,8 @@ class LibraryBackend : public QObject {
 
   SongList FindSongsInDirectory(int id);
   SubdirectoryList SubdirsInDirectory(int id);
+  DirectoryList GetAllDirectories();
+  void ChangeDirPath(int id, const QString& new_path);
 
   QStringList GetAllArtists(const QueryOptions& opt = QueryOptions());
   QStringList GetAllArtistsWithAlbums(const QueryOptions& opt = QueryOptions());