Main: playlist_directory defaults to "/sdcard/Android/data/org.musicpd/files/playlists"

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1233

NEWS

@@ -7,6 +7,7 @@ ver 0.22.11 (not yet released)
   - ffmpeg: support double-precision samples (by converting to single precision)
 * Android
   - build with NDK r23
+  - playlist_directory defaults to "/sdcard/Android/data/org.musicpd/files/playlists"
 
 ver 0.22.10 (2021/08/06)
 * protocol

src/Main.cxx

@@ -157,7 +157,17 @@ glue_daemonize_init(const struct options *options,
 static void
 glue_mapper_init(const ConfigData &config)
 {
-	mapper_init(config.GetPath(ConfigOption::PLAYLIST_DIR));
+	auto playlist_directory = config.GetPath(ConfigOption::PLAYLIST_DIR);
+
+#ifdef ANDROID
+	/* if there is no explicit configuration, store playlists in
+	   "/sdcard/Android/data/org.musicpd/files/playlists" */
+	if (playlist_directory.IsNull())
+		playlist_directory = context->GetExternalFilesDir(Java::GetEnv(),
+								  "playlists");
+#endif
+
+	mapper_init(std::move(playlist_directory));
 }
 
 #ifdef ENABLE_DATABASE