Main: load Android mpd.conf from ExternalFilesDir

See also https://github.com/MusicPlayerDaemon/MPD/issues/1061

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1570

NEWS

@@ -10,6 +10,8 @@ ver 0.23.9 (not yet released)
 * fix bogus volume levels with multiple partitions
 * improve iconv detection
 * macOS: fix macOS 10 build problem (0.23.8 regression)
+* Android
+  - load mpd.conf from app data directory
 
 ver 0.23.8 (2022/07/09)
 * storage

doc/user.rst

@@ -36,7 +36,9 @@ Installing on Android
 
 An experimental Android build is available on Google Play. After installing and launching it, :program:`MPD` will scan the music in your Music directory and you can control it as usual with a :program:`MPD` client.
 
-If you need to tweak the configuration, you can create a file called :file:`mpd.conf` on the data partition (the directory which is returned by Android's :dfn:`getExternalStorageDirectory()` API function). 
+If you need to tweak the configuration, you can create a file called
+:file:`mpd.conf` in MPD's data directory on the external storage
+(usually :file:`Android/data/org.musicpd/files/mpd.conf`).
 
 ALSA is not available on Android; only the :ref:`OpenSL ES
 <sles_output>` output plugin can be used for local playback.

src/Main.cxx

@@ -607,6 +607,17 @@ TryReadConfigFile(ConfigData &config, Path path)
 static void
 LoadConfigFile(JNIEnv *env, ConfigData &config)
 {
+	/* try loading mpd.conf from
+	   "Android/data/org.musicpd/files/mpd.conf" (the app specific
+	   data directory) first */
+	if (const auto dir = context->GetExternalFilesDir(env);
+	    !dir.IsNull() &&
+	    TryReadConfigFile(config, dir / Path::FromFS("mpd.conf")))
+		return;
+
+	/* if that fails, attempt to load "mpd.conf" from the root of
+	   the SD card (pre-0.23.9, ceases to work since Android
+	   12) */
 	if (const auto dir = Environment::getExternalStorageDirectory(env);
 	    !dir.IsNull())
 		TryReadConfigFile(config, dir / Path::FromFS("mpd.conf"));