playlist_song: allow references to songs outside the musicdir

When we have an absolute path that's not inside the music directory,
allow loading it anyway, if we're in "secure" mode (i.e. the client is
connected via UNIX socket).

NEWS

@@ -20,6 +20,8 @@ ver 0.17 (2011/??/??)
   - raop: new output plugin
   - shout: add possibility to set url
   - roar: new output plugin for RoarAudio
+* playlist:
+  - allow references to songs outside the music directory
 * state_file: add option "restore_paused"
 * cue: show CUE track numbers
 * allow port specification in "bind_to_address" settings

src/playlist_song.c

@@ -140,6 +140,12 @@ playlist_check_translate_song(struct song *song, const char *base_uri,
 	if (uri_has_scheme(uri)) {
 		dest = song_remote_new(uri);
 		g_free(uri);
+	} else if (g_path_is_absolute(uri) && secure) {
+		dest = song_file_load(uri, NULL);
+		if (dest == NULL) {
+			song_free(song);
+			return NULL;
+		}
 	} else {
 		dest = db_get_song(uri);
 		g_free(uri);