db_print: print absolute URI of playlist entries

The protocol mandates that playlist URIs are absolute (i.e. full URI
relative to the music directory, not relative to the parent
directory).  This adds the parameter "directory" to the "playlist"
visitor method.

src/db_print.c

@@ -73,21 +73,35 @@ print_visitor_song_info(struct song *song, void *data,
 	return true;
 }
 
+static void
+print_playlist_in_directory(struct client *client,
+			    const struct directory *directory,
+			    const char *name_utf8)
+{
+	if (directory_is_root(directory))
+		client_printf(client, "playlist: %s\n", name_utf8);
+	else
+		client_printf(client, "playlist: %s/%s\n",
+			      directory_get_path(directory), name_utf8);
+}
+
 static bool
-print_visitor_playlist(const struct playlist_metadata *playlist, void *ctx,
+print_visitor_playlist(const struct playlist_metadata *playlist,
+		       const struct directory *directory, void *ctx,
 		       G_GNUC_UNUSED GError **error_r)
 {
 	struct client *client = ctx;
-	client_printf(client, "playlist: %s\n", playlist->name);
+	print_playlist_in_directory(client, directory, playlist->name);
 	return true;
 }
 
 static bool
 print_visitor_playlist_info(const struct playlist_metadata *playlist,
+			    const struct directory *directory,
 			    void *ctx, G_GNUC_UNUSED GError **error_r)
 {
 	struct client *client = ctx;
-	client_printf(client, "playlist: %s\n", playlist->name);
+	print_playlist_in_directory(client, directory, playlist->name);
 
 #ifndef G_OS_WIN32
 	struct tm tm;

src/db_visitor.h

@@ -43,9 +43,11 @@ struct db_visitor {
 	/**
 	 * Visit a playlist.  Optional method.
 	 *
+	 * @param directory the directory the playlist resides in
 	 * @return true to continue the operation, false on error (set error_r)
 	 */
-	bool (*playlist)(const struct playlist_metadata *playlist, void *ctx,
+	bool (*playlist)(const struct playlist_metadata *playlist,
+			 const struct directory *directory, void *ctx,
 			 GError **error_r);
 };
 

src/directory.c

@@ -188,7 +188,7 @@ directory_walk(const struct directory *directory, bool recursive,
 		const struct playlist_vector *pv = &directory->playlists;
 		for (const struct playlist_metadata *i = pv->head;
 		     i != NULL; i = i->next)
-			if (!visitor->playlist(i, ctx, error_r))
+			if (!visitor->playlist(i, directory, ctx, error_r))
 				return false;
 	}