directory: added directory_lookup_song()

Moved code from db_get_song().

src/database.c

@@ -110,10 +110,6 @@ db_get_directory(const char *name)
 struct song *
 db_get_song(const char *file)
 {
-	struct song *song;
-	struct directory *directory;
-	char *duplicated, *shortname, *dir;
-
 	assert(file != NULL);
 
 	g_debug("get song: %s", file);
@@ -121,27 +117,7 @@ db_get_song(const char *file)
 	if (music_root == NULL)
 		return NULL;
 
-	duplicated = g_strdup(file);
-	shortname = strrchr(duplicated, '/');
-	if (!shortname) {
-		shortname = duplicated;
-		dir = NULL;
-	} else {
-		*shortname = '\0';
-		++shortname;
-		dir = duplicated;
-	}
-
-	directory = db_get_directory(dir);
-	if (directory != NULL)
-		song = songvec_find(&directory->songs, shortname);
-	else
-		song = NULL;
-
-	assert(song == NULL || song->parent == directory);
-
-	g_free(duplicated);
-	return song;
+	return directory_lookup_song(music_root, file);
 }
 
 int

src/directory.c

@@ -114,6 +114,36 @@ directory_lookup_directory(struct directory *directory, const char *uri)
 	return found;
 }
 
+struct song *
+directory_lookup_song(struct directory *directory, const char *uri)
+{
+	char *duplicated, *base;
+	struct song *song;
+
+	assert(directory != NULL);
+	assert(uri != NULL);
+
+	duplicated = g_strdup(uri);
+	base = strrchr(duplicated, '/');
+
+	if (base != NULL) {
+		*base++ = 0;
+		directory = directory_lookup_directory(directory, duplicated);
+		if (directory == NULL) {
+			g_free(duplicated);
+			return NULL;
+		}
+	} else
+		base = duplicated;
+
+	song = songvec_find(&directory->songs, base);
+	assert(song == NULL || song->parent == directory);
+
+	g_free(duplicated);
+	return song;
+
+}
+
 void
 directory_sort(struct directory *directory)
 {

src/directory.h

@@ -108,6 +108,16 @@ directory_prune_empty(struct directory *directory);
 struct directory *
 directory_lookup_directory(struct directory *directory, const char *uri);
 
+/**
+ * Looks up a song by its relative URI.
+ *
+ * @param directory the parent (or grandparent, ...) directory
+ * @param uri the relative URI
+ * @return the song, or NULL if none was found
+ */
+struct song *
+directory_lookup_song(struct directory *directory, const char *uri);
+
 void
 directory_sort(struct directory *directory);