playlist: moved saving/loading code to queue_save.c

Create a new library which saves/loads the queue to/from the state
file.

src/queue_save.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2003-2009 The Music Player Daemon Project
+ * http://www.musicpd.org
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+
+#include "queue_save.h"
+#include "queue.h"
+#include "song.h"
+#include "ls.h"
+#include "database.h"
+
+#include <stdlib.h>
+
+void
+queue_save(FILE *fp, const struct queue *queue)
+{
+	for (unsigned i = 0; i < queue_length(queue); i++) {
+		const struct song *song = queue_get(queue, i);
+		char *uri = song_get_uri(song);
+
+		fprintf(fp, "%i:%s\n", i, uri);
+		g_free(uri);
+	}
+}
+
+static struct song *
+get_song(const char *uri)
+{
+	struct song *song;
+
+	song = db_get_song(uri);
+	if (song != NULL)
+		return song;
+
+	if (uri_has_scheme(uri))
+		return song_remote_new(uri);
+
+	return NULL;
+}
+
+int
+queue_load_song(struct queue *queue, const char *line)
+{
+	long ret;
+	char *endptr;
+	struct song *song;
+
+	if (queue_is_full(queue))
+		return -1;
+
+	ret = strtol(line, &endptr, 10);
+	if (ret < 0 || *endptr != ':' || endptr[1] == 0) {
+		g_warning("Malformed playlist line in state file");
+		return -1;
+	}
+
+	line = endptr + 1;
+
+	song = get_song(line);
+	if (song == NULL)
+		return -1;
+
+	queue_append(queue, song);
+	return ret;
+}