SongUpdate: read tags from songs in an archive

Add the TagStream.cxx library, similar to TagFile.cxx, and use it to
load tags from song files inside archives.

1 files changed, 78 insertions, 0 deletions

diff --git a/src/TagStream.cxx b/src/TagStream.cxx
new file mode 100644
index 000000000..8fc1f3312
--- /dev/null
+++ b/src/TagStream.cxx
@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2003-2013 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.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include "config.h"
+#include "TagStream.hxx"
+#include "util/UriUtil.hxx"
+#include "util/Error.hxx"
+#include "DecoderList.hxx"
+#include "DecoderPlugin.hxx"
+#include "InputStream.hxx"
+#include "thread/Mutex.hxx"
+#include "thread/Cond.hxx"
+
+#include <assert.h>
+
+/**
+ * Does the #DecoderPlugin support either the suffix or the MIME type?
+ */
+gcc_pure
+static bool
+CheckDecoderPlugin(const DecoderPlugin &plugin,
+		   const char *suffix, const char *mime)
+{
+	return (mime != nullptr && plugin.SupportsMimeType(mime)) ||
+		(suffix != nullptr && plugin.SupportsSuffix(suffix));
+}
+
+bool
+tag_stream_scan(InputStream &is, const tag_handler &handler, void *ctx)
+{
+	assert(is.ready);
+
+	const char *const suffix = uri_get_suffix(is.uri.c_str());
+	const char *const mime = is.mime.empty() ? nullptr : is.mime.c_str();
+
+	if (suffix == nullptr && mime == nullptr)
+		return false;
+
+	return decoder_plugins_try([suffix, mime, &is,
+				    &handler, ctx](const DecoderPlugin &plugin){
+			is.LockRewind(IgnoreError());
+
+			return CheckDecoderPlugin(plugin, suffix, mime) &&
+				plugin.ScanStream(is, handler, ctx);
+		});
+}
+
+bool
+tag_stream_scan(const char *uri, const tag_handler &handler, void *ctx)
+{
+	Mutex mutex;
+	Cond cond;
+
+	InputStream *is = InputStream::OpenReady(uri, mutex, cond,
+						 IgnoreError());
+	if (is == nullptr)
+		return false;
+
+	bool success = tag_stream_scan(*is, handler, ctx);
+	is->Close();
+	return success;
+}