playlist/flac: re-add the plugin

This reverts commit d7d9dbd2c2798b6ff39acb07a3bed38b6f99e283 by
reimplementing it with the current MPD API.

3 years ago, I was wrong about the "embcue" plugin being able to
replace this one, because "embcue" reads a tag named "CUESHEET", while
this plugin reads the "CUESHEET" FLAC metablock.  There's an important
difference between those two!

1 files changed, 135 insertions, 0 deletions

diff --git a/src/playlist/plugins/FlacPlaylistPlugin.cxx b/src/playlist/plugins/FlacPlaylistPlugin.cxx
new file mode 100644
index 000000000..19b77ef32
--- /dev/null
+++ b/src/playlist/plugins/FlacPlaylistPlugin.cxx
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2003-2015 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.
+ */
+
+/** \file
+ *
+ * Playlist plugin that reads embedded cue sheets from the "CUESHEET"
+ * tag of a music file.
+ */
+
+#include "config.h"
+#include "FlacPlaylistPlugin.hxx"
+#include "../PlaylistPlugin.hxx"
+#include "../SongEnumerator.hxx"
+#include "DetachedSong.hxx"
+#include "fs/Traits.hxx"
+#include "fs/AllocatedPath.hxx"
+#include "fs/NarrowPath.hxx"
+
+#include <FLAC/metadata.h>
+
+#include <string.h>
+
+class FlacPlaylist final : public SongEnumerator {
+	const char *const uri;
+
+	FLAC__StreamMetadata *const cuesheet;
+	const unsigned sample_rate;
+	const FLAC__uint64 total_samples;
+
+	unsigned next_track = 0;
+
+public:
+	FlacPlaylist(const char *_uri,
+		     FLAC__StreamMetadata *_cuesheet,
+		     const FLAC__StreamMetadata &streaminfo)
+		:uri(_uri), cuesheet(_cuesheet),
+		 sample_rate(streaminfo.data.stream_info.sample_rate),
+		 total_samples(streaminfo.data.stream_info.total_samples) {
+	}
+
+	virtual ~FlacPlaylist() {
+		FLAC__metadata_object_delete(cuesheet);
+	}
+
+	virtual DetachedSong *NextSong() override;
+};
+
+DetachedSong *
+FlacPlaylist::NextSong()
+{
+	const FLAC__StreamMetadata_CueSheet &c = cuesheet->data.cue_sheet;
+
+	/* find the next audio track */
+
+	while (next_track < c.num_tracks &&
+	       (c.tracks[next_track].number > c.num_tracks ||
+		c.tracks[next_track].type != 0))
+		++next_track;
+
+	if (next_track >= c.num_tracks)
+		return nullptr;
+
+	FLAC__uint64 start = c.tracks[next_track].offset;
+	++next_track;
+	FLAC__uint64 end = next_track < c.num_tracks
+		? c.tracks[next_track].offset
+		: total_samples;
+
+	auto *song = new DetachedSong(uri);
+	song->SetStartTime(SongTime::FromScale(start, sample_rate));
+	song->SetEndTime(SongTime::FromScale(end, sample_rate));
+	return song;
+}
+
+static SongEnumerator *
+flac_playlist_open_uri(const char *uri,
+		       gcc_unused Mutex &mutex, gcc_unused Cond &cond)
+{
+	if (!PathTraitsUTF8::IsAbsolute(uri))
+		/* only local files supported */
+		return nullptr;
+
+	const auto path_fs = AllocatedPath::FromUTF8(uri);
+	if (path_fs.IsNull())
+		return nullptr;
+
+	const NarrowPath narrow_path_fs(path_fs);
+
+	FLAC__StreamMetadata *cuesheet;
+	if (!FLAC__metadata_get_cuesheet(narrow_path_fs, &cuesheet))
+		return nullptr;
+
+	FLAC__StreamMetadata streaminfo;
+	if (!FLAC__metadata_get_streaminfo(uri, &streaminfo) ||
+	    streaminfo.data.stream_info.sample_rate == 0) {
+		FLAC__metadata_object_delete(cuesheet);
+		return nullptr;
+	}
+
+	return new FlacPlaylist(uri, cuesheet, streaminfo);
+}
+
+static const char *const flac_playlist_suffixes[] = {
+	"flac",
+	nullptr
+};
+
+const struct playlist_plugin flac_playlist_plugin = {
+	"flac",
+
+	nullptr,
+	nullptr,
+	flac_playlist_open_uri,
+	nullptr,
+
+	nullptr,
+	flac_playlist_suffixes,
+	nullptr,
+};