path: root/src/decoder/FLACMetaData.cxx

/*
 * Copyright (C) 2003-2012 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 "FLACMetaData.hxx"

extern "C" {
#include "XiphTags.h"
#include "replay_gain_info.h"
#include "tag.h"
}

#include "tag_handler.h"
#include "tag_table.h"

#include <glib.h>

#include <assert.h>
#include <stdbool.h>
#include <stdlib.h>

static bool
flac_find_float_comment(const FLAC__StreamMetadata *block,
			const char *cmnt, float *fl)
{
	int offset;
	size_t pos;
	int len;
	unsigned char tmp, *p;

	offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, 0,
								     cmnt);
	if (offset < 0)
		return false;

	pos = strlen(cmnt) + 1; /* 1 is for '=' */
	len = block->data.vorbis_comment.comments[offset].length - pos;
	if (len <= 0)
		return false;

	p = &block->data.vorbis_comment.comments[offset].entry[pos];
	tmp = p[len];
	p[len] = '\0';
	*fl = (float)atof((char *)p);
	p[len] = tmp;

	return true;
}

bool
flac_parse_replay_gain(struct replay_gain_info *rgi,
		       const FLAC__StreamMetadata *block)
{
	bool found = false;

	replay_gain_info_init(rgi);

	if (flac_find_float_comment(block, "replaygain_album_gain",
				    &rgi->tuples[REPLAY_GAIN_ALBUM].gain))
		found = true;
	if (flac_find_float_comment(block, "replaygain_album_peak",
				    &rgi->tuples[REPLAY_GAIN_ALBUM].peak))
		found = true;
	if (flac_find_float_comment(block, "replaygain_track_gain",
				    &rgi->tuples[REPLAY_GAIN_TRACK].gain))
		found = true;
	if (flac_find_float_comment(block, "replaygain_track_peak",
				    &rgi->tuples[REPLAY_GAIN_TRACK].peak))
		found = true;

	return found;
}

static bool
flac_find_string_comment(const FLAC__StreamMetadata *block,
			 const char *cmnt, char **str)
{
	int offset;
	size_t pos;
	int len;
	const unsigned char *p;

	*str = nullptr;
	offset = FLAC__metadata_object_vorbiscomment_find_entry_from(block, 0,
								     cmnt);
	if (offset < 0)
		return false;

	pos = strlen(cmnt) + 1; /* 1 is for '=' */
	len = block->data.vorbis_comment.comments[offset].length - pos;
	if (len <= 0)
		return false;

	p = &block->data.vorbis_comment.comments[offset].entry[pos];
	*str = g_strndup((const char *)p, len);

	return true;
}

bool
flac_parse_mixramp(char **mixramp_start, char **mixramp_end,
		   const FLAC__StreamMetadata *block)
{
	bool found = false;

	if (flac_find_string_comment(block, "mixramp_start", mixramp_start))
		found = true;
	if (flac_find_string_comment(block, "mixramp_end", mixramp_end))
		found = true;

	return found;
}

/**
 * Checks if the specified name matches the entry's name, and if yes,
 * returns the comment value (not null-temrinated).
 */
static const char *
flac_comment_value(const FLAC__StreamMetadata_VorbisComment_Entry *entry,
		   const char *name, const char *char_tnum, size_t *length_r)
{
	size_t name_length = strlen(name);
	size_t char_tnum_length = 0;
	const char *comment = (const char*)entry->entry;

	if (entry->length <= name_length ||
	    g_ascii_strncasecmp(comment, name, name_length) != 0)
		return nullptr;

	if (char_tnum != nullptr) {
		char_tnum_length = strlen(char_tnum);
		if (entry->length > name_length + char_tnum_length + 2 &&
		    comment[name_length] == '[' &&
		    g_ascii_strncasecmp(comment + name_length + 1,
					char_tnum, char_tnum_length) == 0 &&
		    comment[name_length + char_tnum_length + 1] == ']')
			name_length = name_length + char_tnum_length + 2;
		else if (entry->length > name_length + char_tnum_length &&
			 g_ascii_strncasecmp(comment + name_length,
					     char_tnum, char_tnum_length) == 0)
			name_length = name_length + char_tnum_length;
	}

	if (comment[name_length] == '=') {
		*length_r = entry->length - name_length - 1;
		return comment + name_length + 1;
	}

	return nullptr;
}

/**
 * Check if the comment's name equals the passed name, and if so, copy
 * the comment value into the tag.
 */
static bool
flac_copy_comment(const FLAC__StreamMetadata_VorbisComment_Entry *entry,
		  const char *name, enum tag_type tag_type,
		  const char *char_tnum,
		  const struct tag_handler *handler, void *handler_ctx)
{
	const char *value;
	size_t value_length;

	value = flac_comment_value(entry, name, char_tnum, &value_length);
	if (value != nullptr) {
		char *p = g_strndup(value, value_length);
		tag_handler_invoke_tag(handler, handler_ctx, tag_type, p);
		g_free(p);
		return true;
	}

	return false;
}

static void
flac_scan_comment(const char *char_tnum,
		  const FLAC__StreamMetadata_VorbisComment_Entry *entry,
		  const struct tag_handler *handler, void *handler_ctx)
{
	if (handler->pair != nullptr) {
		char *name = g_strdup((const char*)entry->entry);
		char *value = strchr(name, '=');

		if (value != nullptr && value > name) {
			*value++ = 0;
			tag_handler_invoke_pair(handler, handler_ctx,
						name, value);
		}

		g_free(name);
	}

	for (const struct tag_table *i = xiph_tags; i->name != nullptr; ++i)
		if (flac_copy_comment(entry, i->name, i->type, char_tnum,
				      handler, handler_ctx))
			return;

	for (unsigned i = 0; i < TAG_NUM_OF_ITEM_TYPES; ++i)
		if (flac_copy_comment(entry,
				      tag_item_names[i], (enum tag_type)i,
				      char_tnum,
				      handler, handler_ctx))
			return;
}

static void
flac_scan_comments(const char *char_tnum,
		   const FLAC__StreamMetadata_VorbisComment *comment,
		   const struct tag_handler *handler, void *handler_ctx)
{
	for (unsigned i = 0; i < comment->num_comments; ++i)
		flac_scan_comment(char_tnum, &comment->comments[i],
				  handler, handler_ctx);
}

void
flac_scan_metadata(const char *track,
		   const FLAC__StreamMetadata *block,
		   const struct tag_handler *handler, void *handler_ctx)
{
	switch (block->type) {
	case FLAC__METADATA_TYPE_VORBIS_COMMENT:
		flac_scan_comments(track, &block->data.vorbis_comment,
				   handler, handler_ctx);
		break;

	case FLAC__METADATA_TYPE_STREAMINFO:
		if (block->data.stream_info.sample_rate > 0)
			tag_handler_invoke_duration(handler, handler_ctx,
						    flac_duration(&block->data.stream_info));
		break;

	default:
		break;
	}
}

void
flac_vorbis_comments_to_tag(struct tag *tag, const char *char_tnum,
			    const FLAC__StreamMetadata_VorbisComment *comment)
{
	flac_scan_comments(char_tnum, comment,
			   &add_tag_handler, tag);
}

bool
flac_scan_file2(const char *file, const char *char_tnum,
		const struct tag_handler *handler, void *handler_ctx)
{
	FLAC__Metadata_SimpleIterator *it;
	FLAC__StreamMetadata *block = nullptr;

	it = FLAC__metadata_simple_iterator_new();
	if (!FLAC__metadata_simple_iterator_init(it, file, 1, 0)) {
		const char *err;
		FLAC_API FLAC__Metadata_SimpleIteratorStatus s;

		s = FLAC__metadata_simple_iterator_status(it);

		switch (s) { /* slightly more human-friendly messages: */
		case FLAC__METADATA_SIMPLE_ITERATOR_STATUS_ILLEGAL_INPUT:
			err = "illegal input";
			break;
		case FLAC__METADATA_SIMPLE_ITERATOR_STATUS_ERROR_OPENING_FILE:
			err = "error opening file";
			break;
		case FLAC__METADATA_SIMPLE_ITERATOR_STATUS_NOT_A_FLAC_FILE:
			err = "not a FLAC file";
			break;
		default:
			err = FLAC__Metadata_SimpleIteratorStatusString[s];
		}
		g_debug("Reading '%s' metadata gave the following error: %s\n",
			file, err);
		FLAC__metadata_simple_iterator_delete(it);
		return false;
	}

	do {
		block = FLAC__metadata_simple_iterator_get_block(it);
		if (!block)
			break;

		flac_scan_metadata(char_tnum, block, handler, handler_ctx);
		FLAC__metadata_object_delete(block);
	} while (FLAC__metadata_simple_iterator_next(it));

	FLAC__metadata_simple_iterator_delete(it);

	return true;
}

struct tag *
flac_tag_load(const char *file, const char *char_tnum)
{
	struct tag *tag = tag_new();

	if (!flac_scan_file2(file, char_tnum, &add_tag_handler, tag) ||
	    tag_is_empty(tag)) {
		tag_free(tag);
		tag = nullptr;
	}

	return tag;
}