format.c

在x86平台上运行不可信任代码的sandbox。

			if(!first) {
				if(seek_table->points[i].sample_number == seek_table->points[j-1].sample_number)
					continue;
			}
		}
		first = false;
		seek_table->points[j++] = seek_table->points[i];
	}

	for(i = j; i < seek_table->num_points; i++) {
		seek_table->points[i].sample_number = FLAC__STREAM_METADATA_SEEKPOINT_PLACEHOLDER;
		seek_table->points[i].stream_offset = 0;
		seek_table->points[i].frame_samples = 0;
	}

	return j;
}

static __inline unsigned utf8len_(const FLAC__byte *utf8)
{
	FLAC__ASSERT(0 != utf8);
	if ((utf8[0] & 0x80) == 0)
		return 1;
	else if ((utf8[0] & 0xE0) == 0xC0 && (utf8[1] & 0xC0) == 0x80)
		return 2;
	else if ((utf8[0] & 0xF0) == 0xE0 && (utf8[1] & 0xC0) == 0x80 && (utf8[2] & 0xC0) == 0x80)
		return 3;
	else
		return 0;
}

FLAC_API FLAC__bool FLAC__format_vorbiscomment_entry_name_is_legal(const char *name)
{
	char c;
	for(c = *name; c; c = *(++name))
		if(c < 0x20 || c == 0x3d || c > 0x7d)
			return false;
	return true;
}

FLAC_API FLAC__bool FLAC__format_vorbiscomment_entry_value_is_legal(const FLAC__byte *value, unsigned length)
{
	if(length == (unsigned)(-1)) {
		while(*value) {
			unsigned n = utf8len_(value);
			if(n == 0)
				return false;
			value += n;
		}
	}
	else {
		const FLAC__byte *end = value + length;
		while(value < end) {
			unsigned n = utf8len_(value);
			if(n == 0)
				return false;
			value += n;
		}
		if(value != end)
			return false;
	}
	return true;
}

FLAC_API FLAC__bool FLAC__format_vorbiscomment_entry_is_legal(const FLAC__byte *entry, unsigned length)
{
	const FLAC__byte *s, *end;

	for(s = entry, end = s + length; s < end && *s != '='; s++) {
		if(*s < 0x20 || *s > 0x7D)
			return false;
	}
	if(s == end)
		return false;

	s++; /* skip '=' */

	while(s < end) {
		unsigned n = utf8len_(s);
		if(n == 0)
			return false;
		s += n;
	}
	if(s != end)
		return false;

	return true;
}

FLAC_API FLAC__bool FLAC__format_cuesheet_is_legal(const FLAC__StreamMetadata_CueSheet *cue_sheet, FLAC__bool check_cd_da_subset, const char **violation)
{
	unsigned i, j;

	if(check_cd_da_subset) {
		if(cue_sheet->lead_in < 2 * 44100) {
			if(violation) *violation = "CD-DA cue sheet must have a lead-in length of at least 2 seconds";
			return false;
		}
		if(cue_sheet->lead_in % 588 != 0) {
			if(violation) *violation = "CD-DA cue sheet lead-in length must be evenly divisible by 588 samples";
			return false;
		}
	}

	if(cue_sheet->num_tracks == 0) {
		if(violation) *violation = "cue sheet must have at least one track (the lead-out)";
		return false;
	}

	if(check_cd_da_subset && cue_sheet->tracks[cue_sheet->num_tracks-1].number != 170) {
		if(violation) *violation = "CD-DA cue sheet must have a lead-out track number 170 (0xAA)";
		return false;
	}

	for(i = 0; i < cue_sheet->num_tracks; i++) {
		if(cue_sheet->tracks[i].number == 0) {
			if(violation) *violation = "cue sheet may not have a track number 0";
			return false;
		}

		if(check_cd_da_subset) {
			if(!((cue_sheet->tracks[i].number >= 1 && cue_sheet->tracks[i].number <= 99) || cue_sheet->tracks[i].number == 170)) {
				if(violation) *violation = "CD-DA cue sheet track number must be 1-99 or 170";
				return false;
			}
		}

		if(check_cd_da_subset && cue_sheet->tracks[i].offset % 588 != 0) {
			if(violation) *violation = "CD-DA cue sheet track offset must be evenly divisible by 588 samples";
			return false;
		}

		if(i < cue_sheet->num_tracks - 1) {
			if(cue_sheet->tracks[i].num_indices == 0) {
				if(violation) *violation = "cue sheet track must have at least one index point";
				return false;
			}

			if(cue_sheet->tracks[i].indices[0].number > 1) {
				if(violation) *violation = "cue sheet track's first index number must be 0 or 1";
				return false;
			}
		}

		for(j = 0; j < cue_sheet->tracks[i].num_indices; j++) {
			if(check_cd_da_subset && cue_sheet->tracks[i].indices[j].offset % 588 != 0) {
				if(violation) *violation = "CD-DA cue sheet track index offset must be evenly divisible by 588 samples";
				return false;
			}

			if(j > 0) {
				if(cue_sheet->tracks[i].indices[j].number != cue_sheet->tracks[i].indices[j-1].number + 1) {
					if(violation) *violation = "cue sheet track index numbers must increase by 1";
					return false;
				}
			}
		}
	}

	return true;
}

/*
 * These routines are private to libFLAC
 */
unsigned FLAC__format_get_max_rice_partition_order(unsigned blocksize, unsigned predictor_order)
{
	return
		FLAC__format_get_max_rice_partition_order_from_blocksize_limited_max_and_predictor_order(
			FLAC__format_get_max_rice_partition_order_from_blocksize(blocksize),
			blocksize,
			predictor_order
		);
}

unsigned FLAC__format_get_max_rice_partition_order_from_blocksize(unsigned blocksize)
{
	unsigned max_rice_partition_order = 0;
	while(!(blocksize & 1)) {
		max_rice_partition_order++;
		blocksize >>= 1;
	}
	return min(FLAC__MAX_RICE_PARTITION_ORDER, max_rice_partition_order);
}

unsigned FLAC__format_get_max_rice_partition_order_from_blocksize_limited_max_and_predictor_order(unsigned limit, unsigned blocksize, unsigned predictor_order)
{
	unsigned max_rice_partition_order = limit;

	while(max_rice_partition_order > 0 && (blocksize >> max_rice_partition_order) <= predictor_order)
		max_rice_partition_order--;

	FLAC__ASSERT(
		(max_rice_partition_order == 0 && blocksize >= predictor_order) ||
		(max_rice_partition_order > 0 && blocksize >> max_rice_partition_order > predictor_order)
	);

	return max_rice_partition_order;
}

void FLAC__format_entropy_coding_method_partitioned_rice_contents_init(FLAC__EntropyCodingMethod_PartitionedRiceContents *object)
{
	FLAC__ASSERT(0 != object);

	object->parameters = 0;
	object->raw_bits = 0;
	object->capacity_by_order = 0;
}

void FLAC__format_entropy_coding_method_partitioned_rice_contents_clear(FLAC__EntropyCodingMethod_PartitionedRiceContents *object)
{
	FLAC__ASSERT(0 != object);

	if(0 != object->parameters)
		free(object->parameters);
	if(0 != object->raw_bits)
		free(object->raw_bits);
	FLAC__format_entropy_coding_method_partitioned_rice_contents_init(object);
}

FLAC__bool FLAC__format_entropy_coding_method_partitioned_rice_contents_ensure_size(FLAC__EntropyCodingMethod_PartitionedRiceContents *object, unsigned max_partition_order)
{
	FLAC__ASSERT(0 != object);

	FLAC__ASSERT(object->capacity_by_order > 0 || (0 == object->parameters && 0 == object->raw_bits));

	if(object->capacity_by_order < max_partition_order) {
		if(0 == (object->parameters = (unsigned*)realloc(object->parameters, sizeof(unsigned)*(1 << max_partition_order))))
			return false;
		if(0 == (object->raw_bits = (unsigned*)realloc(object->raw_bits, sizeof(unsigned)*(1 << max_partition_order))))
			return false;
		object->capacity_by_order = max_partition_order;
	}

	return true;
}