metadata_iterators.c

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	return iterator->type;
}

FLAC_API FLAC__StreamMetadata *FLAC__metadata_simple_iterator_get_block(FLAC__Metadata_SimpleIterator *iterator)
{
	FLAC__StreamMetadata *block = FLAC__metadata_object_new(iterator->type);

	FLAC__ASSERT(0 != iterator);
	FLAC__ASSERT(0 != iterator->file);

	if(0 != block) {
		block->is_last = iterator->is_last;
		block->length = iterator->length;

		if(!read_metadata_block_data_(iterator, block)) {
			FLAC__metadata_object_delete(block);
			return 0;
		}

		/* back up to the beginning of the block data to stay consistent */
		if(0 != fseek(iterator->file, iterator->offset[iterator->depth] + FLAC__STREAM_METADATA_HEADER_LENGTH, SEEK_SET)) {
			iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_SEEK_ERROR;
			FLAC__metadata_object_delete(block);
			return 0;
		}
	}
	else
		iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_MEMORY_ALLOCATION_ERROR;

	return block;
}

FLAC_API FLAC__bool FLAC__metadata_simple_iterator_set_block(FLAC__Metadata_SimpleIterator *iterator, FLAC__StreamMetadata *block, FLAC__bool use_padding)
{
	FLAC__ASSERT_DECLARATION(long debug_target_offset = iterator->offset[iterator->depth];)
	FLAC__bool ret;

	FLAC__ASSERT(0 != iterator);
	FLAC__ASSERT(0 != iterator->file);
	FLAC__ASSERT(0 != block);

	if(!iterator->is_writable) {
		iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_NOT_WRITABLE;
		return false;
	}

	if(iterator->type == FLAC__METADATA_TYPE_STREAMINFO || block->type == FLAC__METADATA_TYPE_STREAMINFO) {
		if(iterator->type != block->type) {
			iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_ILLEGAL_INPUT;
			return false;
		}
	}

	block->is_last = iterator->is_last;

	if(iterator->length == block->length)
		return write_metadata_block_stationary_(iterator, block);
	else if(iterator->length > block->length) {
		if(use_padding && iterator->length >= FLAC__STREAM_METADATA_HEADER_LENGTH + block->length) {
			ret = write_metadata_block_stationary_with_padding_(iterator, block, iterator->length - FLAC__STREAM_METADATA_HEADER_LENGTH - block->length, block->is_last);
			FLAC__ASSERT(!ret || iterator->offset[iterator->depth] == debug_target_offset);
			FLAC__ASSERT(!ret || ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
			return ret;
		}
		else {
			ret = rewrite_whole_file_(iterator, block, /*append=*/false);
			FLAC__ASSERT(!ret || iterator->offset[iterator->depth] == debug_target_offset);
			FLAC__ASSERT(!ret || ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
			return ret;
		}
	}
	else /* iterator->length < block->length */ {
		unsigned padding_leftover = 0;
		FLAC__bool padding_is_last = false;
		if(use_padding) {
			/* first see if we can even use padding */
			if(iterator->is_last) {
				use_padding = false;
			}
			else {
				const unsigned extra_padding_bytes_required = block->length - iterator->length;
				simple_iterator_push_(iterator);
				if(!FLAC__metadata_simple_iterator_next(iterator)) {
					(void)simple_iterator_pop_(iterator);
					return false;
				}
				if(iterator->type != FLAC__METADATA_TYPE_PADDING) {
					use_padding = false;
				}
				else {
					if(FLAC__STREAM_METADATA_HEADER_LENGTH + iterator->length == extra_padding_bytes_required) {
						padding_leftover = 0;
						block->is_last = iterator->is_last;
					}
					else if(iterator->length < extra_padding_bytes_required)
						use_padding = false;
					else {
						padding_leftover = FLAC__STREAM_METADATA_HEADER_LENGTH + iterator->length - extra_padding_bytes_required;
						padding_is_last = iterator->is_last;
						block->is_last = false;
					}
				}
				if(!simple_iterator_pop_(iterator))
					return false;
			}
		}
		if(use_padding) {
			if(padding_leftover == 0) {
				ret = write_metadata_block_stationary_(iterator, block);
				FLAC__ASSERT(!ret || iterator->offset[iterator->depth] == debug_target_offset);
				FLAC__ASSERT(!ret || ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
				return ret;
			}
			else {
				FLAC__ASSERT(padding_leftover >= FLAC__STREAM_METADATA_HEADER_LENGTH);
				ret = write_metadata_block_stationary_with_padding_(iterator, block, padding_leftover - FLAC__STREAM_METADATA_HEADER_LENGTH, padding_is_last);
				FLAC__ASSERT(!ret || iterator->offset[iterator->depth] == debug_target_offset);
				FLAC__ASSERT(!ret || ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
				return ret;
			}
		}
		else {
			ret = rewrite_whole_file_(iterator, block, /*append=*/false);
			FLAC__ASSERT(!ret || iterator->offset[iterator->depth] == debug_target_offset);
			FLAC__ASSERT(!ret || ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
			return ret;
		}
	}
}

FLAC_API FLAC__bool FLAC__metadata_simple_iterator_insert_block_after(FLAC__Metadata_SimpleIterator *iterator, FLAC__StreamMetadata *block, FLAC__bool use_padding)
{
	unsigned padding_leftover = 0;
	FLAC__bool padding_is_last = false;

	FLAC__ASSERT_DECLARATION(long debug_target_offset = iterator->offset[iterator->depth] + FLAC__STREAM_METADATA_HEADER_LENGTH + iterator->length;)
	FLAC__bool ret;

	FLAC__ASSERT(0 != iterator);
	FLAC__ASSERT(0 != iterator->file);
	FLAC__ASSERT(0 != block);

	if(!iterator->is_writable)
		return false;

	if(block->type == FLAC__METADATA_TYPE_STREAMINFO) {
		iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_ILLEGAL_INPUT;
		return false;
	}

	block->is_last = iterator->is_last;

	if(use_padding) {
		/* first see if we can even use padding */
		if(iterator->is_last) {
			use_padding = false;
		}
		else {
			simple_iterator_push_(iterator);
			if(!FLAC__metadata_simple_iterator_next(iterator)) {
				(void)simple_iterator_pop_(iterator);
				return false;
			}
			if(iterator->type != FLAC__METADATA_TYPE_PADDING) {
				use_padding = false;
			}
			else {
				if(iterator->length == block->length) {
					padding_leftover = 0;
					block->is_last = iterator->is_last;
				}
				else if(iterator->length < FLAC__STREAM_METADATA_HEADER_LENGTH + block->length)
					use_padding = false;
				else {
					padding_leftover = iterator->length - block->length;
					padding_is_last = iterator->is_last;
					block->is_last = false;
				}
			}
			if(!simple_iterator_pop_(iterator))
				return false;
		}
	}
	if(use_padding) {
		/* move to the next block, which is suitable padding */
		if(!FLAC__metadata_simple_iterator_next(iterator))
			return false;
		if(padding_leftover == 0) {
			ret = write_metadata_block_stationary_(iterator, block);
			FLAC__ASSERT(iterator->offset[iterator->depth] == debug_target_offset);
			FLAC__ASSERT(ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
			return ret;
		}
		else {
			FLAC__ASSERT(padding_leftover >= FLAC__STREAM_METADATA_HEADER_LENGTH);
			ret = write_metadata_block_stationary_with_padding_(iterator, block, padding_leftover - FLAC__STREAM_METADATA_HEADER_LENGTH, padding_is_last);
			FLAC__ASSERT(iterator->offset[iterator->depth] == debug_target_offset);
			FLAC__ASSERT(ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
			return ret;
		}
	}
	else {
		ret = rewrite_whole_file_(iterator, block, /*append=*/true);
		FLAC__ASSERT(iterator->offset[iterator->depth] == debug_target_offset);
		FLAC__ASSERT(ftell(iterator->file) == debug_target_offset + (long)FLAC__STREAM_METADATA_HEADER_LENGTH);
		return ret;
	}
}

FLAC_API FLAC__bool FLAC__metadata_simple_iterator_delete_block(FLAC__Metadata_SimpleIterator *iterator, FLAC__bool use_padding)
{
	FLAC__ASSERT_DECLARATION(long debug_target_offset = iterator->offset[iterator->depth];)
	FLAC__bool ret;

	if(iterator->type == FLAC__METADATA_TYPE_STREAMINFO) {
		iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_ILLEGAL_INPUT;
		return false;
	}

	if(use_padding) {
		FLAC__StreamMetadata *padding = FLAC__metadata_object_new(FLAC__METADATA_TYPE_PADDING);
		if(0 == padding) {
			iterator->status = FLAC__METADATA_SIMPLE_ITERATOR_STATUS_MEMORY_ALLOCATION_ERROR;
			return false;
		}
		padding->length = iterator->length;
		if(!FLAC__metadata_simple_iterator_set_block(iterator, padding, false)) {
			FLAC__metadata_object_delete(padding);
			return false;
		}
		FLAC__metadata_object_delete(padding);
		if(!FLAC__metadata_simple_iterator_prev(iterator))
			return false;
		FLAC__ASSERT(iterator->offset[iterator->depth] + (long)FLAC__STREAM_METADATA_HEADER_LENGTH + (long)iterator->length == debug_target_offset);
		FLAC__ASSERT(ftell(iterator->file) + (long)iterator->length == debug_target_offset);
		return true;
	}
	else {
		ret = rewrite_whole_file_(iterator, 0, /*append=*/false);
		FLAC__ASSERT(iterator->offset[iterator->depth] + (long)FLAC__STREAM_METADATA_HEADER_LENGTH + (long)iterator->length == debug_target_offset);
		FLAC__ASSERT(ftell(iterator->file) + (long)iterator->length == debug_target_offset);
		return ret;
	}
}



/****************************************************************************
 *
 * Level 2 implementation
 *
 ***************************************************************************/


typedef struct FLAC__Metadata_Node {
	FLAC__StreamMetadata *data;
	struct FLAC__Metadata_Node *prev, *next;
} FLAC__Metadata_Node;

struct FLAC__Metadata_Chain {
	char *filename; /* will be NULL if using callbacks */
	FLAC__Metadata_Node *head;
	FLAC__Metadata_Node *tail;
	unsigned nodes;
	FLAC__Metadata_ChainStatus status;
	long first_offset, last_offset; /*@@@ 2G limit */
	/*
	 * This is the length of the chain initially read from the FLAC file.
	 * it is used to compare against the current length to decide whether
	 * or not the whole file has to be rewritten.
	 */
	unsigned initial_length; /*@@@ 4G limit */
};

struct FLAC__Metadata_Iterator {
	FLAC__Metadata_Chain *chain;
	FLAC__Metadata_Node *current;
};

FLAC_API const char * const FLAC__Metadata_ChainStatusString[] = {
	"FLAC__METADATA_CHAIN_STATUS_OK",
	"FLAC__METADATA_CHAIN_STATUS_ILLEGAL_INPUT",
	"FLAC__METADATA_CHAIN_STATUS_ERROR_OPENING_FILE",
	"FLAC__METADATA_CHAIN_STATUS_NOT_A_FLAC_FILE",
	"FLAC__METADATA_CHAIN_STATUS_NOT_WRITABLE",
	"FLAC__METADATA_CHAIN_STATUS_BAD_METADATA",
	"FLAC__METADATA_CHAIN_STATUS_READ_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_SEEK_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_WRITE_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_RENAME_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_UNLINK_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_MEMORY_ALLOCATION_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_INTERNAL_ERROR",
	"FLAC__METADATA_CHAIN_STATUS_INVALID_CALLBACKS",
	"FLAC__METADATA_CHAIN_STATUS_READ_WRITE_MISMATCH",
	"FLAC__METADATA_CHAIN_STATUS_WRONG_WRITE_CALL"
};


static FLAC__Metadata_Node *node_new_()
{
	return (FLAC__Metadata_Node*)calloc(1, sizeof(FLAC__Metadata_Node));
}

static void node_delete_(FLAC__Metadata_Node *node)
{
	FLAC__ASSERT(0 != node);
	if(0 != node->data)
		FLAC__metadata_object_delete(node->data);
	free(node);
}

static void chain_init_(FLAC__Metadata_Chain *chain)
{
	FLAC__ASSERT(0 != chain);

	chain->filename = 0;
	chain->head = chain->tail = 0;
	chain->nodes = 0;
	chain->status = FLAC__METADATA_CHAIN_STATUS_OK;
	chain->initial_length = 0;
}

static void chain_clear_(FLAC__Metadata_Chain *chain)
{
	FLAC__Metadata_Node *node, *next;

	FLAC__ASSERT(0 != chain);

	for(node = chain->head; node; ) {
		next = node->next;
		node_delete_(node);
		node = next;
	}

	if(0 != chain->filename)
		free(chain->filename);

	chain_init_(chain);
}

static void chain_append_node_(FLAC__Metadata_Chain *chain, FLAC__Metadata_Node *node)
{
	FLAC__ASSERT(0 != chain);
	FLAC__ASSERT(0 != node);
	FLAC__ASSERT(0 != node->data);

	node->next = node->prev = 0;
	node->data->is_last = true;
	if(0 != chain->tail)
		chain->tail->data->is_last = false;

	if(0 == chain->head)
		chain->head = node;
	else {
		FLAC__ASSERT(0 != chain->tail);
		chain->tail->next = node;
		node->prev = chain->tail;
	}
	chain->tail = node;
	chain->nodes++;
}

static void chain_remove_node_(FLAC__Metadata_Chain *chain, FLAC__Metadata_Node *node)
{
	FLAC__ASSERT(0 != chain);
	FLAC__ASSERT(0 != node);

	if(node == chain->head)
		chain->head = node->next;
	else
		node->prev->next = node->next;

	if(node == chain->tail)
		chain->tail = node->prev;