The R Project SVN R

///////////////////////////////////////////////////////////////////////////////

//

/// \file       stream_buffer_encoder.c

/// \brief      Single-call .xz Stream encoder

//

//  Author:     Lasse Collin

//

//  This file has been put into the public domain.

//  You can do whatever you want with this file.

//

///////////////////////////////////////////////////////////////////////////////

#include "index.h"

/// Maximum size of Index that has exactly one Record.

/// Index Indicator + Number of Records + Record + CRC32 rounded up to

/// the next multiple of four.

#define INDEX_BOUND ((1 + 1 + 2 * LZMA_VLI_BYTES_MAX + 4 + 3) & ~3)

/// Stream Header, Stream Footer, and Index

#define HEADERS_BOUND (2 * LZMA_STREAM_HEADER_SIZE + INDEX_BOUND)

extern LZMA_API(size_t)

lzma_stream_buffer_bound(size_t uncompressed_size)

{

	// Get the maximum possible size of a Block.

	const size_t block_bound = lzma_block_buffer_bound(uncompressed_size);

	if (block_bound == 0)

		return 0;

	// Catch the possible integer overflow and also prevent the size of

	// the Stream exceeding LZMA_VLI_MAX (theoretically possible on

	// 64-bit systems).

	if (my_min(SIZE_MAX, LZMA_VLI_MAX) - block_bound < HEADERS_BOUND)

		return 0;

	return block_bound + HEADERS_BOUND;

}

extern LZMA_API(lzma_ret)

lzma_stream_buffer_encode(lzma_filter *filters, lzma_check check,

		lzma_allocator *allocator, const uint8_t *in, size_t in_size,

		uint8_t *out, size_t *out_pos_ptr, size_t out_size)

{

	// Sanity checks

	if (filters == NULL || (unsigned int)(check) > LZMA_CHECK_ID_MAX

			|| (in == NULL && in_size != 0) || out == NULL

			|| out_pos_ptr == NULL || *out_pos_ptr > out_size)

		return LZMA_PROG_ERROR;

	if (!lzma_check_is_supported(check))

		return LZMA_UNSUPPORTED_CHECK;

	// Note for the paranoids: Index encoder prevents the Stream from

	// getting too big and still being accepted with LZMA_OK, and Block

	// encoder catches if the input is too big. So we don't need to

	// separately check if the buffers are too big.

	// Use a local copy. We update *out_pos_ptr only if everything

	// succeeds.

	size_t out_pos = *out_pos_ptr;

	// Check that there's enough space for both Stream Header and

	// Stream Footer.

	if (out_size - out_pos <= 2 * LZMA_STREAM_HEADER_SIZE)

		return LZMA_BUF_ERROR;

	// Reserve space for Stream Footer so we don't need to check for

	// available space again before encoding Stream Footer.

	out_size -= LZMA_STREAM_HEADER_SIZE;

	// Encode the Stream Header.

	lzma_stream_flags stream_flags = {

		.version = 0,

		.check = check,

	};

	if (lzma_stream_header_encode(&stream_flags, out + out_pos)

			!= LZMA_OK)

		return LZMA_PROG_ERROR;

	out_pos += LZMA_STREAM_HEADER_SIZE;

	// Encode a Block but only if there is at least one byte of input.

	lzma_block block = {

		.version = 0,

		.check = check,

		.filters = filters,

	};

	if (in_size > 0)

		return_if_error(lzma_block_buffer_encode(&block, allocator,

				in, in_size, out, &out_pos, out_size));

	// Index

	{

		// Create an Index. It will have one Record if there was

		// at least one byte of input to encode. Otherwise the

		// Index will be empty.

		lzma_index *i = lzma_index_init(allocator);

		if (i == NULL)

			return LZMA_MEM_ERROR;

		lzma_ret ret = LZMA_OK;

		if (in_size > 0)

			ret = lzma_index_append(i, allocator,

					lzma_block_unpadded_size(&block),

					block.uncompressed_size);

		// If adding the Record was successful, encode the Index

		// and get its size which will be stored into Stream Footer.

		if (ret == LZMA_OK) {

			ret = lzma_index_buffer_encode(

					i, out, &out_pos, out_size);

			stream_flags.backward_size = lzma_index_size(i);

		}

		lzma_index_end(i, allocator);

		if (ret != LZMA_OK)

			return ret;

	}

	// Stream Footer. We have already reserved space for this.

	if (lzma_stream_footer_encode(&stream_flags, out + out_pos)

			!= LZMA_OK)

		return LZMA_PROG_ERROR;

	out_pos += LZMA_STREAM_HEADER_SIZE;

	// Everything went fine, make the new output position available

	// to the application.

	*out_pos_ptr = out_pos;

	return LZMA_OK;

}