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///////////////////////////////////////////////////////////////////////////////
//
/// \file block_header_encoder.c
/// \brief Encodes Block Header for .lzma files
//
// Copyright (C) 2007 Lasse Collin
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library 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
// Lesser General Public License for more details.
//
///////////////////////////////////////////////////////////////////////////////
#include "common.h"
#include "check.h"
extern LZMA_API lzma_ret
lzma_block_header_size(lzma_block *options)
{
// Block Header Size + Block Flags + CRC32.
size_t size = 1 + 1 + 4;
// Compressed Size
if (options->compressed_size != LZMA_VLI_VALUE_UNKNOWN) {
if (options->compressed_size > LZMA_VLI_VALUE_MAX / 4 - 1
|| options->compressed_size == 0
|| (options->compressed_size & 3))
return LZMA_PROG_ERROR;
size += lzma_vli_size(options->compressed_size / 4 - 1);
}
// Uncompressed Size
if (options->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN) {
const size_t add = lzma_vli_size(options->uncompressed_size);
if (add == 0)
return LZMA_PROG_ERROR;
size += add;
}
// List of Filter Flags
if (options->filters == NULL
|| options->filters[0].id == LZMA_VLI_VALUE_UNKNOWN)
return LZMA_PROG_ERROR;
for (size_t i = 0; options->filters[i].id != LZMA_VLI_VALUE_UNKNOWN;
++i) {
// Don't allow too many filters.
if (i == 4)
return LZMA_PROG_ERROR;
uint32_t add;
return_if_error(lzma_filter_flags_size(&add,
options->filters + i));
size += add;
}
// Pad to a multiple of four bytes.
options->header_size = (size + 3) & ~(size_t)(3);
// NOTE: We don't verify that Total Size of the Block stays within
// limits. This is because it is possible that we are called with
// exaggerated values to reserve space for Block Header, and later
// called again with lower, real values.
return LZMA_OK;
}
extern LZMA_API lzma_ret
lzma_block_header_encode(const lzma_block *options, uint8_t *out)
{
if ((options->header_size & 3)
|| options->header_size < LZMA_BLOCK_HEADER_SIZE_MIN
|| options->header_size > LZMA_BLOCK_HEADER_SIZE_MAX)
return LZMA_PROG_ERROR;
// Indicate the size of the buffer _excluding_ the CRC32 field.
const size_t out_size = options->header_size - 4;
// Store the Block Header Size.
out[0] = out_size / 4;
// We write Block Flags a little later.
size_t out_pos = 2;
// Compressed Size
if (options->compressed_size != LZMA_VLI_VALUE_UNKNOWN) {
// Compressed Size must be non-zero, fit into a 63-bit
// integer and be a multiple of four. Also the Total Size
// of the Block must fit into 63-bit integer.
if (options->compressed_size == 0
|| (options->compressed_size & 3)
|| options->compressed_size
> LZMA_VLI_VALUE_MAX
|| lzma_block_total_size_get(options) == 0)
return LZMA_PROG_ERROR;
return_if_error(lzma_vli_encode(
options->compressed_size / 4 - 1, NULL,
out, &out_pos, out_size));
}
// Uncompressed Size
if (options->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN)
return_if_error(lzma_vli_encode(
options->uncompressed_size, NULL,
out, &out_pos, out_size));
// Filter Flags
if (options->filters == NULL
|| options->filters[0].id == LZMA_VLI_VALUE_UNKNOWN)
return LZMA_PROG_ERROR;
size_t filter_count = 0;
do {
// There can be at maximum of four filters.
if (filter_count == 4)
return LZMA_PROG_ERROR;
return_if_error(lzma_filter_flags_encode(
options->filters + filter_count,
out, &out_pos, out_size));
} while (options->filters[++filter_count].id
!= LZMA_VLI_VALUE_UNKNOWN);
// Block Flags
out[1] = filter_count - 1;
if (options->compressed_size != LZMA_VLI_VALUE_UNKNOWN)
out[1] |= 0x40;
if (options->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN)
out[1] |= 0x80;
// Padding
memzero(out + out_pos, out_size - out_pos);
// CRC32
integer_write_32(out + out_size, lzma_crc32(out, out_size, 0));
return LZMA_OK;
}
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