133 lines
3.3 KiB
C
133 lines
3.3 KiB
C
///////////////////////////////////////////////////////////////////////////////
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//
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/// \file block_header_encoder.c
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/// \brief Encodes Block Header for .xz files
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//
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// Author: Lasse Collin
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//
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// This file has been put into the public domain.
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// You can do whatever you want with this file.
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//
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///////////////////////////////////////////////////////////////////////////////
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#include "common.h"
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#include "check.h"
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extern LZMA_API(lzma_ret)
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lzma_block_header_size(lzma_block *block)
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{
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if (block->version != 0)
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return LZMA_OPTIONS_ERROR;
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// Block Header Size + Block Flags + CRC32.
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uint32_t size = 1 + 1 + 4;
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// Compressed Size
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if (block->compressed_size != LZMA_VLI_UNKNOWN) {
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const uint32_t add = lzma_vli_size(block->compressed_size);
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if (add == 0 || block->compressed_size == 0)
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return LZMA_PROG_ERROR;
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size += add;
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}
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// Uncompressed Size
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if (block->uncompressed_size != LZMA_VLI_UNKNOWN) {
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const uint32_t add = lzma_vli_size(block->uncompressed_size);
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if (add == 0)
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return LZMA_PROG_ERROR;
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size += add;
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}
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// List of Filter Flags
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if (block->filters == NULL || block->filters[0].id == LZMA_VLI_UNKNOWN)
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return LZMA_PROG_ERROR;
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for (size_t i = 0; block->filters[i].id != LZMA_VLI_UNKNOWN; ++i) {
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// Don't allow too many filters.
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if (i == LZMA_FILTERS_MAX)
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return LZMA_PROG_ERROR;
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uint32_t add;
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return_if_error(lzma_filter_flags_size(&add,
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block->filters + i));
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size += add;
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}
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// Pad to a multiple of four bytes.
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block->header_size = (size + 3) & ~UINT32_C(3);
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// NOTE: We don't verify that the encoded size of the Block stays
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// within limits. This is because it is possible that we are called
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// with exaggerated Compressed Size (e.g. LZMA_VLI_MAX) to reserve
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// space for Block Header, and later called again with lower,
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// real values.
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return LZMA_OK;
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}
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extern LZMA_API(lzma_ret)
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lzma_block_header_encode(const lzma_block *block, uint8_t *out)
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{
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// Validate everything but filters.
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if (lzma_block_unpadded_size(block) == 0
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|| !lzma_vli_is_valid(block->uncompressed_size))
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return LZMA_PROG_ERROR;
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// Indicate the size of the buffer _excluding_ the CRC32 field.
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const size_t out_size = block->header_size - 4;
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// Store the Block Header Size.
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out[0] = out_size / 4;
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// We write Block Flags in pieces.
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out[1] = 0x00;
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size_t out_pos = 2;
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// Compressed Size
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if (block->compressed_size != LZMA_VLI_UNKNOWN) {
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return_if_error(lzma_vli_encode(block->compressed_size, NULL,
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out, &out_pos, out_size));
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out[1] |= 0x40;
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}
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// Uncompressed Size
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if (block->uncompressed_size != LZMA_VLI_UNKNOWN) {
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return_if_error(lzma_vli_encode(block->uncompressed_size, NULL,
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out, &out_pos, out_size));
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out[1] |= 0x80;
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}
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// Filter Flags
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if (block->filters == NULL || block->filters[0].id == LZMA_VLI_UNKNOWN)
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return LZMA_PROG_ERROR;
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size_t filter_count = 0;
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do {
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// There can be a maximum of four filters.
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if (filter_count == LZMA_FILTERS_MAX)
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return LZMA_PROG_ERROR;
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return_if_error(lzma_filter_flags_encode(
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block->filters + filter_count,
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out, &out_pos, out_size));
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} while (block->filters[++filter_count].id != LZMA_VLI_UNKNOWN);
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out[1] |= filter_count - 1;
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// Padding
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memzero(out + out_pos, out_size - out_pos);
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// CRC32
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unaligned_write32le(out + out_size, lzma_crc32(out, out_size, 0));
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return LZMA_OK;
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}
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