X-Git-Url: https://pd.if.org/git/?a=blobdiff_plain;f=lzma%2Fcommon%2Fblock_header_encoder.c;fp=lzma%2Fcommon%2Fblock_header_encoder.c;h=5c5f5424ae85add17c5ef326283762bd557fd5c3;hb=32b8a6b26ed8843828e03e505d2256960bda0980;hp=0000000000000000000000000000000000000000;hpb=d48fc23a4bcf8ca3c406d6e8c8a6f8c6b0fa2f1e;p=zpackage diff --git a/lzma/common/block_header_encoder.c b/lzma/common/block_header_encoder.c new file mode 100644 index 0000000..5c5f542 --- /dev/null +++ b/lzma/common/block_header_encoder.c @@ -0,0 +1,132 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file block_header_encoder.c +/// \brief Encodes Block Header for .xz files +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "common.h" +#include "check.h" + + +extern LZMA_API(lzma_ret) +lzma_block_header_size(lzma_block *block) +{ + if (block->version > 1) + return LZMA_OPTIONS_ERROR; + + // Block Header Size + Block Flags + CRC32. + uint32_t size = 1 + 1 + 4; + + // Compressed Size + if (block->compressed_size != LZMA_VLI_UNKNOWN) { + const uint32_t add = lzma_vli_size(block->compressed_size); + if (add == 0 || block->compressed_size == 0) + return LZMA_PROG_ERROR; + + size += add; + } + + // Uncompressed Size + if (block->uncompressed_size != LZMA_VLI_UNKNOWN) { + const uint32_t add = lzma_vli_size(block->uncompressed_size); + if (add == 0) + return LZMA_PROG_ERROR; + + size += add; + } + + // List of Filter Flags + if (block->filters == NULL || block->filters[0].id == LZMA_VLI_UNKNOWN) + return LZMA_PROG_ERROR; + + for (size_t i = 0; block->filters[i].id != LZMA_VLI_UNKNOWN; ++i) { + // Don't allow too many filters. + if (i == LZMA_FILTERS_MAX) + return LZMA_PROG_ERROR; + + uint32_t add; + return_if_error(lzma_filter_flags_size(&add, + block->filters + i)); + + size += add; + } + + // Pad to a multiple of four bytes. + block->header_size = (size + 3) & ~UINT32_C(3); + + // NOTE: We don't verify that the encoded size of the Block stays + // within limits. This is because it is possible that we are called + // with exaggerated Compressed Size (e.g. LZMA_VLI_MAX) 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 *block, uint8_t *out) +{ + // Validate everything but filters. + if (lzma_block_unpadded_size(block) == 0 + || !lzma_vli_is_valid(block->uncompressed_size)) + return LZMA_PROG_ERROR; + + // Indicate the size of the buffer _excluding_ the CRC32 field. + const size_t out_size = block->header_size - 4; + + // Store the Block Header Size. + out[0] = out_size / 4; + + // We write Block Flags in pieces. + out[1] = 0x00; + size_t out_pos = 2; + + // Compressed Size + if (block->compressed_size != LZMA_VLI_UNKNOWN) { + return_if_error(lzma_vli_encode(block->compressed_size, NULL, + out, &out_pos, out_size)); + + out[1] |= 0x40; + } + + // Uncompressed Size + if (block->uncompressed_size != LZMA_VLI_UNKNOWN) { + return_if_error(lzma_vli_encode(block->uncompressed_size, NULL, + out, &out_pos, out_size)); + + out[1] |= 0x80; + } + + // Filter Flags + if (block->filters == NULL || block->filters[0].id == LZMA_VLI_UNKNOWN) + return LZMA_PROG_ERROR; + + size_t filter_count = 0; + do { + // There can be a maximum of four filters. + if (filter_count == LZMA_FILTERS_MAX) + return LZMA_PROG_ERROR; + + return_if_error(lzma_filter_flags_encode( + block->filters + filter_count, + out, &out_pos, out_size)); + + } while (block->filters[++filter_count].id != LZMA_VLI_UNKNOWN); + + out[1] |= filter_count - 1; + + // Padding + memzero(out + out_pos, out_size - out_pos); + + // CRC32 + unaligned_write32le(out + out_size, lzma_crc32(out, out_size, 0)); + + return LZMA_OK; +}