The R Project SVN R

///////////////////////////////////////////////////////////////////////////////
//
/// \file       block_header.c
/// \brief      Utility functions to handle lzma_block
//
//  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 "index.h"


extern LZMA_API(lzma_ret)
lzma_block_compressed_size(lzma_block *block, lzma_vli unpadded_size)
{
    // Validate everything but Uncompressed Size and filters.
    if (lzma_block_unpadded_size(block) == 0)
        return LZMA_PROG_ERROR;

    const uint32_t container_size = block->header_size
            + lzma_check_size(block->check);

    // Validate that Compressed Size will be greater than zero.
    if (unpadded_size <= container_size)
        return LZMA_DATA_ERROR;

    // Calculate what Compressed Size is supposed to be.
    // If Compressed Size was present in Block Header,
    // compare that the new value matches it.
    const lzma_vli compressed_size = unpadded_size - container_size;
    if (block->compressed_size != LZMA_VLI_UNKNOWN
            && block->compressed_size != compressed_size)
        return LZMA_DATA_ERROR;

    block->compressed_size = compressed_size;

    return LZMA_OK;
}


extern LZMA_API(lzma_vli)
lzma_block_unpadded_size(const lzma_block *block)
{
    // Validate the values that we are interested in i.e. all but
    // Uncompressed Size and the filters.
    //
    // NOTE: This function is used for validation too, so it is
    // essential that these checks are always done even if
    // Compressed Size is unknown.
    if (block == NULL || block->version != 0
            || block->header_size < LZMA_BLOCK_HEADER_SIZE_MIN
            || block->header_size > LZMA_BLOCK_HEADER_SIZE_MAX
            || (block->header_size & 3)
            || !lzma_vli_is_valid(block->compressed_size)
            || block->compressed_size == 0
            || (unsigned int)(block->check) > LZMA_CHECK_ID_MAX)
        return 0;

    // If Compressed Size is unknown, return that we cannot know
    // size of the Block either.
    if (block->compressed_size == LZMA_VLI_UNKNOWN)
        return LZMA_VLI_UNKNOWN;

    // Calculate Unpadded Size and validate it.
    const lzma_vli unpadded_size = block->compressed_size
                + block->header_size
                + lzma_check_size(block->check);

    assert(unpadded_size >= UNPADDED_SIZE_MIN);
    if (unpadded_size > UNPADDED_SIZE_MAX)
        return 0;

    return unpadded_size;
}


extern LZMA_API(lzma_vli)
lzma_block_total_size(const lzma_block *block)
{
    lzma_vli unpadded_size = lzma_block_unpadded_size(block);

    if (unpadded_size != LZMA_VLI_UNKNOWN)
        unpadded_size = vli_ceil4(unpadded_size);

    return unpadded_size;
}