source: vbox/trunk/src/libs/liblzma-5.4.1/common/stream_flags_encoder.c@ 98879

///////////////////////////////////////////////////////////////////////////////
//
/// \file       stream_flags_encoder.c
/// \brief      Encodes Stream Header and Stream Footer 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 "stream_flags_common.h"


static bool
stream_flags_encode(const lzma_stream_flags *options, uint8_t *out)
{
        if ((unsigned int)(options->check) > LZMA_CHECK_ID_MAX)
                return true;

        out[0] = 0x00;
        out[1] = options->check;

        return false;
}


extern LZMA_API(lzma_ret)
lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out)
{
        assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE
                        + 4 == LZMA_STREAM_HEADER_SIZE);

        if (options->version != 0)
                return LZMA_OPTIONS_ERROR;

        // Magic
        memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));

        // Stream Flags
        if (stream_flags_encode(options, out + sizeof(lzma_header_magic)))
                return LZMA_PROG_ERROR;

        // CRC32 of the Stream Header
        const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic),
                        LZMA_STREAM_FLAGS_SIZE, 0);

        write32le(out + sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE,
                        crc);

        return LZMA_OK;
}


extern LZMA_API(lzma_ret)
lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out)
{
        assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic)
                        == LZMA_STREAM_HEADER_SIZE);

        if (options->version != 0)
                return LZMA_OPTIONS_ERROR;

        // Backward Size
        if (!is_backward_size_valid(options))
                return LZMA_PROG_ERROR;

        write32le(out + 4, options->backward_size / 4 - 1);

        // Stream Flags
        if (stream_flags_encode(options, out + 2 * 4))
                return LZMA_PROG_ERROR;

        // CRC32
        const uint32_t crc = lzma_crc32(
                        out + 4, 4 + LZMA_STREAM_FLAGS_SIZE, 0);

        write32le(out, crc);

        // Magic
        memcpy(out + 2 * 4 + LZMA_STREAM_FLAGS_SIZE,
                        lzma_footer_magic, sizeof(lzma_footer_magic));

        return LZMA_OK;
}