83 lines
2.3 KiB
C
83 lines
2.3 KiB
C
///////////////////////////////////////////////////////////////////////////////
|
|
//
|
|
/// \file stream_flags_decoder.c
|
|
/// \brief Decodes Stream Header and Stream Footer from .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_decode(lzma_stream_flags *options, const uint8_t *in)
|
|
{
|
|
// Reserved bits must be unset.
|
|
if (in[0] != 0x00 || (in[1] & 0xF0))
|
|
return true;
|
|
|
|
options->version = 0;
|
|
options->check = in[1] & 0x0F;
|
|
|
|
return false;
|
|
}
|
|
|
|
|
|
extern LZMA_API(lzma_ret)
|
|
lzma_stream_header_decode(lzma_stream_flags *options, const uint8_t *in)
|
|
{
|
|
// Magic
|
|
if (memcmp(in, lzma_header_magic, sizeof(lzma_header_magic)) != 0)
|
|
return LZMA_FORMAT_ERROR;
|
|
|
|
// Verify the CRC32 so we can distinguish between corrupt
|
|
// and unsupported files.
|
|
const uint32_t crc = lzma_crc32(in + sizeof(lzma_header_magic),
|
|
LZMA_STREAM_FLAGS_SIZE, 0);
|
|
if (crc != unaligned_read32le(in + sizeof(lzma_header_magic)
|
|
+ LZMA_STREAM_FLAGS_SIZE))
|
|
return LZMA_DATA_ERROR;
|
|
|
|
// Stream Flags
|
|
if (stream_flags_decode(options, in + sizeof(lzma_header_magic)))
|
|
return LZMA_OPTIONS_ERROR;
|
|
|
|
// Set Backward Size to indicate unknown value. That way
|
|
// lzma_stream_flags_compare() can be used to compare Stream Header
|
|
// and Stream Footer while keeping it useful also for comparing
|
|
// two Stream Footers.
|
|
options->backward_size = LZMA_VLI_UNKNOWN;
|
|
|
|
return LZMA_OK;
|
|
}
|
|
|
|
|
|
extern LZMA_API(lzma_ret)
|
|
lzma_stream_footer_decode(lzma_stream_flags *options, const uint8_t *in)
|
|
{
|
|
// Magic
|
|
if (memcmp(in + sizeof(uint32_t) * 2 + LZMA_STREAM_FLAGS_SIZE,
|
|
lzma_footer_magic, sizeof(lzma_footer_magic)) != 0)
|
|
return LZMA_FORMAT_ERROR;
|
|
|
|
// CRC32
|
|
const uint32_t crc = lzma_crc32(in + sizeof(uint32_t),
|
|
sizeof(uint32_t) + LZMA_STREAM_FLAGS_SIZE, 0);
|
|
if (crc != unaligned_read32le(in))
|
|
return LZMA_DATA_ERROR;
|
|
|
|
// Stream Flags
|
|
if (stream_flags_decode(options, in + sizeof(uint32_t) * 2))
|
|
return LZMA_OPTIONS_ERROR;
|
|
|
|
// Backward Size
|
|
options->backward_size = unaligned_read32le(in + sizeof(uint32_t));
|
|
options->backward_size = (options->backward_size + 1) * 4;
|
|
|
|
return LZMA_OK;
|
|
}
|