1  ///////////////////////////////////////////////////////////////////////////////
       2  //
       3  /// \file       stream_flags_encoder.c
       4  /// \brief      Encodes Stream Header and Stream Footer for .xz files
       5  //
       6  //  Author:     Lasse Collin
       7  //
       8  //  This file has been put into the public domain.
       9  //  You can do whatever you want with this file.
      10  //
      11  ///////////////////////////////////////////////////////////////////////////////
      12  
      13  #include "stream_flags_common.h"
      14  
      15  
      16  static bool
      17  stream_flags_encode(const lzma_stream_flags *options, uint8_t *out)
      18  {
      19  	if ((unsigned int)(options->check) > LZMA_CHECK_ID_MAX)
      20  		return true;
      21  
      22  	out[0] = 0x00;
      23  	out[1] = options->check;
      24  
      25  	return false;
      26  }
      27  
      28  
      29  extern LZMA_API(lzma_ret)
      30  lzma_stream_header_encode(const lzma_stream_flags *options, uint8_t *out)
      31  {
      32  	assert(sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE
      33  			+ 4 == LZMA_STREAM_HEADER_SIZE);
      34  
      35  	if (options->version != 0)
      36  		return LZMA_OPTIONS_ERROR;
      37  
      38  	// Magic
      39  	memcpy(out, lzma_header_magic, sizeof(lzma_header_magic));
      40  
      41  	// Stream Flags
      42  	if (stream_flags_encode(options, out + sizeof(lzma_header_magic)))
      43  		return LZMA_PROG_ERROR;
      44  
      45  	// CRC32 of the Stream Header
      46  	const uint32_t crc = lzma_crc32(out + sizeof(lzma_header_magic),
      47  			LZMA_STREAM_FLAGS_SIZE, 0);
      48  
      49  	write32le(out + sizeof(lzma_header_magic) + LZMA_STREAM_FLAGS_SIZE,
      50  			crc);
      51  
      52  	return LZMA_OK;
      53  }
      54  
      55  
      56  extern LZMA_API(lzma_ret)
      57  lzma_stream_footer_encode(const lzma_stream_flags *options, uint8_t *out)
      58  {
      59  	assert(2 * 4 + LZMA_STREAM_FLAGS_SIZE + sizeof(lzma_footer_magic)
      60  			== LZMA_STREAM_HEADER_SIZE);
      61  
      62  	if (options->version != 0)
      63  		return LZMA_OPTIONS_ERROR;
      64  
      65  	// Backward Size
      66  	if (!is_backward_size_valid(options))
      67  		return LZMA_PROG_ERROR;
      68  
      69  	write32le(out + 4, options->backward_size / 4 - 1);
      70  
      71  	// Stream Flags
      72  	if (stream_flags_encode(options, out + 2 * 4))
      73  		return LZMA_PROG_ERROR;
      74  
      75  	// CRC32
      76  	const uint32_t crc = lzma_crc32(
      77  			out + 4, 4 + LZMA_STREAM_FLAGS_SIZE, 0);
      78  
      79  	write32le(out, crc);
      80  
      81  	// Magic
      82  	memcpy(out + 2 * 4 + LZMA_STREAM_FLAGS_SIZE,
      83  			lzma_footer_magic, sizeof(lzma_footer_magic));
      84  
      85  	return LZMA_OK;
      86  }