src/liblzma/common/block_encoder.h

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       block_encoder.h
   4 /// \brief      Encodes .xz Blocks
   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 #ifndef LZMA_BLOCK_ENCODER_H
  14 #define LZMA_BLOCK_ENCODER_H
  15
  16 #include "common.h"
  17
  18
  19 /// \brief      Biggest Compressed Size value that the Block encoder supports
  20 ///
  21 /// The maximum size of a single Block is limited by the maximum size of
  22 /// a Stream, which in theory is 2^63 - 3 bytes (i.e. LZMA_VLI_MAX - 3).
  23 /// While the size is really big and no one should hit it in practice, we
  24 /// take it into account in some places anyway to catch some errors e.g. if
  25 /// application passes insanely big value to some function.
  26 ///
  27 /// We could take into account the headers etc. to determine the exact
  28 /// maximum size of the Compressed Data field, but the complexity would give
  29 /// us nothing useful. Instead, limit the size of Compressed Data so that
  30 /// even with biggest possible Block Header and Check fields the total
  31 /// encoded size of the Block stays as a valid VLI. This doesn't guarantee
  32 /// that the size of the Stream doesn't grow too big, but that problem is
  33 /// taken care outside the Block handling code.
  34 ///
  35 /// ~LZMA_VLI_C(3) is to guarantee that if we need padding at the end of
  36 /// the Compressed Data field, it will still stay in the proper limit.
  37 ///
  38 /// This constant is in this file because it is needed in both
  39 /// block_encoder.c and block_buffer_encoder.c.
  40 #define COMPRESSED_SIZE_MAX ((LZMA_VLI_MAX - LZMA_BLOCK_HEADER_SIZE_MAX \
  41                 - LZMA_CHECK_SIZE_MAX) & ~LZMA_VLI_C(3))
  42
  43
  44 extern lzma_ret lzma_block_encoder_init(lzma_next_coder *next,
  45                 const lzma_allocator *allocator, lzma_block *block);
  46
  47 #endif