src/liblzma/common/block_buffer_decoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       block_buffer_decoder.c
   4 /// \brief      Single-call .xz Block decoder
   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 "block_decoder.h"
  14
  15
  16 extern LZMA_API(lzma_ret)
  17 lzma_block_buffer_decode(lzma_block *block, const lzma_allocator *allocator,
  18                 const uint8_t *in, size_t *in_pos, size_t in_size,
  19                 uint8_t *out, size_t *out_pos, size_t out_size)
  20 {
  21         if (in_pos == NULL || (in == NULL && *in_pos != in_size)
  22                         || *in_pos > in_size || out_pos == NULL
  23                         || (out == NULL && *out_pos != out_size)
  24                         || *out_pos > out_size)
  25                 return LZMA_PROG_ERROR;
  26
  27         // Initialize the Block decoder.
  28         lzma_next_coder block_decoder = LZMA_NEXT_CODER_INIT;
  29         lzma_ret ret = lzma_block_decoder_init(
  30                         &block_decoder, allocator, block);
  31
  32         if (ret == LZMA_OK) {
  33                 // Save the positions so that we can restore them in case
  34                 // an error occurs.
  35                 const size_t in_start = *in_pos;
  36                 const size_t out_start = *out_pos;
  37
  38                 // Do the actual decoding.
  39                 ret = block_decoder.code(block_decoder.coder, allocator,
  40                                 in, in_pos, in_size, out, out_pos, out_size,
  41                                 LZMA_FINISH);
  42
  43                 if (ret == LZMA_STREAM_END) {
  44                         ret = LZMA_OK;
  45                 } else {
  46                         if (ret == LZMA_OK) {
  47                                 // Either the input was truncated or the
  48                                 // output buffer was too small.
  49                                 assert(*in_pos == in_size
  50                                                 || *out_pos == out_size);
  51
  52                                 // If all the input was consumed, then the
  53                                 // input is truncated, even if the output
  54                                 // buffer is also full. This is because
  55                                 // processing the last byte of the Block
  56                                 // never produces output.
  57                                 //
  58                                 // NOTE: This assumption may break when new
  59                                 // filters are added, if the end marker of
  60                                 // the filter doesn't consume at least one
  61                                 // complete byte.
  62                                 if (*in_pos == in_size)
  63                                         ret = LZMA_DATA_ERROR;
  64                                 else
  65                                         ret = LZMA_BUF_ERROR;
  66                         }
  67
  68                         // Restore the positions.
  69                         *in_pos = in_start;
  70                         *out_pos = out_start;
  71                 }
  72         }
  73
  74         // Free the decoder memory. This needs to be done even if
  75         // initialization fails, because the internal API doesn't
  76         // require the initialization function to free its memory on error.
  77         lzma_next_end(&block_decoder, allocator);
  78
  79         return ret;
  80 }