src/liblzma/common/stream_buffer_decoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       stream_buffer_decoder.c
   4 /// \brief      Single-call .xz Stream decoder
   5 //
   6 //  Copyright (C) 2009 Lasse Collin
   7 //
   8 //  This library is free software; you can redistribute it and/or
   9 //  modify it under the terms of the GNU Lesser General Public
  10 //  License as published by the Free Software Foundation; either
  11 //  version 2.1 of the License, or (at your option) any later version.
  12 //
  13 //  This library is distributed in the hope that it will be useful,
  14 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 //  Lesser General Public License for more details.
  17 //
  18 ///////////////////////////////////////////////////////////////////////////////
  19
  20 #include "stream_decoder.h"
  21
  22
  23 extern LZMA_API(lzma_ret)
  24 lzma_stream_buffer_decode(uint64_t *memlimit, uint32_t flags,
  25                 lzma_allocator *allocator,
  26                 const uint8_t *in, size_t *in_pos, size_t in_size,
  27                 uint8_t *out, size_t *out_pos, size_t out_size)
  28 {
  29         // Sanity checks
  30         if (in_pos == NULL || (in == NULL && *in_pos != in_size)
  31                         || *in_pos > in_size || out_pos == NULL
  32                         || (out == NULL && *out_pos != out_size)
  33                         || *out_pos > out_size)
  34                 return LZMA_PROG_ERROR;
  35
  36         // Catch flags that are not allowed in buffer-to-buffer decoding.
  37         if (flags & LZMA_TELL_ANY_CHECK)
  38                 return LZMA_PROG_ERROR;
  39
  40         // Initialize the Stream decoder.
  41         // TODO: We need something to tell the decoder that it can use the
  42         // output buffer as workspace, and thus save significant amount of RAM.
  43         lzma_next_coder stream_decoder = LZMA_NEXT_CODER_INIT;
  44         lzma_ret ret = lzma_stream_decoder_init(
  45                         &stream_decoder, allocator, *memlimit, flags);
  46
  47         if (ret == LZMA_OK) {
  48                 // Save the positions so that we can restore them in case
  49                 // an error occurs.
  50                 const size_t in_start = *in_pos;
  51                 const size_t out_start = *out_pos;
  52
  53                 // Do the actual decoding.
  54                 ret = stream_decoder.code(stream_decoder.coder, allocator,
  55                                 in, in_pos, in_size, out, out_pos, out_size,
  56                                 LZMA_FINISH);
  57
  58                 if (ret == LZMA_STREAM_END) {
  59                         ret = LZMA_OK;
  60                 } else {
  61                         // Something went wrong, restore the positions.
  62                         *in_pos = in_start;
  63                         *out_pos = out_start;
  64
  65                         if (ret == LZMA_OK) {
  66                                 // Either the input was truncated or the
  67                                 // output buffer was too small.
  68                                 assert(*in_pos == in_size
  69                                                 || *out_pos == out_size);
  70
  71                                 // If all the input was consumed, then the
  72                                 // input is truncated, even if the output
  73                                 // buffer is also full. This is because
  74                                 // processing the last byte of the Stream
  75                                 // never produces output.
  76                                 if (*in_pos == in_size)
  77                                         ret = LZMA_DATA_ERROR;
  78                                 else
  79                                         ret = LZMA_BUF_ERROR;
  80
  81                         } else if (ret == LZMA_MEMLIMIT_ERROR) {
  82                                 // Let the caller know how much memory would
  83                                 // have been needed.
  84                                 uint64_t memusage;
  85                                 (void)stream_decoder.memconfig(
  86                                                 stream_decoder.coder,
  87                                                 memlimit, &memusage, 0);
  88                         }
  89                 }
  90         }
  91
  92         // Free the decoder memory. This needs to be done even if
  93         // initialization fails, because the internal API doesn't
  94         // require the initialization function to free its memory on error.
  95         lzma_next_end(&stream_decoder, allocator);
  96
  97         return ret;
  98 }