src/liblzma/common/stream_buffer_decoder.c

   1 // SPDX-License-Identifier: 0BSD
   2
   3 ///////////////////////////////////////////////////////////////////////////////
   4 //
   5 /// \file       stream_buffer_decoder.c
   6 /// \brief      Single-call .xz Stream decoder
   7 //
   8 //  Author:     Lasse Collin
   9 //
  10 ///////////////////////////////////////////////////////////////////////////////
  11
  12 #include "stream_decoder.h"
  13
  14
  15 extern LZMA_API(lzma_ret)
  16 lzma_stream_buffer_decode(uint64_t *memlimit, uint32_t flags,
  17                 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         // Sanity checks
  22         if (in_pos == NULL || (in == NULL && *in_pos != in_size)
  23                         || *in_pos > in_size || out_pos == NULL
  24                         || (out == NULL && *out_pos != out_size)
  25                         || *out_pos > out_size)
  26                 return LZMA_PROG_ERROR;
  27
  28         // Catch flags that are not allowed in buffer-to-buffer decoding.
  29         if (flags & LZMA_TELL_ANY_CHECK)
  30                 return LZMA_PROG_ERROR;
  31
  32         // Initialize the Stream decoder.
  33         // TODO: We need something to tell the decoder that it can use the
  34         // output buffer as workspace, and thus save significant amount of RAM.
  35         lzma_next_coder stream_decoder = LZMA_NEXT_CODER_INIT;
  36         lzma_ret ret = lzma_stream_decoder_init(
  37                         &stream_decoder, allocator, *memlimit, flags);
  38
  39         if (ret == LZMA_OK) {
  40                 // Save the positions so that we can restore them in case
  41                 // an error occurs.
  42                 const size_t in_start = *in_pos;
  43                 const size_t out_start = *out_pos;
  44
  45                 // Do the actual decoding.
  46                 ret = stream_decoder.code(stream_decoder.coder, allocator,
  47                                 in, in_pos, in_size, out, out_pos, out_size,
  48                                 LZMA_FINISH);
  49
  50                 if (ret == LZMA_STREAM_END) {
  51                         ret = LZMA_OK;
  52                 } else {
  53                         // Something went wrong, restore the positions.
  54                         *in_pos = in_start;
  55                         *out_pos = out_start;
  56
  57                         if (ret == LZMA_OK) {
  58                                 // Either the input was truncated or the
  59                                 // output buffer was too small.
  60                                 assert(*in_pos == in_size
  61                                                 || *out_pos == out_size);
  62
  63                                 // If all the input was consumed, then the
  64                                 // input is truncated, even if the output
  65                                 // buffer is also full. This is because
  66                                 // processing the last byte of the Stream
  67                                 // never produces output.
  68                                 if (*in_pos == in_size)
  69                                         ret = LZMA_DATA_ERROR;
  70                                 else
  71                                         ret = LZMA_BUF_ERROR;
  72
  73                         } else if (ret == LZMA_MEMLIMIT_ERROR) {
  74                                 // Let the caller know how much memory would
  75                                 // have been needed.
  76                                 uint64_t memusage;
  77                                 (void)stream_decoder.memconfig(
  78                                                 stream_decoder.coder,
  79                                                 memlimit, &memusage, 0);
  80                         }
  81                 }
  82         }
  83
  84         // Free the decoder memory. This needs to be done even if
  85         // initialization fails, because the internal API doesn't
  86         // require the initialization function to free its memory on error.
  87         lzma_next_end(&stream_decoder, allocator);
  88
  89         return ret;
  90 }