src/liblzma/common/block_decoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       block_decoder.c
   4 /// \brief      Decodes .lzma Blocks
   5 //
   6 //  Copyright (C) 2007 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 "block_decoder.h"
  21 #include "block_private.h"
  22 #include "raw_decoder.h"
  23 #include "check.h"
  24
  25
  26 struct lzma_coder_s {
  27         enum {
  28                 SEQ_CODE,
  29                 SEQ_PADDING,
  30                 SEQ_CHECK,
  31         } sequence;
  32
  33         /// The filters in the chain; initialized with lzma_raw_decoder_init().
  34         lzma_next_coder next;
  35
  36         /// Decoding options; we also write Compressed Size and Uncompressed
  37         /// Size back to this structure when the encoding has been finished.
  38         lzma_options_block *options;
  39
  40         /// Compressed Size calculated while encoding
  41         lzma_vli compressed_size;
  42
  43         /// Uncompressed Size calculated while encoding
  44         lzma_vli uncompressed_size;
  45
  46         /// Maximum allowed Compressed Size; this takes into account the
  47         /// size of the Block Header and Check fields when Compressed Size
  48         /// is unknown.
  49         lzma_vli compressed_limit;
  50
  51         /// Position when reading the Check field
  52         size_t check_pos;
  53
  54         /// Check of the uncompressed data
  55         lzma_check check;
  56 };
  57
  58
  59 static lzma_ret
  60 block_decode(lzma_coder *coder, lzma_allocator *allocator,
  61                 const uint8_t *restrict in, size_t *restrict in_pos,
  62                 size_t in_size, uint8_t *restrict out,
  63                 size_t *restrict out_pos, size_t out_size, lzma_action action)
  64 {
  65         switch (coder->sequence) {
  66         case SEQ_CODE: {
  67                 if (*out_pos >= out_size)
  68                         return LZMA_OK;
  69
  70                 const size_t in_start = *in_pos;
  71                 const size_t out_start = *out_pos;
  72
  73                 const lzma_ret ret = coder->next.code(coder->next.coder,
  74                                 allocator, in, in_pos, in_size,
  75                                 out, out_pos, out_size, action);
  76
  77                 const size_t in_used = *in_pos - in_start;
  78                 const size_t out_used = *out_pos - out_start;
  79
  80                 // NOTE: We compare to compressed_limit here, which prevents
  81                 // the total size of the Block growing past LZMA_VLI_VALUE_MAX.
  82                 if (update_size(&coder->compressed_size, in_used,
  83                                         coder->compressed_limit)
  84                                 || update_size(&coder->uncompressed_size,
  85                                         out_used,
  86                                         coder->options->uncompressed_size))
  87                         return LZMA_DATA_ERROR;
  88
  89                 lzma_check_update(&coder->check, coder->options->check,
  90                                 out + out_start, out_used);
  91
  92                 if (ret != LZMA_STREAM_END)
  93                         return ret;
  94
  95                 coder->sequence = SEQ_PADDING;
  96         }
  97
  98         // Fall through
  99
 100         case SEQ_PADDING:
 101                 // If Compressed Data is padded to a multiple of four bytes.
 102                 while (coder->compressed_size & 3) {
 103                         if (*in_pos >= in_size)
 104                                 return LZMA_OK;
 105
 106                         if (in[(*in_pos)++] != 0x00)
 107                                 return LZMA_DATA_ERROR;
 108
 109                         if (update_size(&coder->compressed_size, 1,
 110                                         coder->compressed_limit))
 111                                 return LZMA_DATA_ERROR;
 112                 }
 113
 114                 // Compressed and Uncompressed Sizes are now at their final
 115                 // values. Verify that they match the values given to us.
 116                 if (!is_size_valid(coder->compressed_size,
 117                                         coder->options->compressed_size)
 118                                 || !is_size_valid(coder->uncompressed_size,
 119                                         coder->options->uncompressed_size))
 120                         return LZMA_DATA_ERROR;
 121
 122                 // Copy the values into coder->options. The caller
 123                 // may use this information to construct Index.
 124                 coder->options->compressed_size = coder->compressed_size;
 125                 coder->options->uncompressed_size = coder->uncompressed_size;
 126
 127                 if (coder->options->check == LZMA_CHECK_NONE)
 128                         return LZMA_STREAM_END;
 129
 130                 lzma_check_finish(&coder->check, coder->options->check);
 131                 coder->sequence = SEQ_CHECK;
 132
 133         // Fall through
 134
 135         case SEQ_CHECK:
 136                 while (*in_pos < in_size) {
 137                         if (in[(*in_pos)++] != coder->check.buffer[
 138                                         coder->check_pos])
 139                                 return LZMA_DATA_ERROR;
 140
 141                         if (++coder->check_pos == lzma_check_sizes[
 142                                         coder->options->check])
 143                                 return LZMA_STREAM_END;
 144                 }
 145
 146                 return LZMA_OK;
 147         }
 148
 149         return LZMA_PROG_ERROR;
 150 }
 151
 152
 153 static void
 154 block_decoder_end(lzma_coder *coder, lzma_allocator *allocator)
 155 {
 156         lzma_next_coder_end(&coder->next, allocator);
 157         lzma_free(coder, allocator);
 158         return;
 159 }
 160
 161
 162 static lzma_ret
 163 block_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 164                 lzma_options_block *options)
 165 {
 166         // While lzma_block_total_size_get() is meant to calculate the Total
 167         // Size, it also validates the options excluding the filters.
 168         if (lzma_block_total_size_get(options) == 0)
 169                 return LZMA_PROG_ERROR;
 170
 171         // Allocate and initialize *next->coder if needed.
 172         if (next->coder == NULL) {
 173                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
 174                 if (next->coder == NULL)
 175                         return LZMA_MEM_ERROR;
 176
 177                 next->code = &block_decode;
 178                 next->end = &block_decoder_end;
 179                 next->coder->next = LZMA_NEXT_CODER_INIT;
 180         }
 181
 182         // Basic initializations
 183         next->coder->sequence = SEQ_CODE;
 184         next->coder->options = options;
 185         next->coder->compressed_size = 0;
 186         next->coder->uncompressed_size = 0;
 187
 188         // If Compressed Size is not known, we calculate the maximum allowed
 189         // value so that Total Size of the Block still is a valid VLI and
 190         // a multiple of four.
 191         next->coder->compressed_limit
 192                         = options->compressed_size == LZMA_VLI_VALUE_UNKNOWN
 193                                 ? (LZMA_VLI_VALUE_MAX & ~LZMA_VLI_C(3))
 194                                         - options->header_size
 195                                         - lzma_check_sizes[options->check]
 196                                 : options->compressed_size;
 197
 198         // Initialize the check
 199         next->coder->check_pos = 0;
 200         return_if_error(lzma_check_init(&next->coder->check, options->check));
 201
 202         return lzma_raw_decoder_init(&next->coder->next, allocator,
 203                         options->filters);
 204 }
 205
 206
 207 extern lzma_ret
 208 lzma_block_decoder_init(lzma_next_coder *next, lzma_allocator *allocator,
 209                 lzma_options_block *options)
 210 {
 211         lzma_next_coder_init(block_decoder_init, next, allocator, options);
 212 }
 213
 214
 215 extern LZMA_API lzma_ret
 216 lzma_block_decoder(lzma_stream *strm, lzma_options_block *options)
 217 {
 218         lzma_next_strm_init(strm, block_decoder_init, options);
 219
 220         strm->internal->supported_actions[LZMA_RUN] = true;
 221         strm->internal->supported_actions[LZMA_SYNC_FLUSH] = true;
 222
 223         return LZMA_OK;
 224 }