contrib/xz/src/liblzma/common/stream_decoder.c

   1 ///////////////////////////////////////////////////////////////////////////////
   2 //
   3 /// \file       stream_decoder.c
   4 /// \brief      Decodes .xz Streams
   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 "stream_decoder.h"
  14 #include "block_decoder.h"
  15
  16
  17 struct lzma_coder_s {
  18         enum {
  19                 SEQ_STREAM_HEADER,
  20                 SEQ_BLOCK_HEADER,
  21                 SEQ_BLOCK,
  22                 SEQ_INDEX,
  23                 SEQ_STREAM_FOOTER,
  24                 SEQ_STREAM_PADDING,
  25         } sequence;
  26
  27         /// Block or Metadata decoder. This takes little memory and the same
  28         /// data structure can be used to decode every Block Header, so it's
  29         /// a good idea to have a separate lzma_next_coder structure for it.
  30         lzma_next_coder block_decoder;
  31
  32         /// Block options decoded by the Block Header decoder and used by
  33         /// the Block decoder.
  34         lzma_block block_options;
  35
  36         /// Stream Flags from Stream Header
  37         lzma_stream_flags stream_flags;
  38
  39         /// Index is hashed so that it can be compared to the sizes of Blocks
  40         /// with O(1) memory usage.
  41         lzma_index_hash *index_hash;
  42
  43         /// Memory usage limit
  44         uint64_t memlimit;
  45
  46         /// Amount of memory actually needed (only an estimate)
  47         uint64_t memusage;
  48
  49         /// If true, LZMA_NO_CHECK is returned if the Stream has
  50         /// no integrity check.
  51         bool tell_no_check;
  52
  53         /// If true, LZMA_UNSUPPORTED_CHECK is returned if the Stream has
  54         /// an integrity check that isn't supported by this liblzma build.
  55         bool tell_unsupported_check;
  56
  57         /// If true, LZMA_GET_CHECK is returned after decoding Stream Header.
  58         bool tell_any_check;
  59
  60         /// If true, we will tell the Block decoder to skip calculating
  61         /// and verifying the integrity check.
  62         bool ignore_check;
  63
  64         /// If true, we will decode concatenated Streams that possibly have
  65         /// Stream Padding between or after them. LZMA_STREAM_END is returned
  66         /// once the application isn't giving us any new input, and we aren't
  67         /// in the middle of a Stream, and possible Stream Padding is a
  68         /// multiple of four bytes.
  69         bool concatenated;
  70
  71         /// When decoding concatenated Streams, this is true as long as we
  72         /// are decoding the first Stream. This is needed to avoid misleading
  73         /// LZMA_FORMAT_ERROR in case the later Streams don't have valid magic
  74         /// bytes.
  75         bool first_stream;
  76
  77         /// Write position in buffer[] and position in Stream Padding
  78         size_t pos;
  79
  80         /// Buffer to hold Stream Header, Block Header, and Stream Footer.
  81         /// Block Header has biggest maximum size.
  82         uint8_t buffer[LZMA_BLOCK_HEADER_SIZE_MAX];
  83 };
  84
  85
  86 static lzma_ret
  87 stream_decoder_reset(lzma_coder *coder, const lzma_allocator *allocator)
  88 {
  89         // Initialize the Index hash used to verify the Index.
  90         coder->index_hash = lzma_index_hash_init(coder->index_hash, allocator);
  91         if (coder->index_hash == NULL)
  92                 return LZMA_MEM_ERROR;
  93
  94         // Reset the rest of the variables.
  95         coder->sequence = SEQ_STREAM_HEADER;
  96         coder->pos = 0;
  97
  98         return LZMA_OK;
  99 }
 100
 101
 102 static lzma_ret
 103 stream_decode(lzma_coder *coder, const lzma_allocator *allocator,
 104                 const uint8_t *restrict in, size_t *restrict in_pos,
 105                 size_t in_size, uint8_t *restrict out,
 106                 size_t *restrict out_pos, size_t out_size, lzma_action action)
 107 {
 108         // When decoding the actual Block, it may be able to produce more
 109         // output even if we don't give it any new input.
 110         while (true)
 111         switch (coder->sequence) {
 112         case SEQ_STREAM_HEADER: {
 113                 // Copy the Stream Header to the internal buffer.
 114                 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
 115                                 LZMA_STREAM_HEADER_SIZE);
 116
 117                 // Return if we didn't get the whole Stream Header yet.
 118                 if (coder->pos < LZMA_STREAM_HEADER_SIZE)
 119                         return LZMA_OK;
 120
 121                 coder->pos = 0;
 122
 123                 // Decode the Stream Header.
 124                 const lzma_ret ret = lzma_stream_header_decode(
 125                                 &coder->stream_flags, coder->buffer);
 126                 if (ret != LZMA_OK)
 127                         return ret == LZMA_FORMAT_ERROR && !coder->first_stream
 128                                         ? LZMA_DATA_ERROR : ret;
 129
 130                 // If we are decoding concatenated Streams, and the later
 131                 // Streams have invalid Header Magic Bytes, we give
 132                 // LZMA_DATA_ERROR instead of LZMA_FORMAT_ERROR.
 133                 coder->first_stream = false;
 134
 135                 // Copy the type of the Check so that Block Header and Block
 136                 // decoders see it.
 137                 coder->block_options.check = coder->stream_flags.check;
 138
 139                 // Even if we return LZMA_*_CHECK below, we want
 140                 // to continue from Block Header decoding.
 141                 coder->sequence = SEQ_BLOCK_HEADER;
 142
 143                 // Detect if there's no integrity check or if it is
 144                 // unsupported if those were requested by the application.
 145                 if (coder->tell_no_check && coder->stream_flags.check
 146                                 == LZMA_CHECK_NONE)
 147                         return LZMA_NO_CHECK;
 148
 149                 if (coder->tell_unsupported_check
 150                                 && !lzma_check_is_supported(
 151                                         coder->stream_flags.check))
 152                         return LZMA_UNSUPPORTED_CHECK;
 153
 154                 if (coder->tell_any_check)
 155                         return LZMA_GET_CHECK;
 156         }
 157
 158         // Fall through
 159
 160         case SEQ_BLOCK_HEADER: {
 161                 if (*in_pos >= in_size)
 162                         return LZMA_OK;
 163
 164                 if (coder->pos == 0) {
 165                         // Detect if it's Index.
 166                         if (in[*in_pos] == 0x00) {
 167                                 coder->sequence = SEQ_INDEX;
 168                                 break;
 169                         }
 170
 171                         // Calculate the size of the Block Header. Note that
 172                         // Block Header decoder wants to see this byte too
 173                         // so don't advance *in_pos.
 174                         coder->block_options.header_size
 175                                         = lzma_block_header_size_decode(
 176                                                 in[*in_pos]);
 177                 }
 178
 179                 // Copy the Block Header to the internal buffer.
 180                 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
 181                                 coder->block_options.header_size);
 182
 183                 // Return if we didn't get the whole Block Header yet.
 184                 if (coder->pos < coder->block_options.header_size)
 185                         return LZMA_OK;
 186
 187                 coder->pos = 0;
 188
 189                 // Version 1 is needed to support the .ignore_check option.
 190                 coder->block_options.version = 1;
 191
 192                 // Set up a buffer to hold the filter chain. Block Header
 193                 // decoder will initialize all members of this array so
 194                 // we don't need to do it here.
 195                 lzma_filter filters[LZMA_FILTERS_MAX + 1];
 196                 coder->block_options.filters = filters;
 197
 198                 // Decode the Block Header.
 199                 return_if_error(lzma_block_header_decode(&coder->block_options,
 200                                 allocator, coder->buffer));
 201
 202                 // If LZMA_IGNORE_CHECK was used, this flag needs to be set.
 203                 // It has to be set after lzma_block_header_decode() because
 204                 // it always resets this to false.
 205                 coder->block_options.ignore_check = coder->ignore_check;
 206
 207                 // Check the memory usage limit.
 208                 const uint64_t memusage = lzma_raw_decoder_memusage(filters);
 209                 lzma_ret ret;
 210
 211                 if (memusage == UINT64_MAX) {
 212                         // One or more unknown Filter IDs.
 213                         ret = LZMA_OPTIONS_ERROR;
 214                 } else {
 215                         // Now we can set coder->memusage since we know that
 216                         // the filter chain is valid. We don't want
 217                         // lzma_memusage() to return UINT64_MAX in case of
 218                         // invalid filter chain.
 219                         coder->memusage = memusage;
 220
 221                         if (memusage > coder->memlimit) {
 222                                 // The chain would need too much memory.
 223                                 ret = LZMA_MEMLIMIT_ERROR;
 224                         } else {
 225                                 // Memory usage is OK.
 226                                 // Initialize the Block decoder.
 227                                 ret = lzma_block_decoder_init(
 228                                                 &coder->block_decoder,
 229                                                 allocator,
 230                                                 &coder->block_options);
 231                         }
 232                 }
 233
 234                 // Free the allocated filter options since they are needed
 235                 // only to initialize the Block decoder.
 236                 for (size_t i = 0; i < LZMA_FILTERS_MAX; ++i)
 237                         lzma_free(filters[i].options, allocator);
 238
 239                 coder->block_options.filters = NULL;
 240
 241                 // Check if memory usage calculation and Block enocoder
 242                 // initialization succeeded.
 243                 if (ret != LZMA_OK)
 244                         return ret;
 245
 246                 coder->sequence = SEQ_BLOCK;
 247         }
 248
 249         // Fall through
 250
 251         case SEQ_BLOCK: {
 252                 const lzma_ret ret = coder->block_decoder.code(
 253                                 coder->block_decoder.coder, allocator,
 254                                 in, in_pos, in_size, out, out_pos, out_size,
 255                                 action);
 256
 257                 if (ret != LZMA_STREAM_END)
 258                         return ret;
 259
 260                 // Block decoded successfully. Add the new size pair to
 261                 // the Index hash.
 262                 return_if_error(lzma_index_hash_append(coder->index_hash,
 263                                 lzma_block_unpadded_size(
 264                                         &coder->block_options),
 265                                 coder->block_options.uncompressed_size));
 266
 267                 coder->sequence = SEQ_BLOCK_HEADER;
 268                 break;
 269         }
 270
 271         case SEQ_INDEX: {
 272                 // If we don't have any input, don't call
 273                 // lzma_index_hash_decode() since it would return
 274                 // LZMA_BUF_ERROR, which we must not do here.
 275                 if (*in_pos >= in_size)
 276                         return LZMA_OK;
 277
 278                 // Decode the Index and compare it to the hash calculated
 279                 // from the sizes of the Blocks (if any).
 280                 const lzma_ret ret = lzma_index_hash_decode(coder->index_hash,
 281                                 in, in_pos, in_size);
 282                 if (ret != LZMA_STREAM_END)
 283                         return ret;
 284
 285                 coder->sequence = SEQ_STREAM_FOOTER;
 286         }
 287
 288         // Fall through
 289
 290         case SEQ_STREAM_FOOTER: {
 291                 // Copy the Stream Footer to the internal buffer.
 292                 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
 293                                 LZMA_STREAM_HEADER_SIZE);
 294
 295                 // Return if we didn't get the whole Stream Footer yet.
 296                 if (coder->pos < LZMA_STREAM_HEADER_SIZE)
 297                         return LZMA_OK;
 298
 299                 coder->pos = 0;
 300
 301                 // Decode the Stream Footer. The decoder gives
 302                 // LZMA_FORMAT_ERROR if the magic bytes don't match,
 303                 // so convert that return code to LZMA_DATA_ERROR.
 304                 lzma_stream_flags footer_flags;
 305                 const lzma_ret ret = lzma_stream_footer_decode(
 306                                 &footer_flags, coder->buffer);
 307                 if (ret != LZMA_OK)
 308                         return ret == LZMA_FORMAT_ERROR
 309                                         ? LZMA_DATA_ERROR : ret;
 310
 311                 // Check that Index Size stored in the Stream Footer matches
 312                 // the real size of the Index field.
 313                 if (lzma_index_hash_size(coder->index_hash)
 314                                 != footer_flags.backward_size)
 315                         return LZMA_DATA_ERROR;
 316
 317                 // Compare that the Stream Flags fields are identical in
 318                 // both Stream Header and Stream Footer.
 319                 return_if_error(lzma_stream_flags_compare(
 320                                 &coder->stream_flags, &footer_flags));
 321
 322                 if (!coder->concatenated)
 323                         return LZMA_STREAM_END;
 324
 325                 coder->sequence = SEQ_STREAM_PADDING;
 326         }
 327
 328         // Fall through
 329
 330         case SEQ_STREAM_PADDING:
 331                 assert(coder->concatenated);
 332
 333                 // Skip over possible Stream Padding.
 334                 while (true) {
 335                         if (*in_pos >= in_size) {
 336                                 // Unless LZMA_FINISH was used, we cannot
 337                                 // know if there's more input coming later.
 338                                 if (action != LZMA_FINISH)
 339                                         return LZMA_OK;
 340
 341                                 // Stream Padding must be a multiple of
 342                                 // four bytes.
 343                                 return coder->pos == 0
 344                                                 ? LZMA_STREAM_END
 345                                                 : LZMA_DATA_ERROR;
 346                         }
 347
 348                         // If the byte is not zero, it probably indicates
 349                         // beginning of a new Stream (or the file is corrupt).
 350                         if (in[*in_pos] != 0x00)
 351                                 break;
 352
 353                         ++*in_pos;
 354                         coder->pos = (coder->pos + 1) & 3;
 355                 }
 356
 357                 // Stream Padding must be a multiple of four bytes (empty
 358                 // Stream Padding is OK).
 359                 if (coder->pos != 0) {
 360                         ++*in_pos;
 361                         return LZMA_DATA_ERROR;
 362                 }
 363
 364                 // Prepare to decode the next Stream.
 365                 return_if_error(stream_decoder_reset(coder, allocator));
 366                 break;
 367
 368         default:
 369                 assert(0);
 370                 return LZMA_PROG_ERROR;
 371         }
 372
 373         // Never reached
 374 }
 375
 376
 377 static void
 378 stream_decoder_end(lzma_coder *coder, const lzma_allocator *allocator)
 379 {
 380         lzma_next_end(&coder->block_decoder, allocator);
 381         lzma_index_hash_end(coder->index_hash, allocator);
 382         lzma_free(coder, allocator);
 383         return;
 384 }
 385
 386
 387 static lzma_check
 388 stream_decoder_get_check(const lzma_coder *coder)
 389 {
 390         return coder->stream_flags.check;
 391 }
 392
 393
 394 static lzma_ret
 395 stream_decoder_memconfig(lzma_coder *coder, uint64_t *memusage,
 396                 uint64_t *old_memlimit, uint64_t new_memlimit)
 397 {
 398         *memusage = coder->memusage;
 399         *old_memlimit = coder->memlimit;
 400
 401         if (new_memlimit != 0) {
 402                 if (new_memlimit < coder->memusage)
 403                         return LZMA_MEMLIMIT_ERROR;
 404
 405                 coder->memlimit = new_memlimit;
 406         }
 407
 408         return LZMA_OK;
 409 }
 410
 411
 412 extern lzma_ret
 413 lzma_stream_decoder_init(
 414                 lzma_next_coder *next, const lzma_allocator *allocator,
 415                 uint64_t memlimit, uint32_t flags)
 416 {
 417         lzma_next_coder_init(&lzma_stream_decoder_init, next, allocator);
 418
 419         if (memlimit == 0)
 420                 return LZMA_PROG_ERROR;
 421
 422         if (flags & ~LZMA_SUPPORTED_FLAGS)
 423                 return LZMA_OPTIONS_ERROR;
 424
 425         if (next->coder == NULL) {
 426                 next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
 427                 if (next->coder == NULL)
 428                         return LZMA_MEM_ERROR;
 429
 430                 next->code = &stream_decode;
 431                 next->end = &stream_decoder_end;
 432                 next->get_check = &stream_decoder_get_check;
 433                 next->memconfig = &stream_decoder_memconfig;
 434
 435                 next->coder->block_decoder = LZMA_NEXT_CODER_INIT;
 436                 next->coder->index_hash = NULL;
 437         }
 438
 439         next->coder->memlimit = memlimit;
 440         next->coder->memusage = LZMA_MEMUSAGE_BASE;
 441         next->coder->tell_no_check = (flags & LZMA_TELL_NO_CHECK) != 0;
 442         next->coder->tell_unsupported_check
 443                         = (flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0;
 444         next->coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0;
 445         next->coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0;
 446         next->coder->concatenated = (flags & LZMA_CONCATENATED) != 0;
 447         next->coder->first_stream = true;
 448
 449         return stream_decoder_reset(next->coder, allocator);
 450 }
 451
 452
 453 extern LZMA_API(lzma_ret)
 454 lzma_stream_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
 455 {
 456         lzma_next_strm_init(lzma_stream_decoder_init, strm, memlimit, flags);
 457
 458         strm->internal->supported_actions[LZMA_RUN] = true;
 459         strm->internal->supported_actions[LZMA_FINISH] = true;
 460
 461         return LZMA_OK;
 462 }