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 typedef struct {
  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 } lzma_stream_coder;
  84
  85
  86 static lzma_ret
  87 stream_decoder_reset(lzma_stream_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(void *coder_ptr, 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         lzma_stream_coder *coder = coder_ptr;
 109
 110         // When decoding the actual Block, it may be able to produce more
 111         // output even if we don't give it any new input.
 112         while (true)
 113         switch (coder->sequence) {
 114         case SEQ_STREAM_HEADER: {
 115                 // Copy the Stream Header to the internal buffer.
 116                 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
 117                                 LZMA_STREAM_HEADER_SIZE);
 118
 119                 // Return if we didn't get the whole Stream Header yet.
 120                 if (coder->pos < LZMA_STREAM_HEADER_SIZE)
 121                         return LZMA_OK;
 122
 123                 coder->pos = 0;
 124
 125                 // Decode the Stream Header.
 126                 const lzma_ret ret = lzma_stream_header_decode(
 127                                 &coder->stream_flags, coder->buffer);
 128                 if (ret != LZMA_OK)
 129                         return ret == LZMA_FORMAT_ERROR && !coder->first_stream
 130                                         ? LZMA_DATA_ERROR : ret;
 131
 132                 // If we are decoding concatenated Streams, and the later
 133                 // Streams have invalid Header Magic Bytes, we give
 134                 // LZMA_DATA_ERROR instead of LZMA_FORMAT_ERROR.
 135                 coder->first_stream = false;
 136
 137                 // Copy the type of the Check so that Block Header and Block
 138                 // decoders see it.
 139                 coder->block_options.check = coder->stream_flags.check;
 140
 141                 // Even if we return LZMA_*_CHECK below, we want
 142                 // to continue from Block Header decoding.
 143                 coder->sequence = SEQ_BLOCK_HEADER;
 144
 145                 // Detect if there's no integrity check or if it is
 146                 // unsupported if those were requested by the application.
 147                 if (coder->tell_no_check && coder->stream_flags.check
 148                                 == LZMA_CHECK_NONE)
 149                         return LZMA_NO_CHECK;
 150
 151                 if (coder->tell_unsupported_check
 152                                 && !lzma_check_is_supported(
 153                                         coder->stream_flags.check))
 154                         return LZMA_UNSUPPORTED_CHECK;
 155
 156                 if (coder->tell_any_check)
 157                         return LZMA_GET_CHECK;
 158         }
 159
 160         // Fall through
 161
 162         case SEQ_BLOCK_HEADER: {
 163                 if (*in_pos >= in_size)
 164                         return LZMA_OK;
 165
 166                 if (coder->pos == 0) {
 167                         // Detect if it's Index.
 168                         if (in[*in_pos] == 0x00) {
 169                                 coder->sequence = SEQ_INDEX;
 170                                 break;
 171                         }
 172
 173                         // Calculate the size of the Block Header. Note that
 174                         // Block Header decoder wants to see this byte too
 175                         // so don't advance *in_pos.
 176                         coder->block_options.header_size
 177                                         = lzma_block_header_size_decode(
 178                                                 in[*in_pos]);
 179                 }
 180
 181                 // Copy the Block Header to the internal buffer.
 182                 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
 183                                 coder->block_options.header_size);
 184
 185                 // Return if we didn't get the whole Block Header yet.
 186                 if (coder->pos < coder->block_options.header_size)
 187                         return LZMA_OK;
 188
 189                 coder->pos = 0;
 190
 191                 // Version 1 is needed to support the .ignore_check option.
 192                 coder->block_options.version = 1;
 193
 194                 // Set up a buffer to hold the filter chain. Block Header
 195                 // decoder will initialize all members of this array so
 196                 // we don't need to do it here.
 197                 lzma_filter filters[LZMA_FILTERS_MAX + 1];
 198                 coder->block_options.filters = filters;
 199
 200                 // Decode the Block Header.
 201                 return_if_error(lzma_block_header_decode(&coder->block_options,
 202                                 allocator, coder->buffer));
 203
 204                 // If LZMA_IGNORE_CHECK was used, this flag needs to be set.
 205                 // It has to be set after lzma_block_header_decode() because
 206                 // it always resets this to false.
 207                 coder->block_options.ignore_check = coder->ignore_check;
 208
 209                 // Check the memory usage limit.
 210                 const uint64_t memusage = lzma_raw_decoder_memusage(filters);
 211                 lzma_ret ret;
 212
 213                 if (memusage == UINT64_MAX) {
 214                         // One or more unknown Filter IDs.
 215                         ret = LZMA_OPTIONS_ERROR;
 216                 } else {
 217                         // Now we can set coder->memusage since we know that
 218                         // the filter chain is valid. We don't want
 219                         // lzma_memusage() to return UINT64_MAX in case of
 220                         // invalid filter chain.
 221                         coder->memusage = memusage;
 222
 223                         if (memusage > coder->memlimit) {
 224                                 // The chain would need too much memory.
 225                                 ret = LZMA_MEMLIMIT_ERROR;
 226                         } else {
 227                                 // Memory usage is OK.
 228                                 // Initialize the Block decoder.
 229                                 ret = lzma_block_decoder_init(
 230                                                 &coder->block_decoder,
 231                                                 allocator,
 232                                                 &coder->block_options);
 233                         }
 234                 }
 235
 236                 // Free the allocated filter options since they are needed
 237                 // only to initialize the Block decoder.
 238                 for (size_t i = 0; i < LZMA_FILTERS_MAX; ++i)
 239                         lzma_free(filters[i].options, allocator);
 240
 241                 coder->block_options.filters = NULL;
 242
 243                 // Check if memory usage calculation and Block enocoder
 244                 // initialization succeeded.
 245                 if (ret != LZMA_OK)
 246                         return ret;
 247
 248                 coder->sequence = SEQ_BLOCK;
 249         }
 250
 251         // Fall through
 252
 253         case SEQ_BLOCK: {
 254                 const lzma_ret ret = coder->block_decoder.code(
 255                                 coder->block_decoder.coder, allocator,
 256                                 in, in_pos, in_size, out, out_pos, out_size,
 257                                 action);
 258
 259                 if (ret != LZMA_STREAM_END)
 260                         return ret;
 261
 262                 // Block decoded successfully. Add the new size pair to
 263                 // the Index hash.
 264                 return_if_error(lzma_index_hash_append(coder->index_hash,
 265                                 lzma_block_unpadded_size(
 266                                         &coder->block_options),
 267                                 coder->block_options.uncompressed_size));
 268
 269                 coder->sequence = SEQ_BLOCK_HEADER;
 270                 break;
 271         }
 272
 273         case SEQ_INDEX: {
 274                 // If we don't have any input, don't call
 275                 // lzma_index_hash_decode() since it would return
 276                 // LZMA_BUF_ERROR, which we must not do here.
 277                 if (*in_pos >= in_size)
 278                         return LZMA_OK;
 279
 280                 // Decode the Index and compare it to the hash calculated
 281                 // from the sizes of the Blocks (if any).
 282                 const lzma_ret ret = lzma_index_hash_decode(coder->index_hash,
 283                                 in, in_pos, in_size);
 284                 if (ret != LZMA_STREAM_END)
 285                         return ret;
 286
 287                 coder->sequence = SEQ_STREAM_FOOTER;
 288         }
 289
 290         // Fall through
 291
 292         case SEQ_STREAM_FOOTER: {
 293                 // Copy the Stream Footer to the internal buffer.
 294                 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
 295                                 LZMA_STREAM_HEADER_SIZE);
 296
 297                 // Return if we didn't get the whole Stream Footer yet.
 298                 if (coder->pos < LZMA_STREAM_HEADER_SIZE)
 299                         return LZMA_OK;
 300
 301                 coder->pos = 0;
 302
 303                 // Decode the Stream Footer. The decoder gives
 304                 // LZMA_FORMAT_ERROR if the magic bytes don't match,
 305                 // so convert that return code to LZMA_DATA_ERROR.
 306                 lzma_stream_flags footer_flags;
 307                 const lzma_ret ret = lzma_stream_footer_decode(
 308                                 &footer_flags, coder->buffer);
 309                 if (ret != LZMA_OK)
 310                         return ret == LZMA_FORMAT_ERROR
 311                                         ? LZMA_DATA_ERROR : ret;
 312
 313                 // Check that Index Size stored in the Stream Footer matches
 314                 // the real size of the Index field.
 315                 if (lzma_index_hash_size(coder->index_hash)
 316                                 != footer_flags.backward_size)
 317                         return LZMA_DATA_ERROR;
 318
 319                 // Compare that the Stream Flags fields are identical in
 320                 // both Stream Header and Stream Footer.
 321                 return_if_error(lzma_stream_flags_compare(
 322                                 &coder->stream_flags, &footer_flags));
 323
 324                 if (!coder->concatenated)
 325                         return LZMA_STREAM_END;
 326
 327                 coder->sequence = SEQ_STREAM_PADDING;
 328         }
 329
 330         // Fall through
 331
 332         case SEQ_STREAM_PADDING:
 333                 assert(coder->concatenated);
 334
 335                 // Skip over possible Stream Padding.
 336                 while (true) {
 337                         if (*in_pos >= in_size) {
 338                                 // Unless LZMA_FINISH was used, we cannot
 339                                 // know if there's more input coming later.
 340                                 if (action != LZMA_FINISH)
 341                                         return LZMA_OK;
 342
 343                                 // Stream Padding must be a multiple of
 344                                 // four bytes.
 345                                 return coder->pos == 0
 346                                                 ? LZMA_STREAM_END
 347                                                 : LZMA_DATA_ERROR;
 348                         }
 349
 350                         // If the byte is not zero, it probably indicates
 351                         // beginning of a new Stream (or the file is corrupt).
 352                         if (in[*in_pos] != 0x00)
 353                                 break;
 354
 355                         ++*in_pos;
 356                         coder->pos = (coder->pos + 1) & 3;
 357                 }
 358
 359                 // Stream Padding must be a multiple of four bytes (empty
 360                 // Stream Padding is OK).
 361                 if (coder->pos != 0) {
 362                         ++*in_pos;
 363                         return LZMA_DATA_ERROR;
 364                 }
 365
 366                 // Prepare to decode the next Stream.
 367                 return_if_error(stream_decoder_reset(coder, allocator));
 368                 break;
 369
 370         default:
 371                 assert(0);
 372                 return LZMA_PROG_ERROR;
 373         }
 374
 375         // Never reached
 376 }
 377
 378
 379 static void
 380 stream_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
 381 {
 382         lzma_stream_coder *coder = coder_ptr;
 383         lzma_next_end(&coder->block_decoder, allocator);
 384         lzma_index_hash_end(coder->index_hash, allocator);
 385         lzma_free(coder, allocator);
 386         return;
 387 }
 388
 389
 390 static lzma_check
 391 stream_decoder_get_check(const void *coder_ptr)
 392 {
 393         const lzma_stream_coder *coder = coder_ptr;
 394         return coder->stream_flags.check;
 395 }
 396
 397
 398 static lzma_ret
 399 stream_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
 400                 uint64_t *old_memlimit, uint64_t new_memlimit)
 401 {
 402         lzma_stream_coder *coder = coder_ptr;
 403
 404         *memusage = coder->memusage;
 405         *old_memlimit = coder->memlimit;
 406
 407         if (new_memlimit != 0) {
 408                 if (new_memlimit < coder->memusage)
 409                         return LZMA_MEMLIMIT_ERROR;
 410
 411                 coder->memlimit = new_memlimit;
 412         }
 413
 414         return LZMA_OK;
 415 }
 416
 417
 418 extern lzma_ret
 419 lzma_stream_decoder_init(
 420                 lzma_next_coder *next, const lzma_allocator *allocator,
 421                 uint64_t memlimit, uint32_t flags)
 422 {
 423         lzma_next_coder_init(&lzma_stream_decoder_init, next, allocator);
 424
 425         if (flags & ~LZMA_SUPPORTED_FLAGS)
 426                 return LZMA_OPTIONS_ERROR;
 427
 428         lzma_stream_coder *coder = next->coder;
 429         if (coder == NULL) {
 430                 coder = lzma_alloc(sizeof(lzma_stream_coder), allocator);
 431                 if (coder == NULL)
 432                         return LZMA_MEM_ERROR;
 433
 434                 next->coder = coder;
 435                 next->code = &stream_decode;
 436                 next->end = &stream_decoder_end;
 437                 next->get_check = &stream_decoder_get_check;
 438                 next->memconfig = &stream_decoder_memconfig;
 439
 440                 coder->block_decoder = LZMA_NEXT_CODER_INIT;
 441                 coder->index_hash = NULL;
 442         }
 443
 444         coder->memlimit = my_max(1, memlimit);
 445         coder->memusage = LZMA_MEMUSAGE_BASE;
 446         coder->tell_no_check = (flags & LZMA_TELL_NO_CHECK) != 0;
 447         coder->tell_unsupported_check
 448                         = (flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0;
 449         coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0;
 450         coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0;
 451         coder->concatenated = (flags & LZMA_CONCATENATED) != 0;
 452         coder->first_stream = true;
 453
 454         return stream_decoder_reset(coder, allocator);
 455 }
 456
 457
 458 extern LZMA_API(lzma_ret)
 459 lzma_stream_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
 460 {
 461         lzma_next_strm_init(lzma_stream_decoder_init, strm, memlimit, flags);
 462
 463         strm->internal->supported_actions[LZMA_RUN] = true;
 464         strm->internal->supported_actions[LZMA_FINISH] = true;
 465
 466         return LZMA_OK;
 467 }