src/liblzma/common/stream_decoder.c

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