1// SPDX-License-Identifier: 0BSD 2 3/////////////////////////////////////////////////////////////////////////////// 4// 5/// \file stream_decoder.c 6/// \brief Decodes .xz Streams 7// 8// Author: Lasse Collin 9// 10/////////////////////////////////////////////////////////////////////////////// 11 12#include "stream_decoder.h" 13#include "block_decoder.h" 14#include "index.h" 15 16 17typedef struct { 18 enum { 19 SEQ_STREAM_HEADER, 20 SEQ_BLOCK_HEADER, 21 SEQ_BLOCK_INIT, 22 SEQ_BLOCK_RUN, 23 SEQ_INDEX, 24 SEQ_STREAM_FOOTER, 25 SEQ_STREAM_PADDING, 26 } sequence; 27 28 /// Block decoder 29 lzma_next_coder block_decoder; 30 31 /// Block options decoded by the Block Header decoder and used by 32 /// the Block decoder. 33 lzma_block block_options; 34 35 /// Stream Flags from Stream Header 36 lzma_stream_flags stream_flags; 37 38 /// Index is hashed so that it can be compared to the sizes of Blocks 39 /// with O(1) memory usage. 40 lzma_index_hash *index_hash; 41 42 /// Memory usage limit 43 uint64_t memlimit; 44 45 /// Amount of memory actually needed (only an estimate) 46 uint64_t memusage; 47 48 /// If true, LZMA_NO_CHECK is returned if the Stream has 49 /// no integrity check. 50 bool tell_no_check; 51 52 /// If true, LZMA_UNSUPPORTED_CHECK is returned if the Stream has 53 /// an integrity check that isn't supported by this liblzma build. 54 bool tell_unsupported_check; 55 56 /// If true, LZMA_GET_CHECK is returned after decoding Stream Header. 57 bool tell_any_check; 58 59 /// If true, we will tell the Block decoder to skip calculating 60 /// and verifying the integrity check. 61 bool ignore_check; 62 63 /// If true, we will decode concatenated Streams that possibly have 64 /// Stream Padding between or after them. LZMA_STREAM_END is returned 65 /// once the application isn't giving us any new input (LZMA_FINISH), 66 /// and we aren't in the middle of a Stream, and possible 67 /// Stream Padding is a multiple of four bytes. 68 bool concatenated; 69 70 /// When decoding concatenated Streams, this is true as long as we 71 /// are decoding the first Stream. This is needed to avoid misleading 72 /// LZMA_FORMAT_ERROR in case the later Streams don't have valid magic 73 /// bytes. 74 bool first_stream; 75 76 /// Write position in buffer[] and position in Stream Padding 77 size_t pos; 78 79 /// Buffer to hold Stream Header, Block Header, and Stream Footer. 80 /// Block Header has biggest maximum size. 81 uint8_t buffer[LZMA_BLOCK_HEADER_SIZE_MAX]; 82} lzma_stream_coder; 83 84 85static lzma_ret 86stream_decoder_reset(lzma_stream_coder *coder, const lzma_allocator *allocator) 87{ 88 // Initialize the Index hash used to verify the Index. 89 coder->index_hash = lzma_index_hash_init(coder->index_hash, allocator); 90 if (coder->index_hash == NULL) 91 return LZMA_MEM_ERROR; 92 93 // Reset the rest of the variables. 94 coder->sequence = SEQ_STREAM_HEADER; 95 coder->pos = 0; 96 97 return LZMA_OK; 98} 99 100 101static lzma_ret 102stream_decode(void *coder_ptr, const lzma_allocator *allocator, 103 const uint8_t *restrict in, size_t *restrict in_pos, 104 size_t in_size, uint8_t *restrict out, 105 size_t *restrict out_pos, size_t out_size, lzma_action action) 106{ 107 lzma_stream_coder *coder = coder_ptr; 108 109 // When decoding the actual Block, it may be able to produce more 110 // output even if we don't give it any new input. 111 while (true) 112 switch (coder->sequence) { 113 case SEQ_STREAM_HEADER: { 114 // Copy the Stream Header to the internal buffer. 115 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, 116 LZMA_STREAM_HEADER_SIZE); 117 118 // Return if we didn't get the whole Stream Header yet. 119 if (coder->pos < LZMA_STREAM_HEADER_SIZE) 120 return LZMA_OK; 121 122 coder->pos = 0; 123 124 // Decode the Stream Header. 125 const lzma_ret ret = lzma_stream_header_decode( 126 &coder->stream_flags, coder->buffer); 127 if (ret != LZMA_OK) 128 return ret == LZMA_FORMAT_ERROR && !coder->first_stream 129 ? LZMA_DATA_ERROR : ret; 130 131 // If we are decoding concatenated Streams, and the later 132 // Streams have invalid Header Magic Bytes, we give 133 // LZMA_DATA_ERROR instead of LZMA_FORMAT_ERROR. 134 coder->first_stream = false; 135 136 // Copy the type of the Check so that Block Header and Block 137 // decoders see it. 138 coder->block_options.check = coder->stream_flags.check; 139 140 // Even if we return LZMA_*_CHECK below, we want 141 // to continue from Block Header decoding. 142 coder->sequence = SEQ_BLOCK_HEADER; 143 144 // Detect if there's no integrity check or if it is 145 // unsupported if those were requested by the application. 146 if (coder->tell_no_check && coder->stream_flags.check 147 == LZMA_CHECK_NONE) 148 return LZMA_NO_CHECK; 149 150 if (coder->tell_unsupported_check 151 && !lzma_check_is_supported( 152 coder->stream_flags.check)) 153 return LZMA_UNSUPPORTED_CHECK; 154 155 if (coder->tell_any_check) 156 return LZMA_GET_CHECK; 157 } 158 159 // Fall through 160 161 case SEQ_BLOCK_HEADER: { 162 if (*in_pos >= in_size) 163 return LZMA_OK; 164 165 if (coder->pos == 0) { 166 // Detect if it's Index. 167 if (in[*in_pos] == INDEX_INDICATOR) { 168 coder->sequence = SEQ_INDEX; 169 break; 170 } 171 172 // Calculate the size of the Block Header. Note that 173 // Block Header decoder wants to see this byte too 174 // so don't advance *in_pos. 175 coder->block_options.header_size 176 = lzma_block_header_size_decode( 177 in[*in_pos]); 178 } 179 180 // Copy the Block Header to the internal buffer. 181 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, 182 coder->block_options.header_size); 183 184 // Return if we didn't get the whole Block Header yet. 185 if (coder->pos < coder->block_options.header_size) 186 return LZMA_OK; 187 188 coder->pos = 0; 189 coder->sequence = SEQ_BLOCK_INIT; 190 } 191 192 // Fall through 193 194 case SEQ_BLOCK_INIT: { 195 // Checking memusage and doing the initialization needs 196 // its own sequence point because we need to be able to 197 // retry if we return LZMA_MEMLIMIT_ERROR. 198 199 // Version 1 is needed to support the .ignore_check option. 200 coder->block_options.version = 1; 201 202 // Set up a buffer to hold the filter chain. Block Header 203 // decoder will initialize all members of this array so 204 // we don't need to do it here. 205 lzma_filter filters[LZMA_FILTERS_MAX + 1]; 206 coder->block_options.filters = filters; 207 208 // Decode the Block Header. 209 return_if_error(lzma_block_header_decode(&coder->block_options, 210 allocator, coder->buffer)); 211 212 // If LZMA_IGNORE_CHECK was used, this flag needs to be set. 213 // It has to be set after lzma_block_header_decode() because 214 // it always resets this to false. 215 coder->block_options.ignore_check = coder->ignore_check; 216 217 // Check the memory usage limit. 218 const uint64_t memusage = lzma_raw_decoder_memusage(filters); 219 lzma_ret ret; 220 221 if (memusage == UINT64_MAX) { 222 // One or more unknown Filter IDs. 223 ret = LZMA_OPTIONS_ERROR; 224 } else { 225 // Now we can set coder->memusage since we know that 226 // the filter chain is valid. We don't want 227 // lzma_memusage() to return UINT64_MAX in case of 228 // invalid filter chain. 229 coder->memusage = memusage; 230 231 if (memusage > coder->memlimit) { 232 // The chain would need too much memory. 233 ret = LZMA_MEMLIMIT_ERROR; 234 } else { 235 // Memory usage is OK. 236 // Initialize the Block decoder. 237 ret = lzma_block_decoder_init( 238 &coder->block_decoder, 239 allocator, 240 &coder->block_options); 241 } 242 } 243 244 // Free the allocated filter options since they are needed 245 // only to initialize the Block decoder. 246 lzma_filters_free(filters, allocator); 247 coder->block_options.filters = NULL; 248 249 // Check if memory usage calculation and Block decoder 250 // initialization succeeded. 251 if (ret != LZMA_OK) 252 return ret; 253 254 coder->sequence = SEQ_BLOCK_RUN; 255 } 256 257 // Fall through 258 259 case SEQ_BLOCK_RUN: { 260 const lzma_ret ret = coder->block_decoder.code( 261 coder->block_decoder.coder, allocator, 262 in, in_pos, in_size, out, out_pos, out_size, 263 action); 264 265 if (ret != LZMA_STREAM_END) 266 return ret; 267 268 // Block decoded successfully. Add the new size pair to 269 // the Index hash. 270 return_if_error(lzma_index_hash_append(coder->index_hash, 271 lzma_block_unpadded_size( 272 &coder->block_options), 273 coder->block_options.uncompressed_size)); 274 275 coder->sequence = SEQ_BLOCK_HEADER; 276 break; 277 } 278 279 case SEQ_INDEX: { 280 // If we don't have any input, don't call 281 // lzma_index_hash_decode() since it would return 282 // LZMA_BUF_ERROR, which we must not do here. 283 if (*in_pos >= in_size) 284 return LZMA_OK; 285 286 // Decode the Index and compare it to the hash calculated 287 // from the sizes of the Blocks (if any). 288 const lzma_ret ret = lzma_index_hash_decode(coder->index_hash, 289 in, in_pos, in_size); 290 if (ret != LZMA_STREAM_END) 291 return ret; 292 293 coder->sequence = SEQ_STREAM_FOOTER; 294 } 295 296 // Fall through 297 298 case SEQ_STREAM_FOOTER: { 299 // Copy the Stream Footer to the internal buffer. 300 lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos, 301 LZMA_STREAM_HEADER_SIZE); 302 303 // Return if we didn't get the whole Stream Footer yet. 304 if (coder->pos < LZMA_STREAM_HEADER_SIZE) 305 return LZMA_OK; 306 307 coder->pos = 0; 308 309 // Decode the Stream Footer. The decoder gives 310 // LZMA_FORMAT_ERROR if the magic bytes don't match, 311 // so convert that return code to LZMA_DATA_ERROR. 312 lzma_stream_flags footer_flags; 313 const lzma_ret ret = lzma_stream_footer_decode( 314 &footer_flags, coder->buffer); 315 if (ret != LZMA_OK) 316 return ret == LZMA_FORMAT_ERROR 317 ? LZMA_DATA_ERROR : ret; 318 319 // Check that Index Size stored in the Stream Footer matches 320 // the real size of the Index field. 321 if (lzma_index_hash_size(coder->index_hash) 322 != footer_flags.backward_size) 323 return LZMA_DATA_ERROR; 324 325 // Compare that the Stream Flags fields are identical in 326 // both Stream Header and Stream Footer. 327 return_if_error(lzma_stream_flags_compare( 328 &coder->stream_flags, &footer_flags)); 329 330 if (!coder->concatenated) 331 return LZMA_STREAM_END; 332 333 coder->sequence = SEQ_STREAM_PADDING; 334 } 335 336 // Fall through 337 338 case SEQ_STREAM_PADDING: 339 assert(coder->concatenated); 340 341 // Skip over possible Stream Padding. 342 while (true) { 343 if (*in_pos >= in_size) { 344 // Unless LZMA_FINISH was used, we cannot 345 // know if there's more input coming later. 346 if (action != LZMA_FINISH) 347 return LZMA_OK; 348 349 // Stream Padding must be a multiple of 350 // four bytes. 351 return coder->pos == 0 352 ? LZMA_STREAM_END 353 : LZMA_DATA_ERROR; 354 } 355 356 // If the byte is not zero, it probably indicates 357 // beginning of a new Stream (or the file is corrupt). 358 if (in[*in_pos] != 0x00) 359 break; 360 361 ++*in_pos; 362 coder->pos = (coder->pos + 1) & 3; 363 } 364 365 // Stream Padding must be a multiple of four bytes (empty 366 // Stream Padding is OK). 367 if (coder->pos != 0) { 368 ++*in_pos; 369 return LZMA_DATA_ERROR; 370 } 371 372 // Prepare to decode the next Stream. 373 return_if_error(stream_decoder_reset(coder, allocator)); 374 break; 375 376 default: 377 assert(0); 378 return LZMA_PROG_ERROR; 379 } 380 381 // Never reached 382} 383 384 385static void 386stream_decoder_end(void *coder_ptr, const lzma_allocator *allocator) 387{ 388 lzma_stream_coder *coder = coder_ptr; 389 lzma_next_end(&coder->block_decoder, allocator); 390 lzma_index_hash_end(coder->index_hash, allocator); 391 lzma_free(coder, allocator); 392 return; 393} 394 395 396static lzma_check 397stream_decoder_get_check(const void *coder_ptr) 398{ 399 const lzma_stream_coder *coder = coder_ptr; 400 return coder->stream_flags.check; 401} 402 403 404static lzma_ret 405stream_decoder_memconfig(void *coder_ptr, uint64_t *memusage, 406 uint64_t *old_memlimit, uint64_t new_memlimit) 407{ 408 lzma_stream_coder *coder = coder_ptr; 409 410 *memusage = coder->memusage; 411 *old_memlimit = coder->memlimit; 412 413 if (new_memlimit != 0) { 414 if (new_memlimit < coder->memusage) 415 return LZMA_MEMLIMIT_ERROR; 416 417 coder->memlimit = new_memlimit; 418 } 419 420 return LZMA_OK; 421} 422 423 424extern lzma_ret 425lzma_stream_decoder_init( 426 lzma_next_coder *next, const lzma_allocator *allocator, 427 uint64_t memlimit, uint32_t flags) 428{ 429 lzma_next_coder_init(&lzma_stream_decoder_init, next, allocator); 430 431 if (flags & ~LZMA_SUPPORTED_FLAGS) 432 return LZMA_OPTIONS_ERROR; 433 434 lzma_stream_coder *coder = next->coder; 435 if (coder == NULL) { 436 coder = lzma_alloc(sizeof(lzma_stream_coder), allocator); 437 if (coder == NULL) 438 return LZMA_MEM_ERROR; 439 440 next->coder = coder; 441 next->code = &stream_decode; 442 next->end = &stream_decoder_end; 443 next->get_check = &stream_decoder_get_check; 444 next->memconfig = &stream_decoder_memconfig; 445 446 coder->block_decoder = LZMA_NEXT_CODER_INIT; 447 coder->index_hash = NULL; 448 } 449 450 coder->memlimit = my_max(1, memlimit); 451 coder->memusage = LZMA_MEMUSAGE_BASE; 452 coder->tell_no_check = (flags & LZMA_TELL_NO_CHECK) != 0; 453 coder->tell_unsupported_check 454 = (flags & LZMA_TELL_UNSUPPORTED_CHECK) != 0; 455 coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0; 456 coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0; 457 coder->concatenated = (flags & LZMA_CONCATENATED) != 0; 458 coder->first_stream = true; 459 460 return stream_decoder_reset(coder, allocator); 461} 462 463 464extern LZMA_API(lzma_ret) 465lzma_stream_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags) 466{ 467 lzma_next_strm_init(lzma_stream_decoder_init, strm, memlimit, flags); 468 469 strm->internal->supported_actions[LZMA_RUN] = true; 470 strm->internal->supported_actions[LZMA_FINISH] = true; 471 472 return LZMA_OK; 473} 474