1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "media/webm/webm_parser.h" 6 7 // This file contains code to parse WebM file elements. It was created 8 // from information in the Matroska spec. 9 // http://www.matroska.org/technical/specs/index.html 10 // This file contains code for encrypted WebM. Current WebM 11 // encrypted request for comments specification is here 12 // http://wiki.webmproject.org/encryption/webm-encryption-rfc 13 14 #include <iomanip> 15 16 #include "base/logging.h" 17 #include "media/webm/webm_constants.h" 18 19 namespace media { 20 21 enum ElementType { 22 UNKNOWN, 23 LIST, // Referred to as Master Element in the Matroska spec. 24 UINT, 25 FLOAT, 26 BINARY, 27 STRING, 28 SKIP, 29 }; 30 31 struct ElementIdInfo { 32 ElementType type_; 33 int id_; 34 }; 35 36 struct ListElementInfo { 37 int id_; 38 int level_; 39 const ElementIdInfo* id_info_; 40 int id_info_count_; 41 }; 42 43 // The following are tables indicating what IDs are valid sub-elements 44 // of particular elements. If an element is encountered that doesn't 45 // appear in the list, a parsing error is signalled. Some elements are 46 // marked as SKIP because they are valid, but we don't care about them 47 // right now. 48 static const ElementIdInfo kEBMLHeaderIds[] = { 49 {UINT, kWebMIdEBMLVersion}, 50 {UINT, kWebMIdEBMLReadVersion}, 51 {UINT, kWebMIdEBMLMaxIDLength}, 52 {UINT, kWebMIdEBMLMaxSizeLength}, 53 {STRING, kWebMIdDocType}, 54 {UINT, kWebMIdDocTypeVersion}, 55 {UINT, kWebMIdDocTypeReadVersion}, 56 }; 57 58 static const ElementIdInfo kSegmentIds[] = { 59 {LIST, kWebMIdSeekHead}, 60 {LIST, kWebMIdInfo}, 61 {LIST, kWebMIdCluster}, 62 {LIST, kWebMIdTracks}, 63 {LIST, kWebMIdCues}, 64 {LIST, kWebMIdAttachments}, 65 {LIST, kWebMIdChapters}, 66 {LIST, kWebMIdTags}, 67 }; 68 69 static const ElementIdInfo kSeekHeadIds[] = { 70 {LIST, kWebMIdSeek}, 71 }; 72 73 static const ElementIdInfo kSeekIds[] = { 74 {BINARY, kWebMIdSeekID}, 75 {UINT, kWebMIdSeekPosition}, 76 }; 77 78 static const ElementIdInfo kInfoIds[] = { 79 {BINARY, kWebMIdSegmentUID}, 80 {STRING, kWebMIdSegmentFilename}, 81 {BINARY, kWebMIdPrevUID}, 82 {STRING, kWebMIdPrevFilename}, 83 {BINARY, kWebMIdNextUID}, 84 {STRING, kWebMIdNextFilename}, 85 {BINARY, kWebMIdSegmentFamily}, 86 {LIST, kWebMIdChapterTranslate}, 87 {UINT, kWebMIdTimecodeScale}, 88 {FLOAT, kWebMIdDuration}, 89 {BINARY, kWebMIdDateUTC}, 90 {STRING, kWebMIdTitle}, 91 {STRING, kWebMIdMuxingApp}, 92 {STRING, kWebMIdWritingApp}, 93 }; 94 95 static const ElementIdInfo kChapterTranslateIds[] = { 96 {UINT, kWebMIdChapterTranslateEditionUID}, 97 {UINT, kWebMIdChapterTranslateCodec}, 98 {BINARY, kWebMIdChapterTranslateID}, 99 }; 100 101 static const ElementIdInfo kClusterIds[] = { 102 {BINARY, kWebMIdSimpleBlock}, 103 {UINT, kWebMIdTimecode}, 104 {LIST, kWebMIdSilentTracks}, 105 {UINT, kWebMIdPosition}, 106 {UINT, kWebMIdPrevSize}, 107 {LIST, kWebMIdBlockGroup}, 108 }; 109 110 static const ElementIdInfo kSilentTracksIds[] = { 111 {UINT, kWebMIdSilentTrackNumber}, 112 }; 113 114 static const ElementIdInfo kBlockGroupIds[] = { 115 {BINARY, kWebMIdBlock}, 116 {LIST, kWebMIdBlockAdditions}, 117 {UINT, kWebMIdBlockDuration}, 118 {UINT, kWebMIdReferencePriority}, 119 {BINARY, kWebMIdReferenceBlock}, 120 {BINARY, kWebMIdCodecState}, 121 {LIST, kWebMIdSlices}, 122 }; 123 124 static const ElementIdInfo kBlockAdditionsIds[] = { 125 {LIST, kWebMIdBlockMore}, 126 }; 127 128 static const ElementIdInfo kBlockMoreIds[] = { 129 {UINT, kWebMIdBlockAddID}, 130 {BINARY, kWebMIdBlockAdditional}, 131 }; 132 133 static const ElementIdInfo kSlicesIds[] = { 134 {LIST, kWebMIdTimeSlice}, 135 }; 136 137 static const ElementIdInfo kTimeSliceIds[] = { 138 {UINT, kWebMIdLaceNumber}, 139 }; 140 141 static const ElementIdInfo kTracksIds[] = { 142 {LIST, kWebMIdTrackEntry}, 143 }; 144 145 static const ElementIdInfo kTrackEntryIds[] = { 146 {UINT, kWebMIdTrackNumber}, 147 {UINT, kWebMIdTrackUID}, 148 {UINT, kWebMIdTrackType}, 149 {UINT, kWebMIdFlagEnabled}, 150 {UINT, kWebMIdFlagDefault}, 151 {UINT, kWebMIdFlagForced}, 152 {UINT, kWebMIdFlagLacing}, 153 {UINT, kWebMIdMinCache}, 154 {UINT, kWebMIdMaxCache}, 155 {UINT, kWebMIdDefaultDuration}, 156 {FLOAT, kWebMIdTrackTimecodeScale}, 157 {UINT, kWebMIdMaxBlockAdditionId}, 158 {STRING, kWebMIdName}, 159 {STRING, kWebMIdLanguage}, 160 {STRING, kWebMIdCodecID}, 161 {BINARY, kWebMIdCodecPrivate}, 162 {STRING, kWebMIdCodecName}, 163 {UINT, kWebMIdAttachmentLink}, 164 {UINT, kWebMIdCodecDecodeAll}, 165 {UINT, kWebMIdTrackOverlay}, 166 {LIST, kWebMIdTrackTranslate}, 167 {LIST, kWebMIdVideo}, 168 {LIST, kWebMIdAudio}, 169 {LIST, kWebMIdTrackOperation}, 170 {LIST, kWebMIdContentEncodings}, 171 }; 172 173 static const ElementIdInfo kTrackTranslateIds[] = { 174 {UINT, kWebMIdTrackTranslateEditionUID}, 175 {UINT, kWebMIdTrackTranslateCodec}, 176 {BINARY, kWebMIdTrackTranslateTrackID}, 177 }; 178 179 static const ElementIdInfo kVideoIds[] = { 180 {UINT, kWebMIdFlagInterlaced}, 181 {UINT, kWebMIdStereoMode}, 182 {UINT, kWebMIdAlphaMode}, 183 {UINT, kWebMIdPixelWidth}, 184 {UINT, kWebMIdPixelHeight}, 185 {UINT, kWebMIdPixelCropBottom}, 186 {UINT, kWebMIdPixelCropTop}, 187 {UINT, kWebMIdPixelCropLeft}, 188 {UINT, kWebMIdPixelCropRight}, 189 {UINT, kWebMIdDisplayWidth}, 190 {UINT, kWebMIdDisplayHeight}, 191 {UINT, kWebMIdDisplayUnit}, 192 {UINT, kWebMIdAspectRatioType}, 193 {BINARY, kWebMIdColorSpace}, 194 }; 195 196 static const ElementIdInfo kAudioIds[] = { 197 {FLOAT, kWebMIdSamplingFrequency}, 198 {FLOAT, kWebMIdOutputSamplingFrequency}, 199 {UINT, kWebMIdChannels}, 200 {UINT, kWebMIdBitDepth}, 201 }; 202 203 static const ElementIdInfo kTrackOperationIds[] = { 204 {LIST, kWebMIdTrackCombinePlanes}, 205 {LIST, kWebMIdJoinBlocks}, 206 }; 207 208 static const ElementIdInfo kTrackCombinePlanesIds[] = { 209 {LIST, kWebMIdTrackPlane}, 210 }; 211 212 static const ElementIdInfo kTrackPlaneIds[] = { 213 {UINT, kWebMIdTrackPlaneUID}, 214 {UINT, kWebMIdTrackPlaneType}, 215 }; 216 217 static const ElementIdInfo kJoinBlocksIds[] = { 218 {UINT, kWebMIdTrackJoinUID}, 219 }; 220 221 static const ElementIdInfo kContentEncodingsIds[] = { 222 {LIST, kWebMIdContentEncoding}, 223 }; 224 225 static const ElementIdInfo kContentEncodingIds[] = { 226 {UINT, kWebMIdContentEncodingOrder}, 227 {UINT, kWebMIdContentEncodingScope}, 228 {UINT, kWebMIdContentEncodingType}, 229 {LIST, kWebMIdContentCompression}, 230 {LIST, kWebMIdContentEncryption}, 231 }; 232 233 static const ElementIdInfo kContentCompressionIds[] = { 234 {UINT, kWebMIdContentCompAlgo}, 235 {BINARY, kWebMIdContentCompSettings}, 236 }; 237 238 static const ElementIdInfo kContentEncryptionIds[] = { 239 {LIST, kWebMIdContentEncAESSettings}, 240 {UINT, kWebMIdContentEncAlgo}, 241 {BINARY, kWebMIdContentEncKeyID}, 242 {BINARY, kWebMIdContentSignature}, 243 {BINARY, kWebMIdContentSigKeyID}, 244 {UINT, kWebMIdContentSigAlgo}, 245 {UINT, kWebMIdContentSigHashAlgo}, 246 }; 247 248 static const ElementIdInfo kContentEncAESSettingsIds[] = { 249 {UINT, kWebMIdAESSettingsCipherMode}, 250 }; 251 252 static const ElementIdInfo kCuesIds[] = { 253 {LIST, kWebMIdCuePoint}, 254 }; 255 256 static const ElementIdInfo kCuePointIds[] = { 257 {UINT, kWebMIdCueTime}, 258 {LIST, kWebMIdCueTrackPositions}, 259 }; 260 261 static const ElementIdInfo kCueTrackPositionsIds[] = { 262 {UINT, kWebMIdCueTrack}, 263 {UINT, kWebMIdCueClusterPosition}, 264 {UINT, kWebMIdCueBlockNumber}, 265 {UINT, kWebMIdCueCodecState}, 266 {LIST, kWebMIdCueReference}, 267 }; 268 269 static const ElementIdInfo kCueReferenceIds[] = { 270 {UINT, kWebMIdCueRefTime}, 271 }; 272 273 static const ElementIdInfo kAttachmentsIds[] = { 274 {LIST, kWebMIdAttachedFile}, 275 }; 276 277 static const ElementIdInfo kAttachedFileIds[] = { 278 {STRING, kWebMIdFileDescription}, 279 {STRING, kWebMIdFileName}, 280 {STRING, kWebMIdFileMimeType}, 281 {BINARY, kWebMIdFileData}, 282 {UINT, kWebMIdFileUID}, 283 }; 284 285 static const ElementIdInfo kChaptersIds[] = { 286 {LIST, kWebMIdEditionEntry}, 287 }; 288 289 static const ElementIdInfo kEditionEntryIds[] = { 290 {UINT, kWebMIdEditionUID}, 291 {UINT, kWebMIdEditionFlagHidden}, 292 {UINT, kWebMIdEditionFlagDefault}, 293 {UINT, kWebMIdEditionFlagOrdered}, 294 {LIST, kWebMIdChapterAtom}, 295 }; 296 297 static const ElementIdInfo kChapterAtomIds[] = { 298 {UINT, kWebMIdChapterUID}, 299 {UINT, kWebMIdChapterTimeStart}, 300 {UINT, kWebMIdChapterTimeEnd}, 301 {UINT, kWebMIdChapterFlagHidden}, 302 {UINT, kWebMIdChapterFlagEnabled}, 303 {BINARY, kWebMIdChapterSegmentUID}, 304 {UINT, kWebMIdChapterSegmentEditionUID}, 305 {UINT, kWebMIdChapterPhysicalEquiv}, 306 {LIST, kWebMIdChapterTrack}, 307 {LIST, kWebMIdChapterDisplay}, 308 {LIST, kWebMIdChapProcess}, 309 }; 310 311 static const ElementIdInfo kChapterTrackIds[] = { 312 {UINT, kWebMIdChapterTrackNumber}, 313 }; 314 315 static const ElementIdInfo kChapterDisplayIds[] = { 316 {STRING, kWebMIdChapString}, 317 {STRING, kWebMIdChapLanguage}, 318 {STRING, kWebMIdChapCountry}, 319 }; 320 321 static const ElementIdInfo kChapProcessIds[] = { 322 {UINT, kWebMIdChapProcessCodecID}, 323 {BINARY, kWebMIdChapProcessPrivate}, 324 {LIST, kWebMIdChapProcessCommand}, 325 }; 326 327 static const ElementIdInfo kChapProcessCommandIds[] = { 328 {UINT, kWebMIdChapProcessTime}, 329 {BINARY, kWebMIdChapProcessData}, 330 }; 331 332 static const ElementIdInfo kTagsIds[] = { 333 {LIST, kWebMIdTag}, 334 }; 335 336 static const ElementIdInfo kTagIds[] = { 337 {LIST, kWebMIdTargets}, 338 {LIST, kWebMIdSimpleTag}, 339 }; 340 341 static const ElementIdInfo kTargetsIds[] = { 342 {UINT, kWebMIdTargetTypeValue}, 343 {STRING, kWebMIdTargetType}, 344 {UINT, kWebMIdTagTrackUID}, 345 {UINT, kWebMIdTagEditionUID}, 346 {UINT, kWebMIdTagChapterUID}, 347 {UINT, kWebMIdTagAttachmentUID}, 348 }; 349 350 static const ElementIdInfo kSimpleTagIds[] = { 351 {STRING, kWebMIdTagName}, 352 {STRING, kWebMIdTagLanguage}, 353 {UINT, kWebMIdTagDefault}, 354 {STRING, kWebMIdTagString}, 355 {BINARY, kWebMIdTagBinary}, 356 }; 357 358 #define LIST_ELEMENT_INFO(id, level, id_info) \ 359 { (id), (level), (id_info), arraysize(id_info) } 360 361 static const ListElementInfo kListElementInfo[] = { 362 LIST_ELEMENT_INFO(kWebMIdCluster, 1, kClusterIds), 363 LIST_ELEMENT_INFO(kWebMIdEBMLHeader, 0, kEBMLHeaderIds), 364 LIST_ELEMENT_INFO(kWebMIdSegment, 0, kSegmentIds), 365 LIST_ELEMENT_INFO(kWebMIdSeekHead, 1, kSeekHeadIds), 366 LIST_ELEMENT_INFO(kWebMIdSeek, 2, kSeekIds), 367 LIST_ELEMENT_INFO(kWebMIdInfo, 1, kInfoIds), 368 LIST_ELEMENT_INFO(kWebMIdChapterTranslate, 2, kChapterTranslateIds), 369 LIST_ELEMENT_INFO(kWebMIdSilentTracks, 2, kSilentTracksIds), 370 LIST_ELEMENT_INFO(kWebMIdBlockGroup, 2, kBlockGroupIds), 371 LIST_ELEMENT_INFO(kWebMIdBlockAdditions, 3, kBlockAdditionsIds), 372 LIST_ELEMENT_INFO(kWebMIdBlockMore, 4, kBlockMoreIds), 373 LIST_ELEMENT_INFO(kWebMIdSlices, 3, kSlicesIds), 374 LIST_ELEMENT_INFO(kWebMIdTimeSlice, 4, kTimeSliceIds), 375 LIST_ELEMENT_INFO(kWebMIdTracks, 1, kTracksIds), 376 LIST_ELEMENT_INFO(kWebMIdTrackEntry, 2, kTrackEntryIds), 377 LIST_ELEMENT_INFO(kWebMIdTrackTranslate, 3, kTrackTranslateIds), 378 LIST_ELEMENT_INFO(kWebMIdVideo, 3, kVideoIds), 379 LIST_ELEMENT_INFO(kWebMIdAudio, 3, kAudioIds), 380 LIST_ELEMENT_INFO(kWebMIdTrackOperation, 3, kTrackOperationIds), 381 LIST_ELEMENT_INFO(kWebMIdTrackCombinePlanes, 4, kTrackCombinePlanesIds), 382 LIST_ELEMENT_INFO(kWebMIdTrackPlane, 5, kTrackPlaneIds), 383 LIST_ELEMENT_INFO(kWebMIdJoinBlocks, 4, kJoinBlocksIds), 384 LIST_ELEMENT_INFO(kWebMIdContentEncodings, 3, kContentEncodingsIds), 385 LIST_ELEMENT_INFO(kWebMIdContentEncoding, 4, kContentEncodingIds), 386 LIST_ELEMENT_INFO(kWebMIdContentCompression, 5, kContentCompressionIds), 387 LIST_ELEMENT_INFO(kWebMIdContentEncryption, 5, kContentEncryptionIds), 388 LIST_ELEMENT_INFO(kWebMIdContentEncAESSettings, 6, kContentEncAESSettingsIds), 389 LIST_ELEMENT_INFO(kWebMIdCues, 1, kCuesIds), 390 LIST_ELEMENT_INFO(kWebMIdCuePoint, 2, kCuePointIds), 391 LIST_ELEMENT_INFO(kWebMIdCueTrackPositions, 3, kCueTrackPositionsIds), 392 LIST_ELEMENT_INFO(kWebMIdCueReference, 4, kCueReferenceIds), 393 LIST_ELEMENT_INFO(kWebMIdAttachments, 1, kAttachmentsIds), 394 LIST_ELEMENT_INFO(kWebMIdAttachedFile, 2, kAttachedFileIds), 395 LIST_ELEMENT_INFO(kWebMIdChapters, 1, kChaptersIds), 396 LIST_ELEMENT_INFO(kWebMIdEditionEntry, 2, kEditionEntryIds), 397 LIST_ELEMENT_INFO(kWebMIdChapterAtom, 3, kChapterAtomIds), 398 LIST_ELEMENT_INFO(kWebMIdChapterTrack, 4, kChapterTrackIds), 399 LIST_ELEMENT_INFO(kWebMIdChapterDisplay, 4, kChapterDisplayIds), 400 LIST_ELEMENT_INFO(kWebMIdChapProcess, 4, kChapProcessIds), 401 LIST_ELEMENT_INFO(kWebMIdChapProcessCommand, 5, kChapProcessCommandIds), 402 LIST_ELEMENT_INFO(kWebMIdTags, 1, kTagsIds), 403 LIST_ELEMENT_INFO(kWebMIdTag, 2, kTagIds), 404 LIST_ELEMENT_INFO(kWebMIdTargets, 3, kTargetsIds), 405 LIST_ELEMENT_INFO(kWebMIdSimpleTag, 3, kSimpleTagIds), 406 }; 407 408 // Parses an element header id or size field. These fields are variable length 409 // encoded. The first byte indicates how many bytes the field occupies. 410 // |buf| - The buffer to parse. 411 // |size| - The number of bytes in |buf| 412 // |max_bytes| - The maximum number of bytes the field can be. ID fields 413 // set this to 4 & element size fields set this to 8. If the 414 // first byte indicates a larger field size than this it is a 415 // parser error. 416 // |mask_first_byte| - For element size fields the field length encoding bits 417 // need to be masked off. This parameter is true for 418 // element size fields and is false for ID field values. 419 // 420 // Returns: The number of bytes parsed on success. -1 on error. 421 static int ParseWebMElementHeaderField(const uint8* buf, int size, 422 int max_bytes, bool mask_first_byte, 423 int64* num) { 424 DCHECK(buf); 425 DCHECK(num); 426 427 if (size < 0) 428 return -1; 429 430 if (size == 0) 431 return 0; 432 433 int mask = 0x80; 434 uint8 ch = buf[0]; 435 int extra_bytes = -1; 436 bool all_ones = false; 437 for (int i = 0; i < max_bytes; ++i) { 438 if ((ch & mask) != 0) { 439 mask = ~mask & 0xff; 440 *num = mask_first_byte ? ch & mask : ch; 441 all_ones = (ch & mask) == mask; 442 extra_bytes = i; 443 break; 444 } 445 mask = 0x80 | mask >> 1; 446 } 447 448 if (extra_bytes == -1) 449 return -1; 450 451 // Return 0 if we need more data. 452 if ((1 + extra_bytes) > size) 453 return 0; 454 455 int bytes_used = 1; 456 457 for (int i = 0; i < extra_bytes; ++i) { 458 ch = buf[bytes_used++]; 459 all_ones &= (ch == 0xff); 460 *num = (*num << 8) | ch; 461 } 462 463 if (all_ones) 464 *num = kint64max; 465 466 return bytes_used; 467 } 468 469 int WebMParseElementHeader(const uint8* buf, int size, 470 int* id, int64* element_size) { 471 DCHECK(buf); 472 DCHECK_GE(size, 0); 473 DCHECK(id); 474 DCHECK(element_size); 475 476 if (size == 0) 477 return 0; 478 479 int64 tmp = 0; 480 int num_id_bytes = ParseWebMElementHeaderField(buf, size, 4, false, &tmp); 481 482 if (num_id_bytes <= 0) 483 return num_id_bytes; 484 485 if (tmp == kint64max) 486 tmp = kWebMReservedId; 487 488 *id = static_cast<int>(tmp); 489 490 int num_size_bytes = ParseWebMElementHeaderField(buf + num_id_bytes, 491 size - num_id_bytes, 492 8, true, &tmp); 493 494 if (num_size_bytes <= 0) 495 return num_size_bytes; 496 497 if (tmp == kint64max) 498 tmp = kWebMUnknownSize; 499 500 *element_size = tmp; 501 DVLOG(3) << "WebMParseElementHeader() : id " << std::hex << *id << std::dec 502 << " size " << *element_size; 503 return num_id_bytes + num_size_bytes; 504 } 505 506 // Finds ElementType for a specific ID. 507 static ElementType FindIdType(int id, 508 const ElementIdInfo* id_info, 509 int id_info_count) { 510 511 // Check for global element IDs that can be anywhere. 512 if (id == kWebMIdVoid || id == kWebMIdCRC32) 513 return SKIP; 514 515 for (int i = 0; i < id_info_count; ++i) { 516 if (id == id_info[i].id_) 517 return id_info[i].type_; 518 } 519 520 return UNKNOWN; 521 } 522 523 // Finds ListElementInfo for a specific ID. 524 static const ListElementInfo* FindListInfo(int id) { 525 for (size_t i = 0; i < arraysize(kListElementInfo); ++i) { 526 if (id == kListElementInfo[i].id_) 527 return &kListElementInfo[i]; 528 } 529 530 return NULL; 531 } 532 533 static int FindListLevel(int id) { 534 const ListElementInfo* list_info = FindListInfo(id); 535 if (list_info) 536 return list_info->level_; 537 538 return -1; 539 } 540 541 static int ParseUInt(const uint8* buf, int size, int id, 542 WebMParserClient* client) { 543 if ((size <= 0) || (size > 8)) 544 return -1; 545 546 // Read in the big-endian integer. 547 int64 value = 0; 548 for (int i = 0; i < size; ++i) 549 value = (value << 8) | buf[i]; 550 551 if (!client->OnUInt(id, value)) 552 return -1; 553 554 return size; 555 } 556 557 static int ParseFloat(const uint8* buf, int size, int id, 558 WebMParserClient* client) { 559 560 if ((size != 4) && (size != 8)) 561 return -1; 562 563 double value = -1; 564 565 // Read the bytes from big-endian form into a native endian integer. 566 int64 tmp = 0; 567 for (int i = 0; i < size; ++i) 568 tmp = (tmp << 8) | buf[i]; 569 570 // Use a union to convert the integer bit pattern into a floating point 571 // number. 572 if (size == 4) { 573 union { 574 int32 src; 575 float dst; 576 } tmp2; 577 tmp2.src = static_cast<int32>(tmp); 578 value = tmp2.dst; 579 } else if (size == 8) { 580 union { 581 int64 src; 582 double dst; 583 } tmp2; 584 tmp2.src = tmp; 585 value = tmp2.dst; 586 } else { 587 return -1; 588 } 589 590 if (!client->OnFloat(id, value)) 591 return -1; 592 593 return size; 594 } 595 596 static int ParseBinary(const uint8* buf, int size, int id, 597 WebMParserClient* client) { 598 return client->OnBinary(id, buf, size) ? size : -1; 599 } 600 601 static int ParseString(const uint8* buf, int size, int id, 602 WebMParserClient* client) { 603 const uint8* end = static_cast<const uint8*>(memchr(buf, '\0', size)); 604 int length = (end != NULL) ? static_cast<int>(end - buf) : size; 605 std::string str(reinterpret_cast<const char*>(buf), length); 606 return client->OnString(id, str) ? size : -1; 607 } 608 609 static int ParseNonListElement(ElementType type, int id, int64 element_size, 610 const uint8* buf, int size, 611 WebMParserClient* client) { 612 DCHECK_GE(size, element_size); 613 614 int result = -1; 615 switch(type) { 616 case LIST: 617 NOTIMPLEMENTED(); 618 result = -1; 619 break; 620 case UINT: 621 result = ParseUInt(buf, element_size, id, client); 622 break; 623 case FLOAT: 624 result = ParseFloat(buf, element_size, id, client); 625 break; 626 case BINARY: 627 result = ParseBinary(buf, element_size, id, client); 628 break; 629 case STRING: 630 result = ParseString(buf, element_size, id, client); 631 break; 632 case SKIP: 633 result = element_size; 634 break; 635 default: 636 DVLOG(1) << "Unhandled ID type " << type; 637 return -1; 638 }; 639 640 DCHECK_LE(result, size); 641 return result; 642 } 643 644 WebMParserClient::WebMParserClient() {} 645 WebMParserClient::~WebMParserClient() {} 646 647 WebMParserClient* WebMParserClient::OnListStart(int id) { 648 DVLOG(1) << "Unexpected list element start with ID " << std::hex << id; 649 return NULL; 650 } 651 652 bool WebMParserClient::OnListEnd(int id) { 653 DVLOG(1) << "Unexpected list element end with ID " << std::hex << id; 654 return false; 655 } 656 657 bool WebMParserClient::OnUInt(int id, int64 val) { 658 DVLOG(1) << "Unexpected unsigned integer element with ID " << std::hex << id; 659 return false; 660 } 661 662 bool WebMParserClient::OnFloat(int id, double val) { 663 DVLOG(1) << "Unexpected float element with ID " << std::hex << id; 664 return false; 665 } 666 667 bool WebMParserClient::OnBinary(int id, const uint8* data, int size) { 668 DVLOG(1) << "Unexpected binary element with ID " << std::hex << id; 669 return false; 670 } 671 672 bool WebMParserClient::OnString(int id, const std::string& str) { 673 DVLOG(1) << "Unexpected string element with ID " << std::hex << id; 674 return false; 675 } 676 677 WebMListParser::WebMListParser(int id, WebMParserClient* client) 678 : state_(NEED_LIST_HEADER), 679 root_id_(id), 680 root_level_(FindListLevel(id)), 681 root_client_(client) { 682 DCHECK_GE(root_level_, 0); 683 DCHECK(client); 684 } 685 686 WebMListParser::~WebMListParser() {} 687 688 void WebMListParser::Reset() { 689 ChangeState(NEED_LIST_HEADER); 690 list_state_stack_.clear(); 691 } 692 693 int WebMListParser::Parse(const uint8* buf, int size) { 694 DCHECK(buf); 695 696 if (size < 0 || state_ == PARSE_ERROR || state_ == DONE_PARSING_LIST) 697 return -1; 698 699 if (size == 0) 700 return 0; 701 702 const uint8* cur = buf; 703 int cur_size = size; 704 int bytes_parsed = 0; 705 706 while (cur_size > 0 && state_ != PARSE_ERROR && state_ != DONE_PARSING_LIST) { 707 int element_id = 0; 708 int64 element_size = 0; 709 int result = WebMParseElementHeader(cur, cur_size, &element_id, 710 &element_size); 711 712 if (result < 0) 713 return result; 714 715 if (result == 0) 716 return bytes_parsed; 717 718 switch(state_) { 719 case NEED_LIST_HEADER: { 720 if (element_id != root_id_) { 721 ChangeState(PARSE_ERROR); 722 return -1; 723 } 724 725 // Only allow Segment & Cluster to have an unknown size. 726 if (element_size == kWebMUnknownSize && 727 (element_id != kWebMIdSegment) && 728 (element_id != kWebMIdCluster)) { 729 ChangeState(PARSE_ERROR); 730 return -1; 731 } 732 733 ChangeState(INSIDE_LIST); 734 if (!OnListStart(root_id_, element_size)) 735 return -1; 736 737 break; 738 } 739 740 case INSIDE_LIST: { 741 int header_size = result; 742 const uint8* element_data = cur + header_size; 743 int element_data_size = cur_size - header_size; 744 745 if (element_size < element_data_size) 746 element_data_size = element_size; 747 748 result = ParseListElement(header_size, element_id, element_size, 749 element_data, element_data_size); 750 751 DCHECK_LE(result, header_size + element_data_size); 752 if (result < 0) { 753 ChangeState(PARSE_ERROR); 754 return -1; 755 } 756 757 if (result == 0) 758 return bytes_parsed; 759 760 break; 761 } 762 case DONE_PARSING_LIST: 763 case PARSE_ERROR: 764 // Shouldn't be able to get here. 765 NOTIMPLEMENTED(); 766 break; 767 } 768 769 cur += result; 770 cur_size -= result; 771 bytes_parsed += result; 772 } 773 774 return (state_ == PARSE_ERROR) ? -1 : bytes_parsed; 775 } 776 777 bool WebMListParser::IsParsingComplete() const { 778 return state_ == DONE_PARSING_LIST; 779 } 780 781 void WebMListParser::ChangeState(State new_state) { 782 state_ = new_state; 783 } 784 785 int WebMListParser::ParseListElement(int header_size, 786 int id, int64 element_size, 787 const uint8* data, int size) { 788 DCHECK_GT(list_state_stack_.size(), 0u); 789 790 ListState& list_state = list_state_stack_.back(); 791 DCHECK(list_state.element_info_); 792 793 const ListElementInfo* element_info = list_state.element_info_; 794 ElementType id_type = 795 FindIdType(id, element_info->id_info_, element_info->id_info_count_); 796 797 // Unexpected ID. 798 if (id_type == UNKNOWN) { 799 if (list_state.size_ != kWebMUnknownSize || 800 !IsSiblingOrAncestor(list_state.id_, id)) { 801 DVLOG(1) << "No ElementType info for ID 0x" << std::hex << id; 802 return -1; 803 } 804 805 // We've reached the end of a list of unknown size. Update the size now that 806 // we know it and dispatch the end of list calls. 807 list_state.size_ = list_state.bytes_parsed_; 808 809 if (!OnListEnd()) 810 return -1; 811 812 // Check to see if all open lists have ended. 813 if (list_state_stack_.size() == 0) 814 return 0; 815 816 list_state = list_state_stack_.back(); 817 } 818 819 // Make sure the whole element can fit inside the current list. 820 int64 total_element_size = header_size + element_size; 821 if (list_state.size_ != kWebMUnknownSize && 822 list_state.size_ < list_state.bytes_parsed_ + total_element_size) { 823 return -1; 824 } 825 826 if (id_type == LIST) { 827 list_state.bytes_parsed_ += header_size; 828 829 if (!OnListStart(id, element_size)) 830 return -1; 831 return header_size; 832 } 833 834 // Make sure we have the entire element before trying to parse a non-list 835 // element. 836 if (size < element_size) 837 return 0; 838 839 int bytes_parsed = ParseNonListElement(id_type, id, element_size, 840 data, size, list_state.client_); 841 DCHECK_LE(bytes_parsed, size); 842 843 // Return if an error occurred or we need more data. 844 // Note: bytes_parsed is 0 for a successful parse of a size 0 element. We 845 // need to check the element_size to disambiguate the "need more data" case 846 // from a successful parse. 847 if (bytes_parsed < 0 || (bytes_parsed == 0 && element_size != 0)) 848 return bytes_parsed; 849 850 int result = header_size + bytes_parsed; 851 list_state.bytes_parsed_ += result; 852 853 // See if we have reached the end of the current list. 854 if (list_state.bytes_parsed_ == list_state.size_) { 855 if (!OnListEnd()) 856 return -1; 857 } 858 859 return result; 860 } 861 862 bool WebMListParser::OnListStart(int id, int64 size) { 863 const ListElementInfo* element_info = FindListInfo(id); 864 if (!element_info) 865 return false; 866 867 int current_level = root_level_ + list_state_stack_.size() - 1; 868 if (current_level + 1 != element_info->level_) 869 return false; 870 871 WebMParserClient* current_list_client = NULL; 872 if (!list_state_stack_.empty()) { 873 // Make sure the new list doesn't go past the end of the current list. 874 ListState current_list_state = list_state_stack_.back(); 875 if (current_list_state.size_ != kWebMUnknownSize && 876 current_list_state.size_ < current_list_state.bytes_parsed_ + size) 877 return false; 878 current_list_client = current_list_state.client_; 879 } else { 880 current_list_client = root_client_; 881 } 882 883 WebMParserClient* new_list_client = current_list_client->OnListStart(id); 884 if (!new_list_client) 885 return false; 886 887 ListState new_list_state = { id, size, 0, element_info, new_list_client }; 888 list_state_stack_.push_back(new_list_state); 889 890 if (size == 0) 891 return OnListEnd(); 892 893 return true; 894 } 895 896 bool WebMListParser::OnListEnd() { 897 int lists_ended = 0; 898 for (; !list_state_stack_.empty(); ++lists_ended) { 899 const ListState& list_state = list_state_stack_.back(); 900 901 if (list_state.bytes_parsed_ != list_state.size_) 902 break; 903 904 list_state_stack_.pop_back(); 905 906 int64 bytes_parsed = list_state.bytes_parsed_; 907 WebMParserClient* client = NULL; 908 if (!list_state_stack_.empty()) { 909 // Update the bytes_parsed_ for the parent element. 910 list_state_stack_.back().bytes_parsed_ += bytes_parsed; 911 client = list_state_stack_.back().client_; 912 } else { 913 client = root_client_; 914 } 915 916 if (!client->OnListEnd(list_state.id_)) 917 return false; 918 } 919 920 DCHECK_GE(lists_ended, 1); 921 922 if (list_state_stack_.empty()) 923 ChangeState(DONE_PARSING_LIST); 924 925 return true; 926 } 927 928 bool WebMListParser::IsSiblingOrAncestor(int id_a, int id_b) const { 929 DCHECK((id_a == kWebMIdSegment) || (id_a == kWebMIdCluster)); 930 931 if (id_a == kWebMIdCluster) { 932 // kWebMIdCluster siblings. 933 for (size_t i = 0; i < arraysize(kSegmentIds); i++) { 934 if (kSegmentIds[i].id_ == id_b) 935 return true; 936 } 937 } 938 939 // kWebMIdSegment siblings. 940 return ((id_b == kWebMIdSegment) || (id_b == kWebMIdEBMLHeader)); 941 } 942 943 } // namespace media 944
