| // Copyright 2016 The PDFium Authors |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com |
| |
| #include "core/fpdfapi/parser/cpdf_parser.h" |
| |
| #include <ctype.h> |
| #include <stdint.h> |
| |
| #include <algorithm> |
| #include <utility> |
| #include <vector> |
| |
| #include "core/fpdfapi/parser/cpdf_array.h" |
| #include "core/fpdfapi/parser/cpdf_crypto_handler.h" |
| #include "core/fpdfapi/parser/cpdf_dictionary.h" |
| #include "core/fpdfapi/parser/cpdf_document.h" |
| #include "core/fpdfapi/parser/cpdf_linearized_header.h" |
| #include "core/fpdfapi/parser/cpdf_number.h" |
| #include "core/fpdfapi/parser/cpdf_object_stream.h" |
| #include "core/fpdfapi/parser/cpdf_read_validator.h" |
| #include "core/fpdfapi/parser/cpdf_reference.h" |
| #include "core/fpdfapi/parser/cpdf_security_handler.h" |
| #include "core/fpdfapi/parser/cpdf_stream.h" |
| #include "core/fpdfapi/parser/cpdf_stream_acc.h" |
| #include "core/fpdfapi/parser/cpdf_syntax_parser.h" |
| #include "core/fpdfapi/parser/fpdf_parser_utility.h" |
| #include "core/fxcrt/autorestorer.h" |
| #include "core/fxcrt/data_vector.h" |
| #include "core/fxcrt/fx_extension.h" |
| #include "core/fxcrt/fx_safe_types.h" |
| #include "core/fxcrt/scoped_set_insertion.h" |
| #include "third_party/base/check.h" |
| #include "third_party/base/check_op.h" |
| #include "third_party/base/containers/contains.h" |
| #include "third_party/base/containers/span.h" |
| #include "third_party/base/notreached.h" |
| |
| namespace { |
| |
| // A limit on the size of the xref table. Theoretical limits are higher, but |
| // this may be large enough in practice. The max size should always be 1 more |
| // than the max object number. |
| constexpr int32_t kMaxXRefSize = CPDF_Parser::kMaxObjectNumber + 1; |
| |
| // "%PDF-1.7\n" |
| constexpr FX_FILESIZE kPDFHeaderSize = 9; |
| |
| // The required number of fields in a /W array in a cross-reference stream |
| // dictionary. |
| constexpr size_t kMinFieldCount = 3; |
| |
| // V4 trailers are inline. |
| constexpr uint32_t kNoV4TrailerObjectNumber = 0; |
| |
| struct CrossRefV5IndexEntry { |
| uint32_t start_obj_num; |
| uint32_t obj_count; |
| }; |
| |
| CPDF_Parser::ObjectType GetObjectTypeFromCrossRefStreamType( |
| uint32_t cross_ref_stream_type) { |
| switch (cross_ref_stream_type) { |
| case 0: |
| return CPDF_Parser::ObjectType::kFree; |
| case 1: |
| return CPDF_Parser::ObjectType::kNormal; |
| case 2: |
| return CPDF_Parser::ObjectType::kCompressed; |
| default: |
| return CPDF_Parser::ObjectType::kNull; |
| } |
| } |
| |
| // Use the Get*XRefStreamEntry() functions below, instead of calling this |
| // directly. |
| uint32_t GetVarInt(pdfium::span<const uint8_t> input) { |
| uint32_t result = 0; |
| for (uint8_t c : input) |
| result = result * 256 + c; |
| return result; |
| } |
| |
| // The following 3 functions retrieve variable length entries from |
| // cross-reference streams, as described in ISO 32000-1:2008 table 18. There are |
| // only 3 fields for any given entry. |
| uint32_t GetFirstXRefStreamEntry(pdfium::span<const uint8_t> entry_span, |
| pdfium::span<const uint32_t> field_widths) { |
| return GetVarInt(entry_span.first(field_widths[0])); |
| } |
| |
| uint32_t GetSecondXRefStreamEntry(pdfium::span<const uint8_t> entry_span, |
| pdfium::span<const uint32_t> field_widths) { |
| return GetVarInt(entry_span.subspan(field_widths[0], field_widths[1])); |
| } |
| |
| uint32_t GetThirdXRefStreamEntry(pdfium::span<const uint8_t> entry_span, |
| pdfium::span<const uint32_t> field_widths) { |
| return GetVarInt( |
| entry_span.subspan(field_widths[0] + field_widths[1], field_widths[2])); |
| } |
| |
| std::vector<CrossRefV5IndexEntry> GetCrossRefV5Indices(const CPDF_Array* array, |
| uint32_t size) { |
| std::vector<CrossRefV5IndexEntry> indices; |
| if (array) { |
| for (size_t i = 0; i < array->size() / 2; i++) { |
| RetainPtr<const CPDF_Number> pStartNumObj = array->GetNumberAt(i * 2); |
| if (!pStartNumObj) |
| continue; |
| |
| RetainPtr<const CPDF_Number> pCountObj = array->GetNumberAt(i * 2 + 1); |
| if (!pCountObj) |
| continue; |
| |
| int nStartNum = pStartNumObj->GetInteger(); |
| int nCount = pCountObj->GetInteger(); |
| if (nStartNum < 0 || nCount <= 0) |
| continue; |
| |
| indices.push_back( |
| {static_cast<uint32_t>(nStartNum), static_cast<uint32_t>(nCount)}); |
| } |
| } |
| |
| if (indices.empty()) |
| indices.push_back({0, size}); |
| return indices; |
| } |
| |
| std::vector<uint32_t> GetFieldWidths(const CPDF_Array* array) { |
| std::vector<uint32_t> results; |
| if (!array) |
| return results; |
| |
| CPDF_ArrayLocker locker(array); |
| for (const auto& obj : locker) |
| results.push_back(obj->GetInteger()); |
| return results; |
| } |
| |
| class ObjectsHolderStub final : public CPDF_Parser::ParsedObjectsHolder { |
| public: |
| ObjectsHolderStub() = default; |
| ~ObjectsHolderStub() override = default; |
| bool TryInit() override { return true; } |
| }; |
| |
| } // namespace |
| |
| CPDF_Parser::CPDF_Parser(ParsedObjectsHolder* holder) |
| : m_pObjectsHolder(holder), |
| m_CrossRefTable(std::make_unique<CPDF_CrossRefTable>()) { |
| if (!holder) { |
| m_pOwnedObjectsHolder = std::make_unique<ObjectsHolderStub>(); |
| m_pObjectsHolder = m_pOwnedObjectsHolder.get(); |
| } |
| } |
| |
| CPDF_Parser::CPDF_Parser() : CPDF_Parser(nullptr) {} |
| |
| CPDF_Parser::~CPDF_Parser() = default; |
| |
| uint32_t CPDF_Parser::GetLastObjNum() const { |
| return m_CrossRefTable->objects_info().empty() |
| ? 0 |
| : m_CrossRefTable->objects_info().rbegin()->first; |
| } |
| |
| bool CPDF_Parser::IsValidObjectNumber(uint32_t objnum) const { |
| return objnum <= GetLastObjNum(); |
| } |
| |
| FX_FILESIZE CPDF_Parser::GetObjectPositionOrZero(uint32_t objnum) const { |
| const auto* info = m_CrossRefTable->GetObjectInfo(objnum); |
| return (info && info->type == ObjectType::kNormal) ? info->pos : 0; |
| } |
| |
| CPDF_Parser::ObjectType CPDF_Parser::GetObjectType(uint32_t objnum) const { |
| DCHECK(IsValidObjectNumber(objnum)); |
| const auto* info = m_CrossRefTable->GetObjectInfo(objnum); |
| return info ? info->type : ObjectType::kFree; |
| } |
| |
| bool CPDF_Parser::IsObjectFreeOrNull(uint32_t objnum) const { |
| switch (GetObjectType(objnum)) { |
| case ObjectType::kFree: |
| case ObjectType::kNull: |
| return true; |
| case ObjectType::kNormal: |
| case ObjectType::kCompressed: |
| return false; |
| } |
| NOTREACHED_NORETURN(); |
| } |
| |
| bool CPDF_Parser::IsObjectFree(uint32_t objnum) const { |
| return GetObjectType(objnum) == ObjectType::kFree; |
| } |
| |
| bool CPDF_Parser::InitSyntaxParser(RetainPtr<CPDF_ReadValidator> validator) { |
| const absl::optional<FX_FILESIZE> header_offset = GetHeaderOffset(validator); |
| if (!header_offset.has_value()) |
| return false; |
| if (validator->GetSize() < header_offset.value() + kPDFHeaderSize) |
| return false; |
| |
| m_pSyntax = std::make_unique<CPDF_SyntaxParser>(std::move(validator), |
| header_offset.value()); |
| return ParseFileVersion(); |
| } |
| |
| bool CPDF_Parser::ParseFileVersion() { |
| m_FileVersion = 0; |
| uint8_t ch; |
| if (!m_pSyntax->GetCharAt(5, ch)) |
| return false; |
| |
| if (isdigit(ch)) |
| m_FileVersion = FXSYS_DecimalCharToInt(static_cast<wchar_t>(ch)) * 10; |
| |
| if (!m_pSyntax->GetCharAt(7, ch)) |
| return false; |
| |
| if (isdigit(ch)) |
| m_FileVersion += FXSYS_DecimalCharToInt(static_cast<wchar_t>(ch)); |
| return true; |
| } |
| |
| CPDF_Parser::Error CPDF_Parser::StartParse( |
| RetainPtr<IFX_SeekableReadStream> pFileAccess, |
| const ByteString& password) { |
| if (!InitSyntaxParser(pdfium::MakeRetain<CPDF_ReadValidator>( |
| std::move(pFileAccess), nullptr))) |
| return FORMAT_ERROR; |
| SetPassword(password); |
| return StartParseInternal(); |
| } |
| |
| CPDF_Parser::Error CPDF_Parser::StartParseInternal() { |
| DCHECK(!m_bHasParsed); |
| DCHECK(!m_bXRefTableRebuilt); |
| m_bHasParsed = true; |
| m_bXRefStream = false; |
| |
| m_LastXRefOffset = ParseStartXRef(); |
| if (m_LastXRefOffset >= kPDFHeaderSize) { |
| if (!LoadAllCrossRefV4(m_LastXRefOffset) && |
| !LoadAllCrossRefV5(m_LastXRefOffset)) { |
| if (!RebuildCrossRef()) |
| return FORMAT_ERROR; |
| |
| m_bXRefTableRebuilt = true; |
| m_LastXRefOffset = 0; |
| } |
| } else { |
| if (!RebuildCrossRef()) |
| return FORMAT_ERROR; |
| |
| m_bXRefTableRebuilt = true; |
| } |
| Error eRet = SetEncryptHandler(); |
| if (eRet != SUCCESS) |
| return eRet; |
| |
| if (!GetRoot() || !m_pObjectsHolder->TryInit()) { |
| if (m_bXRefTableRebuilt) |
| return FORMAT_ERROR; |
| |
| ReleaseEncryptHandler(); |
| if (!RebuildCrossRef()) |
| return FORMAT_ERROR; |
| |
| eRet = SetEncryptHandler(); |
| if (eRet != SUCCESS) |
| return eRet; |
| |
| m_pObjectsHolder->TryInit(); |
| if (!GetRoot()) |
| return FORMAT_ERROR; |
| } |
| if (GetRootObjNum() == CPDF_Object::kInvalidObjNum) { |
| ReleaseEncryptHandler(); |
| if (!RebuildCrossRef() || GetRootObjNum() == CPDF_Object::kInvalidObjNum) |
| return FORMAT_ERROR; |
| |
| eRet = SetEncryptHandler(); |
| if (eRet != SUCCESS) |
| return eRet; |
| } |
| if (m_pSecurityHandler && !m_pSecurityHandler->IsMetadataEncrypted()) { |
| RetainPtr<const CPDF_Reference> pMetadata = |
| ToReference(GetRoot()->GetObjectFor("Metadata")); |
| if (pMetadata) |
| m_MetadataObjnum = pMetadata->GetRefObjNum(); |
| } |
| return SUCCESS; |
| } |
| |
| FX_FILESIZE CPDF_Parser::ParseStartXRef() { |
| static constexpr char kStartXRefKeyword[] = "startxref"; |
| m_pSyntax->SetPos(m_pSyntax->GetDocumentSize() - strlen(kStartXRefKeyword)); |
| if (!m_pSyntax->BackwardsSearchToWord(kStartXRefKeyword, 4096)) |
| return 0; |
| |
| // Skip "startxref" keyword. |
| m_pSyntax->GetKeyword(); |
| |
| // Read XRef offset. |
| const CPDF_SyntaxParser::WordResult xref_offset_result = |
| m_pSyntax->GetNextWord(); |
| if (!xref_offset_result.is_number || xref_offset_result.word.IsEmpty()) |
| return 0; |
| |
| const FX_SAFE_FILESIZE result = FXSYS_atoi64(xref_offset_result.word.c_str()); |
| if (!result.IsValid() || result.ValueOrDie() >= m_pSyntax->GetDocumentSize()) |
| return 0; |
| |
| return result.ValueOrDie(); |
| } |
| |
| CPDF_Parser::Error CPDF_Parser::SetEncryptHandler() { |
| ReleaseEncryptHandler(); |
| if (!GetTrailer()) |
| return FORMAT_ERROR; |
| |
| RetainPtr<const CPDF_Dictionary> pEncryptDict = GetEncryptDict(); |
| if (!pEncryptDict) |
| return SUCCESS; |
| |
| if (pEncryptDict->GetNameFor("Filter") != "Standard") |
| return HANDLER_ERROR; |
| |
| auto pSecurityHandler = pdfium::MakeRetain<CPDF_SecurityHandler>(); |
| if (!pSecurityHandler->OnInit(pEncryptDict, GetIDArray(), GetPassword())) |
| return PASSWORD_ERROR; |
| |
| m_pSecurityHandler = std::move(pSecurityHandler); |
| return SUCCESS; |
| } |
| |
| void CPDF_Parser::ReleaseEncryptHandler() { |
| m_pSecurityHandler.Reset(); |
| } |
| |
| // Ideally, all the cross reference entries should be verified. |
| // In reality, we rarely see well-formed cross references don't match |
| // with the objects. crbug/602650 showed a case where object numbers |
| // in the cross reference table are all off by one. |
| bool CPDF_Parser::VerifyCrossRefV4() { |
| for (const auto& it : m_CrossRefTable->objects_info()) { |
| if (it.second.pos <= 0) |
| continue; |
| // Find the first non-zero position. |
| FX_FILESIZE SavedPos = m_pSyntax->GetPos(); |
| m_pSyntax->SetPos(it.second.pos); |
| CPDF_SyntaxParser::WordResult word_result = m_pSyntax->GetNextWord(); |
| m_pSyntax->SetPos(SavedPos); |
| if (!word_result.is_number || word_result.word.IsEmpty() || |
| FXSYS_atoui(word_result.word.c_str()) != it.first) { |
| // If the object number read doesn't match the one stored, |
| // something is wrong with the cross reference table. |
| return false; |
| } |
| break; |
| } |
| return true; |
| } |
| |
| bool CPDF_Parser::LoadAllCrossRefV4(FX_FILESIZE xref_offset) { |
| if (!LoadCrossRefV4(xref_offset, true)) |
| return false; |
| |
| RetainPtr<CPDF_Dictionary> trailer = LoadTrailerV4(); |
| if (!trailer) |
| return false; |
| |
| m_CrossRefTable->SetTrailer(std::move(trailer), kNoV4TrailerObjectNumber); |
| const int32_t xrefsize = GetTrailer()->GetDirectIntegerFor("Size"); |
| if (xrefsize > 0 && xrefsize <= kMaxXRefSize) |
| m_CrossRefTable->SetObjectMapSize(xrefsize); |
| |
| FX_FILESIZE xref_stm = GetTrailer()->GetDirectIntegerFor("XRefStm"); |
| std::vector<FX_FILESIZE> xref_stream_list{xref_stm}; |
| std::vector<FX_FILESIZE> xref_list{xref_offset}; |
| std::set<FX_FILESIZE> seen_xref_offset{xref_offset}; |
| |
| // When the trailer doesn't have Prev entry or Prev entry value is not |
| // numerical, GetDirectInteger() returns 0. Loading will end. |
| xref_offset = GetTrailer()->GetDirectIntegerFor("Prev"); |
| while (xref_offset > 0) { |
| // Check for circular references. |
| if (pdfium::Contains(seen_xref_offset, xref_offset)) |
| return false; |
| |
| seen_xref_offset.insert(xref_offset); |
| xref_list.insert(xref_list.begin(), xref_offset); |
| |
| // SLOW ... |
| LoadCrossRefV4(xref_offset, true); |
| |
| RetainPtr<CPDF_Dictionary> pDict(LoadTrailerV4()); |
| if (!pDict) |
| return false; |
| |
| xref_offset = pDict->GetDirectIntegerFor("Prev"); |
| xref_stm = pDict->GetIntegerFor("XRefStm"); |
| xref_stream_list.insert(xref_stream_list.begin(), xref_stm); |
| |
| // SLOW ... |
| m_CrossRefTable = CPDF_CrossRefTable::MergeUp( |
| std::make_unique<CPDF_CrossRefTable>(std::move(pDict), |
| kNoV4TrailerObjectNumber), |
| std::move(m_CrossRefTable)); |
| } |
| |
| // Traverse the xref data structures from oldest to newest. So entries from |
| // later iterations should overwrite existing entries. |
| for (size_t i = 0; i < xref_list.size(); ++i) { |
| if (xref_list[i] > 0 && !LoadCrossRefV4(xref_list[i], false)) |
| return false; |
| |
| if (xref_stream_list[i] > 0 && |
| !LoadCrossRefV5(&xref_stream_list[i], /*is_main_xref=*/false, |
| /*overwrite_existing=*/true)) { |
| return false; |
| } |
| |
| if (i == 0 && !VerifyCrossRefV4()) |
| return false; |
| } |
| return true; |
| } |
| |
| bool CPDF_Parser::LoadLinearizedAllCrossRefV4(FX_FILESIZE main_xref_offset) { |
| if (!LoadCrossRefV4(main_xref_offset, false)) |
| return false; |
| |
| RetainPtr<CPDF_Dictionary> main_trailer = LoadTrailerV4(); |
| if (!main_trailer) |
| return false; |
| |
| // GetTrailer() currently returns the first-page trailer. |
| if (GetTrailer()->GetDirectIntegerFor("Size") == 0) |
| return false; |
| |
| // Read /XRefStm from the first-page trailer. No need to read /Prev for the |
| // first-page trailer, as the caller already did that and passed it in as |
| // |main_xref_offset|. |
| FX_FILESIZE xref_stm = GetTrailer()->GetDirectIntegerFor("XRefStm"); |
| std::vector<FX_FILESIZE> xref_stream_list{xref_stm}; |
| std::vector<FX_FILESIZE> xref_list{main_xref_offset}; |
| std::set<FX_FILESIZE> seen_xref_offset{main_xref_offset}; |
| |
| // Merge the trailers. |
| m_CrossRefTable = CPDF_CrossRefTable::MergeUp( |
| std::make_unique<CPDF_CrossRefTable>(std::move(main_trailer), |
| kNoV4TrailerObjectNumber), |
| std::move(m_CrossRefTable)); |
| |
| // Now GetTrailer() returns the merged trailer, where /Prev is from the |
| // main-trailer. |
| FX_FILESIZE xref_offset = GetTrailer()->GetDirectIntegerFor("Prev"); |
| while (xref_offset > 0) { |
| // Check for circular references. |
| if (pdfium::Contains(seen_xref_offset, xref_offset)) |
| return false; |
| |
| seen_xref_offset.insert(xref_offset); |
| xref_list.insert(xref_list.begin(), xref_offset); |
| |
| // SLOW ... |
| LoadCrossRefV4(xref_offset, true); |
| |
| RetainPtr<CPDF_Dictionary> pDict(LoadTrailerV4()); |
| if (!pDict) |
| return false; |
| |
| xref_offset = pDict->GetDirectIntegerFor("Prev"); |
| xref_stm = pDict->GetIntegerFor("XRefStm"); |
| xref_stream_list.insert(xref_stream_list.begin(), xref_stm); |
| |
| // SLOW ... |
| m_CrossRefTable = CPDF_CrossRefTable::MergeUp( |
| std::make_unique<CPDF_CrossRefTable>(std::move(pDict), |
| kNoV4TrailerObjectNumber), |
| std::move(m_CrossRefTable)); |
| } |
| |
| if (xref_stream_list[0] > 0 && |
| !LoadCrossRefV5(&xref_stream_list[0], /*is_main_xref=*/false, |
| /*overwrite_existing=*/true)) { |
| return false; |
| } |
| |
| // Traverse the xref data structures from oldest to newest. So entries from |
| // later iterations should overwrite existing entries. |
| for (size_t i = 1; i < xref_list.size(); ++i) { |
| if (xref_list[i] > 0 && !LoadCrossRefV4(xref_list[i], false)) |
| return false; |
| |
| if (xref_stream_list[i] > 0 && |
| !LoadCrossRefV5(&xref_stream_list[i], /*is_main_xref=*/false, |
| /*overwrite_existing=*/true)) { |
| return false; |
| } |
| } |
| return true; |
| } |
| |
| bool CPDF_Parser::ParseAndAppendCrossRefSubsectionData( |
| uint32_t start_objnum, |
| uint32_t count, |
| std::vector<CrossRefObjData>* out_objects) { |
| if (!count) |
| return true; |
| |
| // Each entry shall be exactly 20 byte. |
| // A sample entry looks like: |
| // "0000000000 00007 f\r\n" |
| static constexpr int32_t kEntrySize = 20; |
| |
| if (!out_objects) { |
| FX_SAFE_FILESIZE pos = count; |
| pos *= kEntrySize; |
| pos += m_pSyntax->GetPos(); |
| if (!pos.IsValid()) |
| return false; |
| m_pSyntax->SetPos(pos.ValueOrDie()); |
| return true; |
| } |
| const size_t start_obj_index = out_objects->size(); |
| FX_SAFE_SIZE_T new_size = start_obj_index; |
| new_size += count; |
| if (!new_size.IsValid()) |
| return false; |
| |
| if (new_size.ValueOrDie() > kMaxXRefSize) |
| return false; |
| |
| const size_t max_entries_in_file = m_pSyntax->GetDocumentSize() / kEntrySize; |
| if (new_size.ValueOrDie() > max_entries_in_file) |
| return false; |
| |
| out_objects->resize(new_size.ValueOrDie()); |
| |
| DataVector<char> buf(1024 * kEntrySize + 1); |
| buf.back() = '\0'; |
| |
| uint32_t entries_to_read = count; |
| while (entries_to_read > 0) { |
| const uint32_t entries_in_block = std::min(entries_to_read, 1024u); |
| const uint32_t bytes_to_read = entries_in_block * kEntrySize; |
| auto block_span = pdfium::make_span(buf).first(bytes_to_read); |
| if (!m_pSyntax->ReadBlock(pdfium::as_writable_bytes(block_span))) |
| return false; |
| |
| for (uint32_t i = 0; i < entries_in_block; i++) { |
| uint32_t iObjectIndex = count - entries_to_read + i; |
| CrossRefObjData& obj_data = |
| (*out_objects)[start_obj_index + iObjectIndex]; |
| const uint32_t objnum = start_objnum + iObjectIndex; |
| obj_data.obj_num = objnum; |
| ObjectInfo& info = obj_data.info; |
| |
| const char* pEntry = &buf[i * kEntrySize]; |
| if (pEntry[17] == 'f') { |
| info.pos = 0; |
| info.type = ObjectType::kFree; |
| } else { |
| const FX_SAFE_FILESIZE offset = FXSYS_atoi64(pEntry); |
| if (!offset.IsValid()) |
| return false; |
| |
| if (offset.ValueOrDie() == 0) { |
| for (int32_t c = 0; c < 10; c++) { |
| if (!isdigit(pEntry[c])) |
| return false; |
| } |
| } |
| |
| info.pos = offset.ValueOrDie(); |
| |
| // TODO(art-snake): The info.gennum is uint16_t, but version may be |
| // greated than max<uint16_t>. Needs solve this issue. |
| const int32_t version = FXSYS_atoi(pEntry + 11); |
| info.gennum = version; |
| info.type = ObjectType::kNormal; |
| } |
| } |
| entries_to_read -= entries_in_block; |
| } |
| return true; |
| } |
| |
| bool CPDF_Parser::ParseCrossRefV4(std::vector<CrossRefObjData>* out_objects) { |
| if (out_objects) |
| out_objects->clear(); |
| |
| if (m_pSyntax->GetKeyword() != "xref") |
| return false; |
| std::vector<CrossRefObjData> result_objects; |
| while (true) { |
| FX_FILESIZE saved_pos = m_pSyntax->GetPos(); |
| CPDF_SyntaxParser::WordResult word_result = m_pSyntax->GetNextWord(); |
| const ByteString& word = word_result.word; |
| if (word.IsEmpty()) |
| return false; |
| |
| if (!word_result.is_number) { |
| m_pSyntax->SetPos(saved_pos); |
| break; |
| } |
| |
| uint32_t start_objnum = FXSYS_atoui(word.c_str()); |
| if (start_objnum >= kMaxObjectNumber) |
| return false; |
| |
| uint32_t count = m_pSyntax->GetDirectNum(); |
| m_pSyntax->ToNextWord(); |
| |
| if (!ParseAndAppendCrossRefSubsectionData( |
| start_objnum, count, out_objects ? &result_objects : nullptr)) { |
| return false; |
| } |
| } |
| if (out_objects) |
| *out_objects = std::move(result_objects); |
| return true; |
| } |
| |
| bool CPDF_Parser::LoadCrossRefV4(FX_FILESIZE pos, bool bSkip) { |
| m_pSyntax->SetPos(pos); |
| std::vector<CrossRefObjData> objects; |
| if (!ParseCrossRefV4(bSkip ? nullptr : &objects)) |
| return false; |
| |
| MergeCrossRefObjectsData(objects); |
| return true; |
| } |
| |
| void CPDF_Parser::MergeCrossRefObjectsData( |
| const std::vector<CrossRefObjData>& objects) { |
| for (const auto& obj : objects) { |
| switch (obj.info.type) { |
| case ObjectType::kFree: |
| if (obj.info.gennum > 0) |
| m_CrossRefTable->SetFree(obj.obj_num); |
| break; |
| case ObjectType::kNormal: |
| case ObjectType::kObjStream: |
| m_CrossRefTable->AddNormal(obj.obj_num, obj.info.gennum, obj.info.pos); |
| break; |
| case ObjectType::kCompressed: |
| m_CrossRefTable->AddCompressed(obj.obj_num, obj.info.archive.obj_num, |
| obj.info.archive.obj_index); |
| break; |
| } |
| } |
| } |
| |
| bool CPDF_Parser::LoadAllCrossRefV5(FX_FILESIZE xref_offset) { |
| if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/true, |
| /*overwrite_existing=*/false)) { |
| return false; |
| } |
| |
| // Traverse the xref objects from newest to older. So entries from later |
| // iterations should not overwrite existing entries. |
| std::set<FX_FILESIZE> seen_xref_offset; |
| while (xref_offset > 0) { |
| seen_xref_offset.insert(xref_offset); |
| if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/false, |
| /*overwrite_existing=*/false)) { |
| return false; |
| } |
| |
| // Check for circular references. |
| if (pdfium::Contains(seen_xref_offset, xref_offset)) |
| return false; |
| } |
| m_ObjectStreamMap.clear(); |
| m_bXRefStream = true; |
| return true; |
| } |
| |
| bool CPDF_Parser::RebuildCrossRef() { |
| auto cross_ref_table = std::make_unique<CPDF_CrossRefTable>(); |
| |
| const uint32_t kBufferSize = 4096; |
| m_pSyntax->SetReadBufferSize(kBufferSize); |
| m_pSyntax->SetPos(0); |
| |
| std::vector<std::pair<uint32_t, FX_FILESIZE>> numbers; |
| for (CPDF_SyntaxParser::WordResult result = m_pSyntax->GetNextWord(); |
| !result.word.IsEmpty(); result = m_pSyntax->GetNextWord()) { |
| const ByteString& word = result.word; |
| if (result.is_number) { |
| numbers.emplace_back(FXSYS_atoui(word.c_str()), |
| m_pSyntax->GetPos() - word.GetLength()); |
| if (numbers.size() > 2u) |
| numbers.erase(numbers.begin()); |
| continue; |
| } |
| |
| if (word == "(") { |
| m_pSyntax->ReadString(); |
| } else if (word == "<") { |
| m_pSyntax->ReadHexString(); |
| } else if (word == "trailer") { |
| RetainPtr<CPDF_Object> pTrailer = m_pSyntax->GetObjectBody(nullptr); |
| if (pTrailer) { |
| CPDF_Stream* stream_trailer = pTrailer->AsMutableStream(); |
| // Grab the object number from `pTrailer` before potentially calling |
| // std::move(pTrailer) below. |
| const uint32_t trailer_object_number = pTrailer->GetObjNum(); |
| RetainPtr<CPDF_Dictionary> trailer_dict = |
| stream_trailer ? stream_trailer->GetMutableDict() |
| : ToDictionary(std::move(pTrailer)); |
| cross_ref_table = CPDF_CrossRefTable::MergeUp( |
| std::move(cross_ref_table), |
| std::make_unique<CPDF_CrossRefTable>(std::move(trailer_dict), |
| trailer_object_number)); |
| } |
| } else if (word == "obj" && numbers.size() == 2u) { |
| const FX_FILESIZE obj_pos = numbers[0].second; |
| const uint32_t obj_num = numbers[0].first; |
| const uint32_t gen_num = numbers[1].first; |
| |
| m_pSyntax->SetPos(obj_pos); |
| const RetainPtr<CPDF_Stream> pStream = |
| ToStream(m_pSyntax->GetIndirectObject( |
| nullptr, CPDF_SyntaxParser::ParseType::kStrict)); |
| |
| if (pStream && pStream->GetDict()->GetNameFor("Type") == "XRef") { |
| cross_ref_table = CPDF_CrossRefTable::MergeUp( |
| std::move(cross_ref_table), |
| std::make_unique<CPDF_CrossRefTable>( |
| ToDictionary(pStream->GetDict()->Clone()), |
| pStream->GetObjNum())); |
| } |
| |
| if (obj_num < kMaxObjectNumber) { |
| cross_ref_table->AddNormal(obj_num, gen_num, obj_pos); |
| const auto object_stream = |
| CPDF_ObjectStream::Create(std::move(pStream)); |
| if (object_stream) { |
| const auto& object_info = object_stream->object_info(); |
| for (size_t i = 0; i < object_info.size(); ++i) { |
| const auto& info = object_info[i]; |
| if (info.obj_num < kMaxObjectNumber) |
| cross_ref_table->AddCompressed(info.obj_num, obj_num, i); |
| } |
| } |
| } |
| } |
| numbers.clear(); |
| } |
| |
| m_CrossRefTable = CPDF_CrossRefTable::MergeUp(std::move(m_CrossRefTable), |
| std::move(cross_ref_table)); |
| // Resore default buffer size. |
| m_pSyntax->SetReadBufferSize(CPDF_Stream::kFileBufSize); |
| |
| return GetTrailer() && !m_CrossRefTable->objects_info().empty(); |
| } |
| |
| bool CPDF_Parser::LoadCrossRefV5(FX_FILESIZE* pos, |
| bool is_main_xref, |
| bool overwrite_existing) { |
| RetainPtr<const CPDF_Stream> pStream = |
| ToStream(ParseIndirectObjectAt(*pos, 0)); |
| if (!pStream || !pStream->GetObjNum()) { |
| return false; |
| } |
| |
| RetainPtr<const CPDF_Dictionary> pDict = pStream->GetDict(); |
| int32_t prev = pDict->GetIntegerFor("Prev"); |
| if (prev < 0) |
| return false; |
| |
| int32_t size = pDict->GetIntegerFor("Size"); |
| if (size < 0) |
| return false; |
| |
| *pos = prev; |
| |
| auto new_cross_ref_table = std::make_unique<CPDF_CrossRefTable>( |
| /*trailer=*/ToDictionary(pDict->Clone()), |
| /*trailer_object_number=*/pStream->GetObjNum()); |
| if (is_main_xref) { |
| m_CrossRefTable = std::move(new_cross_ref_table); |
| m_CrossRefTable->SetObjectMapSize(size); |
| } else { |
| m_CrossRefTable = CPDF_CrossRefTable::MergeUp( |
| std::move(new_cross_ref_table), std::move(m_CrossRefTable)); |
| } |
| |
| std::vector<CrossRefV5IndexEntry> indices = |
| GetCrossRefV5Indices(pDict->GetArrayFor("Index").Get(), size); |
| |
| std::vector<uint32_t> field_widths = |
| GetFieldWidths(pDict->GetArrayFor("W").Get()); |
| if (field_widths.size() < kMinFieldCount) |
| return false; |
| |
| FX_SAFE_UINT32 dwAccWidth; |
| for (uint32_t width : field_widths) |
| dwAccWidth += width; |
| if (!dwAccWidth.IsValid()) |
| return false; |
| |
| uint32_t total_width = dwAccWidth.ValueOrDie(); |
| auto pAcc = pdfium::MakeRetain<CPDF_StreamAcc>(pStream); |
| pAcc->LoadAllDataFiltered(); |
| |
| pdfium::span<const uint8_t> data_span = pAcc->GetSpan(); |
| uint32_t segindex = 0; |
| for (const auto& index : indices) { |
| FX_SAFE_UINT32 seg_end = segindex; |
| seg_end += index.obj_count; |
| seg_end *= total_width; |
| if (!seg_end.IsValid() || seg_end.ValueOrDie() > data_span.size()) |
| continue; |
| |
| pdfium::span<const uint8_t> seg_span = data_span.subspan( |
| segindex * total_width, index.obj_count * total_width); |
| FX_SAFE_UINT32 safe_new_size = index.start_obj_num; |
| safe_new_size += index.obj_count; |
| if (!safe_new_size.IsValid()) { |
| continue; |
| } |
| |
| // Until SetObjectMapSize() below has been called by a prior loop iteration, |
| // `current_size` is based on the /Size value parsed in LoadCrossRefV5(). |
| // PDFs may not always have the correct /Size. In this case, other PDF |
| // implementations ignore the incorrect size, and PDFium also ignores |
| // incorrect size in trailers for V4 xrefs. |
| const uint32_t current_size = |
| m_CrossRefTable->objects_info().empty() ? 0 : GetLastObjNum() + 1; |
| // So allow `new_size` to be greater than `current_size`, but avoid going |
| // over `kMaxXRefSize`. This works just fine because the loop below checks |
| // against `kMaxObjectNumber`, and the two "max" constants are in sync. |
| const uint32_t new_size = |
| std::min<uint32_t>(safe_new_size.ValueOrDie(), kMaxXRefSize); |
| if (new_size > current_size) { |
| m_CrossRefTable->SetObjectMapSize(new_size); |
| } |
| |
| for (uint32_t i = 0; i < index.obj_count; ++i) { |
| const uint32_t obj_num = index.start_obj_num + i; |
| if (obj_num >= kMaxObjectNumber) { |
| break; |
| } |
| |
| ProcessCrossRefV5Entry(seg_span.subspan(i * total_width, total_width), |
| field_widths, obj_num, overwrite_existing); |
| } |
| |
| segindex += index.obj_count; |
| } |
| return true; |
| } |
| |
| void CPDF_Parser::ProcessCrossRefV5Entry( |
| pdfium::span<const uint8_t> entry_span, |
| pdfium::span<const uint32_t> field_widths, |
| uint32_t obj_num, |
| bool overwrite_existing) { |
| DCHECK_GE(field_widths.size(), kMinFieldCount); |
| ObjectType type; |
| if (field_widths[0]) { |
| const uint32_t cross_ref_stream_obj_type = |
| GetFirstXRefStreamEntry(entry_span, field_widths); |
| type = GetObjectTypeFromCrossRefStreamType(cross_ref_stream_obj_type); |
| if (type == ObjectType::kNull) |
| return; |
| } else { |
| // Per ISO 32000-1:2008 table 17, use the default value of 1 for the xref |
| // stream entry when it is not specified. The `type` assignment is the |
| // equivalent to calling GetObjectTypeFromCrossRefStreamType(1). |
| type = ObjectType::kNormal; |
| } |
| |
| const ObjectType existing_type = GetObjectType(obj_num); |
| if (existing_type == ObjectType::kNull) { |
| const uint32_t offset = GetSecondXRefStreamEntry(entry_span, field_widths); |
| if (pdfium::base::IsValueInRangeForNumericType<FX_FILESIZE>(offset)) |
| m_CrossRefTable->AddNormal(obj_num, 0, offset); |
| return; |
| } |
| |
| if (!overwrite_existing && existing_type != ObjectType::kFree) { |
| return; |
| } |
| |
| if (type == ObjectType::kFree) { |
| m_CrossRefTable->SetFree(obj_num); |
| return; |
| } |
| |
| if (type == ObjectType::kNormal) { |
| const uint32_t offset = GetSecondXRefStreamEntry(entry_span, field_widths); |
| if (pdfium::base::IsValueInRangeForNumericType<FX_FILESIZE>(offset)) |
| m_CrossRefTable->AddNormal(obj_num, 0, offset); |
| return; |
| } |
| |
| DCHECK_EQ(type, ObjectType::kCompressed); |
| const uint32_t archive_obj_num = |
| GetSecondXRefStreamEntry(entry_span, field_widths); |
| if (!IsValidObjectNumber(archive_obj_num)) { |
| return; |
| } |
| |
| const uint32_t archive_obj_index = |
| GetThirdXRefStreamEntry(entry_span, field_widths); |
| m_CrossRefTable->AddCompressed(obj_num, archive_obj_num, archive_obj_index); |
| } |
| |
| RetainPtr<const CPDF_Array> CPDF_Parser::GetIDArray() const { |
| return GetTrailer() ? GetTrailer()->GetArrayFor("ID") : nullptr; |
| } |
| |
| RetainPtr<const CPDF_Dictionary> CPDF_Parser::GetRoot() const { |
| RetainPtr<CPDF_Object> obj = |
| m_pObjectsHolder->GetOrParseIndirectObject(GetRootObjNum()); |
| return obj ? obj->GetDict() : nullptr; |
| } |
| |
| RetainPtr<const CPDF_Dictionary> CPDF_Parser::GetEncryptDict() const { |
| if (!GetTrailer()) |
| return nullptr; |
| |
| RetainPtr<const CPDF_Object> pEncryptObj = |
| GetTrailer()->GetObjectFor("Encrypt"); |
| if (!pEncryptObj) |
| return nullptr; |
| |
| if (pEncryptObj->IsDictionary()) |
| return pdfium::WrapRetain(pEncryptObj->AsDictionary()); |
| |
| if (pEncryptObj->IsReference()) { |
| return ToDictionary(m_pObjectsHolder->GetOrParseIndirectObject( |
| pEncryptObj->AsReference()->GetRefObjNum())); |
| } |
| return nullptr; |
| } |
| |
| ByteString CPDF_Parser::GetEncodedPassword() const { |
| return GetSecurityHandler()->GetEncodedPassword(GetPassword().AsStringView()); |
| } |
| |
| const CPDF_Dictionary* CPDF_Parser::GetTrailer() const { |
| return m_CrossRefTable->trailer(); |
| } |
| |
| CPDF_Dictionary* CPDF_Parser::GetMutableTrailerForTesting() { |
| return m_CrossRefTable->GetMutableTrailerForTesting(); |
| } |
| |
| uint32_t CPDF_Parser::GetTrailerObjectNumber() const { |
| return m_CrossRefTable->trailer_object_number(); |
| } |
| |
| RetainPtr<CPDF_Dictionary> CPDF_Parser::GetCombinedTrailer() const { |
| return m_CrossRefTable->trailer() |
| ? ToDictionary(m_CrossRefTable->trailer()->Clone()) |
| : RetainPtr<CPDF_Dictionary>(); |
| } |
| |
| uint32_t CPDF_Parser::GetInfoObjNum() const { |
| RetainPtr<const CPDF_Reference> pRef = |
| ToReference(m_CrossRefTable->trailer() |
| ? m_CrossRefTable->trailer()->GetObjectFor("Info") |
| : nullptr); |
| return pRef ? pRef->GetRefObjNum() : CPDF_Object::kInvalidObjNum; |
| } |
| |
| uint32_t CPDF_Parser::GetRootObjNum() const { |
| RetainPtr<const CPDF_Reference> pRef = |
| ToReference(m_CrossRefTable->trailer() |
| ? m_CrossRefTable->trailer()->GetObjectFor("Root") |
| : nullptr); |
| return pRef ? pRef->GetRefObjNum() : CPDF_Object::kInvalidObjNum; |
| } |
| |
| RetainPtr<CPDF_Object> CPDF_Parser::ParseIndirectObject(uint32_t objnum) { |
| if (!IsValidObjectNumber(objnum)) |
| return nullptr; |
| |
| // Prevent circular parsing the same object. |
| if (pdfium::Contains(m_ParsingObjNums, objnum)) |
| return nullptr; |
| |
| ScopedSetInsertion<uint32_t> local_insert(&m_ParsingObjNums, objnum); |
| if (GetObjectType(objnum) == ObjectType::kNormal) { |
| FX_FILESIZE pos = GetObjectPositionOrZero(objnum); |
| if (pos <= 0) |
| return nullptr; |
| return ParseIndirectObjectAt(pos, objnum); |
| } |
| if (GetObjectType(objnum) != ObjectType::kCompressed) |
| return nullptr; |
| |
| const ObjectInfo& info = *m_CrossRefTable->GetObjectInfo(objnum); |
| const CPDF_ObjectStream* pObjStream = GetObjectStream(info.archive.obj_num); |
| if (!pObjStream) |
| return nullptr; |
| |
| return pObjStream->ParseObject(m_pObjectsHolder, objnum, |
| info.archive.obj_index); |
| } |
| |
| const CPDF_ObjectStream* CPDF_Parser::GetObjectStream(uint32_t object_number) { |
| // Prevent circular parsing the same object. |
| if (pdfium::Contains(m_ParsingObjNums, object_number)) |
| return nullptr; |
| |
| auto it = m_ObjectStreamMap.find(object_number); |
| if (it != m_ObjectStreamMap.end()) |
| return it->second.get(); |
| |
| const auto* info = m_CrossRefTable->GetObjectInfo(object_number); |
| if (!info || info->type != ObjectType::kObjStream) |
| return nullptr; |
| |
| const FX_FILESIZE object_pos = info->pos; |
| if (object_pos <= 0) |
| return nullptr; |
| |
| // Keep track of `object_number` before doing more parsing. |
| ScopedSetInsertion<uint32_t> local_insert(&m_ParsingObjNums, object_number); |
| |
| RetainPtr<CPDF_Object> object = |
| ParseIndirectObjectAt(object_pos, object_number); |
| if (!object) |
| return nullptr; |
| |
| std::unique_ptr<CPDF_ObjectStream> objs_stream = |
| CPDF_ObjectStream::Create(ToStream(object)); |
| const CPDF_ObjectStream* result = objs_stream.get(); |
| m_ObjectStreamMap[object_number] = std::move(objs_stream); |
| |
| return result; |
| } |
| |
| RetainPtr<CPDF_Object> CPDF_Parser::ParseIndirectObjectAt(FX_FILESIZE pos, |
| uint32_t objnum) { |
| const FX_FILESIZE saved_pos = m_pSyntax->GetPos(); |
| m_pSyntax->SetPos(pos); |
| |
| auto result = m_pSyntax->GetIndirectObject( |
| m_pObjectsHolder, CPDF_SyntaxParser::ParseType::kLoose); |
| m_pSyntax->SetPos(saved_pos); |
| if (result && objnum && result->GetObjNum() != objnum) |
| return nullptr; |
| |
| const bool should_decrypt = m_pSecurityHandler && |
| m_pSecurityHandler->GetCryptoHandler() && |
| objnum != m_MetadataObjnum; |
| if (should_decrypt && |
| !m_pSecurityHandler->GetCryptoHandler()->DecryptObjectTree(result)) { |
| return nullptr; |
| } |
| return result; |
| } |
| |
| FX_FILESIZE CPDF_Parser::GetDocumentSize() const { |
| return m_pSyntax->GetDocumentSize(); |
| } |
| |
| uint32_t CPDF_Parser::GetFirstPageNo() const { |
| return m_pLinearized ? m_pLinearized->GetFirstPageNo() : 0; |
| } |
| |
| void CPDF_Parser::SetLinearizedHeaderForTesting( |
| std::unique_ptr<CPDF_LinearizedHeader> pLinearized) { |
| m_pLinearized = std::move(pLinearized); |
| } |
| |
| RetainPtr<CPDF_Dictionary> CPDF_Parser::LoadTrailerV4() { |
| if (m_pSyntax->GetKeyword() != "trailer") |
| return nullptr; |
| |
| return ToDictionary(m_pSyntax->GetObjectBody(m_pObjectsHolder)); |
| } |
| |
| uint32_t CPDF_Parser::GetPermissions(bool get_owner_perms) const { |
| return m_pSecurityHandler |
| ? m_pSecurityHandler->GetPermissions(get_owner_perms) |
| : 0xFFFFFFFF; |
| } |
| |
| std::unique_ptr<CPDF_LinearizedHeader> CPDF_Parser::ParseLinearizedHeader() { |
| return CPDF_LinearizedHeader::Parse(m_pSyntax.get()); |
| } |
| |
| CPDF_Parser::Error CPDF_Parser::StartLinearizedParse( |
| RetainPtr<CPDF_ReadValidator> validator, |
| const ByteString& password) { |
| DCHECK(!m_bHasParsed); |
| DCHECK(!m_bXRefTableRebuilt); |
| SetPassword(password); |
| m_bXRefStream = false; |
| m_LastXRefOffset = 0; |
| |
| if (!InitSyntaxParser(std::move(validator))) |
| return FORMAT_ERROR; |
| |
| m_pLinearized = ParseLinearizedHeader(); |
| if (!m_pLinearized) |
| return StartParseInternal(); |
| |
| m_bHasParsed = true; |
| |
| m_LastXRefOffset = m_pLinearized->GetLastXRefOffset(); |
| FX_FILESIZE dwFirstXRefOffset = m_LastXRefOffset; |
| bool bLoadV4 = LoadCrossRefV4(dwFirstXRefOffset, false); |
| if (!bLoadV4 && !LoadCrossRefV5(&dwFirstXRefOffset, /*is_main_xref=*/true, |
| /*overwrite_existing=*/false)) { |
| if (!RebuildCrossRef()) |
| return FORMAT_ERROR; |
| |
| m_bXRefTableRebuilt = true; |
| m_LastXRefOffset = 0; |
| } |
| if (bLoadV4) { |
| RetainPtr<CPDF_Dictionary> trailer = LoadTrailerV4(); |
| if (!trailer) |
| return SUCCESS; |
| |
| m_CrossRefTable->SetTrailer(std::move(trailer), kNoV4TrailerObjectNumber); |
| const int32_t xrefsize = GetTrailer()->GetDirectIntegerFor("Size"); |
| if (xrefsize > 0) { |
| // Check if `xrefsize` is correct. If it is incorrect, give up and rebuild |
| // the xref table. |
| const uint32_t expected_last_obj_num = xrefsize - 1; |
| if (GetLastObjNum() != expected_last_obj_num && !RebuildCrossRef()) { |
| return FORMAT_ERROR; |
| } |
| } |
| } |
| |
| Error eRet = SetEncryptHandler(); |
| if (eRet != SUCCESS) |
| return eRet; |
| |
| if (!GetRoot() || !m_pObjectsHolder->TryInit()) { |
| if (m_bXRefTableRebuilt) |
| return FORMAT_ERROR; |
| |
| ReleaseEncryptHandler(); |
| if (!RebuildCrossRef()) |
| return FORMAT_ERROR; |
| |
| eRet = SetEncryptHandler(); |
| if (eRet != SUCCESS) |
| return eRet; |
| |
| m_pObjectsHolder->TryInit(); |
| if (!GetRoot()) |
| return FORMAT_ERROR; |
| } |
| |
| if (GetRootObjNum() == CPDF_Object::kInvalidObjNum) { |
| ReleaseEncryptHandler(); |
| if (!RebuildCrossRef() || GetRootObjNum() == CPDF_Object::kInvalidObjNum) |
| return FORMAT_ERROR; |
| |
| eRet = SetEncryptHandler(); |
| if (eRet != SUCCESS) |
| return eRet; |
| } |
| |
| if (m_pSecurityHandler && m_pSecurityHandler->IsMetadataEncrypted()) { |
| RetainPtr<const CPDF_Reference> pMetadata = |
| ToReference(GetRoot()->GetObjectFor("Metadata")); |
| if (pMetadata) |
| m_MetadataObjnum = pMetadata->GetRefObjNum(); |
| } |
| return SUCCESS; |
| } |
| |
| bool CPDF_Parser::LoadLinearizedAllCrossRefV5(FX_FILESIZE main_xref_offset) { |
| FX_FILESIZE xref_offset = main_xref_offset; |
| if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/false, |
| /*overwrite_existing=*/false)) { |
| return false; |
| } |
| |
| // Traverse the xref objects from newest to older. So entries from later |
| // iterations should not overwrite existing entries. |
| std::set<FX_FILESIZE> seen_xref_offset; |
| while (xref_offset) { |
| seen_xref_offset.insert(xref_offset); |
| if (!LoadCrossRefV5(&xref_offset, /*is_main_xref=*/false, |
| /*overwrite_existing=*/false)) { |
| return false; |
| } |
| |
| // Check for circular references. |
| if (pdfium::Contains(seen_xref_offset, xref_offset)) |
| return false; |
| } |
| m_ObjectStreamMap.clear(); |
| m_bXRefStream = true; |
| return true; |
| } |
| |
| CPDF_Parser::Error CPDF_Parser::LoadLinearizedMainXRefTable() { |
| const FX_SAFE_FILESIZE prev = GetTrailer()->GetIntegerFor("Prev"); |
| const FX_FILESIZE main_xref_offset = prev.ValueOrDefault(-1); |
| if (main_xref_offset < 0) |
| return FORMAT_ERROR; |
| |
| if (main_xref_offset == 0) |
| return SUCCESS; |
| |
| const AutoRestorer<uint32_t> save_metadata_objnum(&m_MetadataObjnum); |
| m_MetadataObjnum = 0; |
| m_ObjectStreamMap.clear(); |
| |
| if (!LoadLinearizedAllCrossRefV4(main_xref_offset) && |
| !LoadLinearizedAllCrossRefV5(main_xref_offset)) { |
| m_LastXRefOffset = 0; |
| return FORMAT_ERROR; |
| } |
| |
| return SUCCESS; |
| } |
| |
| void CPDF_Parser::SetSyntaxParserForTesting( |
| std::unique_ptr<CPDF_SyntaxParser> parser) { |
| m_pSyntax = std::move(parser); |
| } |
| |
| std::vector<unsigned int> CPDF_Parser::GetTrailerEnds() { |
| std::vector<unsigned int> trailer_ends; |
| m_pSyntax->SetTrailerEnds(&trailer_ends); |
| |
| // Traverse the document. |
| m_pSyntax->SetPos(0); |
| while (true) { |
| CPDF_SyntaxParser::WordResult word_result = m_pSyntax->GetNextWord(); |
| if (word_result.is_number) { |
| // The object number was read. Read the generation number. |
| word_result = m_pSyntax->GetNextWord(); |
| if (!word_result.is_number) |
| break; |
| |
| word_result = m_pSyntax->GetNextWord(); |
| if (word_result.word != "obj") |
| break; |
| |
| m_pSyntax->GetObjectBody(nullptr); |
| |
| word_result = m_pSyntax->GetNextWord(); |
| if (word_result.word != "endobj") |
| break; |
| } else if (word_result.word == "trailer") { |
| m_pSyntax->GetObjectBody(nullptr); |
| } else if (word_result.word == "startxref") { |
| m_pSyntax->GetNextWord(); |
| } else if (word_result.word == "xref") { |
| while (true) { |
| word_result = m_pSyntax->GetNextWord(); |
| if (word_result.word.IsEmpty() || word_result.word == "startxref") |
| break; |
| } |
| m_pSyntax->GetNextWord(); |
| } else { |
| break; |
| } |
| } |
| |
| // Stop recording trailer ends. |
| m_pSyntax->SetTrailerEnds(nullptr); |
| return trailer_ends; |
| } |
| |
| bool CPDF_Parser::WriteToArchive(IFX_ArchiveStream* archive, |
| FX_FILESIZE src_size) { |
| static constexpr FX_FILESIZE kBufferSize = 4096; |
| DataVector<uint8_t> buffer(kBufferSize); |
| m_pSyntax->SetPos(0); |
| while (src_size) { |
| const uint32_t block_size = |
| static_cast<uint32_t>(std::min(kBufferSize, src_size)); |
| auto block_span = pdfium::make_span(buffer).first(block_size); |
| if (!m_pSyntax->ReadBlock(block_span)) |
| return false; |
| if (!archive->WriteBlock(pdfium::make_span(buffer).first(block_size))) |
| return false; |
| src_size -= block_size; |
| } |
| return true; |
| } |