Embedpdf/feature/digital signature

constants/annotation_common.h

@@ -20,6 +20,12 @@ inline constexpr char kM[] = "M";
 inline constexpr char kF[] = "F";
 inline constexpr char kAP[] = "AP";
 inline constexpr char kAS[] = "AS";
+inline constexpr char kA[] = "A";
+inline constexpr char kAA[] = "AA";
+inline constexpr char kPopup[] = "Popup";
+inline constexpr char kBS[] = "BS";
+inline constexpr char kBE[] = "BE";
+inline constexpr char kMK[] = "MK";
 inline constexpr char kBorder[] = "Border";
 inline constexpr char kC[] = "C";
 inline constexpr char kStructParent[] = "StructParent";

core/fpdfapi/parser/BUILD.gn

@@ -57,6 +57,12 @@ source_set("parser") {
     "cpdf_read_validator.h",
     "cpdf_reference.cpp",
     "cpdf_reference.h",
+    "cpdf_revision_classifier.cpp",
+    "cpdf_revision_classifier.h",
+    "cpdf_revision_diff.cpp",
+    "cpdf_revision_diff.h",
+    "cpdf_revision_provider.cpp",
+    "cpdf_revision_provider.h",
     "cpdf_security_handler.cpp",
     "cpdf_security_handler.h",
     "cpdf_simple_parser.cpp",

core/fpdfapi/parser/cpdf_crypto_handler.cpp

@@ -53,7 +53,12 @@ bool CPDF_CryptoHandler::IsSignatureDictionary(
   if (!type_obj) {
     type_obj = dictionary->GetDirectObjectFor(pdfium::form_fields::kFT);
   }
-  return type_obj && type_obj->GetString() == pdfium::form_fields::kSig;
+  if (!type_obj) {
+    return false;
+  }
+
+  const ByteString type = type_obj->GetString();
+  return type == pdfium::form_fields::kSig || type == "DocTimeStamp";
 }
 
 DataVector<uint8_t> CPDF_CryptoHandler::EncryptContent(

core/fpdfapi/parser/cpdf_parser.cpp

@@ -22,6 +22,7 @@
 #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_revision_provider.h"
 #include "core/fpdfapi/parser/cpdf_security_handler.h"
 #include "core/fpdfapi/parser/cpdf_stream.h"
 #include "core/fpdfapi/parser/cpdf_stream_acc.h"
@@ -468,6 +469,9 @@ bool CPDF_Parser::LoadAllCrossRefTablesAndStreams(FX_FILESIZE xref_offset) {
     xref_stream_ = true;
   }
 
+  revision_xref_list_ = xref_list;
+  revision_xref_stream_list_ = xref_stream_list;
+
   return true;
 }
 
@@ -676,6 +680,26 @@ bool CPDF_Parser::LoadCrossRefTable(FX_FILESIZE pos, bool skip) {
   return true;
 }
 
+bool CPDF_Parser::ExtractCrossRefTableEntriesAt(FX_FILESIZE pos,
+                                                 ObjectMap* out_objects) {
+  if (!out_objects)
+    return false;
+
+  const FX_FILESIZE saved_pos = syntax_->GetPos();
+  syntax_->SetPos(pos);
+  std::vector<CrossRefObjData> objects;
+  bool ok = ParseCrossRefTable(&objects);
+  syntax_->SetPos(saved_pos);
+
+  if (!ok)
+    return false;
+
+  for (const auto& obj : objects)
+    (*out_objects)[obj.obj_num] = obj.info;
+
+  return true;
+}
+
 void CPDF_Parser::MergeCrossRefObjectsData(
     const std::vector<CrossRefObjData>& objects) {
   for (const auto& obj : objects) {
@@ -1392,6 +1416,21 @@ std::vector<unsigned int> CPDF_Parser::GetTrailerEnds() {
   return trailer_ends;
 }
 
+const CPDF_RevisionProvider* CPDF_Parser::GetRevisionProvider() {
+  if (!has_parsed_ || revision_xref_list_.empty())
+    return nullptr;
+
+  if (!revision_provider_) {
+    revision_provider_ = std::make_unique<CPDF_RevisionProvider>();
+    if (!revision_provider_->Build(this, revision_xref_list_,
+                                   revision_xref_stream_list_)) {
+      revision_provider_.reset();
+      return nullptr;
+    }
+  }
+  return revision_provider_.get();
+}
+
 bool CPDF_Parser::WriteToArchive(IFX_ArchiveStream* archive,
                                  FX_FILESIZE src_size) {
   static constexpr FX_FILESIZE kBufferSize = 4096;

core/fpdfapi/parser/cpdf_parser.h

@@ -29,6 +29,7 @@ class CPDF_LinearizedHeader;
 class CPDF_Object;
 class CPDF_ObjectStream;
 class CPDF_ReadValidator;
+class CPDF_RevisionProvider;
 class CPDF_SecurityHandler;
 class CPDF_SyntaxParser;
 class IFX_ArchiveStream;
@@ -119,6 +120,16 @@ class CPDF_Parser {
   std::vector<unsigned int> GetTrailerEnds();
   bool WriteToArchive(IFX_ArchiveStream* archive, FX_FILESIZE src_size);
 
+  using ObjectMap = std::map<uint32_t, CPDF_CrossRefTable::ObjectInfo>;
+
+  // Re-parse a classic xref table at |pos| and return entries as an ObjectMap.
+  // Does not mutate cross_ref_table_ or any other parser state.
+  bool ExtractCrossRefTableEntriesAt(FX_FILESIZE pos, ObjectMap* out_objects);
+
+  // Returns the revision provider, building it lazily on first access.
+  // Returns nullptr if the parser has not successfully loaded a document.
+  const CPDF_RevisionProvider* GetRevisionProvider();
+
   const CPDF_CrossRefTable* GetCrossRefTableForTesting() const {
     return cross_ref_table_.get();
   }
@@ -211,6 +222,12 @@ class CPDF_Parser {
   std::set<uint32_t> parsing_obj_nums_;
 
   RetainPtr<CPDF_SecurityHandler> security_handler_;
+
+  // Populated by LoadAllCrossRefTablesAndStreams.
+  // Index 0 = newest (main) revision. After Build() reversal, index 0 = oldest.
+  std::vector<FX_FILESIZE> revision_xref_list_;
+  std::vector<FX_FILESIZE> revision_xref_stream_list_;
+  std::unique_ptr<CPDF_RevisionProvider> revision_provider_;
 };
 
 #endif  // CORE_FPDFAPI_PARSER_CPDF_PARSER_H_