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LibPDF: Keep track of the current object index/generation while Parsing

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This information is required to decrypt encrypted strings/streams.
This commit is contained in:
Matthew Olsson 2022-03-21 11:26:31 -07:00 • committed by Andreas Kling
parent 5b316462b2
commit a8de9cf541
2 changed files with 20 additions and 4 deletions
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18
Userland/Libraries/LibPDF/Parser.cpp
View file

@ -613,20 +613,26 @@ PDFErrorOr<Value> Parser::parse_possible_indirect_value_or_ref()
if (m_reader.matches("obj")) { if (m_reader.matches("obj")) {
m_reader.discard(); m_reader.discard();
return TRY(parse_indirect_value(first_number.get<int>(), second_number.value().get<int>())); auto index = first_number.get<int>();
auto generation = second_number.value().get<int>();
VERIFY(index >= 0);
VERIFY(generation >= 0);
return TRY(parse_indirect_value(index, generation));
} }
m_reader.load(); m_reader.load();
return first_number; return first_number;
} }
PDFErrorOr<NonnullRefPtr<IndirectValue>> Parser::parse_indirect_value(int index, int generation) PDFErrorOr<NonnullRefPtr<IndirectValue>> Parser::parse_indirect_value(u32 index, u32 generation)
{ {
if (!m_reader.matches("obj")) if (!m_reader.matches("obj"))
return error("Expected \"obj\" at beginning of indirect value"); return error("Expected \"obj\" at beginning of indirect value");
m_reader.move_by(3); m_reader.move_by(3);
if (matches_eol()) if (matches_eol())
consume_eol(); consume_eol();
push_reference({ index, generation });
auto value = TRY(parse_value()); auto value = TRY(parse_value());
if (!m_reader.matches("endobj")) if (!m_reader.matches("endobj"))
return error("Expected \"endobj\" at end of indirect value"); return error("Expected \"endobj\" at end of indirect value");
@ -634,6 +640,8 @@ PDFErrorOr<NonnullRefPtr<IndirectValue>> Parser::parse_indirect_value(int index,
consume(6); consume(6);
consume_whitespace(); consume_whitespace();
pop_reference();
return make_object<IndirectValue>(index, generation, value); return make_object<IndirectValue>(index, generation, value);
} }
@ -641,7 +649,11 @@ PDFErrorOr<NonnullRefPtr<IndirectValue>> Parser::parse_indirect_value()
{ {
auto first_number = TRY(parse_number()); auto first_number = TRY(parse_number());
auto second_number = TRY(parse_number()); auto second_number = TRY(parse_number());
return parse_indirect_value(first_number.get<int>(), second_number.get<int>()); auto index = first_number.get<int>();
auto generation = second_number.get<int>();
VERIFY(index >= 0);
VERIFY(generation >= 0);
return parse_indirect_value(index, generation);
} }
PDFErrorOr<Value> Parser::parse_number() PDFErrorOr<Value> Parser::parse_number()

6
Userland/Libraries/LibPDF/Parser.h
View file

@ -104,7 +104,7 @@ private:
PDFErrorOr<Value> parse_value(); PDFErrorOr<Value> parse_value();
PDFErrorOr<Value> parse_possible_indirect_value_or_ref(); PDFErrorOr<Value> parse_possible_indirect_value_or_ref();
PDFErrorOr<NonnullRefPtr<IndirectValue>> parse_indirect_value(int index, int generation); PDFErrorOr<NonnullRefPtr<IndirectValue>> parse_indirect_value(u32 index, u32 generation);
PDFErrorOr<NonnullRefPtr<IndirectValue>> parse_indirect_value(); PDFErrorOr<NonnullRefPtr<IndirectValue>> parse_indirect_value();
PDFErrorOr<Value> parse_number(); PDFErrorOr<Value> parse_number();
PDFErrorOr<NonnullRefPtr<NameObject>> parse_name(); PDFErrorOr<NonnullRefPtr<NameObject>> parse_name();
@ -117,6 +117,9 @@ private:
PDFErrorOr<Vector<Command>> parse_graphics_commands(); PDFErrorOr<Vector<Command>> parse_graphics_commands();
void push_reference(Reference const& ref) { m_current_reference_stack.append(ref); }
void pop_reference() { m_current_reference_stack.take_last(); }
bool matches_eol() const; bool matches_eol() const;
bool matches_whitespace() const; bool matches_whitespace() const;
bool matches_number() const; bool matches_number() const;
@ -142,6 +145,7 @@ private:
RefPtr<XRefTable> m_xref_table; RefPtr<XRefTable> m_xref_table;
RefPtr<DictObject> m_trailer; RefPtr<DictObject> m_trailer;
Optional<LinearizationDictionary> m_linearization_dictionary; Optional<LinearizationDictionary> m_linearization_dictionary;
Vector<Reference> m_current_reference_stack;
}; };
}; };