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LibPDF: Extract Parser::parse_inline_image()

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Pure code move, no intended behavior change.

The motivation is just to make Parser::parse_operators() less nested
and more focused.
This commit is contained in:
Nico Weber 2023-12-21 22:01:43 -05:00 committed by Andreas Kling
parent f972eda7ed
commit 3d07684891
Notes: sideshowbarker 2024-07-17 03:03:37 +09:00 
Author: https://github.com/nico
Commit: https://github.com/SerenityOS/serenity/commit/3d07684891
Pull-request: https://github.com/SerenityOS/serenity/pull/22386
2 changed files with 45 additions and 40 deletions
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83
Userland/Libraries/LibPDF/Parser.cpp
View File

@ -520,6 +520,48 @@ PDFErrorOr<NonnullRefPtr<StreamObject>> Parser::parse_stream(NonnullRefPtr<DictO
return stream_object;
}
PDFErrorOr<NonnullRefPtr<StreamObject>> Parser::parse_inline_image()
{
// Inline images contain a dictionary containing arbitrary values between BI and ID,
// and then arbitrary binary data between ID and EI.
// This means they need a special code path in the parser, so that image data in there doesn't confuse the operator parser.
HashMap<DeprecatedFlyString, Value> map = TRY(parse_dict_contents_until("ID"));
m_reader.consume(2); // "ID"
// "Unless the image uses ASCIIHexDecode or ASCII85Decode as one of its filters,
// the ID operator should be followed by a single white-space character,
// and the next character is interpreted as the first byte of image data."
// FIXME: Check for ASCIIHexDecode and ASCII85Decode.
m_reader.consume(1);
// FIMXE: PDF 2.0 added support for `/L` / `/Length` in inline image dicts. If that's present, we don't have to scan for `EI`.
auto stream_start = m_reader.offset();
while (!m_reader.done()) {
// FIXME: Should we allow EI after matches_delimiter() too?
bool expecting_ei = m_reader.matches_whitespace();
m_reader.consume();
if (expecting_ei && m_reader.matches("EI")) {
break;
}
}
if (m_reader.done())
return error("operator stream ended inside inline image");
// Points one past the end of the stream data.
// FIXME: If we add matches_delimiter() to expecting_ei above, this has to be 1 larger in the delimiter case.
auto stream_end = m_reader.offset();
m_reader.consume(2); // "EI"
m_reader.consume_whitespace();
auto stream_bytes = m_reader.bytes().slice(stream_start, stream_end - stream_start);
auto map_object = make_object<DictObject>(move(map));
return make_object<StreamObject>(move(map_object), MUST(ByteBuffer::copy(stream_bytes)));
}
PDFErrorOr<Vector<Operator>> Parser::parse_operators()
{
Vector<Operator> operators;
@ -553,49 +595,10 @@ PDFErrorOr<Vector<Operator>> Parser::parse_operators()
auto operator_type = Operator::operator_type_from_symbol(operator_string);
// Inline images contain a dictionary containing arbitrary values between BI and ID,
// and then arbitrary binary data between ID and EI.
// This means they need a special code path in the parser, so that image data in there doesn't confuse the operator parser.
if (operator_type == OperatorType::InlineImageBegin) {
if (!operator_args.is_empty())
return error("operator args not empty on start of inline image");
HashMap<DeprecatedFlyString, Value> map = TRY(parse_dict_contents_until("ID"));
m_reader.consume(2); // "ID"
// "Unless the image uses ASCIIHexDecode or ASCII85Decode as one of its filters,
// the ID operator should be followed by a single white-space character,
// and the next character is interpreted as the first byte of image data."
// FIXME: Check for ASCIIHexDecode and ASCII85Decode.
m_reader.consume(1);
// FIMXE: PDF 2.0 added support for `/L` / `/Length` in inline image dicts. If that's present, we don't have to scan for `EI`.
auto stream_start = m_reader.offset();
while (!m_reader.done()) {
// FIXME: Should we allow EI after matches_delimiter() too?
bool expecting_ei = m_reader.matches_whitespace();
m_reader.consume();
if (expecting_ei && m_reader.matches("EI")) {
break;
}
}
if (m_reader.done())
return error("operator stream ended inside inline image");
// Points one past the end of the stream data.
// FIXME: If we add matches_delimiter() to expecting_ei above, this has to be 1 larger in the delimiter case.
auto stream_end = m_reader.offset();
m_reader.consume(2); // "EI"
m_reader.consume_whitespace();
auto stream_bytes = m_reader.bytes().slice(stream_start, stream_end - stream_start);
Vector<Value> inline_image_args;
auto map_object = make_object<DictObject>(move(map));
inline_image_args.append(make_object<StreamObject>(move(map_object), MUST(ByteBuffer::copy(stream_bytes))));
operators.append(Operator(OperatorType::InlineImageEnd, move(inline_image_args)));
operators.append(Operator(OperatorType::InlineImageEnd, { TRY(parse_inline_image()) }));
continue;
}

2
Userland/Libraries/LibPDF/Parser.h
View File

@ -73,6 +73,8 @@ public:
void pop_reference() { m_current_reference_stack.take_last(); }
protected:
PDFErrorOr<NonnullRefPtr<StreamObject>> parse_inline_image();
Error error(
ByteString const& message
#ifdef PDF_DEBUG