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LibWeb: Make SVG transform parser less crashy

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Previously, this would blindly use parse_number() without checking if
there was a number to parse. This meant we would crash on transforms
like:
	rotate(BAD 32 0)

Now the attribute just gracefully fails to parse.
This commit is contained in:
MacDue 2023-05-27 16:37:32 +01:00 committed by Andreas Kling
parent 33500bb6db
commit 6f8c2dc322
Notes: sideshowbarker 2024-07-17 03:10:07 +09:00 
Author: https://github.com/MacDue
Commit: https://github.com/SerenityOS/serenity/commit/6f8c2dc322
Pull-request: https://github.com/SerenityOS/serenity/pull/19093
1 changed files with 62 additions and 19 deletions
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81
Userland/Libraries/LibWeb/SVG/AttributeParser.cpp
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@ -519,7 +519,8 @@ Optional<Vector<Transform>> AttributeParser::parse_transform()
m_lexer.consume_specific(',');
consume_whitespace();
};
// FIXME: AttributeParser currently does not handle invalid parses in most cases (e.g. parse_number()) and just crashes.
// FIXME: This parsing is quite lenient, so will accept (with default values) some transforms that should be rejected.
auto parse_optional_number = [&](float default_value = 0.0f) {
consume_comma_whitespace();
if (match_number())
@ -527,12 +528,21 @@ Optional<Vector<Transform>> AttributeParser::parse_transform()
return default_value;
};
auto try_parse_number = [&]() -> Optional<float> {
if (match_number())
return parse_number();
return {};
};
auto parse_function = [&](auto body) -> Optional<Transform> {
consume_whitespace();
if (!m_lexer.consume_specific('('))
return {};
consume_whitespace();
Transform transform { .operation = Transform::Operation { body() } };
auto maybe_operation = body();
if (!maybe_operation.has_value())
return {};
Transform transform { .operation = Transform::Operation { *maybe_operation } };
consume_whitespace();
if (m_lexer.consume_specific(')'))
return transform;
@ -545,53 +555,86 @@ Optional<Vector<Transform>> AttributeParser::parse_transform()
while (!done()) {
Optional<Transform> maybe_transform;
if (m_lexer.consume_specific("translate"sv)) {
maybe_transform = parse_function([&] {
maybe_transform = parse_function([&]() -> Optional<Transform::Translate> {
Transform::Translate translate {};
translate.x = parse_number();
auto maybe_x = try_parse_number();
if (!maybe_x.has_value())
return {};
translate.x = *maybe_x;
translate.y = parse_optional_number();
return translate;
});
} else if (m_lexer.consume_specific("scale"sv)) {
maybe_transform = parse_function([&] {
maybe_transform = parse_function([&]() -> Optional<Transform::Scale> {
Transform::Scale scale {};
scale.x = parse_number();
auto maybe_x = try_parse_number();
if (!maybe_x.has_value())
return {};
scale.x = *maybe_x;
scale.y = parse_optional_number(scale.x);
return scale;
});
} else if (m_lexer.consume_specific("rotate"sv)) {
maybe_transform = parse_function([&] {
maybe_transform = parse_function([&]() -> Optional<Transform::Rotate> {
Transform::Rotate rotate {};
rotate.a = parse_number();
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
rotate.a = *maybe_a;
rotate.x = parse_optional_number();
rotate.y = parse_optional_number();
return rotate;
});
} else if (m_lexer.consume_specific("skewX"sv)) {
maybe_transform = parse_function([&] {
maybe_transform = parse_function([&]() -> Optional<Transform::SkewX> {
Transform::SkewX skew_x {};
skew_x.a = parse_number();
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
skew_x.a = *maybe_a;
return skew_x;
});
} else if (m_lexer.consume_specific("skewY"sv)) {
maybe_transform = parse_function([&] {
maybe_transform = parse_function([&]() -> Optional<Transform::SkewY> {
Transform::SkewY skew_y {};
skew_y.a = parse_number();
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
skew_y.a = *maybe_a;
return skew_y;
});
} else if (m_lexer.consume_specific("matrix"sv)) {
maybe_transform = parse_function([&] {
maybe_transform = parse_function([&]() -> Optional<Transform::Matrix> {
Transform::Matrix matrix;
matrix.a = parse_number();
auto maybe_a = try_parse_number();
if (!maybe_a.has_value())
return {};
matrix.a = *maybe_a;
consume_comma_whitespace();
matrix.b = parse_number();
auto maybe_b = try_parse_number();
if (!maybe_b.has_value())
return {};
matrix.b = *maybe_b;
consume_comma_whitespace();
matrix.c = parse_number();
auto maybe_c = try_parse_number();
if (!maybe_c.has_value())
return {};
matrix.c = *maybe_c;
consume_comma_whitespace();
matrix.d = parse_number();
auto maybe_d = try_parse_number();
if (!maybe_d.has_value())
return {};
matrix.d = *maybe_d;
consume_comma_whitespace();
matrix.e = parse_number();
auto maybe_e = try_parse_number();
if (!maybe_e.has_value())
return {};
matrix.e = *maybe_e;
consume_comma_whitespace();
matrix.f = parse_number();
auto maybe_f = try_parse_number();
if (!maybe_f.has_value())
return {};
matrix.f = *maybe_f;
return matrix;
});
}