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LibWeb/CSS: Reject invalid rules and declarations during parsing

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This implements the `is_valid_in_the_current_context()` methods by
maintaining a stack of contexts, such as whether we're inside a style
rule, or an `@media` block, or the condition of a `@supports` rule.
This commit is contained in:
Sam Atkins 2024-11-01 14:46:35 +00:00 committed by Andreas Kling
parent 3b36ca2711
commit a703aad082
Notes: github-actions[bot] 2024-11-07 14:13:01 +00:00 
Author: https://github.com/AtkinsSJ
Commit: https://github.com/LadybirdBrowser/ladybird/commit/a703aad0824
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/2202
2 changed files with 161 additions and 12 deletions
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146
Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
View file

@ -183,7 +183,9 @@ RefPtr<Supports> Parser::parse_a_supports(TokenStream<T>& tokens)
{
auto component_values = parse_a_list_of_component_values(tokens);
TokenStream<ComponentValue> token_stream { component_values };
m_rule_context.append(ContextType::SupportsCondition);
auto maybe_condition = parse_supports_condition(token_stream);
m_rule_context.take_last();
token_stream.discard_whitespace();
if (maybe_condition && !token_stream.has_next_token())
return Supports::create(m_context.realm(), maybe_condition.release_nonnull());
@ -458,7 +460,9 @@ Optional<AtRule> Parser::consume_an_at_rule(TokenStream<T>& input, Nested nested
// <{-token>
if (token.is(Token::Type::OpenCurly)) {
// Consume a block from input, and assign the result to rule’s child rules.
m_rule_context.append(context_type_for_at_rule(rule.name));
rule.child_rules_and_lists_of_declarations = consume_a_block(input);
m_rule_context.take_last();
// If rule is valid in the current context, return it. Otherwise, return nothing.
if (is_valid_in_the_current_context(rule))
@ -487,6 +491,12 @@ Variant<Empty, QualifiedRule, Parser::InvalidRuleError> Parser::consume_a_qualif
.child_rules = {},
};
// NOTE: Qualified rules inside @keyframes are a keyframe rule.
// We'll assume all others are style rules.
auto type_of_qualified_rule = (!m_rule_context.is_empty() && m_rule_context.last() == ContextType::AtKeyframes)
? ContextType::Keyframe
: ContextType::Style;
// Process input:
for (;;) {
auto& token = input.next_token();
@ -532,7 +542,9 @@ Variant<Empty, QualifiedRule, Parser::InvalidRuleError> Parser::consume_a_qualif
}
// Otherwise, consume a block from input, and let child rules be the result.
m_rule_context.append(type_of_qualified_rule);
rule.child_rules = consume_a_block(input);
m_rule_context.take_last();
// If the first item of child rules is a list of declarations, remove it from child rules and assign it to rule’s declarations.
if (!rule.child_rules.is_empty() && rule.child_rules.first().has<Vector<Declaration>>()) {
@ -1077,7 +1089,9 @@ Vector<RuleOrListOfDeclarations> Parser::parse_a_blocks_contents(TokenStream<T>&
Optional<StyleProperty> Parser::parse_as_supports_condition()
{
m_rule_context.append(ContextType::SupportsCondition);
auto maybe_declaration = parse_a_declaration(m_token_stream);
m_rule_context.take_last();
if (maybe_declaration.has_value())
return convert_to_style_property(maybe_declaration.release_value());
return {};
@ -1198,7 +1212,10 @@ ElementInlineCSSStyleDeclaration* Parser::parse_as_style_attribute(DOM::Element&
return expanded_properties;
};
m_rule_context.append(ContextType::Style);
auto declarations_and_at_rules = parse_a_blocks_contents(m_token_stream);
m_rule_context.take_last();
auto [properties, custom_properties] = extract_properties(declarations_and_at_rules);
auto expanded_properties = expand_shorthands(properties);
return ElementInlineCSSStyleDeclaration::create(element, move(expanded_properties), move(custom_properties));
@ -1521,22 +1538,122 @@ RefPtr<CSSStyleValue> Parser::parse_basic_shape_value(TokenStream<ComponentValue
return nullptr;
}
bool Parser::is_valid_in_the_current_context(Declaration&)
bool Parser::is_valid_in_the_current_context(Declaration const&) const
{
// FIXME: Implement this check
// TODO: Determine if this *particular* declaration is valid here, not just declarations in general.
// Declarations can't appear at the top level
if (m_rule_context.is_empty())
return false;
switch (m_rule_context.last()) {
case ContextType::Unknown:
// If the context is an unknown type, we don't accept anything.
return false;
case ContextType::Style:
case ContextType::Keyframe:
// Style and keyframe rules contain property declarations
return true;
case ContextType::AtLayer:
case ContextType::AtMedia:
case ContextType::AtSupports:
// Grouping rules can contain declarations if they are themselves inside a style rule
return m_rule_context.contains_slow(ContextType::Style);
case ContextType::AtFontFace:
case ContextType::AtProperty:
// @font-face and @property have descriptor declarations
return true;
case ContextType::AtKeyframes:
// @keyframes can only contain keyframe rules
return false;
case ContextType::SupportsCondition:
// @supports conditions accept all declarations
return true;
}
VERIFY_NOT_REACHED();
}
bool Parser::is_valid_in_the_current_context(AtRule&)
bool Parser::is_valid_in_the_current_context(AtRule const& at_rule) const
{
// FIXME: Implement this check
// All at-rules can appear at the top level
if (m_rule_context.is_empty())
return true;
switch (m_rule_context.last()) {
case ContextType::Unknown:
// If the context is an unknown type, we don't accept anything.
return false;
case ContextType::Style:
// Style rules can contain grouping rules
return first_is_one_of(at_rule.name, "layer", "media", "supports");
case ContextType::AtLayer:
case ContextType::AtMedia:
case ContextType::AtSupports:
// Grouping rules can contain anything except @import or @namespace
return !first_is_one_of(at_rule.name, "import", "namespace");
case ContextType::SupportsCondition:
// @supports cannot check for at-rules
return false;
case ContextType::AtFontFace:
case ContextType::AtKeyframes:
case ContextType::Keyframe:
case ContextType::AtProperty:
// These can't contain any at-rules
return false;
}
VERIFY_NOT_REACHED();
}
bool Parser::is_valid_in_the_current_context(QualifiedRule&)
bool Parser::is_valid_in_the_current_context(QualifiedRule const&) const
{
// FIXME: Implement this check
// TODO: Different places accept different kinds of qualified rules. How do we tell them apart? Can we?
// Top level can contain style rules
if (m_rule_context.is_empty())
return true;
switch (m_rule_context.last()) {
case ContextType::Unknown:
// If the context is an unknown type, we don't accept anything.
return false;
case ContextType::Style:
// Style rules can contain style rules
return true;
case ContextType::AtLayer:
case ContextType::AtMedia:
case ContextType::AtSupports:
// Grouping rules can contain style rules
return true;
case ContextType::AtKeyframes:
// @keyframes can contain keyframe rules
return true;
case ContextType::SupportsCondition:
// @supports cannot check qualified rules
return false;
case ContextType::AtFontFace:
case ContextType::AtProperty:
case ContextType::Keyframe:
// These can't contain qualified rules
return false;
}
VERIFY_NOT_REACHED();
}
Parser::PropertiesAndCustomProperties Parser::extract_properties(Vector<RuleOrListOfDeclarations> const& rules_and_lists_of_declarations)
@ -8987,4 +9104,21 @@ RefPtr<StringStyleValue> Parser::parse_opentype_tag_value(TokenStream<ComponentV
return string_value;
}
Parser::ContextType Parser::context_type_for_at_rule(FlyString const& name)
{
if (name == "media")
return ContextType::AtMedia;
if (name == "font-face")
return ContextType::AtFontFace;
if (name == "keyframes")
return ContextType::AtKeyframes;
if (name == "supports")
return ContextType::AtSupports;
if (name == "layer")
return ContextType::AtLayer;
if (name == "property")
return ContextType::AtProperty;
return ContextType::Unknown;
}
}

21
Userland/Libraries/LibWeb/CSS/Parser/Parser.h
View file

@ -175,9 +175,9 @@ private:
};
Optional<FlyString> parse_layer_name(TokenStream<ComponentValue>&, AllowBlankLayerName);
bool is_valid_in_the_current_context(Declaration&);
bool is_valid_in_the_current_context(AtRule&);
bool is_valid_in_the_current_context(QualifiedRule&);
bool is_valid_in_the_current_context(Declaration const&) const;
bool is_valid_in_the_current_context(AtRule const&) const;
bool is_valid_in_the_current_context(QualifiedRule const&) const;
JS::GCPtr<CSSRule> convert_to_rule(Rule const&, Nested);
JS::GCPtr<CSSStyleRule> convert_to_style_rule(QualifiedRule const&, Nested);
JS::GCPtr<CSSFontFaceRule> convert_to_font_face_rule(AtRule const&);
@ -398,6 +398,21 @@ private:
Vector<Token> m_tokens;
TokenStream<Token> m_token_stream;
enum class ContextType {
Unknown,
Style,
AtMedia,
AtFontFace,
AtKeyframes,
Keyframe,
AtSupports,
SupportsCondition,
AtLayer,
AtProperty,
};
static ContextType context_type_for_at_rule(FlyString const&);
Vector<ContextType> m_rule_context;
};
}