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LibWeb: Use TokenStreams when expanding unresolved CSS values

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This fixes a bug where any whitespace inside the `var()` or `attr()`
functions would make the StyleComputer fail to resolve them.
This commit is contained in:
Sam Atkins 2022-09-27 16:46:22 +01:00 committed by Andreas Kling
parent ae64cffd3a
commit 54be317fa9
Notes: sideshowbarker 2024-07-17 06:35:01 +09:00 
Author: https://github.com/AtkinsSJ
Commit: https://github.com/SerenityOS/serenity/commit/54be317fa9
Pull-request: https://github.com/SerenityOS/serenity/pull/15378
2 changed files with 40 additions and 22 deletions
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57
Userland/Libraries/LibWeb/CSS/StyleComputer.cpp
View file

@ -556,7 +556,7 @@ static RefPtr<StyleValue> get_custom_property(DOM::Element const& element, FlySt
return nullptr;
}
bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView property_name, HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>>& dependencies, Vector<Parser::ComponentValue> const& source, Vector<Parser::ComponentValue>& dest, size_t source_start_index) const
bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView property_name, HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>>& dependencies, Parser::TokenStream<Parser::ComponentValue>& source, Vector<Parser::ComponentValue>& dest) const
{
// FIXME: Do this better!
// We build a copy of the tree of ComponentValues, with all var()s and attr()s replaced with their contents.
@ -565,7 +565,7 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
// Arbitrary large value chosen to avoid the billion-laughs attack.
// https://www.w3.org/TR/css-variables-1/#long-variables
const size_t MAX_VALUE_COUNT = 16384;
if (source.size() + dest.size() > MAX_VALUE_COUNT) {
if (source.remaining_token_count() + dest.size() > MAX_VALUE_COUNT) {
dbgln("Stopped expanding CSS variables: maximum length reached.");
return false;
}
@ -578,15 +578,16 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
return new_node;
};
for (size_t source_index = source_start_index; source_index < source.size(); source_index++) {
auto const& value = source[source_index];
while (source.has_next_token()) {
auto const& value = source.next_token();
if (value.is_function()) {
if (value.function().name().equals_ignoring_case("var"sv)) {
auto const& var_contents = value.function().values();
if (var_contents.is_empty())
Parser::TokenStream var_contents { value.function().values() };
var_contents.skip_whitespace();
if (!var_contents.has_next_token())
return false;
auto const& custom_property_name_token = var_contents.first();
auto const& custom_property_name_token = var_contents.next_token();
if (!custom_property_name_token.is(Parser::Token::Type::Ident))
return false;
auto custom_property_name = custom_property_name_token.token().ident();
@ -606,24 +607,32 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
if (auto custom_property_value = get_custom_property(element, custom_property_name)) {
VERIFY(custom_property_value->is_unresolved());
if (!expand_unresolved_values(element, custom_property_name, dependencies, custom_property_value->as_unresolved().values(), dest, 0))
Parser::TokenStream custom_property_tokens { custom_property_value->as_unresolved().values() };
if (!expand_unresolved_values(element, custom_property_name, dependencies, custom_property_tokens, dest))
return false;
continue;
}
// Use the provided fallback value, if any.
if (var_contents.size() > 2 && var_contents[1].is(Parser::Token::Type::Comma)) {
if (!expand_unresolved_values(element, property_name, dependencies, var_contents, dest, 2))
var_contents.skip_whitespace();
if (var_contents.has_next_token()) {
auto const& comma_token = var_contents.next_token();
if (!comma_token.is(Parser::Token::Type::Comma))
return false;
var_contents.skip_whitespace();
if (!expand_unresolved_values(element, property_name, dependencies, var_contents, dest))
return false;
continue;
}
} else if (value.function().name().equals_ignoring_case("attr"sv)) {
continue;
}
if (value.function().name().equals_ignoring_case("attr"sv)) {
// https://drafts.csswg.org/css-values-5/#attr-substitution
auto const& attr_contents = value.function().values();
if (attr_contents.is_empty())
Parser::TokenStream attr_contents { value.function().values() };
attr_contents.skip_whitespace();
if (!attr_contents.has_next_token())
return false;
auto const& attr_name_token = attr_contents.first();
auto const& attr_name_token = attr_contents.next_token();
if (!attr_name_token.is(Parser::Token::Type::Ident))
return false;
auto attr_name = attr_name_token.token().ident();
@ -638,8 +647,13 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
// 2. Otherwise, if the attr() function has a fallback value as its last argument, replace the attr() function by the fallback value.
// If there are any var() or attr() references in the fallback, substitute them as well.
if (attr_contents.size() > 2 && attr_contents[1].is(Parser::Token::Type::Comma)) {
if (!expand_unresolved_values(element, property_name, dependencies, attr_contents, dest, 2))
attr_contents.skip_whitespace();
if (attr_contents.has_next_token()) {
auto const& comma_token = attr_contents.next_token();
if (!comma_token.is(Parser::Token::Type::Comma))
return false;
attr_contents.skip_whitespace();
if (!expand_unresolved_values(element, property_name, dependencies, attr_contents, dest))
return false;
continue;
}
@ -650,7 +664,8 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
auto const& source_function = value.function();
Vector<Parser::ComponentValue> function_values;
if (!expand_unresolved_values(element, property_name, dependencies, source_function.values(), function_values, 0))
Parser::TokenStream source_function_contents { source_function.values() };
if (!expand_unresolved_values(element, property_name, dependencies, source_function_contents, function_values))
return false;
NonnullRefPtr<Parser::Function> function = Parser::Function::create(source_function.name(), move(function_values));
dest.empend(function);
@ -658,8 +673,9 @@ bool StyleComputer::expand_unresolved_values(DOM::Element& element, StringView p
}
if (value.is_block()) {
auto const& source_block = value.block();
Parser::TokenStream source_block_values { source_block.values() };
Vector<Parser::ComponentValue> block_values;
if (!expand_unresolved_values(element, property_name, dependencies, source_block.values(), block_values, 0))
if (!expand_unresolved_values(element, property_name, dependencies, source_block_values, block_values))
return false;
NonnullRefPtr<Parser::Block> block = Parser::Block::create(source_block.token(), move(block_values));
dest.empend(move(block));
@ -679,7 +695,8 @@ RefPtr<StyleValue> StyleComputer::resolve_unresolved_style_value(DOM::Element& e
Vector<Parser::ComponentValue> expanded_values;
HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>> dependencies;
if (!expand_unresolved_values(element, string_from_property_id(property_id), dependencies, unresolved.values(), expanded_values, 0))
Parser::TokenStream unresolved_values { unresolved.values() };
if (!expand_unresolved_values(element, string_from_property_id(property_id), dependencies, unresolved_values, expanded_values))
return {};
if (auto parsed_value = Parser::Parser::parse_css_value({}, Parser::ParsingContext { document() }, property_id, expanded_values))

5
Userland/Libraries/LibWeb/CSS/StyleComputer.h
View file

@ -1,6 +1,6 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2021, Sam Atkins <atkinssj@serenityos.org>
* Copyright (c) 2021-2022, Sam Atkins <atkinssj@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -14,6 +14,7 @@
#include <LibWeb/CSS/CSSFontFaceRule.h>
#include <LibWeb/CSS/CSSStyleDeclaration.h>
#include <LibWeb/CSS/Parser/ComponentValue.h>
#include <LibWeb/CSS/Parser/TokenStream.h>
#include <LibWeb/CSS/Selector.h>
#include <LibWeb/CSS/StyleProperties.h>
#include <LibWeb/Forward.h>
@ -86,7 +87,7 @@ private:
void compute_defaulted_property_value(StyleProperties&, DOM::Element const*, CSS::PropertyID, Optional<CSS::Selector::PseudoElement>) const;
RefPtr<StyleValue> resolve_unresolved_style_value(DOM::Element&, PropertyID, UnresolvedStyleValue const&) const;
bool expand_unresolved_values(DOM::Element&, StringView property_name, HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>>& dependencies, Vector<Parser::ComponentValue> const& source, Vector<Parser::ComponentValue>& dest, size_t source_start_index) const;
bool expand_unresolved_values(DOM::Element&, StringView property_name, HashMap<FlyString, NonnullRefPtr<PropertyDependencyNode>>& dependencies, Parser::TokenStream<Parser::ComponentValue>& source, Vector<Parser::ComponentValue>& dest) const;
template<typename Callback>
void for_each_stylesheet(CascadeOrigin, Callback) const;