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LibRegex: Make parse_disjunction() consume all disjunctions in one frame
This helps us not blow up when too many disjunctions are chained togther in the regex we're parsing. Fixes #12615.
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2 changed files with 33 additions and 21 deletions
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@ -956,28 +956,37 @@ bool ECMA262Parser::parse_pattern(ByteCode& stack, size_t& match_length_minimum,
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bool ECMA262Parser::parse_disjunction(ByteCode& stack, size_t& match_length_minimum, bool unicode, bool named)
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{
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ByteCode left_alternative_stack;
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size_t left_alternative_min_length = 0;
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auto alt_ok = parse_alternative(left_alternative_stack, left_alternative_min_length, unicode, named);
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if (!alt_ok)
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return false;
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size_t total_match_length_minimum = NumericLimits<size_t>::max();
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Vector<ByteCode> alternatives;
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do {
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ByteCode alternative_stack;
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size_t alternative_minimum_length = 0;
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auto alt_ok = parse_alternative(alternative_stack, alternative_minimum_length, unicode, named);
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if (!alt_ok)
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return false;
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if (!match(TokenType::Pipe)) {
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stack.extend(left_alternative_stack);
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match_length_minimum = left_alternative_min_length;
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return alt_ok;
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alternatives.append(move(alternative_stack));
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total_match_length_minimum = min(alternative_minimum_length, total_match_length_minimum);
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if (!match(TokenType::Pipe))
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break;
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consume();
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} while (true);
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Optional<ByteCode> alternative_stack {};
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for (auto& alternative : alternatives) {
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if (alternative_stack.has_value()) {
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ByteCode target_stack;
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target_stack.insert_bytecode_alternation(alternative_stack.release_value(), move(alternative));
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alternative_stack = move(target_stack);
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} else {
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alternative_stack = move(alternative);
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}
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}
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consume();
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ByteCode right_alternative_stack;
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size_t right_alternative_min_length = 0;
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auto continuation_ok = parse_disjunction(right_alternative_stack, right_alternative_min_length, unicode, named);
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if (!continuation_ok)
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return false;
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stack.insert_bytecode_alternation(move(left_alternative_stack), move(right_alternative_stack));
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match_length_minimum = min(left_alternative_min_length, right_alternative_min_length);
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return continuation_ok;
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stack.extend(alternative_stack.release_value());
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match_length_minimum = total_match_length_minimum;
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return true;
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}
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bool ECMA262Parser::parse_alternative(ByteCode& stack, size_t& match_length_minimum, bool unicode, bool named)
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