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LibWeb: Use EOF code point instead of Optional in CSS Tokenizer

Browse source 
Optional seems like a good idea, but in many places we were not
checking if it had a value, which was causing crashes when the
Tokenizer was given malformed input. Using an EOF value along with
is_eof() makes things a lot simpler.
This commit is contained in:
Sam Atkins 2021-07-02 19:44:43 +01:00 • committed by Andreas Kling
parent caff7fff94
commit 985ed47a38
2 changed files with 96 additions and 103 deletions
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191
Userland/Libraries/LibWeb/CSS/Parser/Tokenizer.cpp
View file

@ -14,12 +14,18 @@
//U+FFFD REPLACEMENT CHARACTER (<28>) //U+FFFD REPLACEMENT CHARACTER (<28>)
#define REPLACEMENT_CHARACTER 0xFFFD #define REPLACEMENT_CHARACTER 0xFFFD
static const u32 TOKENIZER_EOF = 0xFFFFFFFF;
static inline void log_parse_error(const SourceLocation& location = SourceLocation::current()) static inline void log_parse_error(const SourceLocation& location = SourceLocation::current())
{ {
dbgln_if(CSS_TOKENIZER_TRACE, "Parse error (css tokenization) {} ", location); dbgln_if(CSS_TOKENIZER_TRACE, "Parse error (css tokenization) {} ", location);
} }
static inline bool is_eof(u32 code_point)
{
return code_point == TOKENIZER_EOF;
}
static inline bool is_quotation_mark(u32 code_point) static inline bool is_quotation_mark(u32 code_point)
{ {
return code_point == 0x22; return code_point == 0x22;
@ -207,48 +213,50 @@ Vector<Token> Tokenizer::parse()
} }
} }
Optional<u32> Tokenizer::next_code_point() u32 Tokenizer::next_code_point()
{ {
if (m_utf8_iterator == m_utf8_view.end()) if (m_utf8_iterator == m_utf8_view.end())
return {}; return TOKENIZER_EOF;
m_prev_utf8_iterator = m_utf8_iterator; m_prev_utf8_iterator = m_utf8_iterator;
++m_utf8_iterator; ++m_utf8_iterator;
dbgln_if(CSS_TOKENIZER_TRACE, "(Tokenizer) Next code_point: {:c}", (char)*m_prev_utf8_iterator); dbgln_if(CSS_TOKENIZER_TRACE, "(Tokenizer) Next code_point: {:c}", (char)*m_prev_utf8_iterator);
return *m_prev_utf8_iterator; return *m_prev_utf8_iterator;
} }
Optional<u32> Tokenizer::peek_code_point(size_t offset) const u32 Tokenizer::peek_code_point(size_t offset) const
{ {
auto it = m_utf8_iterator; auto it = m_utf8_iterator;
for (size_t i = 0; i < offset && it != m_utf8_view.end(); ++i) for (size_t i = 0; i < offset && it != m_utf8_view.end(); ++i)
++it; ++it;
if (it == m_utf8_view.end()) if (it == m_utf8_view.end())
return {}; return TOKENIZER_EOF;
return *it; return *it;
} }
Optional<U32Twin> Tokenizer::peek_twin() const U32Twin Tokenizer::peek_twin() const
{ {
U32Twin values; U32Twin values;
auto it = m_utf8_iterator; auto it = m_utf8_iterator;
for (size_t i = 0; i < 2 && it != m_utf8_view.end(); ++i) { for (size_t i = 0; i < 2 && it != m_utf8_view.end(); ++i) {
if (it == m_utf8_view.end()) if (it == m_utf8_view.end())
return {}; values.set(i, TOKENIZER_EOF);
values.set(i, *it); else
values.set(i, *it);
++it; ++it;
} }
return values; return values;
} }
Optional<U32Triplet> Tokenizer::peek_triplet() const U32Triplet Tokenizer::peek_triplet() const
{ {
U32Triplet values; U32Triplet values;
auto it = m_utf8_iterator; auto it = m_utf8_iterator;
for (size_t i = 0; i < 3 && it != m_utf8_view.end(); ++i) { for (size_t i = 0; i < 3 && it != m_utf8_view.end(); ++i) {
if (it == m_utf8_view.end()) if (it == m_utf8_view.end())
return {}; values.set(i, TOKENIZER_EOF);
values.set(i, *it); else
values.set(i, *it);
++it; ++it;
} }
return values; return values;
@ -279,25 +287,23 @@ Token Tokenizer::create_value_token(Token::TokenType type, u32 value)
u32 Tokenizer::consume_escaped_code_point() u32 Tokenizer::consume_escaped_code_point()
{ {
auto code_point = next_code_point(); auto input = next_code_point();
if (!code_point.has_value()) { if (is_eof(input)) {
log_parse_error(); log_parse_error();
return REPLACEMENT_CHARACTER; return REPLACEMENT_CHARACTER;
} }
auto input = code_point.value();
if (is_ascii_hex_digit(input)) { if (is_ascii_hex_digit(input)) {
StringBuilder builder; StringBuilder builder;
builder.append_code_point(input); builder.append_code_point(input);
size_t counter = 0; size_t counter = 0;
while (is_ascii_hex_digit(peek_code_point().value()) && counter++ < 5) { while (is_ascii_hex_digit(peek_code_point()) && counter++ < 5) {
builder.append_code_point(next_code_point().value()); builder.append_code_point(next_code_point());
} }
if (is_whitespace(peek_code_point().value())) { if (is_whitespace(peek_code_point())) {
(void)next_code_point(); (void)next_code_point();
} }
@ -321,11 +327,11 @@ Token Tokenizer::consume_an_ident_like_token()
{ {
auto string = consume_a_name(); auto string = consume_a_name();
if (string.equals_ignoring_case("url") && is_left_paren(peek_code_point().value())) { if (string.equals_ignoring_case("url") && is_left_paren(peek_code_point())) {
(void)next_code_point(); (void)next_code_point();
for (;;) { for (;;) {
auto maybe_whitespace = peek_twin().value(); auto maybe_whitespace = peek_twin();
if (!(is_whitespace(maybe_whitespace.first) && is_whitespace(maybe_whitespace.second))) { if (!(is_whitespace(maybe_whitespace.first) && is_whitespace(maybe_whitespace.second))) {
break; break;
} }
@ -333,7 +339,7 @@ Token Tokenizer::consume_an_ident_like_token()
(void)next_code_point(); (void)next_code_point();
} }
auto next_two = peek_twin().value(); auto next_two = peek_twin();
// if one of these ", ', ' "', " '" // if one of these ", ', ' "', " '"
if (is_quotation_mark(next_two.first) || is_apostrophe(next_two.first) || (is_whitespace(next_two.first) && (is_quotation_mark(next_two.second) || is_apostrophe(next_two.second)))) { if (is_quotation_mark(next_two.first) || is_apostrophe(next_two.first) || (is_whitespace(next_two.first) && (is_quotation_mark(next_two.second) || is_apostrophe(next_two.second)))) {
return create_value_token(Token::TokenType::Function, string); return create_value_token(Token::TokenType::Function, string);
@ -342,7 +348,7 @@ Token Tokenizer::consume_an_ident_like_token()
return consume_a_url_token(); return consume_a_url_token();
} }
if (is_left_paren(peek_code_point().value())) { if (is_left_paren(peek_code_point())) {
(void)next_code_point(); (void)next_code_point();
return create_value_token(Token::TokenType::Function, string); return create_value_token(Token::TokenType::Function, string);
@ -356,56 +362,56 @@ CSSNumber Tokenizer::consume_a_number()
StringBuilder repr; StringBuilder repr;
Token::NumberType type = Token::NumberType::Integer; Token::NumberType type = Token::NumberType::Integer;
auto next_input = peek_code_point().value(); auto next_input = peek_code_point();
if (is_plus_sign(next_input) || is_hyphen_minus(next_input)) { if (is_plus_sign(next_input) || is_hyphen_minus(next_input)) {
repr.append_code_point(next_code_point().value()); repr.append_code_point(next_code_point());
} }
for (;;) { for (;;) {
auto digits = peek_code_point().value(); auto digits = peek_code_point();
if (!is_ascii_digit(digits)) if (!is_ascii_digit(digits))
break; break;
repr.append_code_point(next_code_point().value()); repr.append_code_point(next_code_point());
} }
auto maybe_number = peek_twin().value(); auto maybe_number = peek_twin();
if (is_full_stop(maybe_number.first) && is_ascii_digit(maybe_number.second)) { if (is_full_stop(maybe_number.first) && is_ascii_digit(maybe_number.second)) {
repr.append_code_point(next_code_point().value()); repr.append_code_point(next_code_point());
repr.append_code_point(next_code_point().value()); repr.append_code_point(next_code_point());
type = Token::NumberType::Number;
for (;;) {
auto digit = peek_code_point();
if (!is_ascii_digit(digit))
break;
repr.append_code_point(next_code_point());
}
}
auto maybe_exp = peek_triplet();
if (is_E(maybe_exp.first) || is_e(maybe_exp.first)) {
if (is_plus_sign(maybe_exp.second) || is_hyphen_minus(maybe_exp.second)) {
if (is_ascii_digit(maybe_exp.third)) {
repr.append_code_point(next_code_point());
repr.append_code_point(next_code_point());
repr.append_code_point(next_code_point());
}
} else if (is_ascii_digit(maybe_exp.second)) {
repr.append_code_point(next_code_point());
repr.append_code_point(next_code_point());
}
type = Token::NumberType::Number; type = Token::NumberType::Number;
for (;;) { for (;;) {
auto digits = peek_code_point(); auto digits = peek_code_point();
if (digits.has_value() && !is_ascii_digit(digits.value()))
break;
repr.append_code_point(next_code_point().value());
}
}
auto maybe_exp = peek_triplet().value();
if (is_E(maybe_exp.first) || is_e(maybe_exp.first)) {
if (is_plus_sign(maybe_exp.second) || is_hyphen_minus(maybe_exp.second)) {
if (is_ascii_digit(maybe_exp.third)) {
repr.append_code_point(next_code_point().value());
repr.append_code_point(next_code_point().value());
repr.append_code_point(next_code_point().value());
}
} else if (is_ascii_digit(maybe_exp.second)) {
repr.append_code_point(next_code_point().value());
repr.append_code_point(next_code_point().value());
}
type = Token::NumberType::Number;
for (;;) {
auto digits = peek_code_point().value();
if (!is_ascii_digit(digits)) if (!is_ascii_digit(digits))
break; break;
repr.append_code_point(next_code_point().value()); repr.append_code_point(next_code_point());
} }
} }
@ -417,7 +423,10 @@ String Tokenizer::consume_a_name()
StringBuilder result; StringBuilder result;
for (;;) { for (;;) {
auto input = next_code_point().value(); auto input = next_code_point();
if (is_eof(input))
break;
if (is_name_code_point(input)) { if (is_name_code_point(input)) {
result.append_code_point(input); result.append_code_point(input);
@ -425,22 +434,22 @@ String Tokenizer::consume_a_name()
} }
auto next = peek_code_point(); auto next = peek_code_point();
if (next.has_value() && is_valid_escape_sequence({ input, next.value() })) { if (!is_eof(next) && is_valid_escape_sequence({ input, next })) {
result.append_code_point(consume_escaped_code_point()); result.append_code_point(consume_escaped_code_point());
continue; continue;
} }
reconsume_current_input_code_point();
break; break;
} }
reconsume_current_input_code_point();
return result.to_string(); return result.to_string();
} }
Token Tokenizer::consume_a_url_token() Token Tokenizer::consume_a_url_token()
{ {
auto token = create_new_token(Token::TokenType::Url); auto token = create_new_token(Token::TokenType::Url);
for (;;) { for (;;) {
if (!is_whitespace(peek_code_point().value())) { if (!is_whitespace(peek_code_point())) {
break; break;
} }
@ -449,14 +458,12 @@ Token Tokenizer::consume_a_url_token()
for (;;) { for (;;) {
auto code_point = peek_code_point(); auto input = peek_code_point();
if (!code_point.has_value()) { if (is_eof(input)) {
log_parse_error(); log_parse_error();
return token; return token;
} }
auto input = code_point.value();
if (is_right_paren(input)) { if (is_right_paren(input)) {
(void)next_code_point(); (void)next_code_point();
return token; return token;
@ -464,20 +471,18 @@ Token Tokenizer::consume_a_url_token()
if (is_whitespace(input)) { if (is_whitespace(input)) {
for (;;) { for (;;) {
if (!is_whitespace(peek_code_point().value())) { if (!is_whitespace(peek_code_point())) {
break; break;
} }
code_point = next_code_point(); input = next_code_point();
} }
if (!code_point.has_value()) { if (is_eof(input)) {
log_parse_error(); log_parse_error();
return token; return token;
} }
input = code_point.value();
if (is_right_paren(input)) { if (is_right_paren(input)) {
return token; return token;
} }
@ -504,7 +509,7 @@ Token Tokenizer::consume_a_url_token()
} }
} }
token.m_value.append_code_point(next_code_point().value()); token.m_value.append_code_point(next_code_point());
} }
} }
@ -513,11 +518,11 @@ void Tokenizer::consume_the_remnants_of_a_bad_url()
for (;;) { for (;;) {
auto next = peek_code_point(); auto next = peek_code_point();
if (!next.has_value()) { if (is_eof(next)) {
return; return;
} }
auto input = next.value(); auto input = next;
if (is_right_paren(input)) { if (is_right_paren(input)) {
(void)next_code_point(); (void)next_code_point();
@ -551,7 +556,7 @@ Token Tokenizer::consume_a_numeric_token()
return token; return token;
} }
if (is_percent(peek_code_point().value())) { if (is_percent(peek_code_point())) {
(void)next_code_point(); (void)next_code_point();
auto token = create_new_token(Token::TokenType::Percentage); auto token = create_new_token(Token::TokenType::Percentage);
@ -567,7 +572,7 @@ Token Tokenizer::consume_a_numeric_token()
bool Tokenizer::starts_with_a_number() const bool Tokenizer::starts_with_a_number() const
{ {
return starts_with_a_number(peek_triplet().value()); return starts_with_a_number(peek_triplet());
} }
bool Tokenizer::starts_with_a_number(U32Triplet values) bool Tokenizer::starts_with_a_number(U32Triplet values)
@ -593,7 +598,7 @@ bool Tokenizer::starts_with_a_number(U32Triplet values)
bool Tokenizer::is_valid_escape_sequence() bool Tokenizer::is_valid_escape_sequence()
{ {
return is_valid_escape_sequence(peek_twin().value()); return is_valid_escape_sequence(peek_twin());
} }
bool Tokenizer::is_valid_escape_sequence(U32Twin values) bool Tokenizer::is_valid_escape_sequence(U32Twin values)
@ -611,7 +616,7 @@ bool Tokenizer::is_valid_escape_sequence(U32Twin values)
bool Tokenizer::would_start_an_identifier() bool Tokenizer::would_start_an_identifier()
{ {
return would_start_an_identifier(peek_triplet().value()); return would_start_an_identifier(peek_triplet());
} }
bool Tokenizer::would_start_an_identifier(U32Triplet values) bool Tokenizer::would_start_an_identifier(U32Triplet values)
@ -640,15 +645,13 @@ Token Tokenizer::consume_string_token(u32 ending_code_point)
auto token = create_new_token(Token::TokenType::String); auto token = create_new_token(Token::TokenType::String);
for (;;) { for (;;) {
auto code_point = next_code_point(); auto input = next_code_point();
if (!code_point.has_value()) { if (is_eof(input)) {
log_parse_error(); log_parse_error();
return token; return token;
} }
auto input = code_point.value();
if (input == ending_code_point) if (input == ending_code_point)
return token; return token;
@ -659,10 +662,10 @@ Token Tokenizer::consume_string_token(u32 ending_code_point)
if (is_reverse_solidus(input)) { if (is_reverse_solidus(input)) {
auto next_input = peek_code_point(); auto next_input = peek_code_point();
if (!next_input.has_value()) if (is_eof(next_input))
continue; continue;
if (is_newline(next_input.value())) { if (is_newline(next_input)) {
(void)next_code_point(); (void)next_code_point();
continue; continue;
} }
@ -678,13 +681,7 @@ Token Tokenizer::consume_string_token(u32 ending_code_point)
void Tokenizer::consume_comments() void Tokenizer::consume_comments()
{ {
start: start:
auto peek = peek_twin(); auto twin = peek_twin();
if (!peek.has_value()) {
log_parse_error();
return;
}
auto twin = peek.value();
if (!(is_solidus(twin.first) && is_asterisk(twin.second))) if (!(is_solidus(twin.first) && is_asterisk(twin.second)))
return; return;
@ -692,14 +689,12 @@ start:
(void)next_code_point(); (void)next_code_point();
for (;;) { for (;;) {
auto peek_inner = peek_twin(); auto twin_inner = peek_twin();
if (!peek_inner.has_value()) { if (is_eof(twin_inner.first) || is_eof(twin_inner.second)) {
log_parse_error(); log_parse_error();
return; return;
} }
auto twin_inner = peek_inner.value();
if (is_asterisk(twin_inner.first) && is_solidus(twin_inner.second)) { if (is_asterisk(twin_inner.first) && is_solidus(twin_inner.second)) {
(void)next_code_point(); (void)next_code_point();
(void)next_code_point(); (void)next_code_point();
@ -714,19 +709,17 @@ Token Tokenizer::consume_a_token()
{ {
consume_comments(); consume_comments();
auto code_point = next_code_point(); auto input = next_code_point();
if (!code_point.has_value()) { if (is_eof(input)) {
return create_new_token(Token::TokenType::EndOfFile); return create_new_token(Token::TokenType::EndOfFile);
} }
auto input = code_point.value();
if (is_whitespace(input)) { if (is_whitespace(input)) {
dbgln_if(CSS_TOKENIZER_TRACE, "is whitespace"); dbgln_if(CSS_TOKENIZER_TRACE, "is whitespace");
auto next = peek_code_point(); auto next = peek_code_point();
while (next.has_value() && is_whitespace(next.value())) { while (is_whitespace(next)) {
(void)next_code_point(); (void)next_code_point();
next = peek_code_point(); next = peek_code_point();
} }
@ -742,8 +735,8 @@ Token Tokenizer::consume_a_token()
if (is_number_sign(input)) { if (is_number_sign(input)) {
dbgln_if(CSS_TOKENIZER_TRACE, "is number sign"); dbgln_if(CSS_TOKENIZER_TRACE, "is number sign");
auto next_input = peek_code_point().value(); auto next_input = peek_code_point();
auto maybe_escape = peek_twin().value(); auto maybe_escape = peek_twin();
if (is_name_code_point(next_input) || is_valid_escape_sequence(maybe_escape)) { if (is_name_code_point(next_input) || is_valid_escape_sequence(maybe_escape)) {
auto token = create_new_token(Token::TokenType::Hash); auto token = create_new_token(Token::TokenType::Hash);
@ -797,7 +790,7 @@ Token Tokenizer::consume_a_token()
return consume_a_numeric_token(); return consume_a_numeric_token();
} }
auto next_twin = peek_twin().value(); auto next_twin = peek_twin();
if (is_hyphen_minus(next_twin.first) && is_greater_than_sign(next_twin.second)) { if (is_hyphen_minus(next_twin.first) && is_greater_than_sign(next_twin.second)) {
(void)next_code_point(); (void)next_code_point();
(void)next_code_point(); (void)next_code_point();
@ -835,7 +828,7 @@ Token Tokenizer::consume_a_token()
if (is_less_than_sign(input)) { if (is_less_than_sign(input)) {
dbgln_if(CSS_TOKENIZER_TRACE, "is less than"); dbgln_if(CSS_TOKENIZER_TRACE, "is less than");
auto maybe_cdo = peek_triplet().value(); auto maybe_cdo = peek_triplet();
if (is_exclamation_mark(maybe_cdo.first) && is_hyphen_minus(maybe_cdo.second) && is_hyphen_minus(maybe_cdo.third)) { if (is_exclamation_mark(maybe_cdo.first) && is_hyphen_minus(maybe_cdo.second) && is_hyphen_minus(maybe_cdo.third)) {
(void)next_code_point(); (void)next_code_point();

8
Userland/Libraries/LibWeb/CSS/Parser/Tokenizer.h
View file

@ -71,10 +71,10 @@ public:
[[nodiscard]] Vector<Token> parse(); [[nodiscard]] Vector<Token> parse();
private: private:
[[nodiscard]] Optional<u32> next_code_point(); [[nodiscard]] u32 next_code_point();
[[nodiscard]] Optional<u32> peek_code_point(size_t offset = 0) const; [[nodiscard]] u32 peek_code_point(size_t offset = 0) const;
[[nodiscard]] Optional<U32Twin> peek_twin() const; [[nodiscard]] U32Twin peek_twin() const;
[[nodiscard]] Optional<U32Triplet> peek_triplet() const; [[nodiscard]] U32Triplet peek_triplet() const;
[[nodiscard]] static Token create_new_token(Token::TokenType); [[nodiscard]] static Token create_new_token(Token::TokenType);
[[nodiscard]] static Token create_value_token(Token::TokenType, String value); [[nodiscard]] static Token create_value_token(Token::TokenType, String value);