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libstdc++: Fix handling of invalid ranges in std::regex [PR102447]

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std::regex currently allows invalid bracket ranges such as [\w-a] which
are only allowed by ECMAScript when in web browser compatibility mode.
It should be an error, because the start of the range is a character
class, not a single character. The current implementation of
_Compiler::_M_expression_term does not provide a way to reject this,
because we only remember a previous character, not whether we just
processed a character class (or collating symbol etc.)

This patch replaces the pair<bool, CharT> used to emulate
optional<CharT> with a custom class closer to pair<tribool,CharT>. That
allows us to track three states, so that we can tell when we've just
seen a character class.

With this additional state the code in _M_expression_term for processing
the _S_token_bracket_dash can be improved to correctly reject the [\w-a]
case, without regressing for valid cases such as [\w-] and [----].

libstdc++-v3/ChangeLog:

	PR libstdc++/102447
	* include/bits/regex_compiler.h (_Compiler::_BracketState): New
	class.
	(_Compiler::_BrackeyMatcher): New alias template.
	(_Compiler::_M_expression_term): Change pair<bool, CharT>
	parameter to _BracketState. Process first character for
	ECMAScript syntax as well as POSIX.
	* include/bits/regex_compiler.tcc
	(_Compiler::_M_insert_bracket_matcher): Pass _BracketState.
	(_Compiler::_M_expression_term): Use _BracketState to store
	state between calls. Improve handling of dashes in ranges.
	* testsuite/28_regex/algorithms/regex_match/cstring_bracket_01.cc:
	Add more tests for ranges containing dashes. Check invalid
	ranges with character class at the beginning.
This commit is contained in:
Jonathan Wakely 2021-12-14 14:32:35 +00:00
parent fda2872270
commit 7ce3c230ed
3 changed files with 152 additions and 68 deletions
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40
libstdc++-v3/include/bits/regex_compiler.h
View File

@ -121,13 +121,45 @@ namespace __detail
void
_M_insert_bracket_matcher(bool __neg);
// Returns true if successfully matched one term and should continue.
// Cache of the last atom seen in a bracketed range expression.
struct _BracketState
{
enum class _Type : char { _None, _Char, _Class } _M_type = _Type::_None;
_CharT _M_char;
void
set(_CharT __c) noexcept { _M_type = _Type::_Char; _M_char = __c; }
_GLIBCXX_NODISCARD _CharT
get() const noexcept { return _M_char; }
void
reset(_Type __t = _Type::_None) noexcept { _M_type = __t; }
explicit operator bool() const noexcept
{ return _M_type != _Type::_None; }
// Previous token was a single character.
_GLIBCXX_NODISCARD bool
_M_is_char() const noexcept { return _M_type == _Type::_Char; }
// Previous token was a character class, equivalent class,
// collating symbol etc.
_GLIBCXX_NODISCARD bool
_M_is_class() const noexcept { return _M_type == _Type::_Class; }
};
template<bool __icase, bool __collate>
using _BracketMatcher
= std::__detail::_BracketMatcher<_TraitsT, __icase, __collate>;
// Returns true if successfully parsed one term and should continue
// compiling a bracket expression.
// Returns false if the compiler should move on.
template<bool __icase, bool __collate>
bool
_M_expression_term(pair<bool, _CharT>& __last_char,
_BracketMatcher<_TraitsT, __icase, __collate>&
__matcher);
_M_expression_term(_BracketState& __last_char,
_BracketMatcher<__icase, __collate>& __matcher);
int
_M_cur_int_value(int __radix);

118
libstdc++-v3/include/bits/regex_compiler.tcc
View File

@ -403,7 +403,7 @@ namespace __detail
_M_insert_character_class_matcher()
{
__glibcxx_assert(_M_value.size() == 1);
_BracketMatcher<_TraitsT, __icase, __collate> __matcher
_BracketMatcher<__icase, __collate> __matcher
(_M_ctype.is(_CtypeT::upper, _M_value[0]), _M_traits);
__matcher._M_add_character_class(_M_value, false);
__matcher._M_ready();
@ -417,26 +417,17 @@ namespace __detail
_Compiler<_TraitsT>::
_M_insert_bracket_matcher(bool __neg)
{
_BracketMatcher<_TraitsT, __icase, __collate> __matcher(__neg, _M_traits);
pair<bool, _CharT> __last_char; // Optional<_CharT>
__last_char.first = false;
if (!(_M_flags & regex_constants::ECMAScript))
{
if (_M_try_char())
{
__last_char.first = true;
__last_char.second = _M_value[0];
}
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
{
__last_char.first = true;
__last_char.second = '-';
}
}
_BracketMatcher<__icase, __collate> __matcher(__neg, _M_traits);
_BracketState __last_char;
if (_M_try_char())
__last_char.set(_M_value[0]);
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
// Dash as first character is a normal character.
__last_char.set('-');
while (_M_expression_term(__last_char, __matcher))
;
if (__last_char.first)
__matcher._M_add_char(__last_char.second);
if (__last_char._M_is_char())
__matcher._M_add_char(__last_char.get());
__matcher._M_ready();
_M_stack.push(_StateSeqT(
*_M_nfa,
@ -447,27 +438,27 @@ namespace __detail
template<bool __icase, bool __collate>
bool
_Compiler<_TraitsT>::
_M_expression_term(pair<bool, _CharT>& __last_char,
_BracketMatcher<_TraitsT, __icase, __collate>& __matcher)
_M_expression_term(_BracketState& __last_char,
_BracketMatcher<__icase, __collate>& __matcher)
{
if (_M_match_token(_ScannerT::_S_token_bracket_end))
return false;
// Add any previously cached char into the matcher and update cache.
const auto __push_char = [&](_CharT __ch)
{
if (__last_char.first)
__matcher._M_add_char(__last_char.second);
else
__last_char.first = true;
__last_char.second = __ch;
if (__last_char._M_is_char())
__matcher._M_add_char(__last_char.get());
__last_char.set(__ch);
};
const auto __flush = [&]
// Add any previously cached char into the matcher and update cache.
const auto __push_class = [&]
{
if (__last_char.first)
{
__matcher._M_add_char(__last_char.second);
__last_char.first = false;
}
if (__last_char._M_is_char())
__matcher._M_add_char(__last_char.get());
// We don't cache anything here, just record that the last thing
// processed was a character class (or similar).
__last_char.reset(_BracketState::_Type::_Class);
};
if (_M_match_token(_ScannerT::_S_token_collsymbol))
@ -476,16 +467,16 @@ namespace __detail
if (__symbol.size() == 1)
__push_char(__symbol[0]);
else
__flush();
__push_class();
}
else if (_M_match_token(_ScannerT::_S_token_equiv_class_name))
{
__flush();
__push_class();
__matcher._M_add_equivalence_class(_M_value);
}
else if (_M_match_token(_ScannerT::_S_token_char_class_name))
{
__flush();
__push_class();
__matcher._M_add_character_class(_M_value, false);
}
else if (_M_try_char())
@ -502,49 +493,50 @@ namespace __detail
// It turns out that no one reads BNFs ;)
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
{
if (!__last_char.first)
if (_M_match_token(_ScannerT::_S_token_bracket_end))
{
if (!(_M_flags & regex_constants::ECMAScript))
{
if (_M_match_token(_ScannerT::_S_token_bracket_end))
{
__push_char('-');
return false;
}
__throw_regex_error(
regex_constants::error_range,
"Unexpected dash in bracket expression. For POSIX syntax, "
"a dash is not treated literally only when it is at "
"beginning or end.");
}
// For "-]" the dash is a literal character.
__push_char('-');
return false;
}
else
else if (__last_char._M_is_class())
{
// "\\w-" is invalid, start of range must be a single char.
__throw_regex_error(regex_constants::error_range,
"Invalid start of range in bracket expression.");
}
else if (__last_char._M_is_char())
{
if (_M_try_char())
{
__matcher._M_make_range(__last_char.second, _M_value[0]);
__last_char.first = false;
// "x-y"
__matcher._M_make_range(__last_char.get(), _M_value[0]);
__last_char.reset();
}
else if (_M_match_token(_ScannerT::_S_token_bracket_dash))
{
__matcher._M_make_range(__last_char.second, '-');
__last_char.first = false;
// "x--"
__matcher._M_make_range(__last_char.get(), '-');
__last_char.reset();
}
else
{
if (_M_scanner._M_get_token()
!= _ScannerT::_S_token_bracket_end)
__throw_regex_error(
regex_constants::error_range,
"Character is expected after a dash.");
__push_char('-');
}
__throw_regex_error(regex_constants::error_range,
"Invalid end of range in bracket expression.");
}
else if (_M_flags & regex_constants::ECMAScript)
{
// A dash that is not part of an existing range. Might be the
// start of a new range, or might just be a literal '-' char.
// Only ECMAScript allows that in the middle of a bracket expr.
__push_char('-');
}
else
__throw_regex_error(regex_constants::error_range,
"Invalid dash in bracket expression.");
}
else if (_M_match_token(_ScannerT::_S_token_quoted_class))
{
__flush();
__push_class();
__matcher._M_add_character_class(_M_value,
_M_ctype.is(_CtypeT::upper,
_M_value[0]));

62
libstdc++-v3/testsuite/28_regex/algorithms/regex_match/cstring_bracket_01.cc
View File

@ -69,6 +69,16 @@ test01()
void
test02()
{
VERIFY(regex_match("-", regex("[-]", regex_constants::ECMAScript)));
VERIFY(regex_match("-", regex("[--]", regex_constants::ECMAScript)));
VERIFY(regex_match("-", regex("[---]", regex_constants::ECMAScript)));
VERIFY(regex_match("-", regex("[----]", regex_constants::ECMAScript)));
VERIFY(regex_match("-", regex("[-----]", regex_constants::ECMAScript)));
VERIFY(regex_match("-", regex("[-]", regex_constants::extended)));
VERIFY(regex_match("-", regex("[--]", regex_constants::extended)));
VERIFY(regex_match("-", regex("[---]", regex_constants::extended)));
VERIFY(regex_match("-", regex("[----]", regex_constants::extended)));
try
{
std::regex re("[-----]", std::regex::extended);
@ -78,7 +88,6 @@ test02()
{
VERIFY(e.code() == std::regex_constants::error_range);
}
std::regex re("[-----]", std::regex::ECMAScript);
VERIFY(!regex_match("b", regex("[-ac]", regex_constants::extended)));
VERIFY(!regex_match("b", regex("[ac-]", regex_constants::extended)));
@ -93,7 +102,27 @@ test02()
}
catch (const std::regex_error& e)
{
VERIFY(e.code() == std::regex_constants::error_range);
}
try
{
regex("[@--]", regex_constants::extended);
VERIFY(false);
}
catch (const std::regex_error& e)
{
VERIFY(e.code() == std::regex_constants::error_range);
}
try
{
regex("[--%]", regex_constants::extended);
VERIFY(false);
}
catch (const std::regex_error& e)
{
VERIFY(e.code() == std::regex_constants::error_range);
}
VERIFY(regex_match("].", regex("[][.hyphen.]-0]*", regex_constants::extended)));
}
@ -158,6 +187,36 @@ test06()
VERIFY(regex_match("a-", debian_cron_namespace_ok));
}
// libstdc++/102447
void
test07()
{
VERIFY(regex_match("-", std::regex("[\\w-]", std::regex::ECMAScript)));
VERIFY(regex_match("a", std::regex("[\\w-]", std::regex::ECMAScript)));
VERIFY(regex_match("-", std::regex("[a-]", std::regex::ECMAScript)));
VERIFY(regex_match("a", std::regex("[a-]", std::regex::ECMAScript)));
try
{
std::regex re("[\\w-a]", std::regex::ECMAScript);
VERIFY(false);
}
catch (const std::regex_error& e)
{
VERIFY(e.code() == std::regex_constants::error_range);
}
try
{
std::regex re("[\\w--]", std::regex::ECMAScript);
VERIFY(false);
}
catch (const std::regex_error& e)
{
VERIFY(e.code() == std::regex_constants::error_range);
}
}
int
main()
{
@ -167,6 +226,7 @@ main()
test04();
test05();
test06();
test07();
return 0;
}