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Regex: avoid infinite loops

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This commit is contained in:
Maxime Coste 2017-10-07 14:25:14 +08:00
parent c47cdc06a7
commit 11abd544c6
2 changed files with 19 additions and 6 deletions
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5
src/regex_impl.cc
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@ -1126,6 +1126,11 @@ auto test_regex = UnitTest{[]{
kak_assert(StringView{vm.captures()[0], vm.captures()[1]} == "oober"); kak_assert(StringView{vm.captures()[0], vm.captures()[1]} == "oober");
kak_assert(StringView{vm.captures()[2], vm.captures()[3]} == "ber"); kak_assert(StringView{vm.captures()[2], vm.captures()[3]} == "ber");
} }
{
TestVM<> vm{R"(()*)"};
kak_assert(not vm.exec(" "));
}
}}; }};
} }

20
src/regex_impl.hh
View File

@ -123,6 +123,7 @@ public:
return false; return false;
Vector<Thread> current_threads, next_threads; Vector<Thread> current_threads, next_threads;
std::unique_ptr<bool[]> inst_processed{new bool[m_program.bytecode.size()]};
const bool no_saves = (m_flags & RegexExecFlags::NoSaves); const bool no_saves = (m_flags & RegexExecFlags::NoSaves);
Utf8It start{m_begin}; Utf8It start{m_begin};
@ -133,7 +134,7 @@ public:
to_next_start(start, m_end, start_chars); to_next_start(start, m_end, start_chars);
if (exec_from(start, no_saves ? nullptr : new_saves<false>(nullptr), if (exec_from(start, no_saves ? nullptr : new_saves<false>(nullptr),
current_threads, next_threads)) current_threads, next_threads, inst_processed.get()))
return true; return true;
if (not (flags & RegexExecFlags::Search)) if (not (flags & RegexExecFlags::Search))
@ -143,7 +144,7 @@ public:
{ {
to_next_start(++start, m_end, start_chars); to_next_start(++start, m_end, start_chars);
if (exec_from(start, no_saves ? nullptr : new_saves<false>(nullptr), if (exec_from(start, no_saves ? nullptr : new_saves<false>(nullptr),
current_threads, next_threads)) current_threads, next_threads, inst_processed.get()))
return true; return true;
} }
while (start != m_end); while (start != m_end);
@ -206,12 +207,17 @@ private:
using Utf8It = typename ChooseUtf8It<Iterator, direction>::Type; using Utf8It = typename ChooseUtf8It<Iterator, direction>::Type;
enum class StepResult { Consumed, Matched, Failed }; enum class StepResult { Consumed, Matched, Failed };
StepResult step(const Utf8It& pos, Thread& thread, Vector<Thread>& threads) StepResult step(const Utf8It& pos, Thread& thread, Vector<Thread>& threads, bool* inst_processed)
{ {
const auto prog_start = m_program.bytecode.data(); const auto prog_start = m_program.bytecode.data();
const auto prog_end = prog_start + m_program.bytecode.size(); const auto prog_end = prog_start + m_program.bytecode.size();
while (true) while (true)
{ {
const auto inst_offset = thread.inst - prog_start;
if (inst_processed[inst_offset])
return StepResult::Failed;
inst_processed[inst_offset] = true;
const Codepoint cp = pos == m_end ? 0 : *pos; const Codepoint cp = pos == m_end ? 0 : *pos;
const CompiledRegex::Op op = (CompiledRegex::Op)*thread.inst++; const CompiledRegex::Op op = (CompiledRegex::Op)*thread.inst++;
switch (op) switch (op)
@ -325,7 +331,7 @@ private:
return StepResult::Failed; return StepResult::Failed;
} }
bool exec_from(const Utf8It& start, Saves* initial_saves, Vector<Thread>& current_threads, Vector<Thread>& next_threads) bool exec_from(const Utf8It& start, Saves* initial_saves, Vector<Thread>& current_threads, Vector<Thread>& next_threads, bool* inst_processed)
{ {
current_threads.push_back({m_program.bytecode.data(), initial_saves}); current_threads.push_back({m_program.bytecode.data(), initial_saves});
next_threads.clear(); next_threads.clear();
@ -333,11 +339,12 @@ private:
bool found_match = false; bool found_match = false;
for (Utf8It pos = start; pos != m_end; ++pos) for (Utf8It pos = start; pos != m_end; ++pos)
{ {
memset(inst_processed, 0, m_program.bytecode.size() * sizeof(bool));;
while (not current_threads.empty()) while (not current_threads.empty())
{ {
auto thread = current_threads.back(); auto thread = current_threads.back();
current_threads.pop_back(); current_threads.pop_back();
switch (step(pos, thread, current_threads)) switch (step(pos, thread, current_threads, inst_processed))
{ {
case StepResult::Matched: case StepResult::Matched:
if (not (m_flags & RegexExecFlags::Search) or // We are not at end, this is not a full match if (not (m_flags & RegexExecFlags::Search) or // We are not at end, this is not a full match
@ -375,12 +382,13 @@ private:
if (found_match) if (found_match)
return true; return true;
memset(inst_processed, 0, m_program.bytecode.size() * sizeof(bool));;
// Step remaining threads to see if they match without consuming anything else // Step remaining threads to see if they match without consuming anything else
while (not current_threads.empty()) while (not current_threads.empty())
{ {
auto thread = current_threads.back(); auto thread = current_threads.back();
current_threads.pop_back(); current_threads.pop_back();
if (step(m_end, thread, current_threads) == StepResult::Matched) if (step(m_end, thread, current_threads, inst_processed) == StepResult::Matched)
{ {
release_saves(m_captures); release_saves(m_captures);
m_captures = thread.saves; m_captures = thread.saves;