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RE/Specific_RE_Matcher: Make Compile() return false for syntax errors

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When creating RE_Matcher instances at runtime and verifying the pattern
compiles via Compile(), the syntax_error flag wasn't respected and
Compile() would return true even for some invalid regular expressions.

For example, compiling /a{1,b}/, Compile() would return true even though
it produced a reporter error while parsing complaining about b not
being valid.

This patch improves the error handling, so that calling Compile() returns
false whenever zeek::detail::synerr() was called while a pattern was
parsed. The use-case is creation of patterns at runtime based on
JavaScript strings. These might be entered or received at runtime via
an API. This change allows to be a bit more robust to detect invalid
input and raising exceptions to notify the user.

This also move syntax_error and csize out of global scope.

If RE_Matcher was to be used as an actual API, we likely should squelch
the reporter errors and mark it as not thread safe, but this is a small
step forward.
This commit is contained in:
Arne Welzel 2024-02-26 20:31:18 +01:00
parent 45152e4879
commit 15ad59bac5
3 changed files with 44 additions and 8 deletions
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34
src/RE.cc
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@ -27,6 +27,8 @@ extern void RE_done_with_scan();
namespace zeek {
namespace detail {
extern bool re_syntax_error;
Specific_RE_Matcher::Specific_RE_Matcher(match_type arg_mt, bool arg_multiline)
: mt(arg_mt), multiline(arg_multiline), equiv_class(NUM_SYM) {
any_ccl = nullptr;
@ -106,12 +108,13 @@ bool Specific_RE_Matcher::Compile(bool lazy) {
return false;
rem = this;
zeek::detail::re_syntax_error = false;
RE_set_input(pattern_text.c_str());
int parse_status = RE_parse();
RE_done_with_scan();
if ( parse_status ) {
if ( parse_status || zeek::detail::re_syntax_error ) {
reporter->Error("error compiling pattern /%s/", pattern_text.c_str());
Unref(nfa);
nfa = nullptr;
@ -533,6 +536,35 @@ TEST_SUITE("re_matcher") {
CHECK(dj->MatchExactly("def"));
delete dj;
}
TEST_CASE("synerr causes Compile() to fail") {
RE_Matcher match1("a{1,2}");
CHECK(match1.Compile());
RE_Matcher match2("a{6,5}");
CHECK_FALSE(match2.Compile());
RE_Matcher match3("a{1,a}");
CHECK_FALSE(match3.Compile());
RE_Matcher match4("a{1,2");
CHECK_FALSE(match4.Compile());
RE_Matcher match5("[1234");
CHECK_FALSE(match5.Compile());
RE_Matcher match6("a[1234}");
CHECK_FALSE(match6.Compile());
RE_Matcher match7("a\"b");
CHECK_FALSE(match7.Compile());
RE_Matcher match8("a\"b\"");
CHECK(match8.Compile());
RE_Matcher match9("a\\\"b");
CHECK(match9.Compile());
}
}
} // namespace zeek