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Reject \x without hex digits in cUnescape #2746

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Reject \x without hex digits in cUnescape #2746

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4 changes: 3 additions & 1 deletion folly/String-inl.h
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Original file line number Diff line number Diff line change
Expand Up @@ -118,7 +118,9 @@ void cUnescape(StringPiece str, String& out, bool strict) {
last = p;
} else if (e == 'X') { // hex
++p;
if (p == str.end()) { // \x at end of string
if (p == str.end() ||
detail::hexTable[static_cast<unsigned char>(*p)] >= 16) {
// \x not followed by a hex digit
if (strict) {
throw_exception<std::invalid_argument>(
"incomplete hex escape sequence");
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12 changes: 12 additions & 0 deletions folly/test/StringTest.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -378,6 +378,18 @@ TEST(Escape, cUnescape) {
cUnescape<std::string>("hello\\q"),
std::invalid_argument,
"invalid escape sequence");

// \x must be followed by at least one hex digit, also before other text.
EXPECT_THROW_RE(
cUnescape<std::string>("hello\\xg"),
std::invalid_argument,
"incomplete hex escape sequence");
EXPECT_THROW_RE(
cUnescape<std::string>("\\x\\n"),
std::invalid_argument,
"incomplete hex escape sequence");
EXPECT_EQ("hello\\xg", cUnescape<std::string>("hello\\xg", false));
EXPECT_EQ("\\x\n", cUnescape<std::string>("\\x\\n", false));
}

TEST(Escape, uriEscape) {
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