Address PR feedback

- Added code comment
- Renamed hook: bytes2hexstring -> bytes2hex
- Improved test case
- Use safe length to avoid potential out-of-bounds error

Author: RaoulSchaffranek

runtime/strings/bytes.cpp

@@ -148,39 +148,36 @@ hook_BYTES_int2bytes(SortInt len, SortInt i, SortEndianness endianness_ptr) {
   return result;
 }
 
-string *bytes2string(string *b, size_t len) {
-  auto *result = static_cast<string *>(kore_alloc_token(sizeof(string) + len));
-  memcpy(result->data, b->data, len);
-  init_with_len(result, len);
-  return result;
-}
-
 SortString hook_BYTES_bytes2string(SortBytes b) {
-  return bytes2string(b, len(b));
+  auto len_b = len(b);
+  auto *result = static_cast<string *>(kore_alloc_token(sizeof(string) + len_b));
+  memcpy(result->data, b->data, len_b);
+  init_with_len(result, len_b);
+  return result;
 }
 
 SortBytes hook_BYTES_string2bytes(SortString s) {
   return hook_BYTES_bytes2string(s);
 }
 
-string *bytes2hexstring(string *b, size_t len) {
+// Convert a bytes array to its hexadecimal string representation
+// For example, the bytes array b'\x01\xef' becomes the string "01ef"
+// syntax String ::= Bytes2Hex( Bytes )
+SortString hook_BYTES_bytes2hex(SortBytes b) {
   static const std::array<char, 16> hexchars
       = {'0', '1', '2', '3', '4', '5', '6', '7',
          '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
+  auto len_b = len(b);
   auto *result
-      = static_cast<string *>(kore_alloc_token(sizeof(string) + len * 2));
-  for (size_t i = 0; i < len; i++) {
+      = static_cast<string *>(kore_alloc_token(sizeof(string) + len_b * 2));
+  for (size_t i = 0; i < len_b; i++) {
     result->data[i * 2] = hexchars.at((b->data[i] >> 4) & 0xf);
     result->data[i * 2 + 1] = hexchars.at(b->data[i] & 0xf);
   }
-  init_with_len(result, len * 2);
+  init_with_len(result, len_b * 2);
   return result;
 }
 
-SortString hook_BYTES_bytes2hexstring(SortBytes b) {
-  return bytes2hexstring(b, len(b));
-}
-
 SortBytes hook_BYTES_substr(SortBytes input, SortInt start, SortInt end) {
   uint64_t ustart = GET_UI(start);
   uint64_t uend = GET_UI(end);

unittests/runtime-strings/bytestest.cpp

@@ -20,7 +20,7 @@ mpz_ptr
 hook_BYTES_bytes2int(string *b, uint64_t endianness, uint64_t signedness);
 string *hook_BYTES_int2bytes(mpz_t len, mpz_t i, uint64_t endianness);
 string *hook_BYTES_bytes2string(string *b);
-string *hook_BYTES_bytes2hexstring(string *b);
+string *hook_BYTES_bytes2hex(string *b);
 string *hook_BYTES_string2bytes(string *s);
 string *hook_BYTES_substr(string *b, mpz_t start, mpz_t end);
 string *hook_BYTES_replaceAt(string *b, mpz_t start, string *b2);
@@ -172,17 +172,17 @@ BOOST_AUTO_TEST_CASE(bytes2string) {
   BOOST_CHECK_EQUAL(0, memcmp(_1234->data, "1234", 4));
 }
 
-BOOST_AUTO_TEST_CASE(bytes2hexstring) {
+BOOST_AUTO_TEST_CASE(bytes2hex) {
   auto empty = make_string("");
-  auto res = hook_BYTES_bytes2hexstring(empty);
+  auto res = hook_BYTES_bytes2hex(empty);
   BOOST_CHECK(res != empty);
   BOOST_CHECK_EQUAL(len(res), 0);
 
-  auto _00ff = make_string("\x00\xff", 2);
-  res = hook_BYTES_bytes2hexstring(_00ff);
-  BOOST_CHECK(res != _00ff);
+  auto _01ef = make_string("\x01\xef", 2);
+  res = hook_BYTES_bytes2hex(_01ef);
+  BOOST_CHECK(res != _01ef);
   BOOST_CHECK_EQUAL(len(res), 4);
-  BOOST_CHECK_EQUAL(0, memcmp(res->data, "00ff", 4));
+  BOOST_CHECK_EQUAL(0, memcmp(res->data, "01ef", 4));
 }
 
 BOOST_AUTO_TEST_CASE(string2bytes) {