bytes2hexstring hook (#1213)

This PR adds a new hook implementation for converting byte arrays into
hex strings.
This is needed by the kontrol-node to encode memory as JSON strings
efficiently.

---------

Co-authored-by: Tamás Tóth <[email protected]>

Author: RaoulSchaffranek

bin/llvm-krun

@@ -9,6 +9,7 @@ expanded_input_file="$(mktemp tmp.in.XXXXXXXXXX)"
 parser_file="$(mktemp tmp.parse.XXXXXXXXXX)"
 temp_inputs=()
 
+# shellcheck disable=SC2329
 cleanup () {
   # shellcheck disable=SC2317
   rm -rf "$input_file" "$expanded_input_file" "$output_file" "$parser_file" "${temp_inputs[@]}"

runtime/strings/bytes.cpp

@@ -1,4 +1,5 @@
 #include <algorithm>
+#include <array>
 #include <cstdint>
 #include <cstdlib>
 #include <cstring>
@@ -162,6 +163,24 @@ SortBytes hook_BYTES_string2bytes(SortString s) {
   return hook_BYTES_bytes2string(s);
 }
 
+// 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_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_b * 2);
+  return result;
+}
+
 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

@@ -20,6 +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_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);
@@ -171,6 +172,19 @@ BOOST_AUTO_TEST_CASE(bytes2string) {
   BOOST_CHECK_EQUAL(0, memcmp(_1234->data, "1234", 4));
 }
 
+BOOST_AUTO_TEST_CASE(bytes2hex) {
+  auto empty = make_string("");
+  auto res = hook_BYTES_bytes2hex(empty);
+  BOOST_CHECK(res != empty);
+  BOOST_CHECK_EQUAL(len(res), 0);
+
+  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, "01ef", 4));
+}
+
 BOOST_AUTO_TEST_CASE(string2bytes) {
   auto empty = make_string("");
   auto res = hook_BYTES_string2bytes(empty);