docs: public int scanCStringLength() throws IOException {
      int pos = index;
      while (true) {
        while (pos < endIndex) {
          if (buffer[pos++] == '\0') {
            return pos - index;
          }
        }
        if (!readMore(STRING_SCAN_SPAN)) {
          throw new EOFException();
        }
        pos = index;
      }
    }