func: static ssize_t vnc_client_read_tls(gnutls_session_t *session, uint8_t *data,
  
                                     size_t datalen)
  
  {
  
      ssize_t ret = gnutls_read(*session, data, datalen);
  
      if (ret < 0) {
  
          if (ret == GNUTLS_E_AGAIN) {
  
              errno = EAGAIN;
  
          } else {
  
              errno = EIO;
  
          }
  
          ret = -1;
  
      }
  
      return ret;
  
  }
  