cached_time = current_time;
    cached_ifc_len = ifc->ifc_len;
    if (cached_ifc_buf != NULL)
        free(cached_ifc_buf);
    if (ifc == &ifc_tmp)
        cached_ifc_buf = ifc_tmp.ifc_buf;
    else {
       cached_ifc_buf = malloc(cached_ifc_len);
       memcpy(cached_ifc_buf, ifc->ifc_buf, ifc->ifc_len);
   }