PF_GR_ANCHOR
snl_add_msg_attr_string(&nw, PF_GR_ANCHOR, path);
snl_add_msg_attr_string(&nw, PF_GR_ANCHOR, anchor);
{ .type = PF_GR_ANCHOR, .off = _OUT(anchor), .arg = (void *)MAXPATHLEN, .cb = nlattr_get_chara },
{ .type = PF_GR_ANCHOR, .off = _OUT(anchor), .arg = (void *)MAXPATHLEN, .cb = nlattr_get_chara },