struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s);
struct X11Private *pr; if (!s) return; pr = (struct X11Private *)sk_get_private_ptr(s);
void x11_close (Socket s) {    struct X11Private *pr = (struct X11Private *)sk_get_private_ptr(s);    if (pr->auth_protocol) {        sfree(pr->auth_protocol);        sfree(pr->auth_data);    }    sfree(pr);    sk_close(s);}