int
my_xs_func(p_struct, OUTLIST buffer, len)
        void *p_struct;
        SV   *buffer;
        int   len;
    CODE:
        {
            char *buf = sv_grow( buffer, len );
            /* was: char *buf = SvGROW( buffer, len ); */
            RETVAL = my_func( p_struct, buf, len );
        }
    OUTPUT:
        RETVAL