SV *
my_xs_func(p_struct, len)
        void *p_struct;
        IV len
    PPCODE:
        {
          char *tmp_buffer = (char *)malloc(len);
          XPUSHs(sv_2mortal(newSViv(my_func(p_struct, tmp_buffer, len))));
          XPUSHs(sv_2mortal(newSVpv(tmp_buffer, 0)));
          free(tmp_buffer);
        }