sysclose

static VALUE
ossl_ssl_close(VALUE self)
{
    SSL *ssl;
    VALUE io;

    /* ossl_ssl_data_get_struct() is not usable here because it may return
     * from this function; */

    Data_Get_Struct(self, SSL, ssl);

    io = ossl_ssl_get_io(self);
    if (!RTEST(rb_funcall(io, rb_intern("closed?"), 0))) {
        if (ssl) {
            ossl_ssl_shutdown(ssl);
            SSL_free(ssl);
        }
        DATA_PTR(self) = NULL;
        if (RTEST(ossl_ssl_get_sync_close(self)))
            rb_funcall(io, rb_intern("close"), 0);
    }

    return Qnil;
}