OpenSSL::X509::Request#add_attribute

static VALUE
ossl_x509req_add_attribute(VALUE self, VALUE attr)
{
    X509_REQ *req;

    GetX509Req(self, req);
    if (!X509_REQ_add1_attr(req, GetX509AttrPtr(attr))) {
        ossl_raise(eX509ReqError, NULL);
    }

    return attr;
}