to_octet_string

static VALUE
ossl_ec_point_to_octet_string(VALUE self, VALUE conversion_form)
{
    EC_POINT *point;
    const EC_GROUP *group;
    point_conversion_form_t form;
    VALUE str;
    size_t len;

    GetECPoint(self, point);
    GetECPointGroup(self, group);
    form = parse_point_conversion_form_symbol(conversion_form);

    len = EC_POINT_point2oct(group, point, form, NULL, 0, ossl_bn_ctx);
    if (!len)
        ossl_raise(eEC_POINT, "EC_POINT_point2oct");
    str = rb_str_new(NULL, (long)len);
    if (!EC_POINT_point2oct(group, point, form,
                            (unsigned char *)RSTRING_PTR(str), len,
                            ossl_bn_ctx))
        ossl_raise(eEC_POINT, "EC_POINT_point2oct");
    return str;
}