CMS_signed_get_attr_count
int have_signed_attrs = (CMS_signed_get_attr_count(si) > 0);
if (CMS_signed_get_attr_count(si) >= 0) {
if (CMS_signed_get_attr_count(sitmp) < 0)
if (CMS_signed_get_attr_count(si) >= 0) {
if (CMS_signed_get_attr_count(si) < 0)
int CMS_signed_get_attr_count(const CMS_SignerInfo *si);