cert_crl_fn)(X509_STORE_CTX *ctx,
                                          X509_CRL *crl, X509 *x);
typedef int (*X509_STORE_CTX_check_policy_fn)(X509_STORE_CTX *ctx);
typedef STACK_OF(X509) *(*X509_STORE_CTX_lookup_certs_fn)(X509_STORE_CTX *ctx,
                                                          const X509_NAME *nm);
typedef STACK_OF(X509_CRL) *(*X509_STORE_CTX_lookup_crls_fn)(const
                                                             X509_STORE_CTX *ctx,
                                   