if(!sk) return NULL;
X509 *X509_find_by_issuer_and_serial(STACK_OF(X509) *sk, X509_NAME *name,		ASN1_INTEGER *serial)	{	int i;	X509_CINF cinf;	X509 x,*x509=NULL;	x.cert_info= &cinf;	cinf.serialNumber=serial;	cinf.issuer=name;	for (i=0; i<sk_X509_num(sk); i++)		{		x509=sk_X509_value(sk,i);		if (X509_issuer_and_serial_cmp(x509,&x) == 0)			return(x509);		}	return(NULL);	}