OpenSSL::PKCS7#signers

static VALUE
ossl_pkcs7_get_signer(VALUE self)
{
    PKCS7 *pkcs7;
    STACK_OF(PKCS7_SIGNER_INFO) *sk;
    PKCS7_SIGNER_INFO *si;
    int num, i;
    VALUE ary;

    GetPKCS7(self, pkcs7);
    if (!(sk = PKCS7_get_signer_info(pkcs7))) {
        OSSL_Debug("OpenSSL::PKCS7#get_signer_info == NULL!");
        return rb_ary_new();
    }
    if ((num = sk_PKCS7_SIGNER_INFO_num(sk)) < 0) {
        ossl_raise(ePKCS7Error, "Negative number of signers!");
    }
    ary = rb_ary_new2(num);
    for (i=0; i<num; i++) {
        si = sk_PKCS7_SIGNER_INFO_value(sk, i);
        rb_ary_push(ary, ossl_pkcs7si_new(si));
    }

    return ary;
}