OpenSSL::Netscape::SPKI#to_s

static VALUE
ossl_spki_to_pem(VALUE self)
{
    NETSCAPE_SPKI *spki;
    char *data;
    VALUE str;

    GetSPKI(self, spki);
    if (!(data = NETSCAPE_SPKI_b64_encode(spki))) {
        ossl_raise(eSPKIError, NULL);
    }
    str = ossl_buf2str(data, rb_long2int(strlen(data)));

    return str;
}