PHP_FUNCTION(openssl_error_string)
{
	char buf[256];
	unsigned long val;

	if (zend_parse_parameters_none() == FAILURE) {
		return;
	}

	php_openssl_store_errors();

	if (OPENSSL_G(errors) == NULL || OPENSSL_G(errors)->top == OPENSSL_G(errors)->bottom) {
		RETURN_FALSE;
	}

	OPENSSL_G(errors)->bottom = (OPENSSL_G(errors)->bottom + 1) % ERR_NUM_ERRORS;
	val = OPENSSL_G(errors)->buffer[OPENSSL_G(errors)->bottom];

	if (val) {
		ERR_error_string_n(val, buf, 256);
		RETURN_STRING(buf);
	} else {
		RETURN_FALSE;
	}
}

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.