An API is a contract between a caller and a callee. The most common forms of API abuse are caused by the caller failing to honor its end of this contract. For example, if a program fails to call chdir() after calling chroot(), it violates the contract that specifies how to change the active root directory in a secure fashion. Another good example of library abuse is expecting the callee to return trustworthy DNS information to the caller. In this case, the caller abuses the callee API by making certain assumptions about its behavior (that the return value can be used for authentication purposes). One can also violate the caller-callee contract from the other side. For example, if a coder subclasses SecureRandom and returns a non-random value, the contract is violated.
Object Model Violation: Erroneous clone() Method
clone() method should call super.clone() to obtain the new object.clone() should obtain the new object by calling super.clone(). If a class fails to follow this convention, a subclass's clone() method will return an object of the wrong type.Example 1: The following two classes demonstrate a bug introduced by failing to call
super.clone(). Because of the way Kibitzer implements clone(), FancyKibitzer's clone method will return an object of type Kibitzer instead of FancyKibitzer.
public class Kibitzer implements Cloneable {
public Object clone() throws CloneNotSupportedException {
Object returnMe = new Kibitzer();
...
}
}
public class FancyKibitzer extends Kibitzer
implements Cloneable {
public Object clone() throws CloneNotSupportedException {
Object returnMe = super.clone();
...
}
}