烟尘：soot.jimple.JimpleBody无法转换为soot.dava.DavaBody

Question

I ran the following code to get the exception handler in .class file:

public void getException(SootMethod method){
    DavaBody db = (DavaBody) method.retrieveActiveBody();
    IterableSet excepFacts = db.get_ExceptionFacts();
    Iterator<ExceptionNode> it = excepFacts.iterator();
    while(it.hasNext()){
        ExceptionNode en = it.next();
        ...
    }
}

I got errors after running above code:

Exception in thread "main" java.lang.ClassCastException: 
soot.jimple.JimpleBody cannot be cast to soot.dava.DavaBody

The method method.retrieveActiveBody() returns Body type, not JimpleBody , so why is this error happening?

Answer 1

Body is the declared type. In your configuration of Soot, it actually returns a JimpleBody.

Answer 2

By the documentation , public Body retrieveActiveBody() is:

Returns the active body if present, else constructs an active body and returns that.

Let's look at the Body class:

public abstract class Body
extends AbstractHost
implements Serializable

So it is Abstract class, and by your exception, it returns JimpleBody , subclass of Body .

If Rabbit is Animal , and Wolf is also Animal , Rabbit is not a Wolf .

You can edit code like that:

if (method.retrieveActiveBody() instanceof JimpleBody) {

} else if (method.retrieveActiveBody() instanceof DavaBody) {

} else if (method.retrieveActiveBody() instanceof BafBody) {

} else if (method.retrieveActiveBody() instanceof StmtBody) {

} else {

}