Question on ProtectionDomain and DomainCombiner

Question

When my classloader creates and adds a protectiondomain (which is my own class that extends ProtectionDomain) for a codesource, I want to register it for a callback (so my policy can call it). Does anyone know if the VM spec says that the AccessController has to keep a reference to the ProtectionDomain passed in, or can it simply make a copy and release the original? Or even worse, if I pass it an object of MyProtectionDomain class, does it have to keep that object (or a copy) or can it legally (within the specs) call getPermissions() and getCodeSource() and create its own ProtectionDomain?
With DomainCombiner, my question is twofold:
1. How do I specify that it should use my DomainCombiner?
2. Can I require it to use that domaincombiner or can the AccessController implementation (of the VM vendor) choose not to use it?

Answer 1

Hi!
For the first question I suggest looking at the java sources to get the right response. I have seen cases in the javadoc which were totally different when looking at the code and running it. My guess is that the ProtectionDomain always returns a clone or immutable stuff (in fact I am pretty sure of this one). Anyway the getters are final so you cannot extend them.
About the second part:
1. DomainCombiners work, AFAIK, with AccessControlContexts - you create a context and supply your combiner along. If you are trying to use merge to protection domains try creating a fresh accesscontrolcontext (acc) with the designated combiner and pass it to the doAsPrivileged method().
2. Again, it depends on what kind of acces control context are you using. AccessController delegates security checks to accs, which use the combiners and then delegate the call to the policy provider (or implementation).
I'm not sure what exactly are you trying to do but I hope it helps.
P.S. post this on the security list - you should get far more responses... I guess.