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From "Guillaume Nodet (JIRA)" <j...@apache.org>
Subject [jira] Commented: (FELIX-953) Bundle#loadClass sometimes return null instead of throwing a CNFE
Date Mon, 23 Feb 2009 16:04:02 GMT

    [ https://issues.apache.org/jira/browse/FELIX-953?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12675959#action_12675959
] 

Guillaume Nodet commented on FELIX-953:
---------------------------------------

I might see why IWire sometimes returns null and sometimes throw an exception (though not
really confident about that yet), but but afaik, IModule really represents the bundle, so
I don't really see why that one would return a null value instead of throwing a CNFE.   Would
that makes sense to you that IModule#getClassByDelegation() always throw an exception ?

Looking deeper in the code, i've just found another possible NPE in ServiceRegistrationImpl#isClassAccessible
where the clazz parameter can be null from a call to ServiceRegistrationImpl#isAssignableTo().
That one is harmless because catched, but it could be avoided nevertheless (which is good
when debugging when i sometimes but a breakpoint exception on NPE).

> Bundle#loadClass sometimes return null instead of throwing a CNFE
> -----------------------------------------------------------------
>
>                 Key: FELIX-953
>                 URL: https://issues.apache.org/jira/browse/FELIX-953
>             Project: Felix
>          Issue Type: Bug
>          Components: Framework
>            Reporter: Guillaume Nodet
>            Priority: Blocker
>         Attachments: FELIX-953.patch
>
>
> Here is a patch:
> {code}
> Index: src/main/java/org/apache/felix/framework/Felix.java
> ===================================================================
> --- src/main/java/org/apache/felix/framework/Felix.java (revision 746347)
> +++ src/main/java/org/apache/felix/framework/Felix.java (working copy)
> @@ -1338,7 +1338,12 @@
>                  throw new ClassNotFoundException(name, ex);
>              }
>          }
> -        return bundle.getCurrentModule().getClassByDelegation(name);
> +        Class clazz = bundle.getCurrentModule().getClassByDelegation(name);
> +        if (clazz == null)
> +        {
> +            throw new ClassNotFoundException(name);
> +        }
> +        return clazz;
>      }
>  
>      /**
> {code}
> I'm wondering if there any reason why ModuleImpl#getClassByDelegation(String) returns
null instead of throwing a NPE.
> Browsing through the code, it seems there are several places where a null value is checked,
then a CNFE thrown.
> This would also avoid possible NPE in felix code as in Felix#createBundleActivator.
> I think it would be nice to iron the definition of IModule#getClassByDelegation to either
remove the thrown CNFE or never returns null, as currently both can happen.
> The IWire interface has exactly the same problem.
> I will try to come up with a patch which will never return a null value for both interfaces.

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