Jigsaw Enhancement RFR round #3: 8159145 Add JVMTI function GetNamedModule

[Daniel D. Daugherty]

On 6/28/16 2:11 PM, serguei.spitsyn at oracle.com wrote:
> On 6/28/16 11:19, Daniel D. Daugherty wrote:
>
>>
>>         I'll have to check the upper layers of this API, but if an
>>         agent can pass a bad 'class_loader' parameter and get this
>>         assert() to fire, then that's not good. Hopefully a bad
>>         'class_loader' parameter is caught at a higher layer.
>
> Not sure, what do you mean.
> Do you mean the generated JVMTI upper layer or the 
> JvmtiEnv::GetNamedModule?
> Probably, the generated code.

I did mean the generated layer.


>
>>
>>         Update: Yes, passing a non-NULL jobject as the class_loader 
>> parameter
>>             when the jobject does not refer to a "class loader" is 
>> caught
>>             at the upper layer.
>
> The upper layer does not check that it is a class loader, just for 
> non-NULL.
> I think, it is good to have an assert here to double-checks the 
> pre-conditions as other caller can be added later.
> But I'm Ok to get rid of it if you suggest.

Please keep the asserts. Basically I was mumbling to myself to
make sure that the asserts could not be reached by user code
and the "Update:" was to indicate that I did do.


>
>>
>> src/share/vm/prims/jvmti.xml
>>     L6550:         <param id="module_ptr">
>>     L6551: <outptr><jobject/></outptr>
>>     L6552:           <description>
>>     L6553:             On return, points to a 
>> <code>java.lang.reflect.Module</code> object.
>>     L6554:           </description>
>>     L6555:         </param>
>>
>>         The above wording doesn't allow for module_ptr to be NULL which
>>         is a mismatch with the description.
>
> I disagree (or maybe I got it incorrectly).
> Pointing to NULL and be NULL is different.
> It is not allowed for the module_ptr to be NULL but Ok to pint to NULL 
> on return.

I think the description needs to be:

     On return, points to a <code>java.lang.reflect.Module</code> object
     or points to a <code>NULL</code>.


Dan