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

[serguei.spitsyn at oracle.com]

On 6/28/16 18:44, David Holmes wrote:
> On 29/06/2016 7:09 AM, serguei.spitsyn at oracle.com wrote:
>> On 6/28/16 14:02, Daniel D. Daugherty wrote:
>>> 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.
>>
>> Ok, thanks.
>>
>>>
>>>
>>>>
>>>>>
>>>>>         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.
>>
>> Ok, thanks.
>>
>>
>>>
>>>
>>>>
>>>>>
>>>>> 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>.
>>
>> Agreed, fixed.
>
> Disagree. You would say that a pointer is NULL, not that it points to 
> a NULL.

Why are you disagree?
The module_ptr is an out argument, it is not allowed to be NULL.
But the returning value by this pointer can be NULL.


Thanks,
Serguei


>
> David
>
>
>>
>> Thanks,
>> Serguei
>>
>>
>>>
>>>
>>> Dan
>>