RFR (S) 8158851: MH.publicLookup() init circularity, triggered by custom SecurityManager with String concat and -limitmods java.base

[Aleksey Shipilev]

On 06/07/2016 06:09 PM, Jim Laskey (Oracle) wrote:
> Generally I disagree with this kind of hack. It will bite you in the
> @$$ at some point. Why not just have a class file containing the bytes?

What's the difference between a small binary blob in a
filesystem/resource vs a small binary blob inlined? Apart from the
additional hassle of packing things into resources (which probably
requires dealing with build?), hitting the I/O for loading it (which
probably defeats the purpose of constructing the class on the fly), etc.

I wonder if the whole LookupHelper business is here to stay: Alan said
that part of mechanics is up to a reimplementation?

Thanks,
-Aleksey

>> On Jun 7, 2016, at 11:56 AM, Aleksey Shipilev <aleksey.shipilev at oracle.com> wrote:
>>
>> On 06/07/2016 04:51 PM, Alan Bateman wrote:
>>> On 07/06/2016 14:38, Aleksey Shipilev wrote:
>>>> Please review a fix for a MH.publicLookup() circularity, which is
>>>> triggered if you run existing String concat tests with -limitmods
>>>> java.base:
>>>>   https://bugs.openjdk.java.net/browse/JDK-8158851
>>>>
>>>> Webrev:
>>>>   http://cr.openjdk.java.net/~shade/8158851/webrev.01/
>>> As a short term fix then this looks okay. It may be (once there is
>>> another round of work on MethodHandles w/modules) that PL moves back to
>>> java.lang.Object but that has many discussion points for another thread.
>>>
>>> If you want then the doPriv in LookupHelper can do away as it is not
>>> required when you can guarantee that it is initialized before a security
>>> manager is set.
>>
>> Done so.
>>
>>> One downside to initializing PL early is that is LookupHelper will
>>> trigger some ASM to be loaded. This could avoid by generating it at link
>>> time and loading the class bytes as resource. Hard to know if it's worth
>>> it as the first lambda usage is going to trigger these classes to load
>>> anyway.
>>
>> Yes. I agree with Claes here, can't we inline the bytecode to avoid
>> messing with ASM?
>>
>> See:
>>  http://cr.openjdk.java.net/~shade/8158851/webrev.02/
>>
>> Still passes all java/lang tests.
>>
>> Thanks,
>> -Aleksey
>>
>>
>