RFR 8157310: jdk.dynalink.linker.support.Lookup should have more checks before adding module read link

[Attila Szegedi]

+1. Nice work!

> On 19 May 2016, at 15:28, Sundararajan Athijegannathan <sundararajan.athijegannathan at oracle.com> wrote:
> 
> Please review http://cr.openjdk.java.net/~sundar/8157310/ for
> https://bugs.openjdk.java.net/browse/JDK-8157310
> 
> What is this fix?
> 
> * When unreflecting caller sensitive methods, dynalink uses specific
> Lookup of actual caller (instead of publicLookup) - in nashorn's case
> it's be the Lookup of script class.
> 
> * Script class may not have read link to the module of the class (of
> caller sensitive member). If there is any IllegalAccessError, dynalink
> adds the read link and tries to
> 
> unreflect again. We don't want unnecessary module link read in such
> cases. Check has been added whether the package is exported from
> declaring module. Note that there is no security issue here.  Even
> before the fix, module read edge does not give any capability. unreflect
> call after adding unnecessary read line would still fail for
> non-exported package case. There were unnecessary module read links
> created - which is being avoided now.
> 
> * Additional "API" in Lookup.java slipped from jigsaw code into
> jdk9-dev. Those unreflectCallerSensitive and
> unreflectConstructorCallerSensitive were meant to be 'interim' somehow
> slipped.  Now, only unreflect and unreflectConstructor in Lookup. Caller
> sensitiveness is hidden in the implementation.  These methods were never
> APIs when dynalink API was created.
> 
> Thanks,
> 
> -Sundar
> 
>