[foreign] RFR 8210998: Missing pointer scope checks

Sundararajan Athijegannathan sundararajan.athijegannathan at oracle.com
Fri Sep 21 12:36:22 UTC 2018

Looks good


On 21/09/18, 5:17 PM, Maurizio Cimadamore wrote:
> Hi,
> while playing around with the Panama API in jshell, I realized that we 
> don't always enforce scope liveness in all contexts. One of the most 
> important cases was:
> Pointer::addr
> But there were other cases left out too (see Reference subclasses).
> This patch adds the missing checks in the right places and also add a 
> comprehensive test which check:
> * Pointer dereference (get/set) after Scope::close() with various 
> pointer shapes
> * Struct/array/callback access after Scope::close
> * Passing pointer/struct/callback after Scope::close
> In writing this tests I uncovered few issues:
> 1) The signature of LayoutType.ofFunction was wrong - it had a 
> Callback<Z> bound on the type variable which was bogus. In fact 
> there's no bound here (this is a leftover from previous code). This 
> also required tweaks to LayoutTypeImpl
> 2) Scope::allocateCallback was NOT associating the callback entry 
> point pointer with the current scope. As a result the callback pointer 
> was accessible even AFTER the owning scope was closed. I fixed it by 
> moving the pointer creation logic inside Scope - now UpcallHandler 
> just has a 'long' entry point, which I think makes the code even clearer.
> 3) CallbackImplGenerator - this code was going out of his way in order 
> to enforce checks on pointer scope; however, on a closer inspection, 
> since this code relied on 'addr()' and Pointer::addr is now checked 
> properly, there's no need to add special cruft.
> 4) The logic for 'setting' arrays into array references was overly 
> convoluted: with Array we can now just do the operation with a bulk 
> pointer copy.
> Webrev:
> http://cr.openjdk.java.net/~mcimadamore/panama/8210998/
> Cheers
> Maurizio

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