OpenSSL and panama-foreign

[Maurizio Cimadamore]

Hi,
thanks for sharing the feedback! I'm glad you got something working. 
Hopefully we can fix the rest :-)

On 10/11/2021 09:20, Rémy Maucherat wrote:
> However, I am running into cores (apparently caused by memory
> corruption) with the panama-foreign branch, while the Java 17 version
> seems solid.

That is interesting information. So, you say that the Java 17 version 
works fine, but when building (latest) panama-foreign, you get some VM 
crash.

Now, looking at the crash, it seems like it occurs in the middle of a 
native call:

```
Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
v  ~RuntimeStub::nep_invoker_blob <------------
J 5738 c1 
org.apache.tomcat.util.openssl.openssl_h.SSL_shutdown(Ljdk/incubator/foreign/Addressable;)I 
(31 bytes) @ 0x00007faf82340d2c [0x00007faf8233cc20+0x000000000000410c]
J 5482 c1 
org.apache.tomcat.util.net.openssl.panama.OpenSSLEngine.closeOutbound()V 
(76 bytes) @ 0x00007faf81a934e4 [0x00007faf81a93280+0x0000000000000264]
```

This area changed quite a bit recently, as we are refactoring and 
consolidating the linking functionalities to make it simpler for 
developers to port the CLInker implementation to other platforms. I 
wonder if a regression sneaked in (possible, the refactoring were quite 
big).

In terms of support for shared scopes, the one thing that has changed 
from 16 to 17 is that now if you pass arguments by reference to 
functions, those references' scopes are "acquired" on function enter and 
"released" on function exit - which means it is not possible, even in a 
shared context, for e.g. the target address of a native function to be 
unloaded in the middle of a native call. But this should add _more_ 
safety, not less.

I suppose that you tested Java 17 by using the jextract available in the 
Panama EA binaries; and that you tested the bits in panama-foreign by 
manually building them, and using the jextract you obtained as a result 
(e.g. using the EA jextract against the latest panama-foreign API will 
NOT work).

Thanks
Maurizio