JNA wrapper for BSD <sys/extattr.h>

[rednoah]

This is a JNA wrapper for the libc xattr functions on BSD platforms (similar to the native bindings already available for Linux and macOS in the platform jar).

The primary motivation for this contribution is UnixUserDefinedFileAttributeView.list() not working in the OpenJDK FreeBSD port:
battleblow/jdk17u@05dca17#r125181377

NOTE:

This code is tested on production on FreeBSD, but we don't have automated test cases because the sys/extattr.h native functions are only available on BSD platforms, and so automated tests on Linux won't work.

[matthiasblaesing]

Thank you for your contribution. I left a few inline comments. Apart from these

• checkstyle found some issues, please have a look at the test results: https://github.com/java-native-access/jna/pull/1549/checks#step:6:13
• please add an entry to CHANGES.md for this change

[rednoah]

I've made the suggested changes.

[matthiasblaesing]

Thank you for the update. Would you please rebase onto master and squash this into a single commit? I'll merge then.

[rednoah]

GitHub still doesn't have a "merge as single commit" button just for the convenience? I'll see what I can do.

[matthiasblaesing]

It has, and literally everytime I used it, it broke something. github has a funny interpretation what is valid author information. The Apache NetBeans project deactivated the button as multiple time merges were done with STUPID_NICK_NAME <[email protected]> as author. From my POV this is not acceptable and in stark contrast to the much more sane behavior of the command line git client.

If a local squash is a problem, please indicate, then I'll do it.

[rednoah]

Well, that didn't work...

[rednoah]

No worries. I'll just make a new clean PR.

[rednoah]

Sorry, I was out-gitted and broke things.

New PR here:
#1551