selinux/acl/smack/etc (xattr) support

hello!

from reading old questions about adding xattr support to duplicity & blockers at the time I have a couple questions about what's possible now. one answer was basically a sidecar file because this information couldn't be put into the tar file itself, another was supporting libarchive which could add that information but had other problems

question: python3's tarfile supports PAX format archives (they're the default) and it can store attrs & other stuff in the TarInfo.pax_headers dictionary and from what i can tell path.py is the place TarInfo objects are adapted into what's stored and restored.

is path.py the only thing that needs to be changed to add the dictionary entries for file attrs? if it isn't that simple what blockers are left? (adding attr support would net acl/selinux support if it was transparent)

thanks josh