mtree acl support

[Tim Kientzle]

On Jan 14, 2014, at 6:47 AM, Mark Felder <feld at freebsd.org> wrote:

> I was recently talking to someone about how one would backup / restore
> ACLs reliably. I didn't see any mention of ACLs in the mtree man page
> and after a quick google I came upon this old mailing list post:
> 
> http://lists.freebsd.org/pipermail/freebsd-hackers/2008-April/024173.html
> 
> patch in list is here: http://heka.cenkes.org/sat/diffs/mtree_acl.diff
> I've mirrored it here: https://feld.me/freebsd/mtree_acl.diff
> 
> This old patch appears to still apply cleanly. I hate to see a patch die
> and be forgotten.

One problem that ‘tar’ has addressed (inspired by Joerg Schilling’s
work on star) is to permit ACLs to be restored even if the user database
is out of date.

This is done by including a fourth field in each ACE with the
numeric user ID.

I suspect you want to do the same for mtree.  I thought
I remembered acl_to_text having an option to use
an extended text format, so it might be a trivial change.

Tim