[ACL-Devel] FS meta information (properties/attributes/...)

[Andreas Gruenbacher]

Robert Watson wrote:
> 
> > How about binary attribute values? It seems your proposed command line
> > utilities choke on them. Shouldn't the user interface allow attributes
> > to be passed in/out in an encoded form, such as a hex dump or base64?
> 
> I haven't yet commited the actually userland (non-management) utils for
> this reason -- I've modified getextattr to dump attributes in a hexdump
> style format by default, and use vis() to generate a string form if ``-s''
> is passed to getextattr.  I'm still thinking about setextattr, and assume
> that input to stdin in a hexdump or base64 format would make most sense.
> Utilities in the FreeBSD x.x-CURRENT branch are still flexible, so I see
> adapting the utilities based on needs that turn up from real-world use.
> 
> Presumably it would be nice to be able to do:
> 
>   getextattr acl_access /var | setextattr -f - acl_access /usr /boot

Yes, like [gs]etfacl.

Are the attribute names you are using fixed? Otherwise, I'd argue for extremely
short system attribute names, such as `acl', `defacl' etc. We should try to
standardize on attribute names to achieve cross-platform portability.

Which leads me to the issue of external attribute representation (again).
Probably the [gs]etextattr utilities should also support converting to/from
portable formats (textual) that we can use to move attributes between systems.
These conversions ideally should be provided by a library that can also be used
by backup utilities. Do you think this is possible?

Also, I think we should have a namespace prefix for attributes, like so:

  system.acl
  system.defacl
  system.cap
  user.md5

Otherwise, I see no reason for incompatible [gs]etextattr utilities.


Thanks,
Andreas

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 Andreas Gruenbacher, a.gruenbacher@computer.org
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