contrary to docs, tar --xattr alone does not extract all xattrs

[Christoph Anton Mitterer]

Hey.

This is with tar 1.34 from Debian unstable.

The info page claims in 4.3.2 Extended File Attributes:
> Attribute names are strings prefixed by a "namespace" name and a dot.
> Currently, four namespaces exist: 'user', 'trusted', 'security' and
> 'system'.  By default, when '--xattr' is used, all names are stored
> in the archive (or extracted, if using '--extract').


However, when doing e.g. (as root):
# tar --selinux --xattrs --acls --numeric-owner --preserve-permissions -cf 
x.tar /bin/ping

with:
# getcap /bin/ping
/bin/ping cap_net_raw=ep

and then:
# tar --selinux --xattrs --acls --numeric-owner --preserve-permissions -xf x.tar

the file has lost its capabilities:
# getcap bin/ping 
#


However, on the same archive file (without recreating it) when using --
xattrs-include='*':
# tar --selinux --xattrs --xattrs-include='*' --acls --numeric-owner 
--preserve-permissions -xf x.tar 
# getcap bin/ping 
bin/ping cap_net_raw=ep


This should either be fixed or some information should go into at least
these sections:
- manpage, at the --xattr option
- info page 3.4.2 'tar' Options, at the --xattr option
- info page 4.3.2 Extended File Attributes

where it should be mentioned, which namespaces are not included per
default.


Thanks,
Chris.

PS: Please keep me CCed if replying.