Re: [Bug-tar] Suprising behavior of extract with --xattrs

[Brian Murray]

On Mon, Jun 10, 2019 at 05:49:49PM -0600, Andreas Dilger wrote:
> On Jun 3, 2019, at 2:27 PM, Brian Murray <address@hidden> wrote:
> > 
> > When enabling extended attribute support in a tar file (--xattrs) all
> > extended attributes are stored in the archive, however when the same archive
> > is extracted only the user.* extended attributes are extracted. To have all
> > the extended attributes read and applied on extraction one must also use the
> > '--xattrs-include=*' option. I find this behavior surprising and especially 
> > so
> > given that the documentation indicates that "By default, when `--xattr' is
> > used, all names are stored in the archive (or extracted, if using
> > `--extract')"[1].
> > 
> > I'm happy to help working on resolving this issue but it isn't clear to me
> > whether the program or the documentation is incorrect. I've read some of 
> > this
> > mailing list's archive but didn't find an explanation as to why restoration 
> > of
> > only 'user.*' extended attributes would not be a bug[2].
> > 
> > [1] https://www.gnu.org/software/tar/manual/tar.html#SEC70
> > [2] Which I reported here https://savannah.gnu.org/bugs/index.php?56421
> 
> As Pavel mentioned, it isn't necessarily safe/correct to extract all xattrs,
> especially in cross-platform usage.  However, it *does* make sense to save
> all of the xattrs, since it is then possible to extract whichever ones that
> are useful.  If the xattrs aren't saved at time of archive creation, they
> may be permanently lost.

Thanks for the information Pavel and Andreas. Given what you've said
I've created a couple of patches, one for the documentation change and
one adding a comment to xattrs.c which clarifies why only user.*
extended attributes are extracted by default.

Cheers,
--
Brian Murray

xattrs-doc.patch
Description: Text Data

xattrs-code.patch
Description: Text Data