On Wed, Jun 12, 2019 at 10:32:22AM -0700, Brian Murray wrote: > On Mon, Jun 10, 2019 at 05:49:49PM -0600, Andreas Dilger wrote: > > On Jun 3, 2019, at 2:27 PM, Brian Murray <br...@ubuntu.com> 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.
I'd forgotten about updating the man page for tar, attached you'll find a patch for that too. -- Brian Murray
diff --git a/doc/tar.1 b/doc/tar.1 index 18136cf..1bb9d30 100644 --- a/doc/tar.1 +++ b/doc/tar.1 @@ -604,7 +604,9 @@ Enable SELinux context support. Disable SELinux context support. .TP .B \-\-xattrs -Enable extended attributes support. +Enable extended attributes support. When creating an archive +\fB\-\-xattrs\-include\fR defaults to \fB'*'\fR and when extracing an +archive \fB\-\-xattrs\-include\fR defaults to \fB'^user.*'\fR. .TP .B \-\-no\-xattrs Disable extended attributes support.
