Re: git archive generates tar with malformed pax extended attribute

On Fri, May 24, 2019 at 08:45:23AM +0200, Keegan Carruthers-Smith wrote:

git archive can generate a malformed tar archive. bsdtar reports the
error "tar: Ignoring malformed pax extended attribute" when reading
the archive. Go's "tar/archive" package also reports the error
"archive/tar: invalid tar header". However, BusyBox's tar does not
report the error (unsure if it just has less error logging).

I can reproduce this when generating the tar on linux and mac. I
tested this with "git version 2.21.0" and a build of next I did today:
"git version 2.22.0.rc1.257.g3120a18244"

Reproduction:

  $ git clone https://github.com/SSW-SCIENTIFIC/NNDD.git
  $ cd NNDD
  $ git archive --format tar c21b98da2ca7f007230e696b2eda5da6589fe137
| tar tf - > /dev/null
  tar: Ignoring malformed pax extended attribute
  tar: Error exit delayed from previous errors.

I can't reproduce on Linux, using GNU tar (1.30) nor with bsdtar 3.3.3
(from Debian's bsdtar package). What does your "tar --version" say?

Git does write a pax header with the commit id in it as a comment.
Presumably that's what it's complaining about (but it is not malformed
according to any tar I've tried). If you feed git-archive a tree rather
than a commit, that is omitted. What does:

  git archive --format tar c21b98da2^{tree} | tar tf - >/dev/null

say? If it doesn't complain, then we know it's indeed the pax comment
field.

-Peff