Tar fails to --exclude files

[Christian Ehrhardt ]

Hi,
this is a regression in tar 1.28-2.1 -> 1.29-1 and by that it is valid for Xenial -> Yakkety, but as well for Debian Stretch.

Fortunately there is at least a simple test:
rm -rf dir; mkdir -p dir/subdir; touch dir/subdir/file; tar -c -f /tmp/test.tar -C dir subdir --exclude subdir/file; tar -tf /tmp/test.tar subdir/file

Correct:
tar: subdir/file: Not found in archive
tar: Exiting with failure status due to previous errors

Wrong:
subdir/file

This could cause quite a few weird/under-the-radar bugs all around - like in my package which suddenly had more binaries. "Fortunately" one of them collided with one of the system, so we found this issue.

I'll report to Debian as well and link the bug.

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: tar 1.29-1
ProcVersionSignature: Ubuntu 4.4.0-23.41-generic 4.4.10
Uname: Linux 4.4.0-23-generic x86_64
ApportVersion: 2.20.1-0ubuntu4
Architecture: amd64
Date: Fri Jun 3 09:46:54 2016
InstallationDate: Installed on 2016-06-01 (1 days ago)
InstallationMedia: Ubuntu-Server 16.10 "Yakkety Yak" - Alpha amd64 (20160601)
SourcePackage: tar
UpgradeStatus: No upgrade log present (probably fresh install)

[Christian Ehrhardt  (paelzer)]

See related discussions:
http://lists.gnu.org/archive/html/bug-tar/2016-05/msg00012.html
http://lists.gnu.org/archive/html/bug-tar/2016-06/msg00014.html

TL;DR:
In reference to my testcase:
BAD:
tar -c -f /tmp/test.tar -C dir subdir --exclude subdir/file
FIXED:
tar -c -f /tmp/test.tar -C dir --exclude subdir/file subdir

Clarifying last bits with upstream, but this probably is a regression for everybody who used it wrong (like me) in the past.

[Christian Ehrhardt  (paelzer)]

This is in fact now the way it always should have been.
So not a bug in tar, but if any in the code using tar.
... closing