[Bug-tar] tar update with change directory option fails

[Ivan Kalvachev]

Some time ago I tried to setup a script that uses tar to do
incremental archives of my home directory. I wanted to archive
/home/user/ without having the "home/user/" inside the archive,
so I tried the "-C" option.

At that time, update just added all files to the archive, again and again.

I workaround the issue and forgot about it.
Recently I was reminded of this bug, so I decided to retest and report it.

Now, tar 1.29 just errors with "Cannot stat: No such file or directory"

Here is a script to reproduce the issue.
---
#/bin/bash

TESTDIR="/tmp/tarCu"
#TESTDIR="./tmp/tarCu"

mkdir -p  $TESTDIR/a
dd if=/dev/zero of=$TESTDIR/a/test.file bs=1K count=1

echo
echo "Create tar archive"
tar -vcf test.tar -C $TESTDIR/ a/

echo
echo "Update tar archive"
tar -vuf test.tar -C $TESTDIR/ a/
---

It doesn't matter if "/tmp" or "./tmp" is used,
the result is the same.


Best Regards
   Ivan Kalvachev