Re: [Bug-tar] Listed incremental fails with new symbolic link

[Peter Kronheimer]

Sergey Poznyakoff wrote:
> Peter Kronheimer <address@hidden> wrote:
>
> > If an existing non-empty directory is deleted and then replaced by a
> > symbolic link (with the same name) pointing to a new target, then the
> > listed-incremental mechanism fails, at least with version 1.15.1.
>
> The listed-incremental mechanism is (mainly) based on comparing mtimes
> of the files in the previous backup with the mtimes of the existing files,
> therefore the proposed testcase is destined to fail at about 50% of
> runs. Tar will be able to catch the following change:
>
> rm -r testbackup/bar
> mkdir bar-target
> ln -s $HOME/tmp/bar-target testbackup/bar
>
> only if enough time has elapsed between  rm and ln for the mtime of
> testbackup to change. So, its a toss-up depending on the underlying
> filesystem timestamp resolution.
>
> On my box, 100 runs of the supplied script produced 54 failures and
> 46 successes.  Inserting a `sleep 1' between `rm' and `mkdir' makes the
> testcase produce 100% of successes.

Hmmm. Turning that transcript into a script (see below) and running it 
on my system gives failure 100% of the time: no successes. Adding a 
"sleep 1" didn't make any difference. My filesystem is ext3 under linux 
on x86.

Have there been relevant changes in gnu tar, since version 1.15.1, which 
might account for this?

test-tar.sh
Description: application/shellscript