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Date:	Mon, 7 Mar 2011 15:43:49 +0100
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: tar --atime-preserve with an empty file triggers a warning
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On Mar  7 07:32, Eric Blake wrote:
> On 03/07/2011 07:20 AM, EXCOFFIER Denis wrote:
> > Hello,
> > 
> > I've the experienced the following (100% reproducible under 1.7.7-1 or
> > 1.7.8-1):
> > 
> > % cp /dev/null empty
> 
> Why not the much simpler:
> 
> : > empty
> 
> > % tar cf empty.tar --atime-preserve empty
> > /usr/bin/tar: empty: Cannot utime: Invalid argument
> > /usr/bin/tar: Exiting with failure status due to previous errors
> > %
> > 
> > Of course the empty.tar is created as expected (ie identical as without
> > `--atime-preserve). The warning is not produced on Solaris, Darwin or
> > Linux,
> > therefore i contacted this list. Do you think, with your expertise, that i
> > should contact bug-tar also?
> 
> No, this list is correct.  utime should not fail on an empty file, so
> you've probably exposed a bug in cygwin1.dll.

THis looks like a tar bug, per the strace.  For some reason, if the
file is empty, tar calls futimens on file descriptor 0 (which is
connected to /dev/tty1 in my case), while it call futimens on
file descriptor 4 (connected to the file empty) if the file empty
is... well, not empty.


Corinna


-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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