Bug#879011: diffoscope: zipinfo diff shows warning differences that are due to temporary file names

[Mike Hommey]

On Thu, Oct 19, 2017 at 04:41:04PM +0900, Mike Hommey wrote:
> On Thu, Oct 19, 2017 at 03:57:29PM +0900, Mike Hommey wrote:
> > On Wed, Oct 18, 2017 at 09:27:29PM +0900, Mike Hommey wrote:
> > > Package: diffoscope
> > > Version: 87
> > > Severity: normal
> > > 
> > > While diffing firefox, zipinfo is run on omni.ja, and issues warnings
> > > like:
> > > warning [/tmp/tmplgigxgm__diffoscope/0/24]:  17283883 extra bytes at beginning or within zipfile
> > > 
> > > Now, when both ends have the same warning, as expected, the diff still
> > > shows a difference because of the /tmp/tmp*__diffoscope/0/fd path.
> > 
> > Note these messages are sent to stderr, and I noticed that for readelf,
> > stderr is not part of the diff. It seems it would make sense to do the
> > same for zipinfo.
> 
> The code actually does the same thing as for readelf. The problem is
> that zipinfo is not consistently sending its warning to stderr.
> 
> $ zipinfo omni.ja > /dev/null
> warning [omni.ja]:  17283876 extra bytes at beginning or within zipfile
>   (attempting to process anyway)
> error [omni.ja]:  reported length of central directory is
>   -17283876 bytes too long (Atari STZip zipfile?  J.H.Holm ZIPSPLIT 1.1
>   zipfile?).  Compensating...
> 
> ^ means the warnings are on stderr, right? Nope
> 
> $ zipinfo omni.ja 2> /dev/null | grep -v 10-Jan-01
> Archive:  omni.ja
> Zip file size: 17400328 bytes, number of entries: 1313
> warning [omni.ja]:  17283876 extra bytes at beginning or within zipfile
>   (attempting to process anyway)
> error [omni.ja]:  reported length of central directory is
>   -17283876 bytes too long (Atari STZip zipfile?  J.H.Holm ZIPSPLIT 1.1
>   zipfile?).  Compensating...
> 1313 files, 17188436 bytes uncompressed, 17188436 bytes compressed:  0.0%
> 
> It looks like it only sends those messages to stderr when it's a tty.

I haven't found a way to make things work with zipinfo's crazy behavior,
however, I was able to get the zip comparator to work by using
libarchive, like for other archive formats. I still need to do some more
cleanup of the code, adjust the apk comparator, and adjust tests.

Mike