Re: [Bug-tar] Possible bug in auto detection of extraction program

[Joerg Schilling]

Paul Eggert <address@hidden> wrote:

> On 04/14/2014 06:41 AM, Sasa Vilic wrote:
> > I guess that in out particular case it just might be that accidentally 
> > checksum is correct.
>
> Thanks for the bug report.  Perhaps tar could be modified to not only 
> look at the checksum, but also attempt to decode the first header (as a 
> sort of "larger" checksum).  That would have fixed your problemand would 
> fix the typical case of this sort of thing,though I suppose it still 
> wouldn't work in general.

Yesterday, I reconstructed the data from the last mail and it is obvious that 
the checksum is not "correct". Star has absolutely no problems to deal with that
archive (except that it reports that the stream is not unpackable). Star 
detects both independently: 

        - this is not a tar archive but a bzip2 compressed stream

        - the checksum is not correct

so this problem in gtar is not caused by what you believe.

I am not sure whether you remember this, but since around 1994, gtar has 
strange problems that frequently result in "skipping to next header" messages.
These problems in the first attempt have only been reported with archives 
created by star and ignored, but since around y2000, there are also reports 
with archives created by gtar. About 10 years ago, there was a change that 
reduced the probability but that did not completely fix the problem.

As a side note: tar is also confused by this archive and reports:

tar tvf /tmp/x.tar         
tar: Blockgröße = 2
tar: Warnung: tar-Datei aufgrund von Quersumme mit Vorzeichen erzeugt
tar: Verzeichnis-Quersummenfehler

Jörg

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