Re: bsdtar(1) can't extract new ISO images

On Aug 7, 2011, at 9:23 AM, Bruce Cran wrote:
> On 06/08/2011 18:02, Martin Matuska wrote:
>> The error is in FreeBSD ISO images.
>> They are created using makefs and that doesn't create ISO files that
>> strictly comple to the ECMA-119 (ISO9660 standard).
>>=20
>> I have already filed a PR at NetBSD (bin/45217):
>> http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=3D45217
>>=20
>> The volume_set_id doesn't have to be filled with 0x20 characters, =
too.
>> I am also preparing a patch for libarchive (different things), but =
that
>> won't fix that one bug - makefs needs to be fixed.
>=20
> Thanks for the information - I suspect this is also the problem I saw =
a few weeks ago on OS X Lion when trying to extract an ISO of Windows =
Server 2003 R2:
>=20
> neutrino:tmp brucec$ tar -xvf =
en_win_srv_2003_r2_standard_with_sp2_cd2_X13-68583.iso
> neutrino:tmp brucec$ echo $?
> 0
>=20
> It would be nice if bsdtar exited with a non-zero code in this case.

I agree, it would be nice.

ISO images frequently begin with a large block of zero bytes that looks =
exactly like a tar end-of-file marker.  So if libarchive doesn't =
recognize it as an ISO, it will often recognize the file as a valid =
empty tar archive that has a bunch of garbage after the end-of-archive =
marker.  So it successfully extracts no files.

This sort of problem should become less common as we continue to refine =
the bidding heuristics used in libarchive.  If you have ideas for =
further improving them, I'm definitely interested.  (At a minimum, I'm =
always interested in seeing at least the first 32k or so of any file =
that "tar -tvvvf" gives the wrong format for.)

Tim

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