Date: Mon, 29 Nov 2004 09:57:02 +0000 From: Andrew Sinclair <syncman@optusnet.com.au> To: kientzle@freebsd.org Cc: Kris Kennaway <kris@obsecurity.org> Subject: bsdtar needs --ignore-zero & --ignore-failed-read Message-ID: <41AAF26E.8090101@optusnet.com.au>
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This follows on from my post to questions@freebsd.org:
Date: 16th Nov 2004 21:35
Subject: Re: 5.3-RC2 tar breaks operation with "(null)"
I've upgraded to 5.3-RC2 in November and have noticed that bsdtar is
now the standard Tape Archiver. While I do appreciate the simplicity of
the new interface, it does lack a couple of essential options; in
particular, those dealing with failed media.
I found this out when attempting to extract an archive from a CD-RW.
It had a few bad blocks so the drive just returned blocks of zero where
these occured. This was enough to stop the extract operation dead in its
tracks. I copied this to disc with dd and ran the extract operation
again but it could not read past the corrupt portion. I was able to work
around it with gtar and the --ignore-zero and --ignore-failed-read
options but I could not find an equivalent solution for bsdtar.
My suggestion is to include these options in libarchive and to
assert --ignore-zero in bsdtar by default on plain files (i.e. those not
on sequential media, not on a character special device file but on a
random access file system). In the case of a plain file extracted with
tar, the complete contents should be read. I'm not aware of any case
where people typically append anything other than TAR dumps to an
archive. For other programs (pkg_add), it may be best to leave this
turned off.
Regards,
Andrew Sinclair.
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