[Cialug] Tar file corruption

[David Champion]

Original post says: "I have a tar file that was bzip2 compressed".

I've attempted to recover corrupted tar.gz files, it's usually not a good
outcome.

If your data is really important, an uncompressed .tar is easier to recover
from but obviously takes up more space. Or verify your compressed tar files
after you write them. Won't help you if the media is damages at a later
date, though.

-dc


On Tue, Apr 30, 2013 at 2:11 PM, Scott Yates <Scott at yatesframe.com> wrote:

> Have you tried looking at the file in a hex editor?  I am not at all sure,
> but I have this idea in my head that tar archives are not compressed, and
> store the file contents in a "head to tail" fashion.
>
>
>
> On Tue, Apr 30, 2013 at 2:05 PM, David Bierce <david at bierce.org> wrote:
>
> > I don't care enough about the data enough to pay for it just thought
> > someone might know of something obvious I missed, like tar -xcf
> > --fix-broken-file :)
> >
> > Though, there is a bitcoin wallet with .034 bitcoins in it...so it might
> > be worth paying someone or actually sitting down and opening the file to
> > see what the data looks like if we have another run on bitcoins :)
> >
> > I tried extracting using 7z, cpio and winzip, but they all barf at the
> > same place, thought with 7z and winzip I cannot confirm they don't just
> > stop reading after the reach zeros.  In either case it seems like there
> was
> > garbage added into the file, not just a few spots of zeros.
> >
> >
> > On Apr 30, 2013, at 1:56 PM, Scott Yates wrote:
> >
> > > I don't know if this will help, but they have a  free version you might
> > try:
> > >
> > > http://www.datanumen.com/atr/
> > >
> > > And wow, 6 hours BEFORE epoch?  I thought the time/date stamp was an
> > > unsigned 32bit value.
> > >
> > >
> > > On Tue, Apr 30, 2013 at 1:51 PM, David Bierce <david at bierce.org>
> wrote:
> > >
> > >> I tried extracting using --ignore-failed-read and --ignore-zero (as
> tar
> > >> reads zeros as an EOF) but after it extracts the first part of the
> file
> > and
> > >> gets to the empty sections (where the bad blocks were zeroed out) and
> > it t
> > >> starts to throw errors and uncompress lots of garbage when it finally
> > gets
> > >> back to data.
> > >>
> > >> I do get some files like this.
> > >>
> > >> Like this
> > >>
> > >> mnt/wine/drive_c/windows/system32/d3d9.dll
> > >> mnt/wine/drive_c/windows/mono/mono-2.0/lib/mono/2.0/culevel.exe
> > >> mnt/wine/drive_c/windows/mono/mono-2.0/lib/mono/2.0/gacutil.exe
> > >> tar: Skipping to next header
> > >> tar: Archive base-256 value is out of off_t range
> > >> tar: Archive value -1099511627776 is out of mode_t range
> > >> 0..18446744073709551615
> > >> \031 at A\377\377\377\377
> > >> tar: \031 at A\377\377\377\377: Unknown file type `z', extracted as
> normal
> > >> file
> > >> tar: @A????: implausibly old time stamp 1969-12-31 18:00:00
> > >> tar: Skipping to next header
> > >>
> > >>
> > >> Which then fills the rest of the drive with invalid hardlinks with fun
> > and
> > >> exciting names like ?@A???? and B???C????y??0??) with a time stamp of
> 6
> > >> hours before epoch.
> > >>
> > >>
> > >> On Apr 30, 2013, at 1:11 PM, Tom Pohl wrote:
> > >>
> > >>> Have you tried the tar option --ignore-failed-read? I think that is
> the
> > >> option that will try to skip past corruption and carry on.
> > >>>
> > >>> Thanks!
> > >>> -Tom
> > >>>
> > >>> On Apr 30, 2013, at 10:58 AM, David Bierce wrote:
> > >>>
> > >>>> I have a tar file that was bzip2 compressed and had a few blocks to
> > bad
> > >> in media transfer, After pulling out the bad blocks, the reconstituted
> > tar
> > >> file appears to only function until the place in the file where the
> > first
> > >> block was corrupted.  After the first block it just doesn't read the
> > rest
> > >> of the data.  I've tried to read the file ignoring zero data, which
> just
> > >> pulls a bunch of junk metadata and file names after the empty block.
> >  I've
> > >> tried to extract it using CPIO, which has the same problem after the
> > empty
> > >> block.
> > >>>>
> > >>>> Does anyone know of a tool that can repair tar files, or at least,
> > try.
> > >> Or it is time time to go digging deep into the file or give up :)
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