[Help-tar] Can't extract - get "Archive contains obsolescent base-64 headers"

[Alexis Huxley]

Hi, I've got a DAT tape I tarred stuff onto about 18 months ago, and I'd
really like to get it back! It was created with GNU tar (don't know what
version) and I'm trying to extract it with GNU tar (1.13.93).

I couldn't remember what block size I used, so I did the 'dd bs=bignum count=1'
trick to read as much as possible off, but limiting it to one block. This
produced a file of size 10240. Fine. I guess I did 'tar cbf 20 $TAPE $STUFF'.

However, when I try to untar it I get:

        dione$ tar tvbf 20 /dev/st0
        drwx------ alexis/alexis     0 2003-08-04 21:49:51 ./
        tar: Skipping to next header
        tar: Archive contains obsolescent base-64 headers
        tar: Error exit delayed from previous errors

I dd'ed off about 10Mb with bs=10k to a file and tried the 'tar t' command 
on that. The result was of course the same.

Next I did a hexdump of the file to verify that it was a tar file and not
a compressed tar file or a cpio or anything else, and, to my inexpert eye,
it looks fine (see below).

I googled and found some stuff about a recent buggy tar and wondered if
my 'tar t' was suffering from this. So I went to the oldest tar I could
find on the FTP site (1.11.8), but I got the same results.

I presume that this means that it was the *creation* of the tar file which
was flawed? Can anybody confirm this?

Is there any way I can extract my data from the tar file? I mean, looking
at the hex dump, it appears that the *entire dump* does not have a header,
but that each file (or each block???) does. Presumanly somewhere buried inside
this is something indicating the size of the file? Assuming I can locate
the beginning of this, will the entire file's contents follow contiguously?
So I could just use to 'dd skip=startoffset bs=1 count=filesize' extract it,
right?

Any help/advice much appreciated!  Thanks!

Oh, probably not relevent, but this is a Linux 2.6 system with a DDS3 tape
drive.

Alexis

00000000  2e 2f 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |./..............|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000060  00 00 00 00 30 30 34 30  37 30 30 00 30 30 30 31  |....0040700.0001|
00000070  37 35 30 00 30 30 30 31  37 35 30 00 30 30 30 30  |750.0001750.0000|
00000080  30 30 30 30 30 30 30 00  30 37 37 31 33 35 33 34  |0000000.07713534|
00000090  33 33 37 00 30 31 30 35  35 35 00 20 35 00 00 00  |337.010555. 5...|
000000a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000100  00 75 73 74 61 72 20 20  00 61 6c 65 78 69 73 00  |.ustar  .alexis.|
00000110  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000120  00 00 00 00 00 00 00 00  00 61 6c 65 78 69 73 00  |.........alexis.|
00000130  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000200  2e 23 61 60 28 04 00 00  00 00 00 00 00 00 00 00  |.#a`(...........|
00000210  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000260  00 00 00 00 30 30 34 30  37 30 30 00 30 30 30 31  |....0040700.0001|
00000270  37 35 30 00 30 30 30 31  37 35 30 00 30 30 30 30  |750.0001750.0000|
00000280  30 30 30 30 30 30 30 00  30 37 37 31 33 35 33 34  |0000000.07713534|
00000290  31 37 36 00 30 31 31 33  35 35 00 20 35 00 00 00  |176.011355. 5...|
000002a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000300  00 75 73 74 61 72 20 20  00 61 6c 65 78 69 73 00  |.ustar  .alexis.|
00000310  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000320  00 00 00 00 00 00 00 00  00 61 6c 65 78 69 73 00  |.........alexis.|
00000330  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000400  2e 2f 64 6f 63 2f 44 44  35 38 2e 44 4f 43 00 00  |./doc/DD58.DOC..|
00000410  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000460  00 00 00 00 30 31 30 30  36 30 30 00 30 30 30 31  |....0100600.0001|
00000470  37 35 30 00 30 30 30 31  37 35 30 00 30 30 30 30  |750.0001750.0000|
00000480  35 31 37 37 36 34 36 00  30 37 31 33 33 36 32 30  |5177646.07133620|
00000490  32 35 32 00 30 31 32 34  30 32 00 20 30 00 00 00  |252.012402. 0...|
000004a0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000500  00 71 70 60 60 20 20 00  00 60 64 60 68 61 00 00  |.qp``  ..`d`ha..|
00000510  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000520  00 00 00 00 00 00 00 00  00 60 64 60 68 61 00 00  |.........`d`ha..|
00000530  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
*
00000600  00 00 01 ba 21 00 01 00  1f 80 07 81 00 00 01 bb  |....!...........|
00000610  00 0c 80 07 81 07 21 ff  c0 c0 20 e0 e0 2e 00 00  |......!... .....|
00000620  01 be 07 dc ff ff ff ff  ff ff ff ff ff ff ff 0f  |................|
00000630  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  |................|
*
00000e00  00 00 01 ba 21 00 01 1e  1f 80 07 00 00 00 00 00  |....!...........|
00000e10  06 60 20 21 00 00 02 60  01 00 00 04 00 00 00 00  |.` !...`........|
00000e20  01 12 00 00 c0 00 00 40  60 00 00 00 00 00 00 00  |address@hidden|
00000e30  00 00 00 00 00 00 00 8d  20 00 00 00 01 01 22 e0  |........ .....".|
00000e40  c0 10 08 0d c7 55 40 00  21 33 20 44 92 92 7a 50  |address@hidden 
D..zP|
00000e50  94 10 42 47 13 33 33 1b  55 15 13 41 41 45 01 01  |..BG.33.U..AAE..|
00000e60  85 c0 10 08 04 10 00 00  00 55 5d d0 60 41 c1 81  |.........U].`A..|
00000e70  84 c8 90 14 d7 03 81 0c  0a 46 52 3a 80 00 15 81  |.........FR:....|
00000e80  04 0c 90 80 08 ca 8a be  7a 42 46 c7 da c6 22 61  |........zBF..."a|

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