Re: [PATCH 1/2] add option to set the offset of the archive

[Matteo Croce]

Il giorno ven 25 ott 2024 alle ore 09:42 Paul Eggert
<eggert@cs.ucla.edu> ha scritto:
>
> On 2024-10-24 10:09, Matteo Croce wrote:
>
> > I know that it's possible to pipe the stream with an external process,
> > but there are some use cases where a seekable file descriptor is
> > preferable.
>
> If it's seekable, why not seek before invoking 'tar'? E.g.:
>
> (dd ibs=1024 skip=1 count=0 && tar -tf -) <inputfile
>
> That way you can use 'tar' as-is, without a new option needed.

Hi,

For some weird reason this works when extracting but not when listing
archive content:

$ ar -tO witalian_cow.deb
debian-binary 0x44
control.tar.xz 0x84
_data-pad 0x6c0
data.tar 0x1000

$ (dd status=none bs=4k skip=1 count=0 && tar xv) <witalian_cow.deb
./
./usr/
./usr/share/
./usr/share/dict/
./usr/share/dict/italian
./usr/share/doc/
./usr/share/doc/witalian/
./usr/share/doc/witalian/README
./usr/share/doc/witalian/README.Debian
./usr/share/doc/witalian/TODO
./usr/share/doc/witalian/changelog.gz
...

$ (dd status=none bs=4k skip=1 count=0 && tar tv) <witalian_cow.deb
drwxr-xr-x root/root         0 2018-06-13 18:37 ./
drwxr-xr-x root/root         0 2018-06-13 18:37 ./usr/
drwxr-xr-x root/root         0 2018-06-13 18:37 ./usr/share/
drwxr-xr-x root/root         0 2018-06-13 18:37 ./usr/share/dict/
-rw-r--r-- root/root   1248830 2018-06-13 18:37 ./usr/share/dict/italian
tar: rmtlseek not stopped at a record boundary
tar: Error is not recoverable: exiting now

Any idea of what happens?

Regards,
-- 
Matteo Croce

perl -e 'for($t=0;;$t++){print chr($t*($t>>8|$t>>13)&255)}' |aplay