can not seek in input: Illegal seek

[radeletp]

When trying to use pixz with clonezilla to check image, the following command is executed:

cat /home/partimag/cust/sdb2.ext4-ptcl-img.xz.aa |
pixz -d |
LC_ALL=C partclone.chkimg -N -s -

Using stream show following stderr which is not really user friendly and might make thing to the user that the integrity of the file is not OK:

"can not seek in input: Illegal seek"

Seems this warning is provided by decode_index function, anyway there is no failure and pixz is correctly behaving even when the input file is stream. Is it possible to remove this warning information from decode_index function?

[ole-tange]

Can also be reproduced with:

echo | pixz | pixz -d | wc

[wookietreiber]

Thanks for reporting. I am not yet well versed with the internals, @vasi can you shed some light on this?

[vasi]

Pixz can decompress fine without an index. The only potential problems I can think of are:

• Some tools might create pixz files with multiple blocks, where the blocks headers don't include a size. In that case, pixz won't be able to do parallel decompression, things will slow down.
• Someone might try to use the "-x" option to pixz, to filter the list of files. That won't work if there's no index.

We should probably turn this message into a warning?

[wookietreiber]

I guess, we could implement a switch that checks early if we are working with a stream or a plain file, then branch off to one section that handles streams and one that handles files. This way, we can capture what capabilities are possible and issue warnings/errors appropriately depending on what the user wants.

[ole-tange]

This issue blocks pixz to be used as a dropin replacement for gzip (sort --compress-program=pixz / tar --use-compress-program pixz / parallel --compress-program pixz).

[mgheorghe]

any update on this ?
i'm keep getting
partclone.c,open_target,1611: open /dev/sda1 error(17)

[jorismak]

Maybe I'm missing how this is supposed to be used,
But i did pixz backup.tar backup.tpxz and it compressed the raw tarball.
If I do pixz -l backup.tpxz I get a fast and nice listing of all the files in the tarball.
But if I do pixz -x /some/file/from/listing backup.tpxz I get this same message 'illegal seek' and it appears to just sit there doing nothing? (Or it takes a long time because the entire archive has to be decompressed anyway because of the illegal seek?).

If I managed to create a tpxz file without an index

• How do I create one with an index?
• Why is the file listing so quick?

EDIT: Found it, I had my -x command line wrong. You need to pipe in the .tpxz file with -x, and it outputs a little blob of tar you need to feed into a tar xpP style commandline.