Re: [Lzip-bug] plzip vs. lzip: different decompression size

[Antonio Diaz Diaz]

Hello Filip.

Filip Van Lerberge wrote:
> I've performed a few tests and it appears that plzip and lzip have
> different behavior when it comes down to decompression:

Feedback messages are different because lzip is usually used to 
decompress single-member files while plzip is more often used to 
decompress multi-member files. Just give a single -v to lzip when 
decompressing multi-member files.

But of course the decompressed output produced by lzip and plzip should 
be identical, and I constantly check very carefully that this is the case:

$ plzip -cvv /dev/fd0 > img.lz
  /dev/fd0:  8.917:1,  0.897 bits/byte, 88.79% saved, 1474560 in, 
165360 out.
$ lzip -cdvv img.lz | md5sum
  img.lz:  8.917:1,  0.897 bits/byte, 88.79% saved.  done
ecb5f45b5c02b11b44f961e6afbce7c3  -
$ plzip -cdvv img.lz | md5sum
  img.lz:  8.917:1,  0.897 bits/byte, 88.79% saved.  done
ecb5f45b5c02b11b44f961e6afbce7c3  -


> # *plzip *-vvdc Archimedes_vda_2014-01-02_18-26-27.img.lz | dd
> of=/lv/archi-plzip.img

Have you tried without dd?:
  plzip -vvdc Archimedes_vda_2014-01-02_18-26-27.img.lz > 
/lv/archi-plzip.img


> -rw-r--r--  1 root root   5492916224 Jan  5 11:18 archi-plzip.img
> -rw-r--r--  1 root root 107374182400 Jan  5 11:54 archi-lzip.img

You may try to compare the two files to see if the first is a truncated 
version of the second. I suspect there is a broken pipe somewhere and 
the plzip output gets truncated as a result.


> The version of lzip in Ubuntu 13.10 is 1.14 (vs. 0.9 for plzip). Is this
> the root cause of the issue I'm experiencing?

I don't think so. AFAIK, no version of plzip has had any "real" bug (one 
producing incorrect output).


> Any plans to update plzip and to update the Ubuntu package?

I don't know about Ubuntu, but Debian already provides the latest 
version of plzip (1.1) in experimental:

http://packages.debian.org/experimental/plzip


Best regards,
Antonio.