Re: [Bug-tar] Re: Lzip support in GNU tar 1.23

[Kevin Day]

On 2/14/10, Antonio Diaz Diaz <address@hidden> wrote:
> Hello Sergey,
>
>  Antonio Diaz Diaz wrote:
>
> >
> > >
> > > > Do you plan to auto-compress/recognize lzip files (.lz)?
> > > >
> > >
> > > No problem.  I'll only need some information on how to discern them
> > > (e.g. by file header signature).  Do you have any pointers?
> > >
> >
> > I see tar-1.22.90 does not yet mention lzip files anywhere. In case my
> last message was lost I send the pointers again.
> >
>
>  I see tar-1.22.91 does not yet mention lzip files anywhere.
>
>  I am beginning to feel worried because, as Vincent Lefevre told me
> recently, "if this isn't fixed before the freeze in (probably) a few weeks,
> this would mean that one would wait for several years before seeing lzip
> support in GNU tar in Debian/stable".
>
>  If the problem is the .tlz suffix, I guess it can remain assigned to lzma
> until lzip is more popular than lzma. I suppose this will eventually happen
> given that lzma is deprecated and the lzip family of compressors is now
> complete.
>
>
>  Best regards,
>  Antonio.
>
>
>

There is the possibility of making up a new extension suffix for lzip.
Given that lzip is not as incredibly popular just yet, it may be
possible to get away with defining a new variation on the extension
and making that the standard via tar's influence.

would this work?
.tar.lzp
.tzp


However, on the other side of this argument, I do not think the
extension should matter.  The purpose for identifying what a file is
or is not is through the magic header.  The magic header between the
two are different, so no matter what the extension may be a properly
written program should be able to tell the difference and handle
accordingly.

The magic header is pretty easy:
modify buffer.c to have this:
  { ct_lzip,     4, "LZIP",  "lzip", "--lzip" },

I thought I sent a patch that does this upstream already, but maybe it
I am mixing memories up.
I do have a patch for 1.22 and this should be easy to apply to 1.23.*


-- 
Kevin Day