Heads up: gtar gone from base system

[Tim Kientzle]

Conrad J. Sabatier wrote:
> 
> In a similar vein, I just discovered that KDE's "ark" can no longer
> properly extract gzipped tar files:
> 
> tar: unrecognized option `--use-compress-program=gunzip'
> 
> Any chance of adding this option to bsdtar?

I'm a little reluctant to do this because it is either
misleading or surprisingly complex:

1) For gtar, --use-compress-program=gunzip is an exact
synonym for -z.  Implementing this equivalence in bsdtar
would be misleading:  First, bsdtar does not use gunzip for -z
(libarchive implements the decompression internally using
libz).  In addition, bsdtar actually ignores the -z
flag on extraction in favor of libarchive's automatic
compression detection.

2) Implementing --use-compress-program=gunzip separately
from -z is surprisingly complex.  At one time, libarchive
actually did this, but it led to a lot of ugly complications.
(In short, a library that invokes client callbacks within
a forked sub-process is just asking for trouble.)

I recommend submitting a change to the "ark" maintainers suggesting
they use "-z" (which is implemented by many different tar programs)
rather than the gtar-specific --use-compress-program=gunzip.
When testing bsdtar against the ports collection, we found that
most programs can be easily tweaked to work equally well with
either bsdtar or gtar.

If the primary maintainers are uninterested in this change, ark
can be patched in the port to use "-z" or to use gtar.  (I just
noticed that the current port of "ark" depends on gtar.)

Tim Kientzle