[Toybox] [PATCH] tar: use same tools for decompression as for compression.

[enh]

i think my argument would have been that implementing the bzip2
*command* is still useful even if you have an error_exit("compression
not supported") for the compression side. i certainly use `gzip -dc`
all the time, and Android's source tree seems to have large numbers of
both that an `gunzip`.

but (as usual with questions of minimalism) there's also the argument
that i think you're putting forth here (that i hadn't thought of
before) that "gunzip is more restrictive". so i can certainly talk to
our build folks about allowing the "un" commands too.

but i think you get the best coverage of "stuff just works with
toybox" if you have the non-"un" commands but have them fail if you're
not building toybox with libz?

On Wed, May 22, 2019 at 8:35 PM Rob Landley <rob at landley.net> wrote:
>
> On 4/29/19 5:58 PM, enh via Toybox wrote:
> > This is what GNU tar does, so Android's build system jail allows
> > bzip2, gzip, and xz, but not bzcat, zcat, and xzcat.
>
> This broke mkroot, at a design level.
>
> I don't plan to implement bzip2 compression side because it's an obsolete
> protocol (and because when I did the first half of it years ago the string
> sorting heuristics were kind of unintelligible). This means toybox hasn't got
> and isn't _going_ to have bzip2, so even though toybox implements bzcat it
> toybox tar will never be able to decompress bzip2 archives by itself, because of
> android's naming limitation.
>
> It also means that toybox can't decompress gzip files by itself until I finish
> gzip compression side (but I intend to write that at some point so I can pass it
> through from the host). And that toybox won't be able to decompress xz since I'm
> not doing xz compression either, just decompression.
>
> (That's why I was using those names. I'm going through my release checklist for
> 0.8.1 and I got to the step of using mkroot to build all the target binaries,
> and I hit this and went "oh right, todo item fell through the cracks...")
>
> Rob