Re: replicating package compression used by dpkg-deb
On Thu, 28 Sep 2006 03:45:16 -0700
Ian Bruce <ian_bruce@fastmail.fm> wrote:
> So it seems that with the currently shipping versions of gzip (I tried
> both "stable/updates" and "testing"), there is actually no way to
> exactly replicate the compression produced by the standard package
> build system.
>
> It appears that dpkg-deb does not exec gzip, and it's not dynamically
> linked with anything except glibc. I suppose that it's statically
> linked against zlib1g or something like it. So the question is, how
> can the exact compression algorithm used by dpkg-deb be made available
> for another piece of software? Is it something that's well-specified,
> or is it liable to change at any moment?
It turns out that the zlib1g-dev package contains a program called
"minigzip" in source form. This is what's needed; "minigzip -9"
reproduces exactly the compression used by dpkg-deb, unlike regular
gzip.
-- Ian Bruce
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