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Date: Tue, 4 Sep 2001 15:52:03 -0400
From: Christopher Faylor <cgf AT redhat DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: press for cygwin
Message-ID: <20010904155203.C7509@redhat.com>
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On Tue, Sep 04, 2001 at 10:52:21AM -0600, Warren Young wrote:
>Christopher Faylor wrote:
>> 
>> >Somebody else mentioned this earlier -- and explained that Debian did
>> >exactly that.  ".deb" files are just ar archives, but .deb implies that
>> >they obey some sort of internal format standard ("CYGWIN-PATCHES" ?
>> >/etc/postinstall?  )
>> >
>> >I actually think this is a pretty good idea.
>> 
>> It does have merits except for the fact that you lose the ability to
>> distinguish between a .gz and .bz2 compressed archive.  
>
>A quick peek at /etc/magic tells me that it's simple to distinguish the
>two, and in fact it's more reliable, since magic numbers don't lie, but
>file names can.  Also, we might say from the outset that Cygwin packages
>are all packed with bzip2, not gzip.

Yes.  As I keep saying (but somehow it seems to consistently be lost in
the translation), I already knew that you could detect the difference
when I sent my original suggestion of using magic numbers.

>I realize the file name detection code exists, so it's easier to leave
>it be than to add more code for magic number checking, but it _is_
>trivial to add magic number checking.  For gzip, a matter of checking
>the first 2 bytes of the file, and for bzip2, the first 3 bytes.

It actually is not trivial at all.  As I also keep mentioning, it
requires that someone who cares about this will have to actually do it
rather than report that it is possible to do it.

>I think it's more likely that WinZip will add bzip2 decompression than a
>rule to handle *.cgw files as .tar.gz.  In other words, bzip2 confusing
>Winzip might be a short-lived state of affairs.  If you doubt that, ask
>yourself if, a few years ago, if you would have guessed that WinZip
>would have added tar and gzip code?

I somehow doubt that WinZip would be incapable of uncompressing files
merely becase they have a "non-standard" extension.

This may solve the "Ah.  It has a .tar.gz extension so I can use WinZip"
problem, but it does not solve the "Ah.  This is some kind of archive,
I wonder if WinZip understands it" problem.  Continuing to move towards
.bz2 compression works around the problem temporarily but neither that
nor naming the archives something different are a long term foolproof
solution.

cgf

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