🚀 go-pugleaf

Glenn Reid replies to Eric Scott:

>> >  Using it for software distribution is
>> > questionable at best.
>>
>> How come?  If you also ship the uncompressor, what makes it "questionable"?

This is a non-issue.  It's obvious when you would use Squash and when you
wouldn't.  Squash is only good for distributing software or what-have-you
between 680x0 machines running NeXTstep.  You can distribute with it the
UnSquashOnly application.  If you are unsure of the integrity of the Squash
program, you would simply check that UnSquashOnly works on the files
before you ship it.

If you are distributing beyond the NeXT-universe, then you obviously
can't use Squash (unless you're Greg and can recompile it for another
machine).

Another concern might be that you want your user to use the NeXT
Installer utility for consistency with other manufacturers.  I do not
know of a way to get Installer to invoke UnSquashOnly--as it stands
Installer uses tar and compress.

Even between NeXT's, there is a usage where Squash falls flat.  That
is dialing into a NeXT over a modem from a NeXT at home, and using
compression to reduce the time to transfer stuff in either direction.
There is no purely command-line utility to Squash or UnSquash.  I end
up using zip and unzip for that purpose.

Squash is a really nice GUI compression utility that is reliable and
compresses very well.  However, there are compressors out there that
are better.  One is comp-2 and expand-2 which come in source and work
from the command line.  Like Squash, comp-2 is memory and cpu intensive.

Eric Scott felt:

>> Trusting one's data to a proprietary (and unique) scheme strikes
>> me as incredibly foolish.

Only if it doesn't work.  Squash works.

I endeavoured and succeeded in getting Greg to put a crc check into
Squash during beta testing.  This provides similar confidence in the
data that you get when you read it off of a hard disk.  In all my
usage of Squash, it has not failed to decompress.  That's more than
I can say for other commercial programs whose format is neither
proprietary or unique--in particular, PKZIP.  Having a disclosed
format offers limited protection against bugs in the software.  If
it is an error in the uncompression software, then maybe you can find
a way to fix it.  However, if it was an error in the compression
software, then it is likely that you cannot recover, no matter how
much you know about the format.

Mark Adler
madler@tybalt.caltech.edu