Date: Mon, 8 Jul 2002 00:05:59 -0400 (EDT) From: Garrett Wollman <wollman@lcs.mit.edu> To: jkh@queasyweasel.com Cc: arch@freebsd.org Subject: Re: Package system flaws? Message-ID: <200207080405.g6845xCf028327@khavrinen.lcs.mit.edu> In-Reply-To: <1A55D91B-921F-11D6-AACD-0003938C7B7E@queasyweasel.com> References: <200207080159.g681xkTX040304@dotar.thuvia.org>
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In article <1A55D91B-921F-11D6-AACD-0003938C7B7E@queasyweasel.com> Jordan writes: [what is that, a GUID in that Message-ID field?!] >Having to seek to the end is, indeed, one of the major draw-backs of >zip. I have no idea why the originators, in their infinite wisdom, put >it there. I do. (Was I the last person to still be using an IBM PC when this happened back in 1988?) Recall that Phil Katz was under legal pressure to create something that was as entirely unlike System Enhancement Associates' ARC as possible. ARC used a `distributed directory' model (stolen from tar) because that made it trivial to append to an archive -- just overwrite the ``end of archive'' block at the end of the file with new data, and eventually a new ``end of archive'' block. Katz wanted to preserve this ability without using the `distributed directory' model, because floppy disks were and are unspeakably slow, and even seeking through an archive to list all the files was painful compared to reading a single sector with all the directory information in it. If the directory is at the beginning, it can never be expanded without making a copy of the entire archive (painfully inconvenient for a 320K archive on a 360K floppy). So, he put the directory at the end, where it was easy to find (in a maximum of two seeks) and could be overwritten when extending the archive, just like the old `end of archive' header in ARC format. -GAWollman -- Garrett A. Wollman | [G]enes make enzymes, and enzymes control the rates of wollman@lcs.mit.edu | chemical processes. Genes do not make ``novelty- Opinions not those of| seeking'' or any other complex and overt behavior. MIT, LCS, CRS, or NSA| - Stephen Jay Gould (1941-2002) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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