Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!wuarchive!brutus.cs.uiuc.edu!apple!keith
From: keith@Apple.COM (Keith Rollin)
Newsgroups: comp.sys.mac.programmer
Subject: Re: HFS Esoterica question
Message-ID: <37421@apple.Apple.COM>
Date: 20 Dec 89 03:30:50 GMT
References: <1631@intercon.com>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 27

In article <1631@intercon.com> amanda@mermaid.intercon.com (Amanda Walker) writes:
>Here's a question for all you file system hackers.  I've been meditating
>upon IM-IV and hex dumps of volume header blocks, and I can't find a
>definitive answer to a simple question: is the extents file on an HFS
>volume guaranteed to be contiguous?  All the examples I can find are,
>and IM-IV seems to imply it, but it doesn't actually say.  There's space
>for up to 3 extents in the volume header, but for more than that you'd
>have to look in the file itself, which seems uncomfortably recursive :-).
>

Amanda,

The extents file is not guaranteed to be contiguous. It can be split up into
3 extents of its own. Beyond that, I don't know what happens. Some sort of
system failure, I suppose. However, I've never seen more than one extent, and
there is probably some sort of methematical reason why you'll never exceed the
3 set aside for the extents file. I've never seen any that spans more than
even 1 extent.

So the answer is, no, we don't go recurcurcurcurcursive.

-- 
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"Argue for your Apple, and sure enough, it's yours" - Keith Rollin, Contusions