Path: utzoo!utgpu!jarvis.csri.toronto.edu!torsqnt!tmsoft!masnet!canremote!keith@apple.com
From: keith@apple.com@canremote.uucp (keith@Apple.COM)
Newsgroups: comp.sys.mac.programmer
Subject: Re: HFS Esoterica question
Message-ID: <89122504043290@masnet.uucp>
Date: 21 Dec 89 05:03:00 GMT
Organization: Canada Remote Systems Limited, Mississauga, ON, Canada
Lines: 34

From: keith@Apple.COM (Keith Rollin)
Orga: Apple Computer Inc, Cupertino, CA

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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