Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!mips!apple!keith
From: keith@Apple.COM (Keith Rollin)
Newsgroups: comp.sys.mac.system
Subject: Re: Alias resolution: right or wrong?
Message-ID: <53613@apple.Apple.COM>
Date: 4 Jun 91 01:39:59 GMT
References: <1991May31.170319.1179@neon.Stanford.EDU> <13808@goofy.Apple.COM> <13848@goofy.Apple.COM>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 23

In article <13848@goofy.Apple.COM> lsr@Apple.COM (Larry Rosenstein) writes:
>
>According to IM 6, when you create an alias to a file, the system creates a
>file ID for the file.  The file ID will let the alias track the file
>anywhere on the same volume even if it has changed name.  (The file ID is a
>unique ID for files, in the same way that the dir ID is a unique ID for
>directories.)

IMO, Inside Mac VI is slightly misleading on this score. Files have
always had unique file IDs associated with them (see the field at byte
offset 20 in the picture on page 172 of IM IV). However, there was no
quick way to look up a file's catalog entry based on that ID. With 7.0,
HFS now has the ability to create special hidden catalog entries
(called "file thread records") that allow this quick lookup. When IM
refers to being able to create IDs for files, it is really referring to
these new records.

-- 
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Keith Rollin  ---  Apple Computer, Inc. 
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"But where the senses fail us, reason must step in."  - Galileo