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From: oster@dewey.soe.berkeley.edu (David Phillip Oster)
Newsgroups: comp.sys.mac.programmer
Subject: Re: HFS Help
Message-ID: <31429@ucbvax.BERKELEY.EDU>
Date: 21 Sep 89 05:39:26 GMT
References: <12562@orstcs.CS.ORST.EDU> <1989Sep21.014654.27408@polyslo.CalPoly.EDU> <RANG.89Sep20230303@derby.cs.wisc.edu>
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Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster)
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This point is clearly covered in Inside Mac v. 4. the "vRef" of a folder
is really a "wRef" a working directory reference. It only lives for a
short time. You cannot depend on it from session to session. There is
another number, a 4-byte dirId that is the permanent identifier of the
folder, even if the folder is renamed. There is a system call that takes a
wRef and a real volume reference and returns the dirId.
PBHOpen() takes a volume Id, a dirId, and a file name and opens the file.
To store a file descriptor from run to run, you need a triple: the volume
name, the dirId, and the file name. To be really safe, you need the full
path name too, so you can use it on a remote file system that doesn't
really support dirIds. You need the volume name as a string since it may
get a different number depending on the order of the mounting of the disks
at boot time.