Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!husc6!ogccse!littlei!omepd!psu-cs!fitzgerd
From: fitzgerd@psu-cs.UUCP (Don Fitzgerald)
Newsgroups: comp.sys.mac.programmer
Subject: VCB Blocks, Volume Ref#'s and other mysteries
Message-ID: <1668@psu-cs.UUCP>
Date: 17 Feb 89 00:31:42 GMT
Organization: Dept. of Computer Science, Portland State University; Portland OR
Lines: 18

I have bumped into what I think is a very interesting situation.  After a call  to GetVol I get a volume reference number for my HD20 which seems reasonable.
A few lines later I make a call to PBHGetVInfo and ioVRefNum gives me a
different Number !  I had set ioVolindex as one and there were not any other
volumes mounted.  Hmmm interesting.

After a slight moment of fustration I consulted IM Vol IV and found out about
the VCB Block, quickly grabbed myself a ptr to look at with GetVCBQHdr and 
proceeded to unHash this mystery with LSP 2.0's LightsBug1 (A very nice tool
for Pascal Programmers !!).  Low and behold the queue contained exactly what
PBHGetVInfo had returned. After several tries the error remained consistant.

So there aremy questions. If the VCB Block contains the information that 
GetVol and PBHGetVInfo look at how did they get different answers?  How
does a person go about finding unique identifiers for volumes in the presence
of Multifinder?

To Compile or To Delete that is the question,
                                                 Don