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From: andyp@treehouse.UUCP (Andy Peterman)
Newsgroups: comp.sys.mac.programmer
Subject: Re: More Vol RefNum + WD ID Help Needed
Message-ID: <911@treehouse.UUCP>
Date: 9 Jun 91 18:30:53 GMT
References: <1991Jun9.062859.3306@gpu.utcs.utoronto.ca>
Organization: The Treehouse
Lines: 59

In article <1991Jun9.062859.3306@gpu.utcs.utoronto.ca> topix@gpu.utcs.utoronto.ca (R. Munroe) writes:
>And here is what I'm doing to open my stored working directory ID:
>
>    WDPBRec    wdpb;
>    HFileInfo  pb;
>
>    {
>        /* ..... read wdpb.ioNamePtr (volumeName), wdpb.ioWDDirID (wdID),
>                 and reply.fName (fileName) from prefs file ..... */
>
>        wdpb.ioCompletion = NIL_POINTER;
>        wdpb.ioNamePtr = (StringPtr)volumeName;
>        wdpb.ioWDDirID = wdID;
>
>        error = PBOpenWD (&wdpb, FALSE);
>
>        pb.ioNamePtr = (StringPtr)fileName;
>        pb.ioVRefNum = wdpb.ioVRefNum;
>        pb.ioFDirIndex = 0;
>        pb.ioDirID = 0;
>
>        error = PBGetFInfo (&pb, FALSE);
>    }
>
>PBOpenWD always returns fnfErr (file not found).  What am I doing
>wrong?  If I print out my variables, I find that, sure enough, my
>volume name, working directory ID, and file name are just as I had
>stored them - so I don't think the problem is with that.

Why do you need to open a WD?  Apple has been trying to get people to
stop using working directories and you can probably get by without them.

First, get the volumeRefNum:

        pb.ioNamePtr = (StringPtr)volumeName;
	pb.ioVRefNum = 0;
        pb.ioVolIndex = -1;
	error = PBGetVolInfo (&pb, FALSE);

This returns ioVRefNum, along with a bunch of other information (to be
sure you have the correct volume, you could have also saved the creation
date of the volume and check it at this time).

Now, to access the file, use any of the PBH calls, for example:

	pb.ioNamePtr = (StringPtr)fileName;
	pb.ioVRefNum = volumeRefNum;  // Leave out if same pb from last call	
	pb.ioFDirIndex = 0;
	pb.ioDirID = wdID;
	error = PBHGetFInfo (&pb, FALSE);

Note that as long as you call the File Manager routines synchronously
(with the second parameter FALSE), you do not need to clear ioCompletion
- the trap dispatcher does that for you.

-- 
Andy Peterman                       |  Everything you know 
treehouse!andyp@gvgpsa.gvg.tek.com  |       is wrong! 
(916) 273-4569                      |               FST