Re: FSGetVolumeInfo does not get updated volume info on mounts/dismounts (Tiger)

• Subject: Re: FSGetVolumeInfo does not get updated volume info on mounts/dismounts (Tiger)
• From: Byron Han <email@hidden>
• Date: Thu, 26 May 2005 15:45:22 -1000
• Delivered-to: email@hidden
• Delivered-to: email@hidden

On May 26, 2005, at 3:41 PM, Arshad Tayyeb wrote:

Hi Larry,

Thanks for trying your code out.

I am definitely ejecting them with the eject key; they are unmounted as far as everything else is concerned. And if I run the process again, it works fine.

And it only has this problem on Tiger.

I have some sample code which demonstrates this problem, if anyone cares to try:
http://www.snarshad.com/~arshad/tocreader.sit
(if you want to just look at the source file, it's http:// www.snarshad.com/~arshad/tocreader.c - it's a modified version of Apple's AudioCDSample.c)

It has the source code, makefile, and compiled binary; I'm curious if other people's Tiger systems exhibit this problem, maybe it's just me.

Thanks,

-Arshad

On May 26, 2005, at 6:32 PM, Laurence Harris wrote:

On 5/26/05 4:50 PM, Arshad Tayyeb didst favor us with:

I have an application that needs to find any mounted CDs and get
their TOCs.
It pretty much works under Panther, but in Tiger I get the following
problem:

When calling FSGetVolumeInfo and iterating over the volumes, the
first time I call it, it works fine. It returns me the volRef
numbers -100, -101 (for the 2 drives I always have mounted), and -112
(for example) for the currently mounted CD.

Then I eject the CD, and load a different CD, and run that code again
(during the same run of the program).

The I get -100, -101, and -112 *again*!  And -112 is no longer a
valid ref number.

I have code that iterates over the volumes using FSGetVolumeInfo and I'm not
seeing this. Even if I insert a CD I just ejected, it mounts with the next
vRefNum. How are you ejecting these disks? Are you doing it programmatically
and not unmounting them?

Larry

If I quit the program and re-launch it correctly identifies -113 as
the new CD's volume reference.

This problem is not limited to CDs - it also occurs when mounting/
dismounting iPods, for example.

My guess is that once I call FSGetVolumeInfo, it caches the volumes
for the lifespan of the current process.

Is this a bug in Tiger?  And can anyone think of any way around it?
Is there any way to flush the File Manager's cache of volume
information?

Thanks,
-Arshad

Here's the code I'm using (approximately):

while (1)  /* bug occurs when the code runs more than once
during the process' lifetime */
{
char x[1024];
gets(x); /* this makes it prompt me, if I hit enter it will
re-scan for volumes */
findalltocs();
printf("Reading....\n");
result = noErr;

short ref = GetDefaultAudioCDRefNum();
printf("ref : %d\n", ref);

for (volumeIndex = 1; result == noErr || result != nsvErr;
volumeIndex++)
{
FSVolumeRefNum  actualVolume;
HFSUniStr255  volumeName;
FSVolumeInfo  volumeInfo;

bzero((void *) &volumeInfo, sizeof(volumeInfo));

result = FSGetVolumeInfo(kFSInvalidVolumeRefNum,
volumeIndex,
&actualVolume,
kFSVolInfoFSInfo,
&volumeInfo,
&volumeName,
NULL);

printf("Vol %d %d\n", volumeIndex, actualVolume);  /*
actual volume is the volume ref */
...
}
}

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