Double callback from Disk Arbitration when mounting disk image

Question

I have a problem using DiskArbitration framework, to catch disk image mounting I register for DARegisterDiskMountApprovalCallback. The problem is that each time a disk image is mounted, the callback is called twice. Why is that and how can I solve this?

score 1 · Answer 1 · answered Apr 17 '14 at 00:28

When a disk is mounted you often see an event for the whole disk and then events for distinct partitions on that disk. You'll need to distinguish.

static void got_disk(DADiskRef disk, void *context)
{
    CFDictionaryRef dict = DADiskCopyDescription(disk);
    NSNumber *whole = CFDictionaryGetValue(dict, kDADiskDescriptionMediaWholeKey);
    if (![whole boolValue]) {
        // Handle your event only with the partition, not the "whole" disk
        ...
    }
}

It's very handy to put a CFShow(dict) in your event handler and see what you get.

score 1 · Accepted Answer · edited Mar 18 '13 at 19:04

1

I ended up coding something to detect the 2nd mount and ignore it.

edited Mar 18 '13 at 19:04

Cezar

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answered May 27 '10 at 17:53

Nyx0uf

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score 0 · Answer 3 · edited Dec 30 '11 at 15:02

0

I use these the catch that. I'm not sure of the difference these are to what you're doing but they work.

[[[NSWorkspace sharedWorkspace] notificationCenter] addObserver:self selector:@selector(mediaMounted:) name:NSWorkspaceDidMountNotification object:[NSWorkspace sharedWorkspace]];

[[[NSWorkspace sharedWorkspace] notificationCenter] addObserver:self selector:@selector(mediaUnmounted:) name:NSWorkspaceWillUnmountNotification object:[NSWorkspace sharedWorkspace]];

edited Dec 30 '11 at 15:02

Quinn Taylor

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answered May 26 '10 at 16:21

regulus6633

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I can't use NSWorkspace, it comes from appKit which isn't not daemon safe, and I need to run this as a daemon. – Nyx0uf May 26 '10 at 18:23

score 0 · Answer 4 · answered May 26 '10 at 20:41

0

Did you put a breakpoint in your callback to see what are the call-stack when it is called ? It can gives you some hints on what is going on.

answered May 26 '10 at 20:41

Laurent Etiemble

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@Nyxem When it is hit twice, does the callstack gives you some information ? – Laurent Etiemble May 26 '10 at 20:55

Double callback from Disk Arbitration when mounting disk image

4 Answers4