New Volume Mount Notification

When you mount a new network volume, you must tell the system about it. You do this by calling the DiskArbitration routine DiskArbDiskAppearedWithMountpointPing_auto. This routine isn't part of the standard DiskArbitration framework headers, so you have to declare your own prototype for it. The correct prototype is shown in Listing 1.

Listing 1  DiskArbDiskAppearedWithMountpointPing_auto prototype

extern kern_return_t DiskArbDiskAppearedWithMountpointPing_auto(
    char *   disk,
    unsigned flags,
    char *   mountpoint
) __attribute__((weak_import));

enum {
    kDiskArbDiskAppearedEjectableMask              = 1 << 1,
    kDiskArbDiskAppearedNetworkDiskMask            = 1 << 3
};

The parameters to this routine are:

• disk is the device on which the disk is mounted. In the case of a network volume, you can use any unique string. However, it must match the f_mntfromname value returned by statfs for your volume.

• flags must be kDiskArbDiskAppearedEjectableMask | kDiskArbDiskAppearedNetworkDiskMask.

• mountpoint is an absolute path to the directory on which the volume is mounted. Typically this is a unique subdirectory that you create within /Volumes.

This routine is part of the old (pre-Mac OS X 10.3), private, DiskArbitration framework interface. When we introduced a new, public DiskArbitration interface in Mac OS X 10.3, we didn't introduce a replacement for this routine because, in the long term, DiskArbitration will automatically learn about new network volumes by way of a kernel notification. So, ultimately, you won't need to call this routine for your volume to appear on the desktop. For that reason, we strongly recommend that you weak link against this symbol and, if it's not present, just don't call it.

For more information about this technique, see Technical Note TN2064, 'Ensuring Backwards Binary Compatibility - Weak Linking and Availability Macros on Mac OS X'.

Finally, because you're calling the old, private DiskArbitration framework interface, you have to explicitly initialize that interface. You do this by calling DiskArbInit, the prototype of which is given in Listing 2. If you fail to do this, it's likely that DiskArbDiskAppearedWithMountpointPing_auto will fail with an error code of 5 (KERN_FAILURE).

Listing 2  DiskArbInit prototype

extern kern_return_t DiskArbInit(void) __attribute__((weak_import));

As with DiskArbDiskAppearedWithMountpointPing_auto, you should weak link to this routine and not call it if it's not present.