Derived From:None
Mix-in Classes:None
Declared In:storage/VolumeRoster.h
Class Overview

Constructor and Destructor



Creates a new BVolumeRoster object. You don't have to "initialize" the object before using it (as you do with most other Storage Kit classes). You can call GetNextVolume() (or whatever) immediately after constructing.


virtual ~BVolumeRoster();

Destroys the object. If this BVolumeRoster object was watching volumes, the watch is called off.

Member Functions


status_t GetBootVolume(BVolume* boot_vol);

Initializes boot_vol to refer to the "boot volume." This is the volume that was used to boot the computer. boot_vol must be allocated before you pass it in. If the boot volume can't be found, the argument is uninitialized.

(Currently, this function looks for the volume that's mounted at /boot. The only way to fool the system into thinking that there isn't a boot volume is to rename /boot—not a smart thing to do.)

Return CodeDescription


The boot volume was successfully retrieved.


The boot volume wasn't found.

GetNextVolume(), Rewind()

status_t GetNextVolume(BVolume* volume);void Rewind();

GetNextVolume() retrieves the "next" volume from the volume list and uses it to initialize the argument (which must be allocated). When the function return B_BAD_VALUE, you've reached the end of the list.

Rewind() rewinds the volume list such that the next GetNextVolume() will return the first element in the list.

Return CodeDescription


The next volume was successfully retrieved.


You've reached the end of the volume list.

StartWatching(), StopWatching(), Messenger()

status_t StartWatching(BMessengermessenger = be_app_messenger );void StopWatching();BMessenger Messenger() const;

These functions start and stop the BVolumeRoster's volume-watching facility. (This is actually just a convenient cover for the Node Monitor.)

  • StartWatching() registers a request for notifications of volume mounts and unmounts. The notifications are sent (as BMessages) to the BHandler / BLooper pair specified by the argument. There are separate messages for mounting and unmounting; their formats are described below. The caller retains possession of the BHandler / BLooper that the BMessenger represents. The volume watching continues until this BVolumeRoster object is destroyed, or until you call…

  • StopWatching(). This function tells the volume-watcher to stop watching. In other words, notifications of volume mounts and unmounts are no longer sent to the BVolumeRoster's target.

  • Messenger() returns a copy of the BMessenger object that was set in the previous StartWatching() call.

There are separate notifications (BMessages) for volume-mounted and volume-unmounted events. See the B_DEVICE_MOUNTED and B_DEVICE_UNMOUNTED descriptions in "The Node Monitor" section of this chapter.

Return CodeDescription


The volume-watcher was successfully started or stopped.


Poorly formed BMessenger.


Couldn't allocate resources.

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