Device Events
Applications, including services, can register to receive notification of device events. For example, a catalog service can receive notice of volumes being mounted or dismounted so it can adjust the paths to files on the volume. The system notifies an application that a device event has occurred by sending the application a WM_DEVICECHANGE message. The system notifies a service that a device event has occurred by invoking the service's event handler function, HandlerEx.
To receive device event notices, call the RegisterDeviceNotification function with a DEV_BROADCAST_HANDLE structure. Be sure to set the dbch_handle member to the device handle obtained from the CreateFile function. Also, set the dbch_devicetype member to DBT_DEVTYP_HANDLE. The function returns a device notification handle. Note that this is not the same as the volume handle.
When your application receives notification, if the event type is DBT_CUSTOMEVENT, you may have received one of the device events defined in IoEvent.h. To determine if one of these events has occurred, use the following steps.
- Treat the event data as a DEV_BROADCAST_HDR structure. Verify that the dbch_devicetype member is set to DBT_DEVTYP_HANDLE.
- If dbch_devicetype is DBT_DEVTYP_HANDLE, the event data is really a pointer to a DEV_BROADCAST_HANDLE structure.
- Compare the dbch_eventguid member to the GUIDs listed in the following table using the IsEqualGUID function.
| Device Event GUID | Meaning |
|---|---|
|
GUID_IO_CDROM_EXCLUSIVE_LOCK bc56c139-7a10-47ee-a294-4c6a38f0149a |
The CD-ROM device has been locked for exclusive access.
|
|
GUID_IO_CDROM_EXCLUSIVE_UNLOCK a3b6d27d-5e35-4885-81e5-ee18c00ed779 |
A CD-ROM device that was locked for exclusive access has been unlocked.
|
|
GUID_IO_DEVICE_BECOMING_READY d07433f0-a98e-11d2-917a-00a0c9068ff3 |
Media spin-up is in progress. |
|
GUID_IO_DEVICE_EXTERNAL_REQUEST d07433d0-a98e-11d2-917a-00a0c9068ff3 |
There are several possible causes for this event; for more information, refer to T10 MMC specification of the GET EVENT STATUS NOTIFICATION Command, at http://www.t10.org/. |
|
GUID_IO_MEDIA_ARRIVAL d07433c0-a98e-11d2-917a-00a0c9068ff3 |
Removable media has been added to the device. The dbch_data member is a pointer to a CLASS_MEDIA_CHANGE_CONTEXT structure. The NewState member provides status information. For example, a value of MediaUnavailable indicates that the media is not available (for example, due to an active recording session).
|
|
GUID_IO_MEDIA_EJECT_REQUEST d07433d1-a98e-11d2-917a-00a0c9068ff3 |
The removable media's drive has received a request from the user to eject the specified slot or media. |
|
GUID_IO_MEDIA_REMOVAL d07433c1-a98e-11d2-917a-00a0c9068ff3 |
Removable media has been removed from the device or is unavailable. The dbch_data member is a pointer to a CLASS_MEDIA_CHANGE_CONTEXT structure. The NewState member provides status information. For example, a value of MediaUnavailable indicates that the media is not available (for example, due to an active recording session).
|
|
GUID_IO_VOLUME_CHANGE 7373654a-812a-11d0-bec7-08002be2092f |
The volume label has changed. |
|
GUID_IO_VOLUME_CHANGE_SIZE 3a1625be-ad03-49f1-8ef8-6bbac182d1fd |
The size of the file system on the volume has changed.
|
|
GUID_IO_VOLUME_DISMOUNT d16a55e8-1059-11d2-8ffd-00a0c9a06d32 |
An attempt to dismount the volume is in progress. You should close all handles to files and directories on the volume. This event will not necessarily be preceded by a GUID_IO_VOLUME_LOCK event. |
|
GUID_IO_VOLUME_DISMOUNT_FAILED e3c5b178-105d-11d2-8ffd-00a0c9a06d32 |
An attempt to dismount a volume failed. This often happens because another process failed to respond to a GUID_IO_VOLUME_DISMOUNT notice by closing its outstanding handles. Because the dismount failed, you may reopen any handles to the affected volume. |
|
GUID_IO_VOLUME_FVE_STATUS_CHANGE 062998b2-ee1f-4b6a-b857-e76cbbe9a6da |
The volume's BitLocker Drive Encryption status has changed. This event is signaled when BitLocker is enabled or disabled, or when encryption begins, ends, pauses, or resumes.
|
|
GUID_IO_VOLUME_LOCK 50708874-c9af-11d1-8fef-00a0c9a06d32 |
Another process is attempting to lock the volume. You should close all handles to files and directories on the volume. |
|
GUID_IO_VOLUME_LOCK_FAILED ae2eed10-0ba8-11d2-8ffb-00a0c9a06d32 |
An attempt to lock a volume failed. This often happens because another process failed to respond to a GUID_IO_VOLUME_LOCK event by closing its outstanding handles. Because the lock failed, you may reopen any handles to the affected volume. |
|
GUID_IO_VOLUME_MOUNT b5804878-1a96-11d2-8ffd-00a0c9a06d32 |
The volume has been mounted by another process. You may open one or more handles to it. |
|
GUID_IO_VOLUME_NAME_CHANGE 2de97f83-4c06-11d2-a532-00609713055a |
The volume name has been changed. |
|
GUID_IO_VOLUME_NEED_CHKDSK 799a0960-0a0b-4e03-ad88-2fa7c6ce748a |
A file system has detected corruption on the volume. The application should run CHKDSK on the volume or notify the user to do so.
|
|
GUID_IO_VOLUME_PHYSICAL_CONFIGURATION_CHANGE 2de97f84-4c06-11d2-a532-00609713055a |
The physical makeup or current physical state of the volume has changed. |
|
GUID_IO_VOLUME_PREPARING_EJECT c79eb16e-0dac-4e7a-a86c-b25ceeaa88f6 |
The file system is preparing the disc to be ejected. For example, the file system is stopping a background formatting operation or closing the session on write-once media.
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GUID_IO_VOLUME_UNIQUE_ID_CHANGE af39da42-6622-41f5-970b-139d092fa3d9 |
The volume's unique identifier has been changed. For more information about the unique identifier, see IOCTL_MOUNTDEV_QUERY_UNIQUE_ID.
|
|
GUID_IO_VOLUME_UNLOCK 9a8c3d68-d0cb-11d1-8fef-00a0c9a06d32 |
The volume has been unlocked by another process. You may open one or more handles to it. |
|
GUID_IO_VOLUME_WEARING_OUT 873113ca-1486-4508-82ac-c3b2e5297aaa |
The media is wearing out. This event is sent when a file system determines that the error rate on a volume is too high, or its defect replacement space is almost exhausted.
|
The GUID_IO_VOLUME_DISMOUNT and GUID_IO_VOLUME_DISMOUNT_FAILED events are related, as are the GUID_IO_VOLUME_LOCK and GUID_IO_VOLUME_LOCK_FAILED event. The GUID_IO_VOLUME_DISMOUNT and GUID_IO_VOLUME_LOCK events indicate that an operation is being attempted. You should act on the event notification, and record the action taken. The GUID_IO_VOLUME_DISMOUNT_FAILED and GUID_IO_VOLUME_LOCK_FAILED events indicate that the attempted operation failed. You may then use your record to undo the actions you made in response to the operation.
The dbch_hdevnotify member of the DEV_BROADCAST_HANDLE structure indicates the affected device. Note that this is the device notification handle returned by RegisterDeviceNotification, not a volume handle. To perform operations on the volume, map this handle to the corresponding volume handle.
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Build date: 2/7/2012
