The IoGetDeviceAttachmentBaseRef routine returns a pointer to the lowest-level device object in a file system or device driver stack.

PDEVICE_OBJECT
  IoGetDeviceAttachmentBaseRef(
    IN PDEVICE_OBJECT  DeviceObject
    ); 

Parameters

DeviceObject

Pointer to a device object in the stack.

Return Value

IoGetDeviceAttachmentBaseRef returns a pointer to the device object at the bottom of the file system or device driver stack. If the given device object is not attached to a driver stack, IoGetDeviceAttachmentBaseRef returns NULL.

Comments

A file system filter driver typically calls IoGetDeviceAttachmentBaseRef to get the lowest-level device object in a file system driver stack. Often this is done when the filter driver receives notification that a file system has registered or unregistered itself as an active file system. The filter driver's notification callback routine calls IoGetDeviceAttachmentBaseRef to get a pointer to the file system's control device object, and then calls ObQueryNameString to retrieve this object's name for debugging purposes.

IoGetDeviceAttachmentBaseRef increments the reference count on the device object at the bottom of the stack. Thus every successful call to IoGetDeviceAttachmentBaseRef must be matched by a subsequent call to ObDereferenceObject.

Requirements

Versions: This routine is available on Update Rollup for Windows 2000 Service Pack 4 (SP4) and on Windows XP and later.

IRQL: <= DISPATCH_LEVEL

Headers: Declared in ntifs.h. Include ntifs.h.

See Also

IoEnumerateDeviceObjectList, IoGetLowerDeviceObject, IoRegisterFsRegistrationChange, IoUnregisterFsRegistrationChange, ObDereferenceObject, ObQueryNameString