IoGetDeviceAttachmentBaseRef function (ntifs.h)

Article
02/22/2024

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

Syntax

PDEVICE_OBJECT IoGetDeviceAttachmentBaseRef(
  [in] PDEVICE_OBJECT DeviceObject
);

Parameters

[in] DeviceObject

A 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 the device object pointer in DeviceObject.

Remarks

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

Requirement	Value
Minimum supported client	Windows 2000 SP4 Update Rollup; Windows XP
Target Platform	Universal
Header	ntifs.h (include Ntifs.h)
Library	NtosKrnl.lib
DLL	NtosKrnl.exe
IRQL	<= DISPATCH_LEVEL