WMI_SET_DATABLOCK_CALLBACK callback function (wmilib.h)

Article
10/21/2021

The DpWmiSetDataBlock routine changes all data items in a single instance of a data block. This routine is optional.

Syntax

WMI_SET_DATABLOCK_CALLBACK WmiSetDatablockCallback;

NTSTATUS WmiSetDatablockCallback(
  [in] PDEVICE_OBJECT DeviceObject,
  [in] PIRP Irp,
  [in] ULONG GuidIndex,
  [in] ULONG InstanceIndex,
  [in] ULONG BufferSize,
  [in] PUCHAR Buffer
)
{...}

Parameters

[in] DeviceObject

Pointer to the driver's WDM DEVICE_OBJECT structure.

[in] Irp

Pointer to the IRP.

[in] GuidIndex

Specifies the data block by its zero-based index into the list of GUIDs provided by the driver in the WMILIB_CONTEXT structure it passed to WmiSystemControl.

[in] InstanceIndex

If the block specified by GuidIndex has multiple instances, InstanceIndex specifies the instance.

[in] BufferSize

Specifies the size in bytes of the buffer at Buffer.

[in] Buffer

Pointer to a buffer that contains new values for the instance.

Return value

DpWmiSetDataBlock returns STATUS_SUCCESS or an appropriate error status such as the following:

If the driver cannot complete the request immediately, it can return STATUS_PENDING.

Remarks

WMI calls a driver's DpWmiSetDataBlock routine after the driver calls WmiSystemControl in response to an IRP_MN_CHANGE_SINGLE_INSTANCE request.

The driver is responsible for validating all input arguments. Specifically, the driver must do the following:

Verify that the GuidIndex value is between zero and GuidCount-1, based on the GuidCount member of the WMILIB_CONTEXT structure.
Verify that the driver has not flagged the specified data block for removal. If the driver recently specified the WMIREG_FLAG_REMOVE_GUID flag in a WMIGUIDREGINFO structure that is contained in a WMILIB_CONTEXT structure, it is possible for a set request to arrive before the removal occurs.
Verify that the InstanceIndex value is within the range of instance indexes that are supported by the driver for the data block.
Verify that Buffer and BufferSize describe a valid-sized data block, including any padding that exists between data items, and that the contents of the buffer are valid for the data block.
Verify that the specified data block is one for which the driver allows caller-initiated modifications. In other words, the driver should not allow modifications to data blocks that you intended to be read-only.

Do not assume the thread context is that of the initiating user-mode application—a higher-level driver might have changed it.

If a driver implements a DpWmiSetDataBlock routine, the driver must place the routine's address in the SetWmiDataBlock member of the WMILIB_CONTEXT structure that it passes to WmiSystemControl. If a driver does not implement a DpWmiSetDataBlock routine, it must set SetWmiDataBlock to NULL. In the latter case, WMI returns STATUS_READ_ONLY to the caller.

This routine can be pageable.

For more information about implementing this routine, see Calling WmiSystemControl to Handle WMI IRPs.

Requirements

Requirement	Value
Target Platform	Desktop
Header	wmilib.h (include Wmilib.h)
IRQL	Called at PASSIVE_LEVEL.