WdfDeviceQueryProperty method
[Applies to KMDF and UMDF]
The WdfDeviceQueryProperty method retrieves a specified device property.
Syntax
NTSTATUS WdfDeviceQueryProperty( [in] WDFDEVICE Device, [in] DEVICE_REGISTRY_PROPERTY DeviceProperty, [in] ULONG BufferLength, [out] PVOID PropertyBuffer, [out] PULONG ResultLength );
Parameters
- Device [in]
-
A handle to a framework device object.
- DeviceProperty [in]
-
A DEVICE_REGISTRY_PROPERTY-typed enumerator that identifies the device property to be retrieved.
- BufferLength [in]
-
The size, in bytes, of the buffer that is pointed to by PropertyBuffer.
- PropertyBuffer [out]
-
A caller-supplied pointer to a caller-allocated buffer that receives the requested information. The pointer can be NULL if the BufferLength parameter is zero.
- ResultLength [out]
-
A caller-supplied location that, on return, contains the size, in bytes, of the information that the method stored in PropertyBuffer. If the function's return value is STATUS_BUFFER_TOO_SMALL, this location receives the required buffer size.
Return value
If the operation succeeds, WdfDeviceQueryProperty returns STATUS_SUCCESS. Additional return values include:
| Return code | Description |
|---|---|
|
The supplied buffer is too small to receive the information. |
|
The specified DeviceProperty value is invalid |
|
The device's drivers have not yet reported the device's properties. |
The method might return other NTSTATUS values.
A bug check occurs if the driver supplies an invalid object handle.
Remarks
Before receiving device property data, drivers typically call the WdfDeviceQueryProperty method just to obtain the required buffer size. For some properties, the data size can change between when the required size is returned and when the driver calls WdfDeviceQueryProperty again. Therefore, drivers should call WdfDeviceQueryProperty inside a loop that executes until the return status is not STATUS_BUFFER_TOO_SMALL.
It is best to use WdfDeviceQueryProperty only if the required buffer size is known and unchanging, because in that case the driver has to call WdfDeviceQueryProperty only once. If the required buffer size is unknown or varies, the driver should call WdfDeviceAllocAndQueryProperty.
Alternatively, you can use WdfDeviceQueryPropertyEx to access device properties that are exposed through the Unified Property Model.
Examples
The following code example obtains a device's DevicePropertyBusTypeGuid property. The example calls WdfDeviceQueryProperty instead of WdfDeviceAllocAndQueryProperty because the length of a GUID is known.
GUID busTypeGuid;
ULONG resultLength = 0;
NTSTATUS status;
status = WdfDeviceQueryProperty(
device,
DevicePropertyBusTypeGuid,
sizeof(GUID),
(PVOID)&busTypeGuid,
&resultLength
);
Requirements
|
Minimum KMDF version | 1.0 |
|---|---|
|
Minimum UMDF version | 2.0 |
|
Header |
|
|
Library |
|
|
IRQL | PASSIVE_LEVEL |
|
DDI compliance rules | DriverCreate, KmdfIrql, KmdfIrql2 |
See also
