WdfFdoInitAllocAndQueryProperty method
[Applies to KMDF and UMDF]
The WdfFdoInitAllocAndQueryProperty method allocates a buffer and retrieves a specified device property.
Syntax
NTSTATUS WdfFdoInitAllocAndQueryProperty( [in] PWDFDEVICE_INIT DeviceInit, [in] DEVICE_REGISTRY_PROPERTY DeviceProperty, [in] POOL_TYPE PoolType, [in, optional] PWDF_OBJECT_ATTRIBUTES PropertyMemoryAttributes, [out] WDFMEMORY *PropertyMemory );
Parameters
- DeviceInit [in]
-
A pointer to a WDFDEVICE_INIT structure that the driver obtained from its EvtDriverDeviceAdd callback function.
- DeviceProperty [in]
-
A DEVICE_REGISTRY_PROPERTY-typed enumerator value that identifies the device property to be retrieved.
- PoolType [in]
-
A POOL_TYPE-typed enumerator value that specifies the type of memory to be allocated.
- PropertyMemoryAttributes [in, optional]
-
A pointer to a caller-allocated WDF_OBJECT_ATTRIBUTES structure that describes object attributes for the memory object that WdfFdoInitAllocAndQueryProperty will allocate. This parameter is optional and can be WDF_NO_OBJECT_ATTRIBUTES.
- PropertyMemory [out]
-
A pointer to a WDFMEMORY-typed location that receives a handle to a framework memory object.
Return value
If the operation succeeds, the method returns STATUS_SUCCESS. Additional return values include:
| Return code | Description |
|---|---|
|
The specified DeviceProperty value is invalid. |
|
the WDFDEVICE_INIT structure was not obtained from driver's EvtDriverDeviceAdd callback function. |
The method might also return other NTSTATUS values.
Remarks
The driver must call WdfFdoInitAllocAndQueryProperty before calling WdfDeviceCreate. For more information about calling WdfDeviceCreate, see Creating a Framework Device Object.
After calling WdfDeviceCreate, a driver can obtain device property information by calling WdfDeviceAllocAndQueryProperty.
For more information about the WdfFdoInitAllocAndQueryProperty method, see Creating Device Objects in a Function Driver.
Alternatively, you can use WdfFdoInitAllocAndQueryPropertyEx to access device properties that are exposed through the Unified Property Model.
Examples
The following code example calls WdfFdoInitAllocAndQueryProperty to obtain a handle to a framework memory object that contains the name of a device's setup class. Then, the example calls WdfMemoryGetBuffer to obtain a pointer to the buffer that contains the setup class name's Unicode string.
NTSTATUS status = STATUS_SUCCESS;
PVOID pMemoryBuffer = NULL;
WDFMEMORY memory = NULL;
status = WdfFdoInitAllocAndQueryProperty(
DeviceInit,
DevicePropertyClassName,
NonPagedPool,
WDF_NO_OBJECT_ATTRIBUTES,
&memory
);
if(NT_SUCCESS(status)){
pMemoryBuffer = WdfMemoryGetBuffer(
memory,
NULL
);
}
Requirements
|
Minimum KMDF version | 1.0 |
|---|---|
|
Minimum UMDF version | 2.0 |
|
Header |
|
|
Library |
|
|
IRQL | PASSIVE_LEVEL |
|
DDI compliance rules | DeviceInitAPI, DriverCreate, KmdfIrql, KmdfIrql2 |
See also
