WdfRequestIsFrom32BitProcess function (wdfrequest.h)

Article
02/22/2024

[Applies to KMDF and UMDF]

The WdfRequestIsFrom32BitProcess method checks whether the originator of a specified I/O request is a 32-bit user-mode application.

Syntax

BOOLEAN WdfRequestIsFrom32BitProcess(
  [in] WDFREQUEST Request
);

Parameters

[in] Request

A handle to a framework request object.

Return value

On 64-bit systems,WdfRequestIsFrom32BitProcess returns TRUE if the originator of the current I/O request is a 32-bit user-mode process, and FALSE otherwise. On 32-bit systems, WdfRequestIsFrom32BitProcess always returns TRUE.

A bug check occurs if the driver supplies an invalid object handle.

Remarks

Drivers can call WdfRequestIsFrom32BitProcess to determine whether an I/O request is likely to contain data elements that need to be converted, or "thunked," before they can be used in a 64-bit driver.

The specified request handle must have been obtained from one of the driver's I/O queues and not from a call to WdfRequestCreate.

Examples

The following code example determines if an I/O request came from a 32-bit application.

VOID
MyEvtIoRead(
    IN WDFQUEUE  Queue,
    IN WDFREQUEST  Request,
    IN size_t  Length
    )
{
...
    if (WdfRequestIsFrom32BitProcess(Request)) {
        //
        // The driver is running on a 64-bit computer and the 
        // I/O request came from a 32-bit application.
        //
...
    }
...
}

Requirements

Requirement	Value
Target Platform	Universal
Minimum KMDF version	1.0
Minimum UMDF version	2.0
Header	wdfrequest.h (include Wdf.h)
Library	Wdf01000.sys (KMDF); WUDFx02000.dll (UMDF)
IRQL	<=DISPATCH_LEVEL
DDI compliance rules	DriverCreate(kmdf), InvalidReqAccess(kmdf), InvalidReqAccessLocal(kmdf), KmdfIrql(kmdf), KmdfIrql2(kmdf), KmdfIrqlExplicit(kmdf)

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