DispatchQueryInformation routine

The DispatchQueryInformation routine services IRPs containing the IRP_MJ_QUERY_INFORMATION I/O function code.

Syntax


DRIVER_DISPATCH DispatchQueryInformation;

NTSTATUS DispatchQueryInformation(
  _Inout_  struct _DEVICE_OBJECT *DeviceObject,
  _Inout_  struct _IRP *Irp
)
{ ... }

Parameters

DeviceObject [in, out]

Caller-supplied pointer to a DEVICE_OBJECT structure. This is the device object for the target device, previously created by the driver's AddDevice routine.

Irp [in, out]

Caller-supplied pointer to an IRP structure that describes the requested I/O operation.

Return value

If the routine succeeds, it must return STATUS_SUCCESS. Otherwise, it must return one of the error status values defined in Ntstatus.h.

Remarks

A driver's DispatchQueryInformation routine should be named XxxDispatchQueryInformation, where Xxx is a driver-specific prefix. The driver's DriverEntry routine must store the DispatchQueryInformation routine's address in DriverObject->MajorFunction[IRP_MJ_QUERY_INFORMATION].

Input parameters for all DispatchXxx routines are supplied in the IRP structure pointed to by Irp. Additional parameters are supplied in the driver's associated I/O stack location, which is described by the IO_STACK_LOCATION structure and can be obtained by calling IoGetCurrentIrpStackLocation.

Generally, all DispatchXxx routines execute in an arbitrary thread context at IRQL = PASSIVE_LEVEL, but there are exceptions. For more information, see Dispatch Routines and IRQLs.

For more information about DispatchQueryInformation routines, see Writing Dispatch Routines. For more information about IRPs, see Handling IRPs.

Examples

To define a DispatchQueryInformation callback routine, you must first provide a function declaration that identifies the type of callback routine you're defining. Windows provides a set of callback function types for drivers. Declaring a function using the callback function types helps Code Analysis for Drivers, Static Driver Verifier (SDV), and other verification tools find errors, and it's a requirement for writing drivers for the Windows operating system.

For example, to define a DispatchQueryInformation callback routine that is named MyDispatchQueryInformation, use the DRIVER_DISPATCH type as shown in this code example:


DRIVER_DISPATCH MyDispatchQueryInformation;

Then, implement your callback routine as follows:



_Use_decl_annotations_
NTSTATUS
  MyDispatchQueryInformation(
    struct _DEVICE_OBJECT  *DeviceObject,
    struct _IRP  *Irp
    )
  {
      // Function body
  }

The DRIVER_DISPATCH function type is defined in the Wdm.h header file. To more accurately identify errors when you run the code analysis tools, be sure to add the _Use_decl_annotations_ annotation to your function definition. The _Use_decl_annotations_ annotation ensures that the annotations that are applied to the DRIVER_DISPATCH function type in the header file are used. For more information about the requirements for function declarations, see Declaring Functions by Using Function Role Types for WDM Drivers. For information about _Use_decl_annotations_, see Annotating Function Behavior.

Requirements

Header

Wdm.h (include Wdm.h, Ntddk.h, or Ntifs.h)

IRQL

Called at PASSIVE_LEVEL (see Remarks section).

 

 

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