IoCallDriver源码剖析

 

IoCallDriver是一个宏：

#define IoCallDriver(a,b)   \

        IofCallDriver(a,b)

显然用的是IofCallDriver();

IofCallDriver()代码如下：

NTSTATUS

FASTCALL

IofCallDriver(

    IN PDEVICE_OBJECT DeviceObject,

    IN OUT PIRP Irp

    )

{

    if (pIofCallDriver != NULL) {



        //

        // This routine will either jump immediately to IovCallDriver or

        // IoPerfCallDriver.

        //

        return pIofCallDriver(DeviceObject, Irp, _ReturnAddress());

    }



    return IopfCallDriver(DeviceObject, Irp);

}

pIofCallDriver 好像是(在头文件定义)

extern PIO_CALL_DRIVER        pIofCallDriver;

PIO_CALL_DRIVER则是一个函数指针

typedef

NTSTATUS

(FASTCALL *PIO_CALL_DRIVER) (

    IN      PDEVICE_OBJECT  DeviceObject,

    IN OUT  PIRP            Irp,

    IN      PVOID           ReturnAddress

    );

 

再来说IopfCallDriver

NTSTATUS

FORCEINLINE

IopfCallDriver(

    IN PDEVICE_OBJECT DeviceObject,

    IN OUT PIRP Irp

    )



/*++



Routine Description:



    This routine is invoked to pass an I/O Request Packet (IRP) to another

    driver at its dispatch routine.



Arguments:



    DeviceObject - Pointer to device object to which the IRP should be passed.



    Irp - Pointer to IRP for request.



Return Value:



    Return status from driver's dispatch routine.



--*/



{

    PIO_STACK_LOCATION irpSp;

    PDRIVER_OBJECT driverObject;

    NTSTATUS status;



    //

    // Ensure that this is really an I/O Request Packet.

    //



    ASSERT( Irp->Type == IO_TYPE_IRP );



    //

    // Update the IRP stack to point to the next location.
　　//可见Irp的那个数组标号越大表示越顶层设备

    //

    Irp->CurrentLocation--;



    if (Irp->CurrentLocation <= 0) {

        KiBugCheck3( NO_MORE_IRP_STACK_LOCATIONS, (ULONG_PTR) Irp, 0, 0 );

    }



    irpSp = IoGetNextIrpStackLocation( Irp );

    Irp->Tail.Overlay.CurrentStackLocation = irpSp;



    //

    // Save a pointer to the device object for this request so that it can

    // be used later in completion.

    //



    irpSp->DeviceObject = DeviceObject;





    //

    // Invoke the driver at its dispatch routine entry point.

    //



    driverObject = DeviceObject->DriverObject;

　　

    //

    // Prevent the driver from unloading.

    // 用给定的驱动对象进行调用



　　

    status = driverObject->MajorFunction[irpSp->MajorFunction]( DeviceObject,

                                                              Irp );



    return status;

}