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FastIoDispatch example

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Newsgroups: comp.os.ms-windows.programmer.nt.kernel-mode
Subject: FastIoDispatch, example code
Message-ID: <01bc23ed$36cc47f0$d0e43fc0@djm8>
From: "Duane J. McCrory"
Date: Wed, 26 Feb 1997 13:48:28 GMT
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I got a request for sample FastIoDispatch code. Here's an example for Ioctls.
static FAST_IO_DISPATCH fast_io_dispatch;

static NTSTATUS driver_dispatch_device_control(IN DEVICE_OBJECT *
  dev, IN
IRP *irp) {
    PIO_STACK_LOCATION irp_stk;
    NTSTATUS status;

    // in my case, I never need an IRP for a device_control opera
    // tion
    // so if my IRP_MJ_DEVICE_CONTROL function happens to get cal
    // led
    // I can make use of the fast procedure that I've implemented

    irp_stk = IoGetCurrentIrpStackLocation(irp);

    driver_dispatch_device_control_fast(irp_stk->FileObject, TRUE
     ,
        irp_stk->Parameters.DeviceIoControl.Type3InputBuffer,
        irp_stk->Parameters.DeviceIoControl.InputBufferLength,
        irp->UserBuffer,
        irp_stk->Parameters.DeviceIoControl.OutputBufferLength,
        irp_stk->Parameters.DeviceIoControl.IoControlCode,
        &irp->IoStatus, dev);
    status = irp->IoStatus.Status;
    IoCompleteRequest(irp, IO_NO_INCREMENT);
    return status;
}

static BOOLEAN driver_dispatch_device_control_fast(IN FILE_OBJECT
*FileObject,
        IN BOOLEAN Wait, IN PVOID InputBuffer OPTIONAL, IN ULONG
InputBufferLength,
        OUT PVOID OutputBuffer OPTIONAL, IN ULONG OutputBufferLen
         gth,
        IN ULONG IoControlCode, OUT PIO_STATUS_BLOCK IoStatus, IN
DEVICE_OBJECT *dev) {

    // setup default result
    IoStatus->Status = STATUS_SUCCESS;
    IoStatus->Information = 0;

    switch (IoControlCode) {
    case IOCTL_OUTPUT_TO_APPLICATION:
        // this is an example for sending data to an application
        if (OutputBufferLength >= sizeof(YOUR_OUTPUT_AREA)) {
         __try {
         *(YOUR_OUTPUT_AREA *)OutputBuffer =          d>
         IoStatus->Information = sizeof(YOUR_OUTPUT_AREA);
         } __except(EXCEPTION_EXECUTE_HANDLER) {
         IoStatus->Status = GetExceptionCode();
         }
        } else
        IoStatus->Status = STATUS_INVALID_PARAMETER;
        return TRUE;
    default:
        // Set default return information
        IoStatus->Status = STATUS_NOT_IMPLEMENTED;
        return TRUE;
    }
    // note that you would return FALSE if you want the standard
IRP_MJ_DEVICE_CONTROL
    // dispatch routine called, in my case I always return TRUE
}

NTSTATUS PROCEDURE DriverEntry(IN DRIVER_OBJECT *drv, IN PUNICODE
  _STRING
RegistryPath) {
    .
    .
    .
    RtlZeroMemory(&fast_io_dispatch, sizeof(fast_io_dispatch));
    fast_io_dispatch.SizeOfFastIoDispatch = sizeof(fast_io_dispat
     ch);
    fast_io_dispatch.FastIoDeviceControl =
driver_dispatch_device_control_fast;
    drv->FastIoDispatch = &fast_io_dispatch;
    drv->MajorFunction[IRP_MJ_CREATE] = driver_dispatch;
    drv->MajorFunction[IRP_MJ_CLOSE] = driver_dispatch;
    drv->MajorFunction[IRP_MJ_DEVICE_CONTROL] =
driver_dispatch_device_control;
    drv->MajorFunction[IRP_MJ_READ] = driver_dispatch;
    drv->MajorFunction[IRP_MJ_WRITE] = driver_dispatch;
    drv->MajorFunction[IRP_MJ_CLEANUP] = driver_dispatch;
    drv->MajorFunction[IRP_MJ_SHUTDOWN] = driver_dispatch;

    drv->DriverUnload = driver_unload;
    .
    .
    .
}
--
Duane.

*** The comments and opinions expressed above are my own and ***
*** do not necessarily represent those of Unisys Corporation ***

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