一个类似windows
源代码在线查看： null.c
/* $Id: null.c 21842 2006-05-07 19:16:11Z ion $
*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS kernel
* FILE: services/null/null.c
* PURPOSE: NULL device driver
* PROGRAMMER: David Welch (welch@mcmail.com)
* UPDATE HISTORY:
* 13/08/1998: Created
* 29/04/2002: Fixed bugs, added zero-stream device
* 28/06/2004: Compile against the DDK, use PSEH where necessary
*/
/* INCLUDES */
#include
#include
#include "null.h"
/* OBJECTS */
static const NULL_EXTENSION nxNull = NullBitBucket;
static const NULL_EXTENSION nxZero = NullZeroStream;
/* FUNCTIONS */
static NTSTATUS STDCALL
NullDispatch(PDEVICE_OBJECT DeviceObject, PIRP Irp)
{
PIO_STACK_LOCATION piosStack = IoGetCurrentIrpStackLocation(Irp);
NTSTATUS nErrCode;
nErrCode = STATUS_SUCCESS;
Irp->IoStatus.Information = 0;
switch(piosStack->MajorFunction)
{
/* opening and closing handles to the device */
case IRP_MJ_CREATE:
case IRP_MJ_CLOSE:
switch(NULL_DEVICE_TYPE(DeviceObject))
{
case NullBitBucket:
case NullZeroStream:
break;
default:
ASSERT(FALSE);
}
break;
/* write data */
case IRP_MJ_WRITE:
{
switch(NULL_DEVICE_TYPE(DeviceObject))
{
case NullBitBucket:
Irp->IoStatus.Information = piosStack->Parameters.Write.Length;
break;
case NullZeroStream:
nErrCode = STATUS_INVALID_DEVICE_REQUEST;
break;
default:
ASSERT(FALSE);
}
break;
}
/* read data */
case IRP_MJ_READ:
{
switch(NULL_DEVICE_TYPE(DeviceObject))
{
case NullBitBucket:
nErrCode = STATUS_END_OF_FILE;
break;
case NullZeroStream:
_SEH_TRY
{
RtlZeroMemory(Irp->AssociatedIrp.SystemBuffer, piosStack->Parameters.Read.Length);
Irp->IoStatus.Information = piosStack->Parameters.Read.Length;
}
_SEH_HANDLE
{
nErrCode = _SEH_GetExceptionCode();
}
_SEH_END;
break;
default:
ASSERT(FALSE);
}
break;
}
case IRP_MJ_QUERY_VOLUME_INFORMATION:
switch(piosStack->Parameters.QueryVolume.FsInformationClass)
{
case FileFsDeviceInformation:
{
ULONG BufferLength = piosStack->Parameters.QueryVolume.Length;
PFILE_FS_DEVICE_INFORMATION FsDeviceInfo = (PFILE_FS_DEVICE_INFORMATION)Irp->AssociatedIrp.SystemBuffer;
if (BufferLength >= sizeof(FILE_FS_DEVICE_INFORMATION))
{
FsDeviceInfo->DeviceType = FILE_DEVICE_NULL;
FsDeviceInfo->Characteristics = 0; /* FIXME: fix this !! */
Irp->IoStatus.Information = sizeof(FILE_FS_DEVICE_INFORMATION);
nErrCode = STATUS_SUCCESS;
}
else
{
Irp->IoStatus.Information = 0;
nErrCode = STATUS_BUFFER_OVERFLOW;
}
}
break;
default:
Irp->IoStatus.Information = 0;
nErrCode = STATUS_NOT_IMPLEMENTED;
}
break;
default:
Irp->IoStatus.Information = 0;
nErrCode = STATUS_NOT_IMPLEMENTED;
}
Irp->IoStatus.Status = nErrCode;
IoCompleteRequest(Irp, IO_NO_INCREMENT);
return (nErrCode);
}
static VOID STDCALL
NullUnload(PDRIVER_OBJECT DriverObject)
{
}
/* TODO: \Device\Zero should be memory-mappable */
NTSTATUS STDCALL
DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
{
PDEVICE_OBJECT pdoNullDevice;
PDEVICE_OBJECT pdoZeroDevice;
UNICODE_STRING wstrNullDeviceName = RTL_CONSTANT_STRING(L"\\Device\\Null");
UNICODE_STRING wstrZeroDeviceName = RTL_CONSTANT_STRING(L"\\Device\\Zero");
NTSTATUS nErrCode;
/* register driver routines */
DriverObject->MajorFunction[IRP_MJ_CLOSE] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_CREATE] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_WRITE] = NullDispatch;
DriverObject->MajorFunction[IRP_MJ_READ] = NullDispatch;
DriverObject->DriverUnload = NullUnload;
/* create null device */
nErrCode = IoCreateDevice(DriverObject,
sizeof(NULL_EXTENSION),
&wstrNullDeviceName,
FILE_DEVICE_NULL,
0,
FALSE,
&pdoNullDevice);
/* failure */
if(!NT_SUCCESS(nErrCode))
{
return (nErrCode);
}
pdoNullDevice->DeviceExtension = (PVOID)&nxNull;
/* create zero device */
nErrCode = IoCreateDevice(DriverObject,
sizeof(NULL_EXTENSION),
&wstrZeroDeviceName,
FILE_DEVICE_NULL,
FILE_READ_ONLY_DEVICE, /* zero device is read-only */
FALSE,
&pdoZeroDevice);
/* failure */
if(!NT_SUCCESS(nErrCode))
{
IoDeleteDevice(pdoNullDevice);
return (nErrCode);
}
pdoZeroDevice->DeviceExtension = (PVOID)&nxZero;
pdoZeroDevice->Flags |= DO_BUFFERED_IO;
return (nErrCode);
}
/* EOF */
