reactos/drivers/dd/null/null.c

   1 /* $Id: null.c,v 1.10 2002/09/08 10:22:05 chorns Exp $
   2  *
   3  * COPYRIGHT:        See COPYING in the top level directory
   4  * PROJECT:          ReactOS kernel
   5  * FILE:             services/null/null.c
   6  * PURPOSE:          NULL device driver
   7  * PROGRAMMER:       David Welch (welch@mcmail.com)
   8  * UPDATE HISTORY:
   9  *              13/08/1998: Created
  10  *              29/04/2002: Fixed bugs, added zero-stream device
  11  */
  12
  13 /* INCLUDES */
  14 #include <ddk/ntddk.h>
  15 #include "null.h"
  16
  17 /* OBJECTS */
  18 static const NULL_EXTENSION nxNull = NullBitBucket;
  19 static const NULL_EXTENSION nxZero = NullZeroStream;
  20
  21 /* FUNCTIONS */
  22 NTSTATUS STDCALL
  23 NullDispatch(PDEVICE_OBJECT DeviceObject, PIRP Irp)
  24 {
  25  PIO_STACK_LOCATION piosStack = IoGetCurrentIrpStackLocation(Irp);
  26  NTSTATUS nErrCode;
  27
  28  nErrCode = STATUS_SUCCESS;
  29
  30  switch(piosStack->MajorFunction)
  31  {
  32   /* opening and closing handles to the device */
  33   case IRP_MJ_CREATE:
  34   case IRP_MJ_CLOSE:
  35   {
  36    break;
  37   }
  38
  39   /* write data */
  40   case IRP_MJ_WRITE:
  41   {
  42    switch(NULL_DEVICE_TYPE(DeviceObject))
  43    {
  44     case NullBitBucket:
  45      Irp->IoStatus.Information = piosStack->Parameters.Write.Length;
  46      break;
  47
  48     case NullZeroStream:
  49     default:
  50      Irp->IoStatus.Information = 0;
  51      nErrCode = STATUS_NOT_IMPLEMENTED;
  52    }
  53
  54    break;
  55   }
  56
  57   /* read data */
  58   case IRP_MJ_READ:
  59   {
  60    switch(NULL_DEVICE_TYPE(DeviceObject))
  61    {
  62     case NullBitBucket:
  63      Irp->IoStatus.Information = 0;
  64      nErrCode = STATUS_END_OF_FILE;
  65      break;
  66
  67     case NullZeroStream:
  68      RtlZeroMemory(Irp->AssociatedIrp.SystemBuffer, piosStack->Parameters.Read.Length);
  69      Irp->IoStatus.Information = piosStack->Parameters.Read.Length;
  70      break;
  71
  72     default:
  73      Irp->IoStatus.Information = 0;
  74      nErrCode = STATUS_NOT_IMPLEMENTED;
  75    }
  76
  77    break;
  78   }
  79
  80   /* unsupported operations */
  81   default:
  82   {
  83    nErrCode = STATUS_NOT_IMPLEMENTED;
  84   }
  85  }
  86
  87  Irp->IoStatus.Status = nErrCode;
  88  IoCompleteRequest(Irp, IO_NO_INCREMENT);
  89
  90  return (nErrCode);
  91 }
  92
  93 NTSTATUS STDCALL
  94 NullUnload(PDRIVER_OBJECT DriverObject)
  95 {
  96  return(STATUS_SUCCESS);
  97 }
  98
  99 NTSTATUS STDCALL
 100 DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
 101 {
 102  PDEVICE_OBJECT pdoNullDevice;
 103  PDEVICE_OBJECT pdoZeroDevice;
 104  UNICODE_STRING wstrDeviceName;
 105  NTSTATUS nErrCode;
 106
 107  /* register driver routines */
 108  DriverObject->MajorFunction[IRP_MJ_CLOSE] = NullDispatch;
 109  DriverObject->MajorFunction[IRP_MJ_CREATE] = NullDispatch;
 110  DriverObject->MajorFunction[IRP_MJ_WRITE] = NullDispatch;
 111  DriverObject->MajorFunction[IRP_MJ_READ] = NullDispatch;
 112  /* DriverObject->MajorFunction[IRP_MJ_QUERY_INFORMATION] = NullDispatch; */
 113  DriverObject->DriverUnload = NullUnload;
 114
 115  /* create null device */
 116  RtlInitUnicodeStringFromLiteral(&wstrDeviceName, L"\\Device\\Null");
 117
 118  nErrCode = IoCreateDevice
 119  (
 120   DriverObject,
 121   sizeof(NULL_EXTENSION),
 122   &wstrDeviceName,
 123   FILE_DEVICE_NULL,
 124   0,
 125   FALSE,
 126   &pdoNullDevice
 127  );
 128
 129  /* failure */
 130  if(!NT_SUCCESS(nErrCode))
 131  {
 132   return (nErrCode);
 133  }
 134
 135  pdoNullDevice->DeviceExtension = (PVOID)&nxNull;
 136
 137  /* create zero device */
 138  RtlInitUnicodeStringFromLiteral(&wstrDeviceName, L"\\Device\\Zero");
 139
 140  nErrCode = IoCreateDevice
 141  (
 142   DriverObject,
 143   sizeof(NULL_EXTENSION),
 144   &wstrDeviceName,
 145   FILE_DEVICE_NULL,
 146   FILE_READ_ONLY_DEVICE, /* zero device is read-only */
 147   FALSE,
 148   &pdoZeroDevice
 149  );
 150
 151  /* failure */
 152  if(!NT_SUCCESS(nErrCode))
 153  {
 154   IoDeleteDevice(pdoNullDevice);
 155   return (nErrCode);
 156  }
 157
 158  pdoZeroDevice->DeviceExtension = (PVOID)&nxZero;
 159  pdoZeroDevice->Flags |= DO_BUFFERED_IO;
 160
 161  return (nErrCode);
 162 }
 163
 164 /* EOF */