reactos/drivers/dd/null/null.c

   1 /* $Id$
   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  *              28/06/2004: Compile against the DDK, use PSEH where necessary
  12  */
  13
  14 /* INCLUDES */
  15 #include <ntddk.h>
  16
  17 #include <rosrtl/string.h>
  18 #include <pseh.h>
  19
  20 #include "null.h"
  21
  22 /* OBJECTS */
  23 static const NULL_EXTENSION nxNull = NullBitBucket;
  24 static const NULL_EXTENSION nxZero = NullZeroStream;
  25
  26 /* FUNCTIONS */
  27 NTSTATUS STDCALL
  28 NullDispatch(PDEVICE_OBJECT DeviceObject, PIRP Irp)
  29 {
  30  PIO_STACK_LOCATION piosStack = IoGetCurrentIrpStackLocation(Irp);
  31  NTSTATUS nErrCode;
  32
  33  nErrCode = STATUS_SUCCESS;
  34  Irp->IoStatus.Information = 0;
  35
  36  switch(piosStack->MajorFunction)
  37  {
  38   /* opening and closing handles to the device */
  39   case IRP_MJ_CREATE:
  40   case IRP_MJ_CLOSE:
  41    switch(NULL_DEVICE_TYPE(DeviceObject))
  42    {
  43     case NullBitBucket:
  44     case NullZeroStream:
  45      break;
  46
  47     default:
  48      ASSERT(FALSE);
  49    }
  50
  51    break;
  52
  53   /* write data */
  54   case IRP_MJ_WRITE:
  55   {
  56    switch(NULL_DEVICE_TYPE(DeviceObject))
  57    {
  58     case NullBitBucket:
  59      Irp->IoStatus.Information = piosStack->Parameters.Write.Length;
  60      break;
  61
  62     case NullZeroStream:
  63      nErrCode = STATUS_INVALID_DEVICE_REQUEST;
  64      break;
  65
  66     default:
  67      ASSERT(FALSE);
  68    }
  69
  70    break;
  71   }
  72
  73   /* read data */
  74   case IRP_MJ_READ:
  75   {
  76    switch(NULL_DEVICE_TYPE(DeviceObject))
  77    {
  78     case NullBitBucket:
  79      nErrCode = STATUS_END_OF_FILE;
  80      break;
  81
  82     case NullZeroStream:
  83      _SEH_TRY
  84      {
  85       RtlZeroMemory(Irp->AssociatedIrp.SystemBuffer, piosStack->Parameters.Read.Length);
  86       Irp->IoStatus.Information = piosStack->Parameters.Read.Length;
  87      }
  88      _SEH_HANDLE
  89      {
  90       nErrCode = _SEH_GetExceptionCode();
  91      }
  92      _SEH_END;
  93
  94      break;
  95
  96     default:
  97      Irp->IoStatus.Information = 0;
  98      nErrCode = STATUS_NOT_IMPLEMENTED;
  99    }
 100
 101    break;
 102   }
 103
 104   default:
 105    ASSERT(FALSE);
 106  }
 107
 108  Irp->IoStatus.Status = nErrCode;
 109  IoCompleteRequest(Irp, IO_NO_INCREMENT);
 110
 111  return (nErrCode);
 112 }
 113
 114 VOID STDCALL
 115 NullUnload(PDRIVER_OBJECT DriverObject)
 116 {
 117 }
 118
 119 /* TODO: \Device\Zero should be memory-mappable */
 120 NTSTATUS STDCALL
 121 DriverEntry(PDRIVER_OBJECT DriverObject, PUNICODE_STRING RegistryPath)
 122 {
 123  PDEVICE_OBJECT pdoNullDevice;
 124  PDEVICE_OBJECT pdoZeroDevice;
 125  UNICODE_STRING wstrDeviceName;
 126  NTSTATUS nErrCode;
 127
 128  /* register driver routines */
 129  DriverObject->MajorFunction[IRP_MJ_CLOSE] = NullDispatch;
 130  DriverObject->MajorFunction[IRP_MJ_CREATE] = NullDispatch;
 131  DriverObject->MajorFunction[IRP_MJ_WRITE] = NullDispatch;
 132  DriverObject->MajorFunction[IRP_MJ_READ] = NullDispatch;
 133  DriverObject->DriverUnload = NullUnload;
 134
 135  /* create null device */
 136  RtlRosInitUnicodeStringFromLiteral(&wstrDeviceName, L"\\Device\\Null");
 137
 138  nErrCode = IoCreateDevice
 139  (
 140   DriverObject,
 141   sizeof(NULL_EXTENSION),
 142   &wstrDeviceName,
 143   FILE_DEVICE_NULL,
 144   0,
 145   FALSE,
 146   &pdoNullDevice
 147  );
 148
 149  /* failure */
 150  if(!NT_SUCCESS(nErrCode))
 151  {
 152   return (nErrCode);
 153  }
 154
 155  pdoNullDevice->DeviceExtension = (PVOID)&nxNull;
 156
 157  /* create zero device */
 158  RtlRosInitUnicodeStringFromLiteral(&wstrDeviceName, L"\\Device\\Zero");
 159
 160  nErrCode = IoCreateDevice
 161  (
 162   DriverObject,
 163   sizeof(NULL_EXTENSION),
 164   &wstrDeviceName,
 165   FILE_DEVICE_NULL,
 166   FILE_READ_ONLY_DEVICE, /* zero device is read-only */
 167   FALSE,
 168   &pdoZeroDevice
 169  );
 170
 171  /* failure */
 172  if(!NT_SUCCESS(nErrCode))
 173  {
 174   IoDeleteDevice(pdoNullDevice);
 175   return (nErrCode);
 176  }
 177
 178  pdoZeroDevice->DeviceExtension = (PVOID)&nxZero;
 179  pdoZeroDevice->Flags |= DO_BUFFERED_IO;
 180
 181  return (nErrCode);
 182 }
 183
 184 /* EOF */