Kernel Mode Driver Framework >> Pascal (PNP) >> Timer

DPC

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參考資訊：
1. Source Code

由於I/O Timer的Timer間隔固定為一秒，如果使用者想要可以彈性設定的Timer間隔，則需要使用DPC Timer，使用的步驟：
1. KeInitializeTimer()
2. KeInitializeDpc()
3. KeSetTimer()
4. KeCancelTimer()

DPC Timer如果使用KeSetTimer()做設定時，其Timer為一次性，也就是Callback僅會被呼叫一次，如果要使用週期性Timer，則需要改用KeSetTimerEx()，KeSetTimerEx()宣告如下：

function krnlKeSetTimerEx(Timer:PKTIMER; LowPart:ULONG; HighPart:ULONG; Period:LONG; Dpc:PKDPC):Boolean; stdcall;

DueTime是第一次Timer的間隔，之後的間隔則使用Period數值。

main.pas

unit main;

interface
  uses
    DDDK;
    
  const
    DEV_NAME = '\Device\MyDriver';
    SYM_NAME = '\DosDevices\MyDriver';
    IOCTL_START = (FILE_DEVICE_UNKNOWN shl 16) or (FILE_ANY_ACCESS shl 14) or ($800 shl 2) or (METHOD_BUFFERED);
    IOCTL_STOP = (FILE_DEVICE_UNKNOWN shl 16) or (FILE_ANY_ACCESS shl 14) or ($801 shl 2) or (METHOD_BUFFERED);

  function __DriverEntry(pOurDriver:PDRIVER_OBJECT; pOurRegistry:PUNICODE_STRING):NTSTATUS; stdcall;

implementation
var
  cnt: ULONG;
  dpc: TKDpc;
  obj: KTIMER;
  pDevice: PDEVICE_OBJECT;

procedure OnTimer(Dpc:KDPC; DeferredContext:Pointer; SystemArgument1:Pointer; SystemArgument2:Pointer); stdcall;
begin
  cnt:= cnt + 1;
  DbgPrint('DpcTimer: %d', [cnt]);
end;

procedure IrpFileCreate(Device:WDFDEVICE; Request:WDFREQUEST; FileObject:WDFFILEOBJECT); stdcall;
begin
  DbgPrint('IrpFileCreate', []);
  WdfRequestComplete(Request, STATUS_SUCCESS);
end;

procedure IrpFileClose(FileObject:WDFFILEOBJECT); stdcall;
begin
  DbgPrint('IrpFileClose', []);
end;

procedure IrpIOCTL(Queue:WDFQUEUE; Request:WDFREQUEST; OutputBufferLength:ULONG; InputBufferLength:ULONG; IoControlCode:ULONG); stdcall;
var
  tt: LARGE_INTEGER;
  
begin
  if IoControlCode = IOCTL_START then begin
    DbgPrint('IOCTL_START', []);
    cnt:= 0;
    tt.HighPart:= tt.HighPart or -1;
    tt.LowPart:= ULONG(-10000000);
    KeSetTimerEx(@obj, tt.LowPart, tt.HighPart, 1000, @dpc);
  end
  else if IoControlCode = IOCTL_STOP then begin
    DbgPrint('IOCTL_STOP', []);
    KeCancelTimer(@obj);
  end;
  WdfRequestComplete(Request, STATUS_SUCCESS);
end;

function AddDevice(pOurDriver:WDFDRIVER; pDeviceInit:PWDFDEVICE_INIT):NTSTATUS; stdcall;
var
  device: WDFDEVICE;
  suDevName: UNICODE_STRING;
  szSymName: UNICODE_STRING;
  file_cfg: WDF_FILEOBJECT_CONFIG;
  ioqueue_cfg: WDF_IO_QUEUE_CONFIG;

begin
  WdfDeviceInitSetIoType(pDeviceInit, WdfDeviceIoBuffered);
  WDF_FILEOBJECT_CONFIG_INIT(@file_cfg, @IrpFileCreate, @IrpFileClose, Nil);
  WdfDeviceInitSetFileObjectConfig(pDeviceInit, @file_cfg, WDF_NO_OBJECT_ATTRIBUTES);
  
  RtlInitUnicodeString(@suDevName, DEV_NAME);
  RtlInitUnicodeString(@szSymName, SYM_NAME);
  WdfDeviceInitAssignName(pDeviceInit, @suDevName);
  WdfDeviceCreate(@pDeviceInit, WDF_NO_OBJECT_ATTRIBUTES, @device);
  WdfDeviceCreateSymbolicLink(device, @szSymName);
  
  pDevice:= WdfDeviceWdmGetDeviceObject(device);
  KeInitializeTimer(@obj);
  KeInitializeDpc(@dpc, OnTimer, pDevice);
  WDF_IO_QUEUE_CONFIG_INIT_DEFAULT_QUEUE(@ioqueue_cfg, WdfIoQueueDispatchSequential);
  ioqueue_cfg.EvtIoDeviceControl:= @IrpIOCTL;
  Result:= WdfIoQueueCreate(device, @ioqueue_cfg, WDF_NO_OBJECT_ATTRIBUTES, WDF_NO_HANDLE);
end;

function __DriverEntry(pOurDriver:PDRIVER_OBJECT; pOurRegistry:PUNICODE_STRING):NTSTATUS; stdcall;
var
  config: WDF_DRIVER_CONFIG;
  
begin
  WDF_DRIVER_CONFIG_INIT(@config, AddDevice);
  WdfDriverCreate(pOurDriver, pOurRegistry, WDF_NO_OBJECT_ATTRIBUTES, @config, WDF_NO_HANDLE);
  Result:= STATUS_SUCCESS;
end;
end.

AddDevice()初始化Timer以及DPC Object
IrpIOCTL()啟動或停止DPC Timer
OnTimer()僅列印訊息，其餘事情不做

app.pas

program main;

{$APPTYPE CONSOLE}

uses
  Windows,
  Messages,
  SysUtils,
  Variants,
  Classes,
  Graphics,
  Controls,
  Forms,
  DIALOGS;

const
  METHOD_BUFFERED = 0;
  METHOD_IN_DIRECT = 1;
  METHOD_OUT_DIRECT = 2;
  METHOD_NEITHER = 3;
  FILE_ANY_ACCESS = 0;
  FILE_DEVICE_UNKNOWN = $22;
  IOCTL_START = (FILE_DEVICE_UNKNOWN shl 16) or (FILE_ANY_ACCESS shl 14) or ($800 shl 2) or (METHOD_BUFFERED);
  IOCTL_STOP = (FILE_DEVICE_UNKNOWN shl 16) or (FILE_ANY_ACCESS shl 14) or ($801 shl 2) or (METHOD_BUFFERED);

var
  fd: DWORD;
  ret: DWORD;

begin
  fd:= CreateFile('\\.\MyDriver', GENERIC_READ or GENERIC_WRITE, FILE_SHARE_READ, Nil, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
  if (fd <> INVALID_HANDLE_VALUE) then
  begin
    DeviceIoControl(fd, IOCTL_START, Nil, 0, Nil, 0, ret, Nil);
    Sleep(3000);
    DeviceIoControl(fd, IOCTL_STOP, Nil, 0, Nil, 0, ret, Nil);
    CloseHandle(fd);
  end else
  begin
    WriteLn(Output, 'failed to open mydriver');
  end;
end.

結果

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