Delphi驱动开发研究第七篇--与用户进程通讯（共享内存篇）

最新推荐文章于 2022-09-23 00:06:46 发布

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最新推荐文章于 2022-09-23 00:06:46 发布 · 817 阅读

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CC 4.0 BY-SA版权

文章标签：

#delphi #通讯 #timer #service #object #ddk

本文介绍了如何在Delphi驱动程序中使用共享内存与用户进程进行通信，避免了特定进程地址空间的限制。通过创建MDL、分配非分页内存并映射到用户进程，实现驱动程序每秒更新一次系统时间到共享内存，供用户进程读取。文章还探讨了计时器、内存管理和线程同步等问题。

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上篇教程我们学习了通过Section在用户进程和内核驱动程序之间共享信息的方法，但是这种方法有一个缺点，就是驱动程序被硬性限制在具体进程的地址上下文中，即驱动程序所使用的虚拟地址位于此进程的地址空间中。我们在本例中使用的方法将没有这个缺点。对于驱动程序来说，这种方法更为自然些。
首先来看看驱动程序。

unit SharingMemory;

interface

uses
    nt_status, ntoskrnl, native, winioctl, fcall, macros;

function _DriverEntry(pDriverObject:PDRIVER_OBJECT; pusRegistryPath:PUNICODE_STRING): NTSTATUS; stdcall;

implementation

uses
    seh;

var
    g_pSharedMemory: PVOID;
    g_pMdl: PVOID;
    g_pUserAddress: PVOID;
    g_fTimerStarted: boolean;
    g_usDeviceName, g_usSymbolicLinkName: UNICODE_STRING;

{更新系统时间到共享内存}
procedure UpdateTime; stdcall;
var
    SysTime:LARGE_INTEGER;
begin
    KeQuerySystemTime(@SysTime);
    ExSystemTimeToLocalTime(@SysTime, g_pSharedMemory);
end;

procedure TimerRoutine(pDeviceObject:PDEVICE_OBJECT; pContext:PVOID); stdcall;
begin
    UpdateTime;
end;

{清理过程--释放资源}
procedure Cleanup(pDeviceObject:PDEVICE_OBJECT); stdcall;
begin
    if g_fTimerStarted then
    begin
      IoStopTimer(pDeviceObject);
      DbgPrint('SharingMemory: Timer stopped'#13#10);
    end;

    if (g_pUserAddress <> nil) and (g_pMdl <> nil) then
    begin
      MmUnmapLockedPages(g_pUserAddress, g_pMdl);
      DbgPrint('SharingMemory: Memory at address %08X unmapped'#13#10,
               g_pUserAddress);
      g_pUserAddress := nil;
    end;

    if g_pMdl <> nil then
    begin
      IoFreeMdl(g_pMdl);
      DbgPrint('SharingMemory: MDL at address %08X freed'#13#10,
               g_pMdl);
      g_pMdl := nil;
    end;

    if g_pSharedMemory <> nil then
    begin
      ExFreePool(g_pSharedMemory);
      DbgPrint('SharingMemory: Memory at address %08X released'#13#10,
               g_pSharedMemory);
      g_pSharedMemory := nil;
    end;
end;

function DispatchCleanup(pDeviceObject:PDEVICE_OBJECT; p_Irp:PIRP): NTSTATUS; stdcall;
begin
    DbgPrint(#13#10'SharingMemory: Entering DispatchCleanup'#13#10);
    Cleanup(pDeviceObject);

    p_Irp^.IoStatus.Status := STATUS_SUCCESS;
    p_Irp^.IoStatus.Information := 0;
    IofCompleteRequest(p_Irp, IO_NO_INCREMENT);

    DbgPrint('SharingMemory: Leaving DispatchCleanup'#13#10);
    result := STATUS_SUCCESS;
end;

function DispatchCreateClose(p_DeviceObject:PDEVICE_OBJECT; p_Irp:PIRP): NTSTATUS; stdcall;
begin
    p_Irp^.IoStatus.Status := STATUS_SUCCESS;
    p_Irp^.IoStatus.Information := 0;

    IofCompleteRequest(p_Irp, IO_NO_INCREMENT);

    result := STATUS_SUCCESS;
end;

function DispatchControl(p_DeviceObject: PDEVICE_OBJECT; p_Irp:PIRP): NTSTATUS; stdcall;
label
    SafePlace;
var
    dwContext:DWORD;
    psl:PIO_STACK_LOCATION;
    IOCTL_GIVE_ME_YOUR_MEMORY: DWORD;
    pSystemBuffer: PVOID;
begin
    DbgPrint(#13#10'SharingMemory: Entering DispatchControl'#13#10);
    IOCTL_GIVE_ME_YOUR_MEMORY := CTL_CODE(FILE_DEVICE_UNKNOWN,
                                          $800, METHOD_BUFFERED,
                                          FILE_READ_ACCESS);
    p_Irp^.IoStatus.Status := STATUS_UNSUCCESSFUL;
    p_Irp^.IoStatus.Information := 0;
    psl := IoGetCurrentIrpStackLocation(p_Irp); {取IRP的stack location的指针}
    if psl^.Parameters.DeviceIoControl.IoControlCode = IOCTL_GIVE_ME_YOUR_MEMORY then
    begin
      {是我们控制码就开始处理}
      if psl^.Parameters.DeviceIoControl.OutputBufferLength >= sizeof(PVOID) then
      begin
        g_pSharedMemory := ExAllocatePool(NonPagedPool, PAGE_SIZE);
        if g_pSharedMemory <> nil then
        begin
          DbgPrint('SharingMemory: %X bytes of nonpaged memory allocated at address %08X'#13#10,
                   PAGE_SIZE, g_pSharedMemory);
          g_pMdl := IoAllocateMdl(g_pSharedMemory, PAGE_SIZE,
                                  false, false, nil);
          if g_pMdl <> nil then
          begin
            DbgPrint('SharingMemory: MDL allocated at address %08X'#13#10,