关于跨进程使用回调函数的研究：以跨进程获取Richedit中RTF流为例。

建议先参考我上次写的博文跨进程获取Richedit中Text： 获得QQ聊天输入框中的内容

    拿到这个问题，我习惯性地会从VCL内核开始分析。找到TRichEdit声明的单元，分析TRichEdit保存为RTF流的代码。（分析VCL内核代码方便了解Windows标准API的封装和使用）     打开声明TRichEdit的ComCtrls.pas单元。搜索"TRichEditStrings"（保存流使用TRichEdit.Lines.SaveToStream方法，TRichEditStrings为TRichEdit.Line的类型）   TRichEditStrings = class(TStrings)
  private
    RichEdit: TCustomRichEdit;
    FPlainText: Boolean;
    FConverter: TConversion;
    procedure EnableChange(const Value: Boolean);
  protected
    function Get(Index: Integer): string; override;
    function GetCount: Integer; override;
    procedure Put(Index: Integer; const S: string); override;
    procedure SetUpdateState(Updating: Boolean); override;
    procedure SetTextStr(const Value: string); override;
  public
    destructor Destroy; override;
    procedure Clear; override;
    procedure AddStrings(Strings: TStrings); override;
    procedure Delete(Index: Integer); override;
    procedure Insert(Index: Integer; const S: string); override;
    procedure LoadFromFile(const FileName: string); override;
    procedure LoadFromStream(Stream: TStream); override;
    procedure SaveToFile(const FileName: string); override;
    procedure SaveToStream(Stream: TStream); override;
    property PlainText: Boolean read FPlainText write FPlainText;
  end; 寻找到SaveToStream的方法  procedure TRichEditStrings.SaveToStream(Stream: TStream); var    EditStream: TEditStream;
   TextType: Longint;    StreamInfo: TRichEditStreamInfo;    Converter: TConversion; begin    if FConverter <> nil then Converter := FConverter    else Converter := RichEdit.DefaultConverter.Create;    StreamInfo.Stream := Stream;    StreamInfo.Converter := Converter;    try      with EditStream do      begin        dwCookie := LongInt(Pointer(@StreamInfo));        pfnCallBack := @StreamSave;        dwError := 0;      end;      if PlainText then TextType := SF_TEXT      else TextType := SF_RTF;      SendMessage(RichEdit.Handle, EM_STREAMOUT, TextType, Longint(@EditStream));      if EditStream.dwError <> 0 then        raise EOutOfResources.Create(sRichEditSaveFail);    finally      if FConverter = nil then Converter.Free;    end; end;
看关键的一句：“ SendMessage(RichEdit.Handle, EM_STREAMOUT, TextType, Longint(@EditStream));” 这下明白了，获取RTF关键的是向Richedit发送EM_STREAMOUT消息。   关于EM_STREAMOUT消息想了解更多可以查阅MSDN：   EM_STREAMOUT      wParam = (WPARAM) (UINT) uFormat ;      lParam = (LPARAM) (EDITSTREAM FAR *) lpStream ; 进程间的内存地址是相对的。 A进程$00450000内存地址值为34，那么B进程$00450000内存地址就不一定是34了。  在发送EM_STREAMOUT消息时，lParam参数表示的地址就是相对于目标进程的。  跨进程访问内存主要用到如下API函数：  GetWindowThreadProcessId -- 根据窗体句柄获得其所在的线程、进程ID OpenProcess -- 打开进程并返回访问句柄 VirtualAllocEx -- 分配进程虚拟内存空间，返回所分配的内存地址。 VirtualFreeEx -- 释放进程虚拟内存空间 ReadProcessMemory、WriteProcessMemory -- 读写进程内存数据。 和以往不一样，这个消息用到了回调函数“ pfnCallBack := @StreamSave;” 函数也是存放在内存中的数据（一些机器指令），访问函数同样会碰到进程间不能直接访问内存的问题。 也就是说：需要将函数数据写入到目标进程中，才能被正常调用。  【如何获得函数的数据？】
function MyFunction(A, B: Integer): Integer;
begin
  Result := A + B;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Edit1.Text := IntToStr(Integer(@MyFunction));
end; 函数地址容易得到。调试如上代码，点击按钮获得函数地址，打开CPU查看器（Ctrl+Alt+C），定位函数地址。 这样将看到如图： 03C2 --------add eax,edx
7105 --------jon +$05
E81f43FBFF --call @IntOver
C3 --------- ret 前面就是十六进制数据，后面就是该数据表示的机器指令。 这些就是函数数据，将它写入到目标进程就可以调用了！！！ 两个进程载入相同的DLL那么DLL的函数地址则是相同的，也就是说API函数SendMessage在A、B两个进程的地址一致。有了这点，利用系统API函数SendMessage发送WM_COPYDATA消息就可以交互数据了。 当然，如果指令里有相对地址的访问也得克隆才成，比如上面的" E81f43FBFF --call @IntOver "就用到了相对地址。囧  可以将编译条件中“溢出、范围、IO"检查都关掉，减少相对地址的访问。 跨进程之前，先在本进程实验通过再说：  【第一个实验：正常调用回调函数】  function MySendMessage(hWnd: HWND; Msg: UINT; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;
begin
  Result := SendMessage(hWnd, Msg, wParam, lParam);
end;

type
  TMySendMessage = function (hWnd: HWND; Msg: UINT; wParam: WPARAM; lParam: LPARAM): LRESULT; stdcall;

var vMySendMessage: TMySendMessage = MySendMessage;

function EditStreamCallBack(dwCookie: Longint; pbBuff: PByte;
  cb: Longint; var pcb: Longint): Longint; stdcall;
var
  vCopyDataStruct: TCopyDataStruct;
begin
  pcb := cb;
  vCopyDataStruct.dwData := 0;
  vCopyDataStruct.cbData := cb;
  vCopyDataStruct.lpData := pbBuff;
  vMySendMessage(dwCookie, WM_COPYDATA, 0, Integer(@vCopyDataStruct));
  Result := ERROR_SUCCESS;
end;

procedure TForm1.Button3Click(Sender: TObject);
var
  vEditStream: TEditStream;
begin
  vEditStream.dwCookie := Handle;
  vEditStream.dwError := 0;
  vEditStream.pfnCallback := EditStreamCallBack;
  FMemoryStream := TMemoryStream.Create;
  SendMessage(RichEdit1.Handle, EM_STREAMOUT, SF_RTF, Integer(@vEditStream));
  FMemoryStream.Position := 0;
  Memo1.Lines.LoadFromStream(FMemoryStream);
  FMemoryStream.Free;
end; “ EditStreamCallBack“就是要复制到目标进程的函数数据。 调试通过后，获得其十六进制数据。  
{ 55          } PUSH EBP { 8BEC        } MOV EBP,ESP
{ 83C4F4      } ADD ESP,$F4
{ 8B4510      } MOV EAX,DWORD PTR [EBP+$10]
{ 8B5514      } MOV EDX,DWORD PTR [EBP+$14]
{ 8902        } MOV DWORD PTR [EDX],EAX
{ 33D2        } XOR EDX,EDX
{ 8955F4      } MOV DWORD PTR [EBP-$0C],EDX
{ 8945F8      } MOV DWORD PTR [EBP-$08],EAX
{ 8B450C      } MOV EAX,DWORD PTR [EBP+$0C]
{ 8945FC      } MOV DWORD PTR [EBP-$04],EAX
{ 8D45F4      } LEA EAX,DWORD PTR [EBP-$0C]
{ 50          } PUSH EAX
{ 6A00        } PUSH $00
{ 6A4A        } PUSH $4A
{ 8B4508      } MOV EAX,DWORD PTR [EBP+$08]
{ 50          } PUSH EAX
{ FF15B88C4500} CALL DWORD PTR [$00458CB8]
{ 33C0        } XOR EAX,EAX
{ 8BE5        } MOV ESP,EBP
{ 5D          } POP EBP
{ C21000      } RET $0010 其中 { FF15B88C4500} CALL DWORD PTR [$00458CB8]里的 [$00458CB8] 里是相对地址，不同的调试环境会不一样。 我们这里 [$00458CB8]里存放的就是系统API函数SendMessage的地址。 【第二个实验：拼装函数数据】 const
  EditStreamCallBackBytes =
#$55 + //                     PUSH EBP
#$8B#$EC + //                 MOV EBP,ESP
#$83#$C4#$F4 + //             ADD ESP,$F4
#$8B#$45#$10 + //             MOV EAX,DWORD PTR [EBP+$10]
#$8B#$55#$14 + //             MOV EDX,DWORD PTR [EBP+$14]
#$89#$02 + //                 MOV DWORD PTR [EDX],EAX
#$33#$D2 + //                 XOR EDX,EDX
#$89#$55#$F4 + //             MOV DWORD PTR [EBP-$0C],EDX
#$89#$45#$F8 + //             MOV DWORD PTR [EBP-$08],EAX
#$8B#$45#$0C + //             MOV EAX,DWORD PTR [EBP+$0C]
#$89#$45#$FC + //             MOV DWORD PTR [EBP-$04],EAX
#$8D#$45#$F4 + //             LEA EAX,DWORD PTR [EBP-$0C]
#$50 + //                     PUSH EAX
#$6A#$00 + //                 PUSH $00
#$6A#$4A + //                 PUSH $4A
#$8B#$45#$08 + //             MOV EAX,DWORD PTR [EBP+$08]
#$50 + //                     PUSH EAX
#$FF#$15#$00#$00#$00#$00 + // CALL DWORD PTR [H] -- String Index:43
#$33#$C0 + //                 XOR EAX,EAX
#$8B#$E5 + //                 MOV ESP,EBP
#$5D + //                     POP EBP
#$C2#$10#$00 + //             RET $0010
#$00#$00#$00#$00 + //         Api Address -- String Index:55
#$00#$00#$00#$00 + //         _editstream : dwCookie -- String Index:59
#$00#$00#$00#$00 + //         _editstream : dwError
#$00#$00#$00#$00; //          _editstream : pfnCallback

type
  TVclApi = packed record //JMP DWORD PTR [$HHHHHHHH]
    rJmp: Word; // FF 25
    rAddress: PInteger; // API实际地址
  end;
  PVclApi = ^TVclApi;

procedure TForm1.Button2Click(Sender: TObject);
type
  PEditStream = ^TEditStream;
var
  vEditStreamCallBack: string;
begin
  vEditStreamCallBack := EditStreamCallBackBytes;
  PInteger(@vEditStreamCallBack[43])^ := Integer(@vEditStreamCallBack[55]);
  PInteger(@vEditStreamCallBack[55])^ := PVclApi(@SendMessage)^.rAddress^;
  PEditStream(@vEditStreamCallBack[59])^.dwCookie := Handle;
  PEditStream(@vEditStreamCallBack[59])^.pfnCallback := @vEditStreamCallBack[1];
  FMemoryStream := TMemoryStream.Create;
  SendMessage(RichEdit1.Handle, EM_STREAMOUT, SF_RTF, Integer(@vEditStreamCallBack[59]));
  FMemoryStream.Position := 0;
  Memo1.Lines.LoadFromStream(FMemoryStream);
  FMemoryStream.Free;
end; VCL中调用API时使用JMP指令。 ” PVclApi(@SendMessage)^.rAddress^”就是获得SendMessage实际地址。  好了，本进程的实验做完后，我们就要拿另一个进程开刀了。 封装一下，最终代码如下：

uses RichEdit;

{$WARN SYMBOL_DEPRECATED OFF}

type
  TRichEditStreamReader = class
  private
    FStream: TStream;
    FHandle: THandle;
  protected
    procedure WndProc(var Message: TMessage); virtual;
  public
    constructor Create(AStream: TStream);
    destructor Destroy; override;
    property Handle: THandle read FHandle;
  end;

{ TRichEditStreamReader }

constructor TRichEditStreamReader.Create(AStream: TStream);
begin
  FStream := AStream;
  FHandle := AllocateHWnd(WndProc);
end;

destructor TRichEditStreamReader.Destroy;
begin
  DeallocateHWnd(FHandle);
  inherited;
end;

procedure TRichEditStreamReader.WndProc(var Message: TMessage);
begin
  case Message.Msg of
    WM_COPYDATA:
      begin
        if not Assigned(FStream) then Exit;
        FStream.Write(PCopyDataStruct(Message.LParam)^.lpData^,
          PCopyDataStruct(Message.LParam)^.cbData);
      end;
  end;
end;

function Process_ReadRichEditStream(
  AHandle: THandle; AStream: TStream; AFormat: Longword): Boolean;
type
  TVclApi = packed record //JMP DWORD PTR [$HHHHHHHH]
    rJmp: Word; // FF 25
    rAddress: PInteger; // API实际地址
  end;
  PVclApi = ^TVclApi;
const
  EditStreamCallBackBytes =
#$55 + //                     PUSH EBP
#$8B#$EC + //                 MOV EBP,ESP
#$83#$C4#$F4 + //             ADD ESP,$F4
#$8B#$45#$10 + //             MOV EAX,DWORD PTR [EBP+$10]
#$8B#$55#$14 + //             MOV EDX,DWORD PTR [EBP+$14]
#$89#$02 + //                 MOV DWORD PTR [EDX],EAX
#$33#$D2 + //                 XOR EDX,EDX
#$89#$55#$F4 + //             MOV DWORD PTR [EBP-$0C],EDX
#$89#$45#$F8 + //             MOV DWORD PTR [EBP-$08],EAX
#$8B#$45#$0C + //             MOV EAX,DWORD PTR [EBP+$0C]
#$89#$45#$FC + //             MOV DWORD PTR [EBP-$04],EAX
#$8D#$45#$F4 + //             LEA EAX,DWORD PTR [EBP-$0C]
#$50 + //                     PUSH EAX
#$6A#$00 + //                 PUSH $00
#$6A#$4A + //                 PUSH $4A
#$8B#$45#$08 + //             MOV EAX,DWORD PTR [EBP+$08]
#$50 + //                     PUSH EAX
#$FF#$15#$00#$00#$00#$00 + // CALL DWORD PTR [H] -- String Index:43
#$33#$C0 + //                 XOR EAX,EAX
#$8B#$E5 + //                 MOV ESP,EBP
#$5D + //                     POP EBP
#$C2#$10#$00 + //             RET $0010
#$00#$00#$00#$00 + //         Api Address -- String Index:55
#$00#$00#$00#$00 + //         _editstream : dwCookie -- String Index:59
#$00#$00#$00#$00 + //         _editstream : dwError
#$00#$00#$00#$00; //          _editstream : pfnCallback
type
  PEditStream = ^TEditStream;
var
  vEditStreamCallBack: string;
  vProcessId: DWORD;
  vProcess: THandle;
  vPointer: Pointer;
  vNumberOfBytesRead: Cardinal;
  vRichEditStreamReader: TRichEditStreamReader;
begin
  Result := False;
  if not Assigned(AStream) then Exit;
  if not IsWindow(AHandle) then Exit;
  GetWindowThreadProcessId(AHandle, @vProcessId);
  vProcess := OpenProcess(PROCESS_VM_OPERATION or PROCESS_VM_READ or
    PROCESS_VM_WRITE, False, vProcessId);
  try
    vPointer := VirtualAllocEx(vProcess, nil, 4096, MEM_RESERVE or MEM_COMMIT,
      PAGE_READWRITE);
    vRichEditStreamReader := TRichEditStreamReader.Create(AStream);
    try
      vEditStreamCallBack := EditStreamCallBackBytes;
      PInteger(@vEditStreamCallBack[43])^ := Integer(vPointer) + 55 - 1;
      PInteger(@vEditStreamCallBack[55])^ := PVclApi(@SendMessage)^.rAddress^;
      PEditStream(@vEditStreamCallBack[59])^.dwCookie := vRichEditStreamReader.Handle;
      PEditStream(@vEditStreamCallBack[59])^.pfnCallback := vPointer;
      WriteProcessMemory(vProcess, vPointer, @vEditStreamCallBack[1],
        Length(vEditStreamCallBack), vNumberOfBytesRead);
      SendMessage(AHandle, EM_STREAMOUT, AFormat, Integer(Integer(vPointer) + 59 - 1));
    finally
      vRichEditStreamReader.Free;
      VirtualFreeEx(vProcess, vPointer, 0, MEM_RELEASE);
    end;
  finally
    CloseHandle(vProcess);
  end;
end; { Process_ReadRichEditStream }

procedure TForm1.Button1Click(Sender: TObject);
var
  vHandle: THandle;
  vMemoryStream: TMemoryStream;
begin
  vHandle := FindWindow('WordPadClass', nil);
  if vHandle = 0 then Exit;
  vHandle := FindWindowEx(vHandle, 0, 'RICHEDIT50W', nil);
  if vHandle = 0 then Exit;
  vMemoryStream := TMemoryStream.Create;
  try
    Process_ReadRichEditStream(vHandle, vMemoryStream, SF_RTF);
    vMemoryStream.Position := 0;
    RichEdit1.PlainText := False;
    RichEdit1.Lines.LoadFromStream(vMemoryStream);
  finally
    vMemoryStream.Free;
  end;
end;