今天忽然明白了运行时程序补丁的原理：

补丁程序运行，启动应用程序，此时补丁程序利用OpenProcess，WriteProcessMemory写入某个内存即可实现动态Patch程序。Like this：

{....}

var

 WindowName: Integer;

 ProcessId: Integer;

 ThreadId: Integer;

 buf: PChar;

 HandleWindow: Integer;

 Write: Cardinal;

 

{....}

const

 WindowTitle = 'a program name';

 Address = $A662D6;

 PokeValue = $4A;

 NumberOfBytes = 2;

 

{....}

procedure TForm1.Button1Click(Sender: TObject);

begin

 WindowName := FindWindow(nil, WindowTitle);

 if WindowName = 0 then

 begin

   MessageDlg('Program not running.', mtWarning, [mbOK], 0);

 end;

 ThreadId := GetWindowThreadProcessId(WindowName, @ProcessId);

 HandleWindow := OpenProcess(PROCESS_ALL_ACCESS, False, ProcessId);

 GetMem(buf, 1);

 buf^ := Chr(PokeValue);

 WriteProcessMemory(HandleWindow, ptr(Address), buf, NumberOfBytes, Write);

 FreeMem(buf);

 CloseHandle(HandleWindow);

end;