类库大魔王
类库大魔王 懒惰,傲慢,以及无耐心

关于OutputDebugString 的模拟

这篇文章中可以知道,通过简单的几步设置,便可模拟OutputDebugString,可以用下面的代码描述:

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struct dbwin_buffer {
        DWORD   dwProcessId;
        char    data[4096-sizeof(DWORD)];
};

void MyOutputDebugString(LPCTSTR lpOutputString)
{
    static HANDLE hMutex = OpenMutex(MUTEX_ALL_ACCESS,      // request full access
                 FALSE,                 // handle not inheritable
                 "DBWinMutex");
    if(hMutex != NULL)
    {
      TSharedMem SharedMem("DBWIN_BUFFER", sizeof(struct dbwin_buffer));
      if(!SharedMem.IsUnique())
      {
        HANDLE hBufEvent, hDataEvent;
        hBufEvent = OpenEvent(EVENT_ALL_ACCESS, FALSE, "DBWIN_BUFFER_READY");
        if(hBufEvent != NULL)
        {
          hDataEvent = OpenEvent(EVENT_ALL_ACCESS, FALSE, "DBWIN_DATA_READY");
          if(hDataEvent!=NULL)
          {               
            if(WaitForSingleObject(hBufEvent, 10000)==WAIT_OBJECT_0)
            {
              struct dbwin_buffer *buffer = (struct dbwin_buffer *)SharedMem.Buffer();
              DWORD dwPID = GetCurrentProcessId();
              memcpy(buffer, &dwPID, sizeof(DWORD));
              lstrcpyn(buffer->data, lpOutputString, 4096-sizeof(DWORD));
              SetEvent(hDataEvent);
            }                    
            CloseHandle(hDataEvent);
          }                         //if(hDataEvent != NULL)
          CloseHandle(hBufEvent);
        }                        //if(hBufEvent != NULL)
      }                          //if(!SharedMem.IsUnique())
      ReleaseMutex(hMutex);  
    }                         //if(hMutex != NULL)
}

但,事实上,我在VS.NET2003 的环境下,并不能向它的debugger 输出任何内容,而且检测到并没有这个内存映射区域,也没有这2个Event,但同时,它仍能很好地拦截系统OutputDebugString 的输出,看来它是通过API Hook 之类的其它手段了。但我没有验证,尽管上面这段代码和OutputDebugString 产生的输出都能很好地被LLYF DebugCapture 这些程序拦截到。

感觉本文不错,不妨小额鼓励我一下!
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