【问题标题】:How do you send a named pipe string from umnanaged to managed code space?如何将命名管道字符串从非托管代码空间发送到托管代码空间?
【发布时间】:2011-03-01 05:33:55
【问题描述】:

我似乎遇到了命名管道 101 问题。我有一个非常简单的设置来连接从 C++ 非托管应用程序传输到 C# 托管应用程序的单一命名管道。管道连接,但我无法通过管道发送“消息”,除非我关闭似乎刷新缓冲区并传递消息的句柄。好像消息被屏蔽了。我尝试颠倒客户端/服务器的角色并使用不同的标志组合调用它们,但没有任何运气。我可以轻松地从 C# 托管到 C++ 非托管的另一个方向发送消息。有没有人有任何见解。你们中的任何人都可以成功地将消息从 C++ 非托管发送到 C# 托管吗?我可以找到很多内部管理或非管理管道的示例,但没有管理到/来自未管理的内部管理 - 只是声称能够做到。

在清单中,为了清楚起见,我省略了很多包装材料。我认为相关的关键位是管道连接/创建/读写方法。不要太担心这里的阻塞/线程。

C# 服务器端

    // This runs in its own thread and so it is OK to block
    private void ConnectToClient()
    {
        // This server will listen to the sending client
        if (m_InPipeStream == null)
        {
            m_InPipeStream =
                new NamedPipeServerStream("TestPipe", PipeDirection.In, 1);
        }

        // Wait for client to connect to our server
        m_InPipeStream.WaitForConnection();

        // Verify client is running
        if (!m_InPipeStream.IsConnected)
        {
            return;
        }

        // Start listening for messages on the client stream
        if (m_InPipeStream != null && m_InPipeStream.CanRead)
        {
            ReadThread = new Thread(new ParameterizedThreadStart(Read));
            ReadThread.Start(m_InPipeStream);
        }
    }


    // This runs in its own thread and so it is OK to block
    private void Read(object serverObj)
    {
        NamedPipeServerStream pipeStream = (NamedPipeServerStream)serverObj;
        using (StreamReader sr = new StreamReader(pipeStream))
        {
            while (true)
            {
                string buffer = "" ;
                try
                {
                    // Blocks here until the handle is closed by the client-side!!
                    buffer = sr.ReadLine();   // <<<<<<<<<<<<<<  Sticks here
                }
                catch
                {
                    // Read error
                    break;
                }

                // Client has disconnected?
                if (buffer == null || buffer.Length == 0)
                    break;

                // Fire message received event if message is non-empty
                if (MessageReceived != null && buffer != "")
                {
                    MessageReceived(buffer);
                }
            }
        }
    }

C++ 客户端

    // Static - running in its own thread.
    DWORD CNamedPipe::ListenForServer(LPVOID arg)
    {
        // The calling app (this) is passed as the parameter
        CNamedPipe* app = (CNamedPipe*)arg;

        // Out-Pipe: connect as a client to a waiting server
        app->m_hOutPipeHandle =
        CreateFile("\\\\.\\pipe\\TestPipe",
               GENERIC_WRITE,
               0,
               NULL,
               OPEN_EXISTING,
               FILE_ATTRIBUTE_NORMAL,
               NULL);
        // Could not create handle
        if (app->m_hInPipeHandle == NULL ||
            app->m_hInPipeHandle == INVALID_HANDLE_VALUE)
        {
            return 1;
        }

        return 0;
    }


    // Sends a message to the server
    BOOL CNamedPipe::SendMessage(CString message)
    {
    DWORD dwSent;

        if (m_hOutPipeHandle == NULL ||
            m_hOutPipeHandle == INVALID_HANDLE_VALUE)
        {
            return FALSE;
        }
        else
        {
            BOOL bOK =
                WriteFile(m_hOutPipeHandle,
                          message, message.GetLength()+1, &dwSent, NULL);
            //FlushFileBuffers(m_hOutPipeHandle);             // <<<<<<< Tried this
            return (!bOK || (message.GetLength()+1) != dwSent) ? FALSE : TRUE;
        }
    }


    // Somewhere in the Windows C++/MFC code...
    ...
    // This write is non-blocking. It just passes through having loaded the pipe.
    m_pNamedPipe->SendMessage("Hi de hi");
    ...

【问题讨论】:

    标签: c# c++ windows mfc named-pipes


    【解决方案1】:

    sr.ReadLine() 期望看到换行符以知道行尾。因为它既不接收新行也不接收流尾,它等待更多。 试试:

    m_pNamedPipe->SendMessage("Hi de hi\n")
    

    或一些 sr.Read() 方法。

    【讨论】:

    • 就是这样!现在一切正常,非常感谢。我完全忘记了换行的需要,我太专注于管道的机制(第 1 层)我忘记了消息格式(第 2 层)。
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