Question

我有一个程序，其中父进程生成子进程，然后与之进行通信。

父进程是一个VB应用程序，子进程是一个C＃控制台应用程序。

父进程（暂时删除了错误处理）：

Private Function InitialieExtConversionProcess() As Boolean

Dim lResult As Long
Dim SA As SECURITY_ATTRIBUTES
Dim sInfo As STARTUPINFO
Dim sCommandLine As String

SA.bInheritHandle = True

'Create the pipe that Hyperspace will write to
lResult = CreatePipe(m_pipeOut.hReadPipe, m_pipeOut.hWritePipe, SA, 0)

'Ensure that the read handle is not inherited
lResult = SetHandleInformation(m_pipeOut.hReadPipe, HANDLE_FLAG_INHERIT, 0)


'Create the pipe that Hyperspace will read from
lResult = CreatePipe(m_pipeIn.hReadPipe, m_pipeIn.hWritePipe, SA, 0)

'Ensure that the write handle is not inherited
lResult = SetHandleInformation(m_pipeIn.hWritePipe, HANDLE_FLAG_INHERIT, 0)

'Create the external process
sCommandLine = "some_path\ExtProcess.exe"
sInfo.hStdInput = m_pipeIn.hReadPipe
sInfo.hStdError = m_pipeOut.hWritePipe
sInfo.hStdOutput = m_pipeOut.hWritePipe
sInfo.dwFlags = STARTF_USESTDHANDLES
lResult = CreateProcess(0, sCommandLine, 0, 0, 1, CREATE_NO_WINDOW, 0, 0,   sInfo, m_pInfo)

InitialieExtConversionProcess = True

End Function

然后我使用WriteFile和ReadFile来编写和读取子进程

lResult = WriteFile(m_pipeIn.hWritePipe, sOutput, Len(sOutput), 0, 0)
...
lResult = ReadFile(m_pipeOut.hReadPipe, sInput, Len(sInput), 0, ByVal 0)

子进程（C＃控制台应用程序）：

IntPtr hOutput = GetStdHandle(STD_OUTPUT_HANDLE);
IntPtr hInput = GetStdHandle(STD_INPUT_HANDLE);              
AnonymousPipeClientStream pipeClientRead = new     AnonymousPipeClientStream(PipeDirection.In, hInput.ToString());
AnonymousPipeClientStream pipeClientWrite = new AnonymousPipeClientStream(PipeDirection.Out, hOutput.ToString());

arr = new byte[300];
pipeClientRead.Read(arr, 0, 300);
...
arr = Encoding.ASCII.GetBytes(strResult);
pipeClientWrite.Write(arr, 0, arr.Length);
pipeClientWrite.Flush();

这里的沟通正如预期的那样。我能够成功读写。

当父进程关闭时，子进程中的Read操作返回false。但是当子进程自行杀死时（如下所示），父进程继续等待ReadFile。为什么会这样？

arr = new byte[300];
pipeClientRead.Read(arr, 0, 300);
--->Environment.exit(1);<----
arr = Encoding.ASCII.GetBytes(strResult);
pipeClientWrite.Write(arr, 0, arr.Length);
pipeClientWrite.Flush();

我密切关注这个msdn示例： https://msdn.microsoft.com/en-us/library/windows/desktop/ms682499(v=vs.85).aspx

Answer 1

我发现了什么是错误的。

我需要在创建后关闭子进程的句柄。

lResult = CreateProcess(0, sCommandLine, 0, 0, 1, CREATE_NO_WINDOW, 0, 0,   sInfo, m_pInfo)
CloseHnadle(m_pipeIn.hReadPipe)
CloseHandle(m_pipeOut.hWritePipe)

匿名管道：父进程中的ReadFile会在子进程被终止时继续等待

1 个答案: