检测.NET应用程序中重定向控制台输出中的关闭管道

为了解决这个问题,我必须在win32文件句柄上编写自己的基本流实现。这并不十分困难,因为我不需要实现异步支持、缓冲或查找。

不幸的是,需要使用不安全的代码,但对于将在本地完全信任的情况下运行的控制台应用程序来说,这通常不是问题。

核心流程如下:

class HandleStream : Stream
{
    SafeHandle _handle;
    FileAccess _access;
    bool _eof;

    public HandleStream(SafeHandle handle, FileAccess access)
    {
        _handle = handle;
        _access = access;
    }

    public override bool CanRead
    {
        get { return (_access & FileAccess.Read) != 0; }
    }

    public override bool CanSeek
    {
        get { return false; }
    }

    public override bool CanWrite
    {
        get { return (_access & FileAccess.Write) != 0; }
    }

    public override void Flush()
    {
        // use external buffering if you need it.
    }

    public override long Length
    {
        get { throw new NotSupportedException(); }
    }

    public override long Position
    {
        get { throw new NotSupportedException(); }
        set { throw new NotSupportedException(); }
    }

    static void CheckRange(byte[] buffer, int offset, int count)
    {
        if (offset < 0 || count < 0 || (offset + count) < 0
            || (offset + count) > buffer.Length)
            throw new ArgumentOutOfRangeException();
    }

    public bool EndOfStream
    {
        get { return _eof; }
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        CheckRange(buffer, offset, count);
        int result = ReadFileNative(_handle, buffer, offset, count);
        _eof |= result == 0;
        return result;
    }

    public override void Write(byte[] buffer, int offset, int count)
    {
        int notUsed;
        Write(buffer, offset, count, out notUsed);
    }

    public void Write(byte[] buffer, int offset, int count, out int written)
    {
        CheckRange(buffer, offset, count);
        int result = WriteFileNative(_handle, buffer, offset, count);
        _eof |= result == 0;
        written = result;
    }

    public override long Seek(long offset, SeekOrigin origin)
    {
        throw new NotSupportedException();
    }

    public override void SetLength(long value)
    {
        throw new NotSupportedException();
    }

    [return: MarshalAs(UnmanagedType.Bool)]
    [DllImport("kernel32", SetLastError=true)]
    static extern unsafe bool ReadFile(
        SafeHandle hFile, byte* lpBuffer, int nNumberOfBytesToRead,
        out int lpNumberOfBytesRead, IntPtr lpOverlapped);

    [return: MarshalAs(UnmanagedType.Bool)]
    [DllImport("kernel32.dll", SetLastError=true)]
    static extern unsafe bool WriteFile(
        SafeHandle hFile, byte* lpBuffer, int nNumberOfBytesToWrite, 
        out int lpNumberOfBytesWritten, IntPtr lpOverlapped);

    unsafe static int WriteFileNative(SafeHandle hFile, byte[] buffer, int offset, int count)
    {
        if (buffer.Length == 0)
            return 0;

        fixed (byte* bufAddr = &buffer[0])
        {
            int result;
            if (!WriteFile(hFile, bufAddr + offset, count, out result, IntPtr.Zero))
            {
                // Using Win32Exception just to get message resource from OS.
                Win32Exception ex = new Win32Exception(Marshal.GetLastWin32Error());
                int hr = ex.NativeErrorCode | unchecked((int) 0x80000000);
                throw new IOException(ex.Message, hr);
            }

            return result;
        }
    }

    unsafe static int ReadFileNative(SafeHandle hFile, byte[] buffer, int offset, int count)
    {
        if (buffer.Length == 0)
            return 0;

        fixed (byte* bufAddr = &buffer[0])
        {
            int result;
            if (!ReadFile(hFile, bufAddr + offset, count, out result, IntPtr.Zero))
            {
                Win32Exception ex = new Win32Exception(Marshal.GetLastWin32Error());
                int hr = ex.NativeErrorCode | unchecked((int) 0x80000000);
                throw new IOException(ex.Message, hr);
            }
            return result;
        }
    }
}

BufferedStream 如果需要,可以围绕它进行缓冲,但是对于控制台输出, TextWriter 无论如何都将进行字符级缓冲,并且只在换行时刷新。

河流泛滥 Win32Exception 提取错误消息,而不是调用 FormatMessage 本身。

在这个流的基础上,我能够为控制台I/O编写一个简单的包装器:

static class ConsoleStreams
{
    enum StdHandle
    {
        Input = -10,
        Output = -11,
        Error = -12,
    }

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern IntPtr GetStdHandle(int nStdHandle);  

    static SafeHandle GetStdHandle(StdHandle h)
    {
        return new SafeFileHandle(GetStdHandle((int) h), true);
    }

    public static HandleStream OpenStandardInput()
    {
        return new HandleStream(GetStdHandle(StdHandle.Input), FileAccess.Read);
    }

    public static HandleStream OpenStandardOutput()
    {
        return new HandleStream(GetStdHandle(StdHandle.Output), FileAccess.Write);
    }

    public static HandleStream OpenStandardError()
    {
        return new HandleStream(GetStdHandle(StdHandle.Error), FileAccess.Write);
    }

    static TextReader _in;
    static StreamWriter _out;
    static StreamWriter _error;

    public static TextWriter Out
    {
        get
        {
            if (_out == null)
            {
                _out = new StreamWriter(OpenStandardOutput());
                _out.AutoFlush = true;
            }
            return _out;
        }
    }

    public static TextWriter Error
    {
        get
        {
            if (_error == null)
            {
                _error = new StreamWriter(OpenStandardError());
                _error.AutoFlush = true;
            }
            return _error;
        }
    }

    public static TextReader In
    {
        get
        {
            if (_in == null)
                _in = new StreamReader(OpenStandardInput());
            return _in;
        }
    }
}

最后一个结果是,在管道的另一端终止连接后,写入控制台输出会导致一个很好的异常消息:

管道正在关闭

通过捕捉和忽略 IOException 在最外面的一层,我看起来很好去。

我同意,如果没有错误报告,控制台流对您没有任何用处。我很好奇为什么他们选择不考虑这个。

对于那些想跟随的人,请查看下面的链接,找到一个相当古老但仍然相关的uuconsolestream列表…

http://www.123aspx.com/Rotor/RotorSrc.aspx?rot=42958