无法打开 pipe。 GLE=2

Question

I'm trying to interact with pipes: C# server -> C++ client

I don't need something really complex, if the server is able to send data to client it's more than enough

I don't know why I'm getting this error: Could not open pipe. GLE=2

I'm using Microsoft examples C++ client and C# server

This is what I'm trying to do:

C# SERVER

    private void Form1_Load(object sender, EventArgs e)
    {
        Thread t = new Thread(Server);
        t.IsBackground = true;
        t.Start();
    }

    private void Server()
    {
        while (true)
        {
            using (NamedPipeServerStream pipeServer = new NamedPipeServerStream("mynamedpipe", PipeDirection.Out))
            {
                Console.WriteLine("NamedPipeServerStream object created.");

                // Wait for a client to connect
                Console.Write("Waiting for client connection...");
                pipeServer.WaitForConnection();

                Console.WriteLine("Client connected.");
                try
                {
                    // Read user input and send that to the client process.
                    using (StreamWriter sw = new StreamWriter(pipeServer))
                    {
                        sw.AutoFlush = true;
                        sw.WriteLine("testing msg");
                    }
                }
                // Catch the IOException that is raised if the pipe is broken
                // or disconnected.
                catch (IOException err)
                {
                    Console.WriteLine("ERROR: {0}", err.Message);
                }
            }
        }            
    }

C++ CLIENT

#include <conio.h>
#include "pch.h"
#include <windows.h> 
#include <stdio.h> 
#include <tchar.h>
#include <strsafe.h>
#include "client.h"

#define BUFSIZE 512

int _tmain()
{
    HANDLE hPipe;
    LPCTSTR lpvMessage = TEXT("Default message from client.");
    TCHAR  chBuf[BUFSIZE];
    BOOL   fSuccess = FALSE;
    DWORD  cbRead, cbToWrite, cbWritten, dwMode;
    LPCTSTR lpszPipename = TEXT("mynamedpipe");    

    // Try to open a named pipe; wait for it, if necessary. 

    while (1)
    {
        hPipe = CreateFile(
            lpszPipename,   // pipe name 
            GENERIC_READ |  // read and write access 
            GENERIC_WRITE,
            0,              // no sharing 
            NULL,           // default security attributes
            OPEN_EXISTING,  // opens existing pipe 
            0,              // default attributes 
            NULL);          // no template file 

      // Break if the pipe handle is valid. 

        if (hPipe != INVALID_HANDLE_VALUE)
            break;

        // Exit if an error other than ERROR_PIPE_BUSY occurs. 

        if (GetLastError() != ERROR_PIPE_BUSY)
        {
            _tprintf(TEXT("Could not open pipe. GLE=%d\n"), GetLastError());
            return -1;
        }

        // All pipe instances are busy, so wait for 20 seconds. 

        if (!WaitNamedPipe(lpszPipename, 20000))
        {
            printf("Could not open pipe: 20 second wait timed out.");
            return -1;
        }
    }

    // The pipe connected; change to message-read mode. 

    dwMode = PIPE_READMODE_MESSAGE;
    fSuccess = SetNamedPipeHandleState(
        hPipe,    // pipe handle 
        &dwMode,  // new pipe mode 
        NULL,     // don't set maximum bytes 
        NULL);    // don't set maximum time 
    if (!fSuccess)
    {
        _tprintf(TEXT("SetNamedPipeHandleState failed. GLE=%d\n"), GetLastError());
        return -1;
    }

    // Send a message to the pipe server. 

    cbToWrite = (lstrlen(lpvMessage) + 1) * sizeof(TCHAR);
    _tprintf(TEXT("Sending %d byte message: \"%s\"\n"), cbToWrite, lpvMessage);

    fSuccess = WriteFile(
        hPipe,                  // pipe handle 
        lpvMessage,             // message 
        cbToWrite,              // message length 
        &cbWritten,             // bytes written 
        NULL);                  // not overlapped 

    if (!fSuccess)
    {
        _tprintf(TEXT("WriteFile to pipe failed. GLE=%d\n"), GetLastError());
        return -1;
    }

    printf("\nMessage sent to server, receiving reply as follows:\n");

    do
    {
        // Read from the pipe. 

        fSuccess = ReadFile(
            hPipe,    // pipe handle 
            chBuf,    // buffer to receive reply 
            BUFSIZE * sizeof(TCHAR),  // size of buffer 
            &cbRead,  // number of bytes read 
            NULL);    // not overlapped 

        if (!fSuccess && GetLastError() != ERROR_MORE_DATA)
            break;

        _tprintf(TEXT("\"%s\"\n"), chBuf);
    } while (!fSuccess);  // repeat loop if ERROR_MORE_DATA 

    if (!fSuccess)
    {
        _tprintf(TEXT("ReadFile from pipe failed. GLE=%d\n"), GetLastError());
        return -1;
    }

    printf("\n<End of message, press ENTER to terminate connection and exit>");
    _getch();

    CloseHandle(hPipe);

    return 0;
}

EDIT:

Changed the error print line to this:

std::error_code ec{ static_cast<std::int32_t>(GetLastError()), std::system_category() };
_tprintf(TEXT("WriteFile to pipe failed. GLE=%d\n"));
_tprintf(ec.message().c_str);
return -1;

Answer 1

The pipe name you used on the C++ side is incorrect. It should be: "\\\\.\\pipe\\mynamedpipe" .

Also, change the C# side to the following:

using ( var pipeServer = new NamedPipeServerStream( "mynamedpipe", PipeDirection.InOut, 1, PipeTransmissionMode.Message ) ) { }