C++ Win32: How to run pipe client executable with CreateProcessA() in a new console window

Question

In my project I have two applications, one is Pipe Server and Pipe Client(Slave). I am trying to send text via pipe to display it on client's console. Thus effectively creating disposable consoles.

I have tested the code by manually running the server first and then client. It runs perfectly. Then I added some code in the constructor of Server to invoke Slave.exe with pipename as arguments however the console of Slave disappears after couple seconds. Slave's Constructor calls this function:

int OpenNamedPipe(std::string pipename)
{

    pipeurl += pipename;
    hPipe = CreateNamedPipe(
        pipeurl .c_str(),                            // pipe name 
        PIPE_ACCESS_DUPLEX | FILE_FLAG_OVERLAPPED,   // read/write access 
        PIPE_TYPE_BYTE |                             // Datatype Byte
        PIPE_WAIT,                                   // blocking mode 
        1,                                           // max. instances  
        outputBuffer,                                // output buffer size 
        inputBuffer,                                 // input buffer size 
        0,                                  // client time-out 
        NULL);                             // default security attribute 

    if (hPipe == INVALID_HANDLE_VALUE)
    {
        try
        {
            Throw_Last_Error("CreateNamedPipe failed");
        }
        catch (const std::runtime_error err)
        {
            std::cout << "Runtime Error: " << err.what();
            return 0;
        }
    }
    int timeout = 100000;


    PROCESS_INFORMATION pi;
    ZeroMemory(&pi, sizeof(pi));
    STARTUPINFO si;
    ZeroMemory(&si, sizeof(si));
    int retnVal = CreateProcessA("Slave.exe", (LPSTR)pipename.c_str(), NULL, NULL, NULL, DETACHED_PROCESS, NULL, NULL, &si, &pi);
    if (!retnVal)
    {
        retnVal = GetLastError();
    }
    if (!ConnectNamedPipe(hPipe, NULL))
    {
        if (!GetLastError() == ERROR_PIPE_CONNECTED)
        {
            try
            {
                Throw_Last_Error("Error while connecting to named pipe.");
            }
            catch (std::runtime_error err)
            {
                std::cout << "GLE= " << GetLastError();
                Block();
                return 0;
            }
        }
    }

    std::cout << "Connected to pipe.\n";
    return 0;
}

In Client's main program:

int main(int argc, char *argv[])
{
    AllocConsole();
    std::string argstr = " ";
    argstr = argv[1];
    PipeClient pc(argstr);
    pc.Update();
    system("pause");
    return 0;
}

Now I need both Server's console and Client's console to remain open for further testing but when Server is waiting for the Slave to connect to pipe, Slave's console and process closes, which shouldn't happen as I have paused it before it can return.

Edit: Pipe Client object constructor:

PipeClient(std::string pipename)
{
    pipeName = pipeName + pipename;
    Connect();
    if (hPipe != INVALID_HANDLE_VALUE || GetLastError() != ERROR_PIPE_BUSY)
    {
        std::cout << "Created Pipe, GLE=" << GetLastError();

    }
    if (hPipe == INVALID_HANDLE_VALUE)
    {
        ThrowLastError("Failed to connect to named pipe.");
    }
}
int Connect()
{
    while (true)
    {
        WaitNamedPipeA(pipeName.c_str(), NMPWAIT_WAIT_FOREVER);
        hPipe = CreateFileA(
            pipeName.c_str(),
            GENERIC_READ |
            GENERIC_WRITE,
            0,
            NULL,
            OPEN_EXISTING,
            0,
            NULL
        );
        if (hPipe != INVALID_HANDLE_VALUE || GetLastError() != ERROR_PIPE_BUSY)
        {
            std::cout << "Created Pipe, GLE=" << GetLastError();
            break;
        }
    }
    return 0;
}

Class Fields:

DWORD inputBuffer = 256;
DWORD outputBuffer = 256;
HANDLE hPipe;
std::string pipeName = "\\\\.\\pipe\\";
char * testpipename = "\\\\.\\pipe\\namedpipe";

Github repo:https://github.com/BhayanakMoth2/PipedConsole

Answer 1

So I fixed the problem, I was not using the CreateProcess function properly.

This should be the fixed function call:

std::string cmd = "Slave.exe " + pipename;
    int retnVal = CreateProcessA("Slave.exe", (LPSTR)cmd.c_str(), NULL, NULL, NULL, CREATE_NEW_CONSOLE, NULL, NULL, &si, &pi);

I misread the documentation. And the reason Slave.exe was crashing because the arguments were not being passed properly and so when it reached:

 argstr = argv[1]

it crashed silently. The second argument in CreateProcessA() fixes this problem by properly passing the arguments.