cannot write through opened socket

user4592357

open socket with above code, it returns port number
port = // get the port number

const QString sPort(Port);
auto args = QStringList() << sPort << sPort;

if (!QProcess::startDetached(sClientName, args))
{
    const QString sProgFullPath{ QString::fromLatin1(pDir) +
        QLatin1String("/bin/") + sClientName };
    if (!QProcess::startDetached(sProgFullPath, args))
        return false;
}

Christian Ehrlicher

This code can not work. Follow the QTcpServer examples.

user4592357

@Christian-Ehrlicher this is working code.
i just tried this
i created socket with above method, and run telnet localhost $port
then i sent message to telnet using this port, and it was sent...
so... is that other app faulty?

user4592357

@Christian-Ehrlicher my bad
the other app expects file descriptors, and i'm providing socket port
so, how should i work with that app?

Christian Ehrlicher

@user4592357 said in cannot write through opened socket:

so, how should i work with that app?

It's your app - how should we know?

user4592357

@Christian-Ehrlicher i mean it is accepting file descriptors, and i have socket (port).

how should i convert socket to fd?
can i do that?

Christian Ehrlicher

@user4592357 said in cannot write through opened socket:

how should i convert socket to fd?

By taking a look at the documentation: https://doc.qt.io/qt-5/qabstractsocket.html#socketDescriptor

user4592357

@Christian-Ehrlicher thanks for the link

so when i create the child app like this, when main app is closed, child app still exists, as it was started detached:

if (!QProcess::startDetached(sClientName, args))
{
    const QString sProgFullPath{ QString::fromLatin1(pDir) +
        QLatin1String("/bin/") + sClientName };
    if (!QProcess::startDetached(sProgFullPath, args))
        return false;
}

i tried to convert this to using start() instead, but looks it's not equivalent (because now error signal is async?)
what's the correct way to nest such call?

QProcess p1;
p1.start(sClientName, args);
connect(&p1, &QProcess::errorOccurred, []
{
    const QString sProgFullPath{ QString::fromLatin1(pDir) +
        QLatin1String("/bin/") + sClientName };

     QProcess p2;
     p2.start(sProgFullPath, args);
     connect(&p2, &QProcess::errorOccurred, []
     {
          // how do i return false from here?
    });
}

Christian Ehrlicher

Start both directly instead waiting for the first one.

user4592357

@Christian-Ehrlicher what if both succeed?

user4592357

@Christian-Ehrlicher what about https://doc.qt.io/qt-5/qprocess.html#execute?