Execute window command line-by-line using QProcess

[ChrisW67]

QIODevice relies on the Qt event loop to process writes to the subprocess, and that is not functioning here. You need to waitForBytesWritten()/waitForBytesRead(), or you need to write using asynchronous methods. Here is a very crude example:

#include <QtCore>
 
class PopLister: public QObject
{
    Q_OBJECT
public:
    enum State { Starting, SentUser, SentPass, SentList, ReadList, Stopping };
 
    explicit PopLister(QObject *p = 0):
        QObject(p),
        process(new QProcess(this)),
        state(Starting)
    {
        process->setProcessChannelMode(QProcess::MergedChannels);
        connect(process, SIGNAL(readyRead()), SLOT(handleOutput()));
    }
 
    void start()
    {
        QStringList args;
        args << "s_client" << "-connect" << "server:995";
        process->start("openssl",  args);
        state = Starting;
    }
 
private slots:
    void handleOutput() {
        while (process->canReadLine()) {
            QByteArray line = process->readLine();
 
            if (line.startsWith("+OK")) {
                switch (state) {
                case Starting:
                    process->write("USER username\r\n");
                    state = SentUser;
                    break;
                case SentUser:
                    process->write("PASS password\r\n");
                    state = SentPass;
                    break;
                case SentPass:
                    listData.clear();
                    process->write("LIST\r\n");
                    state = SentList;
                    break;
                case SentList:
                    state = ReadList;
                    break;
                case ReadList:  // suppress compiler warnings
                case Stopping:
                    break;
                }
            }
            else if(line.startsWith("-ERR")) {
                qDebug() << line;
                process->write("QUIT\r\n");
                state = Stopping;
            }
            else if (state == ReadList) {
                if (line == ".\r\n") {
                    qDebug() << listData;
                    process->write("QUIT\r\n");
                    state = Stopping;
                }
                else {
                    listData += line;
                }
            }
            else if (state == Stopping) {
                qDebug() << line;
            }
        }
    }
private:
    QProcess *process;
    State state;
    QByteArray listData;
};
 
int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    PopLister lister;
    lister.start();
    return app.exec();
}
#include "main.moc"

#include <QtCore>

class PopLister: public QObject
{
    Q_OBJECT
public:
    enum State { Starting, SentUser, SentPass, SentList, ReadList, Stopping };

    explicit PopLister(QObject *p = 0):
        QObject(p),
        process(new QProcess(this)),
        state(Starting)
    {
        process->setProcessChannelMode(QProcess::MergedChannels);
        connect(process, SIGNAL(readyRead()), SLOT(handleOutput()));
    }

    void start()
    {
        QStringList args;
        args << "s_client" << "-connect" << "server:995";
        process->start("openssl",  args);
        state = Starting;
    }

private slots:
    void handleOutput() {
        while (process->canReadLine()) {
            QByteArray line = process->readLine();

            if (line.startsWith("+OK")) {
                switch (state) {
                case Starting:
                    process->write("USER username\r\n");
                    state = SentUser;
                    break;
                case SentUser:
                    process->write("PASS password\r\n");
                    state = SentPass;
                    break;
                case SentPass:
                    listData.clear();
                    process->write("LIST\r\n");
                    state = SentList;
                    break;
                case SentList:
                    state = ReadList;
                    break;
                case ReadList:  // suppress compiler warnings
                case Stopping:
                    break;
                }
            }
            else if(line.startsWith("-ERR")) {
                qDebug() << line;
                process->write("QUIT\r\n");
                state = Stopping;
            }
            else if (state == ReadList) {
                if (line == ".\r\n") {
                    qDebug() << listData;
                    process->write("QUIT\r\n");
                    state = Stopping;
                }
                else {
                    listData += line;
                }
            }
            else if (state == Stopping) {
                qDebug() << line;
            }
        }
    }
private:
    QProcess *process;
    State state;
    QByteArray listData;
};

int main(int argc, char **argv)
{
    QCoreApplication app(argc, argv);
    PopLister lister;
    lister.start();
    return app.exec();
}
#include "main.moc"

To copy to clipboard, switch view to plain text mode