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QNetworkReply emits an error signal twice when a ContentNotFoundError occurs when an event loop starts in an error slot

Im using QtSDK 4.7.3

I do this in (void test ()):

mgr = new QNetworkAccessManager();
reply = mgr->get(QNetworkRequest(QUrl("http://developer.qt.nokia.com/fileNotExisting.txt")));

connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
    SLOT(onError(QNetworkReply::NetworkError)), Qt::ConnectionType::UniqueConnection);

And of course, the onError slot is raised:

if (networkError == QNetworkReply::NetworkError::ContentNotFoundError)
{
// Messagebox starts an event loop which
// causes this slot to be called again
QMessageBox m;
m.exec();
}

If I don't have the / eventloop message in the onError slot, there is no failure, and everything works. But when it is there, the onError slot is called again when m.exec () is called. When both message boxes are closed and I leave the onError function, the application crashes. The application tries to remove / free memory when this happens. The error "Access to read access violation location" does not help, and the call stack is located deep in the Qt dll.

:
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Qt (post).

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, : main.cpp

#include "contentnotfound.h"
#include <QtGui/QApplication>
#include <QTimer>

int main(int argc, char *argv[])
{
QApplication a(argc, argv);

ContentNotFound cnf;

// false: start test after application event loop have started
if (true) { cnf.test(); }
else { QTimer::singleShot(2000, &cnf, SLOT(test())); }

return a.exec();
}

contentnotfound.h

#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QMessageBox>

class ContentNotFound : public QObject
{
Q_OBJECT

public slots:
void test()
{
    mgr = new QNetworkAccessManager();
    reply = mgr->get(QNetworkRequest(QUrl("http://developer.qt.nokia.com/fileNotExisting.txt")));

    connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
        SLOT(onError(QNetworkReply::NetworkError)), Qt::ConnectionType::UniqueConnection);
}

private slots:
void onError(QNetworkReply::NetworkError networkError)
{
    //reply->disconnect(); // Disconnect all signals

    if (networkError == QNetworkReply::NetworkError::ContentNotFoundError)
    {
        // Messagebox starts an event loop which
        // causes this slot to be called again
        QMessageBox m;
        m.exec();
    }
}

private:
QNetworkAccessManager* mgr;
QNetworkReply* reply;

};
+5
1

Qt , 4.8.0: https://bugreports.qt.io/browse/QTBUG-16333

:

contentnotfound.h:

#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QMessageBox>

class ContentNotFound : public QObject
{
Q_OBJECT

public slots:
void test()
{
    qRegisterMetaType<QNetworkReply::NetworkError>("QNetworkReply::NetworkError");
    mgr = new QNetworkAccessManager(this);
    reply = mgr->get(QNetworkRequest(QUrl("http://developer.qt.nokia.com/fileNotExisting.txt")));

    connect(reply, SIGNAL(error(QNetworkReply::NetworkError)),
        SLOT(onError(QNetworkReply::NetworkError)), Qt::QueuedConnection);
}

private slots:
void onError(QNetworkReply::NetworkError networkError)
{
    //reply->disconnect(); // Disconnect all signals

    if (networkError == QNetworkReply::ContentNotFoundError)
    {
        // Messagebox starts an event loop which
        // causes this slot to be called again
        QMessageBox m;
        m.exec();
    }
}

private:
QNetworkAccessManager* mgr;
QNetworkReply* reply;

};
+3

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