QNetworkInformation on RPI4b causing Segmentation Fault

WallPulse

Hey all, I am trying to use the QNetworkInformation class to do some basic checks about weather or not the current system is connected to a wifi network is able to reach the internet. It seems like a perfect solution to my use case except that whenever I try to call either networkInformation→supportedFeatures() or networkInformation→reachability(), I get a segmentation fault and my program exits. I am a little confused on why this is happening and if there is any way to fix it. I am currently working on a Raspberry pi4b with the default Raspbian OS on it. When I run program before the Seg fault occurs I get the following warning msgs which seems to be a part of this issue, but it is completely beyond me if there is a way to rectify/fix these msgs.

Has anyone run into something like this before?

Warning Messages:

qt.dbus.integration: Could not connect "org.freedesktop.NetworkManager" to "stateChanged"
qt.dbus.integration: Could not connect "org.freedesktop.NetworkManager" to "connectivityChanged"
qt.dbus.integration: Could not connect "org.freedesktop.NetworkManager" to "deviceTypeChanged"
qt.dbus.integration: Could not connect "org.freedesktop.NetworkManager" to "meteredChanged"

Code Snippet:

void checkInternetConnectivity(){
	
    QNetworkInformation *networkInformation = QNetworkInformation::instance();

    qDebug() << networkInformation->availableBackends();


    bool result = networkInformation->loadDefaultBackend();
    qDebug() << "loaded backend: " << result;

    qDebug() << "Features:" << networkInformation->supportedFeatures();
   // qDebug() << networkInformation->reachability();


}

Thanks for any help ahead of time

ChrisW67

@WallPulse said in QNetworkInformation on RPI4b causing Segmentation Fault:

It seems like a perfect solution to my use case except that whenever I try to call either networkInformation→supportedFeatures() or networkInformation→reachability(), I get a segmentation fault and my program exits. I

Have you checked that networkInformation is not null?

From the docs:

QNetworkInformation is a singleton and stays alive from the first successful load() until destruction of the QCoreApplication object.

Have you called QNetworkInformation::load(), or one of its replacements, before calling QNetworkInformation::instance()?

WallPulse

@ChrisW67

Thank you, that fixed it! My bad for missing that.

Calling QNetworkInformation::loadDefaultBackend() before calling the features function worked