create a custom canbus plugin

Gabriele11_ · wrote on 21 Jun 2020, 16:00

Hi all,
I'm trying to implement a custom canbus plugin. Following this qt doc: https://doc.qt.io/qt-5/qtcanbus-backends.html

and opening source file like "socketcanbus" plugin, I created a shared library plugin, which is compiling correctly and is giving me the .dll file at the end of build. Here following my .pro file:
####################################################################
TARGET = cnhvirtualcanbus

QT += core serialbus

TEMPLATE = lib
CONFIG += plugin

CONFIG += c++14

DEFINES -= UNICODE

DEFINES += QT_DEPRECATED_WARNINGS

SOURCES +=
camelplugin.cpp
canvirtualconnection.cpp

HEADERS +=
canvirtualconnection.h

DISTFILES += CamelPlugin.json

Default rules for deployment.

unix {
target.path = $$[QT_INSTALL_PLUGINS]/generic
}
!isEmpty(target.path): INSTALLS += target

TARGET = $$qtLibraryTarget(cnhvirtualcanbus)
DESTDIR = ..\build

target.path = ..\build
INSTALLS += target

win32: LIBS += -L$$PWD/lib/ -lQtCanSim

INCLUDEPATH += $$PWD/.
DEPENDPATH += $$PWD/.

##########################################################

Here the .cpp interface (I don't have a corresponding .h, only cpp implementation):
################################################################
#include <QtSerialBus/qcanbus.h>
#include <QtSerialBus/qcanbusdevice.h>
#include <QtSerialBus/qcanbusfactory.h>

#include "canvirtualconnection.h"

class camelPlugin : public QObject, public QCanBusFactoryV2
{
Q_OBJECT
Q_PLUGIN_METADATA(IID "org.qt-project.Qt.QCanBusFactoryV2" FILE "CamelPlugin.json")
Q_INTERFACES(QCanBusFactoryV2)
public:

//reimplement pure virtual function
QList<QCanBusDeviceInfo> availableDevices(QString *errorMessage) const override
{
    Q_UNUSED(errorMessage);

   QList<QCanBusDeviceInfo> result;

   return result;
}
QCanBusDevice *createDevice(const QString &interfaceName, QString *errorMessage) const override
{
    Q_UNUSED(errorMessage);
    Q_UNUSED(interfaceName);

    auto device = new CanVirtualConnection();

    return device;
}

};
######################################################

now, in my application, which is supposed to load the plugin, I have this lines of code in main.cpp:

#################################################################
QCoreApplication::addLibraryPath("C:/Users/Gabriele/Desktop/CamelPlugin/build");

QPluginLoader* camelPlugin = new QPluginLoader("cnhvirtualcanbusd");

if(!camelPlugin->load())
{
    qDebug()<<camelPlugin->errorString();
}

######################################################

When I run the application I got this error: "Failed to extract plugin meta data from 'C:/Users/Gabriele/Desktop/CamelPlugin/build/cnhvirtualcanbusd.dll'"

So, my plugin is reached but cannot be loaded. Anyone can help me to solve this issue?
I guess the problem is in re-implementing the "QCanBusFactoryV2", but I have no idea how to fix this.

Thanks for support