QTcpSocket pointer produces SIGSEGV in a view. (QT5) - c++

Question

Hi,
I've got a SIGSEGV when I want to use a QTcpSocket with the following code. (more explanation at the very bottom)
Function to create a QTTCPSocket (which will keep the QTcpSocket pointer):
std::shared_ptr<QTTCPSocket> createQtSocket(std::string host, unsigned int port)
{
QTcpSocket *sock = new QTcpSocket;
sock->connectToHost(QHostAddress(QString::fromStdString(host)), port);
if (!sock->waitForConnected())
throw std::runtime_error("Connection refused");
return std::make_shared<QTTCPSocket>(sock);
}
QTTCPSocket class:
class QTTCPSocket {
public:
QTTCPSocket(QTcpSocket *socket)
: _socket(socket)
{};
~QTTCPSocket() = default;
void send(const std::string &msg)
{
std::cout << msg << std::endl;
_socket->write(&msg[0], static_cast<qint64>(msg.length())); // produces a SIGSEGV if called from a qt event (a button for example)
_socket->waitForBytesWritten(0);
}
private:
QTcpSocket *_socket;
};
Main function:
int main()
{
std::shared_ptr<QTTCPSocket> socket = createQtSocket("127.0.0.1", 33333);
ViewStateMachine vsm(socket);
vsm.init();
vsm.start();
}
ViewStateMachine class (hpp):
class ViewStateMachine {
public:
ViewStateMachine(std::shared_ptr<QTTCPSocket> sock);
void init();
void start();
std::shared_ptr<QTTCPSocket> getSock();
private:
LoginView *_loginView;
std::shared_ptr<QTTCPSocket> _sock;
};
ViewStateMachine class (cpp):
#include "ViewStateMachine.hpp"
ViewStateMachine::ViewStateMachine(std::shared_ptr<QTTCPSocket> socket)
: _sock(std::move(socket))
{
}
void ViewStateMachine::init()
{
_loginView = new LoginView(this);
_loginView->init();
}
void ViewStateMachine::start()
{
_loginView->show();
}
std::shared_ptr<QTTCPSocket> ViewStateMachine::getSock()
{
_sock->send("test1"); // SIGSEGV inside (check above)
return _sock; // if I remove _sock->send("test1"), it SIGSEGV in the shared_ptr's constructor (only if called from a qt event (a button for example)
}
LoginView is a passive class, which register an event with QObject::connect(_connectBtn, SIGNAL(clicked()), this, SLOT(onClick_connectBtn())); with onClick_connectBtn() a member function of LoginView.
All these pieces of code might be confused so here a step-by-step explanation:
Start in main(): create a QTcpSocket * contained in a QTTCPSocket class contained in a std::shared_ptr<QTTCPSocket>.
Create a ViewStateMachine instance with the shared_ptr, which will be stored in the instance. We will call it vsm.
Call vsm.init() which will create a LoginView instance with this (vsm). LoginView will store the ViewStateMachine instance.
Call vsm.start() which will call _loginView.show() (from QT's QWidget), it will show the login view.
Everything works well and we can see the login view.
However, if I want to use my socket in the LoginView :
* when I want to use it from _loginView->init() or in the LoginView's constructor, it works well!
* when I want to use it from LoginView::onClick_connectBtn (called by QT, perhaps in a special environment like a constructor, not sure), it produces a SIGSEGV where I commented above in the code (shared_ptr's constructor or write function from the QT' socket).
To get the socket from LoginView, I use ViewStateMachine::getSock() (_viewStateMachine->getSock()).
Valgrind shows
pure virtual method called
terminate called without an active exception
The shared_ptr's constructor produces a SIGSEGV when it uses its mutex to increment the value.
The write SIGSEGV when I use _socket (QT' socket). The pointer address didn't change from beginning to end.
If there's any other question, please ask!
Thanks a lot for helping :).
EDIT: It works if I replace every std::shared_ptr with a C pointer.