How to kill yourself in qt program?

mirro

Why does the following method not work?

int res = QProcess::execute("kill", QStringList() << QString::number(QCoreApplication::applicationPid()));

JonB

@mirro
I already answered:

@JonB said in How to kill yourself in qt program?:

@mirro Why not tell us whether in that case your SERVICE_CONTROL_STOP code is actually hit, or would you like us to guess?

Do you not think we need to know whether your function is being hit? Just pasting more code and not telling us what does/does not happen is not helpful when asking a question.

Also this now a Windows programming question, nothing to do with Qt.

ChrisW67

@mirro said in How to kill yourself in qt program?:

int res = QProcess::execute("kill", QStringList() << QString::number(QCoreApplication::applicationPid()));

I assume that res is -1 or -2 but you never check.

Your code is plainly written for Windows (OpenServiceW, DeleteService, CloseServiceHandle) and there is no such beast as kill in that environment by default.
That call would only work on a Linux box if kill is in the executable's PATH at the time of this call and the SIGTERM signal is not being ignored or otherwise intercepted/blocked. If it worked then you would never expect to execute the return true line.

Why do you not just use one of:

mirro

@ChrisW67
The QCoreApplication::quit() method is invalid, and this process program still exists.

Axel Spoerl

@mirro said in How to kill yourself in qt program?:

@ChrisW67
The QCoreApplication::quit() method is invalid

Have you read the documentation of the method?

and this process program still exists

That happens, when something in your code prevents the application from shutting down gracefully. E.g. a window that can’t be closed, a thread that doesn’t return. Could also be a memory leak. Definitively something in your application, that needs to be fixed.

You can directly call the exit() slot. That’s shoots the problem down in most cases - instead of solving it. You risk that your application crashes on shutdown, unless the problem is solved.

Bonnie

@mirro From your code, uninstallService() is called without app.exec() being called so it is not suitable to use QCoreApplication::quit() or QCoreApplication::exit() since there's no eventloop here.
By the way, is your program a console project? If yes it should print qDebug messages but I don't see any output (or do you redirect them in messageHandler? In that case you need also post them).
This line may even never been reached. There's big chance that somewhere in your code before this line is hanging.
I think you should use debugger to check where does it stuck.
If it can reach the end of uninstallService(), there's no need to call any quit() or exit() because it returns in main().

JonB

@mirro
Your code gets the PID of itself and tries to issue an OS command of kill <pid>. Don't know where you got the idea of this from, Windows does not come with a kill command, so unless you have added one it won't find the command to run.

I don't know why you are trying to kill yourself, but if you really want to do this you might as well call exit() or _exit() directly. That is not advisable/tidy, but it's still neater than trying to issue an OS command to kill yourself.

As @Bonnie has noted, if you simply allow your uninstallService() to run to its end execution will return into main() where it goes return 0 and so will exit anyway. We do not know why you do not allow it simply to do that.

The exit, or your kill, will only happen if you invoke your program with a command line argument. The uninstallService() will only be hit if you invoke it as PixelStreamServerTalkTest --uninstall. Note that has two hyphens, --uninstall. The only way you should see your program continuing to run is if you run it with no command line arguments, i.e. plain PixelStreamServerTalkTest. This is common for a Windows service: with command line arguments, like --install/--uninstall it does a corresponding action and exits, but if no arguments are passed it runs all the time doing whatever it does as a Windows service. Show how you actually invoke your program to run.

mirro

@JonB
Why does the SERVICE_CONTROL_STOP message not respond when SetServiceStatus is set to the SERVICE_STOPPED state?

    serviceStatus.dwCurrentState = SERVICE_STOPPED;
    SetServiceStatus(serviceStatusHandle, &serviceStatus);

JonB

@mirro Why not tell us whether in that case your SERVICE_CONTROL_STOP code is actually hit, or would you like us to guess?

mirro

@JonB
Why cannot I respond to the SERVICE_CONTROL_STOP message event when using the ControlService(scService, SERVICE_CONTROL_STOP, &status) method?

SC_HANDLE scManager = OpenSCManager(nullptr, nullptr, SC_MANAGER_CREATE_SERVICE);
if (!scManager) {
    qDebug() << "Failed to open SCManager. Error:" << GetLastError();
    return false;
}
//
std::wstring serviceNameW = serviceName.toStdWString();
SC_HANDLE scService = OpenServiceW(scManager, serviceNameW.c_str(), DELETE);
if (!scService) {
    qDebug() << "Failed to open service. Error:" << GetLastError();
    CloseServiceHandle(scManager);
    return false;
}
//
SERVICE_STATUS status;
ControlService(scService, SERVICE_CONTROL_STOP, &status);

JonB

@mirro
I already answered:

@JonB said in How to kill yourself in qt program?:

@mirro Why not tell us whether in that case your SERVICE_CONTROL_STOP code is actually hit, or would you like us to guess?

Do you not think we need to know whether your function is being hit? Just pasting more code and not telling us what does/does not happen is not helpful when asking a question.

Also this now a Windows programming question, nothing to do with Qt.