FUSE (Filesystem in Userspace) with Qt Programming

Question

I'm trying to use FUSE with Qt, but fuse_main() and app.exec() has their own event loop. This mean that if I start one the other will not start, since the first that starts prevents the other to start as shown below. How to deal with this?

For more info about fuse, go to http://fuse.sourceforge.net/

Please, if possible, provide example.

Thank you, Leandro.

Example:

this one will prevent fuse to start:

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv); // qt event loop
    a.exec();
    fuse_main(argc, argv, &hello_oper); // fuse event loop, it will not start
    return 0;
}

and this one will prevent qt to start:

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv); // it will not start due to fuse_main invocation
    fuse_main(argc, argv, &hello_oper);
    return a.exec();
}

Answer 1

You should run the filesystem on a separate thread.

Answer 2

i've create a simple example of how FUSE and Qt can be used together, see: https://github.com/qknight/qt-fuse-example

the fuse_main(..) convenience function can't be used as then you would not have any means of: - reroute the posix signals - you can't shutdown the fuse process easily, like with using QFuse.cpp: fuse_unmount(TUP_MNT, fs.ch); pthread_join(fs.pid, NULL);

as discussed on the fuse-devel mailinglist, there are two good ways to integrate FUSE into Qt:

1. implement it (as i did in qt-fuse):

   Qt mainloop is running, FUSE mainloop is also running, both in different threads. i solved some issues in regards to POSIX::signal to Qt::signal conversion, so a clear shutdown is possible.

2. modify the FUSE library to have direct access from the Qt event loop:

   Qt mainloop is running, no need for a FUSE mainloop as it would be integrated into the Qt mainloop. didn't look into this but it might have different advantages.

hope this helps

Answer 3

You can also run FUSE on a separate process and communicate via sockets/pipes/RPC/... It is preferred in the case that FUSE crashes or is busy doing something, your GUI is still working.