Detect user logout / shutdown in Python / GTK under Linux - SIGTERM/HUP not received

gtk, linux, pygtk, python, sigterm

Solution

OK, I finally found the solution :)

You simply can't rely on signals in this case. You have to connect to the Desktop Session in order to get notified that a logout is going to happen.

import gnome.ui

gnome.program_init('Program', self.version) # This is going to trigger a warning that program name has been set twice, you can ignore this, it seems to be a problem with a recent version of glib, the warning is all over the place out there
client = gnome.ui.master_client() # connect us to gnome session manager, we need to init the program before this
client.connect('save-yourself', self.on_logout) # This gets called when the user confirms the logout/shutdown
client.connect('shutdown-cancelled', self.on_logout_cancel) # This gets called when the logout/shutdown is canceled
client.connect('die', self.on_logout) # Don't know when this gets called it never got in my tests

def on_logout(self, *args):
    # save settings an create a file that tells the wrapper that we have exited correctly!
    # we'll still return with status code 1, but that's just gtk crashing somehow

def on_logout_cancel(self, *args):
    # simply delete the logout file if it exists

One important note here: Don't try to exit your program in `on_logout`, if you do so, GNOME won't recognize that your program has been exited and will give you the dialog that some programs are still running.

Problem

OK this is presumably a hard one, I've got an pyGTK application that has random crashes due to X Window errors that I can't catch/control. So I created a wrapper that restarts the app as soon as it detects a crash, now comes the problem, when the user logs out or shuts down the system, the app exits with status 1. But on some X errors it does so too. So I tried literally anything to catch the shutdown/logout, with no success, here's what I've tried: ``` import pygtk import gtk import sys class Test(gtk.Window): def delete_event(self, widget, event, data=None): open("delete_event", "wb") def destroy_event(self, widget, data=None): open("destroy_event", "wb") def destroy_event2(self, widget, event, data=None): open("destroy_event2", "wb") def __init__(self): gtk.Window.__init__(self, gtk.WINDOW_TOPLEVEL) self.show() self.connect("delete_event", self.delete_event) self.connect("destroy", self.destroy_event) self.connect("destroy-event", self.destroy_event2) def foo(): open("add_event", "wb") def ex(): open("sys_event", "wb") from signal import * def clean(sig): f = open("sig_event", "wb") f.write(str(sig)) f.close() exit(0) for sig in (SIGABRT, SIGILL, SIGINT, SIGSEGV, SIGTERM): signal(sig, lambda *args: clean(sig)) def at(): open("at_event", "wb") import atexit atexit.register(at) f = Test() sys.exitfunc = ex gtk.quit_add(gtk.main_level(), foo) gtk.main() open("exit_event", "wb") ``` Not one of these succeeds, is there any low level way to detect the system shutdown? Google didn't find anything related to that. I guess there must be a way, am I right? :/ EDIT: OK, more stuff. I've created this shell script: ``` #!/bin/bash trap test_term TERM trap test_hup HUP test_term(){ echo "teeeeeeeeeerm" >~/Desktop/term.info exit 0 } test_hup(){ echo "huuuuuuuuuuup" >~/Desktop/hup.info exit 1 } while [ true ] do echo "idle..." sleep 2 done ``` And also created a .desktop file to run it: ``` [Desktop Entry] Name=Kittens GenericName=Kittens Comment=Kitten Script Exec=kittens StartupNotify=true Terminal=false Encoding=UTF-8 Type=Application Categories=Network;GTK; Name[de_DE]=Kittens ``` Normally this should create the term file on logout and the hup file when it has been started with &. But not on my System. GDM doesn't care about the script at all, when I relog, it's still running. I've also tried using `shopt -s huponexit`, with no success. EDIT2: Also here's some more information aboute the real code, the whole thing looks like this: ``` Wrapper Script, that catches errors and restarts the programm -> Main Programm with GTK Mainloop -> Background Updater Thread ``` The flow is like this: ``` Start Wrapper -> enter restart loop while restarts < max: -> start program -> check return code -> write error to file or exit the wrapper on 0 ``` Now on shutdown, `start program` return 1. That means either it did hanup or the parent process terminated, the main problem is to figure out which of these two did just happen. X Errors result in a 1 too. Trapping in the shellscript doesn't work. If you want to take a look at the actual code check it out over at GitHub: http://github.com/BonsaiDen/Atarashii

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