Add --pidfile option to vde_vmnet #27
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That way the pidfile will be owned by the user running the daemon, and we can safely add e.g. `pkill -f /var/run/vde_vmnet.pid` to the sudoers file. Signed-off-by: Jan Dubois <jan.dubois@suse.com>
If nothing else, just to be able to test the cleanup of the pidfile... Signed-off-by: Jan Dubois <jan.dubois@suse.com>
| @@ -215,6 +216,12 @@ static interface_ref start(VDECONN *vdeconn, struct cli_options *cliopt) { | |||
| return iface; | |||
| } | |||
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| static sigjmp_buf jmpbuf; | |||
| static void signalhandler(int signal) { | |||
| printf("\nReceived signal %d\n", signal); | |||
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printf is not safe to be used in a signal handler
https://stackoverflow.com/questions/16891019/how-to-avoid-using-printf-in-a-signal-handler
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It is, but then we would have to call _exit instead and rely on the OS to close handles and and other cleanup because we are going to call siglongjmp next.
- If a signal handler interrupts the execution of an unsafe function, and the handler terminates via a call to longjmp(3) or siglongjmp(3) and the program subsequently calls an unsafe function, then the behavior of the program is undefined.
I don't really care strongly either way: most of the time things work correctly because the signal didn't interrupt an unsafe function, and we get the information printed, and regular cleanup called.
I haven't actually seen it fail at all, but even if it does, we would just see the process crash instead, which would then continue with OS-level cleanup the same way as if we had called _exit; but we get a different exit code instead.
Now, given that in non-debugging situations this all runs as a daemon, nobody will see either the output on stdout, nor the crash exit code, so I don't think this matters very much at all.
I'm fine with just calling _exit(0) in the signal handler and not doing anything else, if you prefer that.
That way the pidfile will be owned by the user running the daemon, and we can safely add e.g.
pkill -f /var/run/vde_vmnet.pidto the sudoers file.Also adds a signal handler for SIGHUB, SIGINT, and SIGTERM.