svn commit: r230869 - head/usr.sbin/daemon

[Mikolaj Golub]

On Sun, 5 Feb 2012 22:46:48 +0100 Pawel Jakub Dawidek wrote:

 PJD> On Sun, Feb 05, 2012 at 11:27:10PM +0200, Mikolaj Golub wrote:
 >> Ok, using hastd code as a reference :-) here is my implementation.

 PJD> - I'd not pass selected signals to the child. The parent can still be
 PJD>   killed with a whole bunch of different signals that are not passed or
 PJD>   cannot be caught or the child process handle them gracefully.
 PJD>   Signals should be send to the PID from the pidfile anyway. If someone
 PJD>   is sending signals to the parent he has no right to expect well
 PJD>   behaviour from the parent.

Well, sending a whole bunch of different signals to parent we might not expect
right behavior, but why not to provide it for the "standard" ones? E.g. on
shutdown init(8) will send SIGTERM and the daemon will gracefully exit
terminating the child and cleaning up the pidfile. If the the child process
does not handle SIGTERM gracefully I don't see much difference from having
only this one process alive or two (with its monitoring daemon).

The pidfile is seen in ps(1) output for the daemon process, which allows to
identify the monitoring daemon with its child. Or we could change its
proctitle to something like "daemon: cmdname[pid]", similar to what sshd does.
So people would expect that terminating a daemon will terminate the process it
monitors.

 PJD> - Now that we handle the pidfile fully in the parent, I'd move dropping
 PJD>   provileges after fork(2) and pidfile_write(3). This way pidfiles will
 PJD>   always be created with root privileges and we can forget about all the
 PJD>   mess with pid directories, etc.

 PJD> - With the above you can wait for child to exit with simple wait(2).

Yes, it looks like much simpler, see the attached patch. But I don't think I
like it much as it still looks like a half measure to me.

-- 
Mikolaj Golub

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