site_archiver@lists.apple.com Delivered-To: darwin-kernel@lists.apple.com Terry Lambert <tlambert@apple.com> wrote:

On Apr 10, 2009, at 11:55 AM, Bill Janssen <janssen@parc.com> wrote:

...

Terry Lambert <tlambert@apple.com> wrote:

...

On Apr 10, 2009, at 9:31 AM, Bill Janssen <janssen@parc.com> wrote:

...

Michael Smith <drivers@mu.org> wrote:

...

On Apr 9, 2009, at 9:30 AM, Bill Janssen wrote:

...

Michael Smith <drivers@mu.org> wrote: > It's usually straightforward for the daemon to vend the > appropriate > self-manipulation functionality; frequently you want to gate this > with > application-specific logic anyway.

Well, the daemon does a lot of things, but what I'm concerned with is stop, start, and restart.

Why do you need 'stop'? Why can't you just ask the daemon to enter a state where it refuses requests?

Because I want to fix it with new code.

So just fix it and tell it to exit.

When a process exits and launchd restarts it, launchd doesn't know if it's running old code or new code when it's relaunched, it just knows its path.

Sure, but the old code does bad things on exit (like saving state in an invalid format). I'm pretty sure I need, in the general case, to be able to stop it, fix things, and restart it.

Support a command to exit without saving state before your first deployment.

Robust systems self-heal rather than requiring an external agency. Why do you need it stopped while you fix things externally, rather than having a check to see if things need to be fixed be the first thing you do when you restart, and self-heal?

If nothing else, instead of installing the binary for your process, install the binary for the fix process instead, and have the last thing it does as it fixes things is replace its binary and exit.

We intentionally erected a protection domain barrier here, where processes that do what your process wants to do have to ask permission to perform privileged operations, or at least politely request those privileged operations be performed on their behalf.

Your code needs to either ask politely like everyone else, or run as root.

Just to finish this off, here's what I did. My daemon is now a /Library/LaunchDaemon/foo.plist daemon, RunAtLoad and KeepAlive, with UserName set to the user it belongs to. So it gets run (and restarted) in the startup context. I've added prologue code (not Prolog code :-) to the daemon's initialization routine which checks for a blocking file in a certain place, and if it's there, just loops and waits for it to go away, which when it does the daemon process exits. This check happens before the daemon does any initialization. So "stop" is basically, "touch" the blocking file and "kill -TERM" the daemon; "start" just removes the blocking file; and "restart" is "kill -TERM" the daemon. Actions the user can perform without admin privileges. Still seems convoluted. Bill _______________________________________________ Do not post admin requests to the list. They will be ignored. Darwin-kernel mailing list (Darwin-kernel@lists.apple.com) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/darwin-kernel/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com