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From: Charlie Brady <charlieb-supervision@budge.apana.org.au>
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Subject: Re: supervising postfix
Date: Sat, 16 Oct 2004 16:42:30 -0400 (EDT)
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On Sat, 16 Oct 2004, Charlie Brady wrote:

> I don't see the logic in postfix interpreting this as a fatal error. 
> Postfix wanted to be the process group leader. It already was. Where's 
> the fatal problem?

I notice that elsewhere in postfix (in pipe_command.c) setsid failure is 
not fatal:

...
        /*
         * Child. Run the child in a separate process group so that the
         * parent can kill not just the child but also its offspring.
         */
    case 0:
        set_ugid(args.uid, args.gid);
        if (setsid() < 0)
            msg_warn("setsid failed: %m");
...

You could do the same in master.c:

...
    /*
     * Run in a separate process group, so that "postfix stop" can terminate
     * all MTA processes cleanly. Give up if we can't separate from our
     * parent process. We're not supposed to blow away the parent.
     */
    if (setsid() == -1)
        msg_fatal("unable to set session and process group ID: %m");
...

The comment of course is bogus, one wouldn't blow away the parent if 
setsid() fails, since that implies the parent is already in a separate 
process group.

BTW, don't expect to use multilog with postfix:

...                                                                                                    
    /*
     * If started from a terminal, get rid of any tty association. This also
     * means that all errors and warnings must go to the syslog daemon.
     */
    for (fd = 0; fd < 3; fd++) {
        (void) close(fd);
        if (open("/dev/null", O_RDWR, 0) != fd)
            msg_fatal("open /dev/null: %m");
    }
...

The comment there is also bogus, since there is not test for being started 
from a terminal.

---
Charlie