From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <b66ccdb4c92100075eeb3caa2560248a@quanstro.net>
To: 9fans@9fans.net
From: erik quanstrom <quanstro@quanstro.net>
Date: Thu, 27 Nov 2008 09:54:39 -0500
In-Reply-To: <140e7ec30811262349m764d4166kdd44141bf6afc2a3@mail.gmail.com>
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Subject: Re: [9fans] APE and listen(2B)
Topicbox-Message-UUID: 535ddeb6-ead4-11e9-9d60-3106f5b1d025

> On Thu, Nov 27, 2008 at 1:35 PM,  <lucio@proxima.alt.za> wrote:
>> Now, (a) I'm hoping someone can compile reveal.c (pcc -o reveal
>> -D_POSIX_SOURCES -D_BSD_EXTENSION reveal.c -lbsd) in a pristine APE
>> environment and prove to me that it works unmodified or, (b) somebody
>> can give me some pointers on figuring out how to make sure it works.
>
> # pcc -o reveal -D_POSIX_SOURCE -D_BSD_EXTENSION reveal.c -lbsd
> cpp: reveal.c:58 No newline at end of file
> /tmp/reveal.c:45[stdin:934] syntax error, last name: socklen_t
> /tmp/reveal.c:55[stdin:944] case/default outside a switch
> /tmp/reveal.c:58[stdin:947] syntax error, last name: 0
> pcc: cpp: 8c 71799: error
>
>  After removing the (socklen_t*) typecast...
> # pcc -o reveal -D_POSIX_SOURCE -D_BSD_EXTENSION reveal.c -lbsd
> # ./reveal
> ERRNO: 12
> socket accept: Invalid argument
>
> -sqweek

the problem seems to be in ape/lib/bsd/listen.c.  after the
fork, he sets up atexit(_killmuxsid).  the problem is that
this is _killmuxsid

void
_killmuxsid(void)
{
	if(_muxsid != -1 && (_mainpid == getpid() || _mainpid == -1))
		kill(-_muxsid,SIGTERM);
}

unless i've missed something, there are no arrangements
made to properly reference count the mux fd between processes.

children detach (_detachbuf) so they won't kill off the mux process, but
in the parent, _mainpid is still set, so as soon as the parent
exits, the mux should die.

the real solution involves reference counting.  but in your case,
not forking would make more sense.  in fact, if you wanted
to start reveal from listen(1), you could dispense with the
for(;;) and the fork.

- erik