Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!cs.utexas.edu!yale!cmcl2!stealth.acf.nyu.edu!brnstnd
From: brnstnd@stealth.acf.nyu.edu
Newsgroups: comp.unix.wizards
Subject: Re: How do you pass file descriptors over IPC?
Message-ID: <20465:May402:16:4490@stealth.acf.nyu.edu>
Date: 4 May 90 02:16:44 GMT
References: <2395@uakari.primate.wisc.edu>
Reply-To: brnstnd@stealth.acf.nyu.edu (Dan Bernstein)
Distribution: usa
Organization: IR
Lines: 16

In article <2395@uakari.primate.wisc.edu> bin@primate.wisc.edu (Brain in Neutral) writes:
> The BSD IPC documentation makes mention of the possibility of passing
> file descriptors between processes using IPC.

You set up a UNIX-domain socket connection, then use sendmsg() and
recvmsg(). Don't pass any iovs, just a few descriptors. They'll be
renumbered and placed into the receiving array; and they'll be open in
the receiving process.

> Which BSD programs (if any) do this?  I could then perhaps grab the
> source from uunet and examine it.

I don't know of any offhand; it's not a commonly appreciated feature.
I'm using it a bit in some upcoming programs.

---Dan