From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@quanstro.net>
Date: Fri,  5 Nov 2010 06:58:33 -0400
To: 9fans@9fans.net
Message-ID: <3c5bbf46c1bea0e36235f391b63b969f@plug.quanstro.net>
In-Reply-To: <20101105102946.GA12171@shutemov.name>
References: <20101105102946.GA12171@shutemov.name>
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Subject: Re: [9fans] Passing a file descriptor between processes
Topicbox-Message-UUID: 77a74544-ead6-11e9-9d60-3106f5b1d025

On Fri Nov  5 06:32:55 EDT 2010, kirill@shutemov.name wrote:
> One of the ugliest interface in Unix is passing a file descriptor between
> processes [1]. Does Plan9 provide any mechanism for it?
>
> [1] http://book.chinaunix.net/special/ebook/addisonWesley/APUE2/0201433079/ch17lev1sec4.html

there is no mechanism similar to sending fds over a socket.
the two ways of file descriptor sharing are via
(a) rfork(2); and
(b) srv(3)

rfork (optionally) allows a process to share a file descriptor
table with a child process.  srv allows a process to post a file
descriptor by a given name in /srv.  the normal file operations
apply on that file.  in particular, it must be opened
before use.

- erik