From owner-freebsd-hackers  Wed Aug  4 10: 0:32 1999
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Date: Wed, 4 Aug 1999 12:59:44 -0400 (EDT)
From: "Brian F. Feldman" <green@FreeBSD.org>
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To: Assar Westerlund <assar@sics.se>
Cc: Mike Smith <mike@smith.net.au>,
	Matthew Dillon <dillon@apollo.backplane.com>,
	Ollivier Robert <roberto@keltia.freenix.fr>, hackers@FreeBSD.org
Subject: Re: Jail syscalls
In-Reply-To: <5lr9ljssjj.fsf@assaris.sics.se>
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On 4 Aug 1999, Assar Westerlund wrote:

> "Brian F. Feldman" <green@FreeBSD.ORG> writes:
> > On Tue, 3 Aug 1999, Mike Smith wrote:
> > > 
> > > Actually, with interfaces like this you should generally pass a pointer 
> > > to the structure in userspace, and stick a version number constant in 
> > > the beginning of the structure.  The size is often not enough of a 
> > > determining factor...
> > 
> > Actually, the structure shouldn't change size because it should be
> > using a sockaddr.
> 
> No, because sizeof(struct sockaddr) < sizeof(struct sockaddr_in6).
> This is kind of bad but that's the way it is.  It would make sense to
> use a `struct sockaddr_storage' but I still think it's worthwhile and
> better to have a version number.

As I read it, sockaddr is a transparent type (overloaded, as it were).
So we would use something like:
	struct jail {
		...
		struct sockaddr;
		char [SOCK_MAXADDRLEN - sizeof(struct sockaddr)];
		char [sizeof(int) - SOCK_MAXADDRLEN % sizeof(int)];/* padding */
		...
	}

> 
> /assar
> 
> 
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 Brian Fundakowski Feldman      _ __ ___ ____  ___ ___ ___  
 green@FreeBSD.org                   _ __ ___ | _ ) __|   \ 
     FreeBSD: The Power to Serve!        _ __ | _ \._ \ |) |
       http://www.FreeBSD.org/              _ |___/___/___/ 



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