From owner-freebsd-current  Mon Feb 11 19:48:41 2002
Delivered-To: freebsd-current@freebsd.org
Received: from newman2.bestweb.net (newman2.bestweb.net [209.94.102.67])
	by hub.freebsd.org (Postfix) with ESMTP id A294537B659
	for <current@FreeBSD.ORG>; Mon, 11 Feb 2002 18:19:13 -0800 (PST)
Received: from okeeffe.bestweb.net (okeefe.bestweb.net [209.94.100.110])
	by newman2.bestweb.net (Postfix) with ESMTP
	id 871EC23006; Mon, 11 Feb 2002 21:18:08 -0500 (EST)
Received: by okeeffe.bestweb.net (Postfix, from userid 0)
	id AE7B99F3DE; Mon, 11 Feb 2002 21:12:46 -0500 (EST)
Date: Mon, 11 Feb 2002 10:14:04 -0500 (EST)
From: Daniel Eischen <eischen@pcnet1.pcnet.com>
To: Bruce Evans <bde@zeta.org.au>
Cc: Kevin Day <toasty@shell.dragondata.com>, current@FreeBSD.ORG, 
Subject: Re: function name collision on "getcontext" with ports/editors/joe
Message-Id: <20020212021246.AE7B99F3DE@okeeffe.bestweb.net>
Sender: owner-freebsd-current@FreeBSD.ORG
Precedence: bulk
List-ID: <freebsd-current.FreeBSD.ORG>
List-Archive: <http://docs.freebsd.org/mail/> (Web Archive)
List-Help: <mailto:majordomo@FreeBSD.ORG?subject=help> (List Instructions)
List-Subscribe: <mailto:majordomo@FreeBSD.ORG?subject=subscribe%20freebsd-current>
List-Unsubscribe: <mailto:majordomo@FreeBSD.ORG?subject=unsubscribe%20freebsd-current>
X-Loop: FreeBSD.ORG

On Mon, 11 Feb 2002, Bruce Evans wrote:
> On Sun, 10 Feb 2002, Daniel Eischen wrote:
> 
> > On Mon, 11 Feb 2002, Bruce Evans wrote:
> > > <sys/signal.h> includes <machine/signal.h> for the normal namespace
> > > pollution that was needed to use sigreturn(2) (except sigreturn(2)
> > > itself isn't actually declared anywhere).  Including <sys/ucontext.h>
> > > gives the corresponding namespace pollution for using the current
> > > sigreturn(2).  This is probably a mistake.  (Don't believe the
> > > sigreturn man page; it documents osigreturn(2) for the i386 only.)
> > > Programs shouldn't have any problems with this, since they should
> > > define _POSIX_SOURCE if they only want the POSIX namespace ;-).
> >
> > Poking about on a Solaris 8 system shows that they have a
> > <ucontext.h> that defines the {get,set,make,swap}context
> > prototypes.  <ucontext.h> also includes <sys/ucontext.h>
> > to get the definitions for ucontext_t.
> 
> <sys/ucontext.h> is just as nonstandard as <machine/ucontext.h>.
> 
> > Under FreeBSD, <ucontext.h> is a link to <sys/ucontext.h>,
> > which both declare ucontext_t and {get,set,make,swap}context.
> 
> The link part is intentional.  We have to have <sys/ucontext.h> for
> use in the kernel, so it is simpler not to have a separate user
> header.  The only advantage of the Solaris implementation is that
> it punishes applications that include the nonstandard header.
> 
> > What do you recommend we do?  Should we not include <sys/ucontext.h>
> > from <sys/signal.h>, or do what Solaris does, or just leave
> > everything as is?
> 
> Don't include <sys/ucontext.h> from <sys/signal.h>, and fix whatever
> breaks.  I think applications that use the new sigreturn can be required
> to include both <signal.h> and <ucontext.h>.  There should be fewer
> of them than there used to be -- they can now use setcontext().  The
> old sigcontext/sigreturn stuff should be cleaned up too (don't export
> it to userland).

It breaks more than that.  Applications that just want to use
sigaction, sigaltstack, etc, only need to include <signal.h>,
but that also defines sigreturn as:

  int     sigreturn __P((ucontext_t *));

Removing <sys/ucontext.h> from <sys/signal.h> prevents ucontext_t
from being defined, so all users of <signal.h> would choke.

We can change the prototype of sigreturn back to struct sigcontext *,
or just forward declare ucontext_t in <signal.h> or <sys/signal.h>.

-- 
Dan Eischen



To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message

To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-current" in the body of the message