From owner-freebsd-hackers  Mon Jan 29 12: 7:34 2001
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From: Luigi Rizzo <rizzo@aciri.org>
Message-Id: <200101292007.f0TK7Bc34876@iguana.aciri.org>
Subject: Re: [kernel patch] fcntl(...) to close many descriptors
In-Reply-To: <200101292000.PAA37796@khavrinen.lcs.mit.edu> from Garrett Wollman at "Jan 29, 2001  3: 0:23 pm"
To: wollman@khavrinen.lcs.mit.edu (Garrett Wollman)
Date: Mon, 29 Jan 2001 12:07:11 -0800 (PST)
Cc: rizzo@aciri.org, hackers@FreeBSD.ORG
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> Of course it can, and the manual page doesn't even suggest what you
> say.  It says:
> 
>      There is no way to simulate system calls that have multiple return values
>      such as pipe(2).

ok, sorry for the confusion then (though, how does one tell from
the manpage for pipe(2) what is going on there!)

	cheers
	luigi

> pipe(2) is a special case in that it returns two values rather than
> one.  The actual pipe(2) system call has *no* formal parameters; the
> unpacking of the two values returned into the declared C formal
> parameter is done by an assembly-language stub.  (This was done for
> reasons of speed; it is much faster to return two values than it is to
> copyout() a two-element array.


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