Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!usc!apple!agate!dog.ee.lbl.gov!elf.ee.lbl.gov!torek
From: torek@elf.ee.lbl.gov (Chris Torek)
Newsgroups: comp.unix.programmer
Subject: Re: Nice() in Sys V.4
Keywords: nice(), priocntl(), ioctl()
Message-ID: <11480@dog.ee.lbl.gov>
Date: 26 Mar 91 20:36:24 GMT
References: <318@secola.Columbia.NCR.COM> <1991Mar21.141753.28726@nncrcae.Columbia.NCR.COM> <11393@dog.ee.lbl.gov> <3424@inews.intel.com>
Reply-To: torek@elf.ee.lbl.gov (Chris Torek)
Organization: Lawrence Berkeley Laboratory, Berkeley
Lines: 22
X-Local-Date: Tue, 26 Mar 91 12:36:24 PST

In article <3424@inews.intel.com> bhoughto@nevin.intel.com
(Blair P. Houghton) writes:
>It's clear what is meant by what [the quoted part of the manual] said.

It is clear from the confusion over the following wording from `select'
that it is not at all clear what a `zero pointer' is:

	Any of
	.IR readfds ,
	.IR writefds ,
	and
	.I exceptfds
	may be given as zero pointers if no descriptors are of interest.

In this case `zero pointer' means *both* `a pointer to an int-0' and `a
null pointer to int'!  Both work; the latter is what the author of the
manual page intended, because the pointer-to-zero method is more
expensive (in terms of system call time) and also fails when the number
of file descriptors exceeds 32 (or more precisely, sizeof(int)*CHAR_BIT).
-- 
In-Real-Life: Chris Torek, Lawrence Berkeley Lab CSE/EE (+1 415 486 5427)
Berkeley, CA		Domain:	torek@ee.lbl.gov