Xref: utzoo comp.unix.wizards:6557 comp.unix.questions:5642
Path: utzoo!mnetor!uunet!husc6!hao!noao!arizona!lm
From: lm@arizona.edu (Larry McVoy)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Re: A Question Concerning Device Drivers
Message-ID: <3823@megaron.arizona.edu>
Date: 11 Feb 88 21:19:54 GMT
References: <2879@watale.waterloo.edu>
Reply-To: lm@megaron.arizona.edu.UUCP (Larry McVoy)
Distribution: na
Organization: University of Arizona, Tucson
Lines: 18
Keywords: ?

In article <2879@watale.waterloo.edu> watmelon@watale.waterloo.edu (Mech. Eng. Robotics Group) writes:
>In System V, is the cpass/passc combination the only way to pass data
>between a user's buffer and a character driver?
>It seems to be a bit of a waste of time to copy data one character at a time
>when you could probably do some kind of block copy.
>Are there other ways of passing the data?

copyout(driverbuf,userbuf,n)
caddr_t driverbuf, userbuf;
unsigned n;

copyin(userbuf,driverbuf,n)
....

The kernel will not know if the user didn't have enough buffer space.
-- 
Larry McVoy	lm@arizona.edu or ...!{uwvax,sun}!arizona.edu!lm
		Use the force - read the source.