A Question Concerning Device Drivers

[Larry McVoy]

In article <2879 at watale.waterloo.edu> watmelon at 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 at arizona.edu or ...!{uwvax,sun}!arizona.edu!lm
		Use the force - read the source.