On Fri, Jan 11, 2019 at 6:59 PM Dave Horsfall <dave@horsfall.org> wrote:

> On Fri, 11 Jan 2019, Noel Chiappa wrote:
>
> [ ... ]
>
> >         ioctl (0, FIONREAD, &nch);
> >                        if (nch == 0) {
> >                                tk_yield ();
> >                                continue;
> >                        }
> >                }
> >                if ((c = getchar()) == EOF) {
> >
> > so that ioctl() must look to see if there is any data waiting in the
> > terminal input buffer (I'm too lazy to go see what FIONREAD does, right
> > at the moment).
>
> As I dimly recall (because I'm too sick/lazy to look it up), it returns
> the number of characters in the input queue (at that time) so that you
> won't block (and time out, if you wrote it thus).
>
> It was quite useful, if you didn't like the horrible semantics of
> select(), or, for that matter, SysV poll() (?) which was only slightly
> better.
>
> Of course, FIONREAD wasn't always reliable, because by the time you got to
> using it the keyboard (l)user could have deleted some characters etc, and
> you *could* be left there hanging on a timeout (with signals, which for
> some reason I hate with a passion, as I've posted here before, as they
> are just too brutal).
>

This is why RAW mode was born, but then you're duplicating the kernel
cooking code in your ap :(


> No doubt someone here will tell me that Plan9 did it right :-)  I really
> must run it up some time, before I finally kark it (I'm in my late 60s).
>

No doubt...

Warner