From: Warner Losh <imp@bsdimp.com>
To: Dave Horsfall <dave@horsfall.org>
Cc: The Eunuchs Hysterical Society <tuhs@tuhs.org>
Subject: Re: [TUHS] V6 networking & alarm syscall
Date: Fri, 11 Jan 2019 19:33:10 -0700 [thread overview]
Message-ID: <CANCZdfqdX5MdXWxWGkvsJD9zZwkPg7wLTbWrYNcNH65tQw0W_Q@mail.gmail.com> (raw)
In-Reply-To: <alpine.BSF.2.21.9999.1901121237300.90857@aneurin.horsfall.org>
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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
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next prev parent reply other threads:[~2019-01-12 2:34 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-12 1:24 Noel Chiappa
2019-01-12 1:58 ` Dave Horsfall
2019-01-12 2:33 ` Warner Losh [this message]
-- strict thread matches above, loose matches on Subject: below --
2019-01-13 10:52 Paul Ruizendaal
2019-01-13 15:39 ` Warner Losh
[not found] <mailman.1.1547258402.6716.tuhs@minnie.tuhs.org>
2019-01-12 11:13 ` Paul Ruizendaal
2019-01-12 4:14 Noel Chiappa
2019-01-11 23:27 Paul Ruizendaal
2019-01-10 23:12 Paul Ruizendaal
2019-01-11 0:17 ` Clem cole
2019-01-11 15:33 ` ron
2019-01-11 18:45 ` Clem Cole
2019-01-11 19:06 ` David
2019-01-11 22:08 ` reed
2019-01-11 22:18 ` Larry McVoy
2019-01-12 12:04 ` reed
2019-01-12 17:20 ` Clem Cole
2019-01-12 18:16 ` Eric Allman
2019-01-13 1:16 ` Madeline Autumn-Rose
2019-01-11 22:47 ` Clem Cole
2019-01-11 22:55 ` Eric Allman
2019-01-11 23:32 ` Warner Losh
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