Newsgroups: comp.os.minix
Path: utzoo!henry
From: henry@utzoo.uucp (Henry Spencer)
Subject: Re: System calls: particularly checking if input is available on stdin
Message-ID: <1989Sep22.203509.10874@utzoo.uucp>
Organization: U of Toronto Zoology
References: <1730@draken.nada.kth.se>
Date: Fri, 22 Sep 89 20:35:09 GMT

In article <1730@draken.nada.kth.se> matsl@nada.kth.se (Mats Luthman) writes:
>I know how to do it in both BSD and AT&T UNIX, but I can't find a fcntl
>function in libc.a (on MINIX-ST)...

This function did not exist in V7, which is what Minix is modelled on.
Nor did the ability to determine presence of pending input.

>.... doesn't say very much about how to use them, and gtty and stty
>aren't even mentioned (in the index).

Minix has probably emulated V7 in this regard:  gtty and stty were obsolete
backwards-compatibility interfaces for ioctl.  They can't do anything that
ioctl can't.

>... Another thing I can't find is macros for the mode parameter to open().

Again, in V7 there weren't any.  The mode parameter was specified as integer
values (0 readonly, 1 writeonly, 2 readwrite).

>Another thing I want to know: if I want a certain function to be called
>every time there is input available on a file descriptor, what do I do?
>There is no SIGIO signal, so I wonder if it is at all possible.

Can't be done in V7.  SIGIO is a hideous botch; I'm not surprised that
Andy didn't put it into Minix.
-- 
"Where is D.D. Harriman now,   |     Henry Spencer at U of Toronto Zoology
when we really *need* him?"    | uunet!attcan!utzoo!henry henry@zoo.toronto.edu