Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!att!chinet!les
From: les@chinet.chi.il.us (Leslie Mikesell)
Newsgroups: comp.unix.wizards,comp.unix.i386
Subject: Re: STREAMS tty drivers for SysV
Message-ID: <8687@chinet.chi.il.us>
Date: 12 Jun 89 15:57:45 GMT
References: <KLEMETS.89Jun8171157@tum.sics.se> <45@calcite.UUCP>
Reply-To: les@chinet.chi.il.us (Leslie Mikesell)
Followup-To: comp.unix.wizards
Distribution: comp
Organization: Chinet - Public Access Unix
Lines: 14

In article <45@calcite.UUCP> vjs@calcite.UUCP (Vernon Schryver) writes:

>It is impossible to put a SVID-compliant tty under the SVR3.[012] stream head
>as it comes on the 3B2 source tapes.  There is no provision for VTIM/VMIN in
>the SVR3 streams head, and you cannot do it below the head in SVR3 streams.
>Also, the SVR3 stream head believes a non-blocking read returns EAGAIN like
>BSD ttys and other, reasonable SV devices, instead of 0 like SVID tty's.

AT&T 3B2's with Starlan have a streams based tty emulation for logging in
over the net, and it does show exactly the problems you mention.  The
most common trouble is with programs that don't check for a negative return
from read() after setting O_NDELAY (and why should they?).

Les Mikesell