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000115_fdc@watsun.cc.columbia.edu_Mon Nov 5 10:36:42 EST 2001.msg
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Article: 12933 of comp.protocols.kermit.misc
Path: newsmaster.cc.columbia.edu!watsun.cc.columbia.edu!fdc
From: fdc@watsun.cc.columbia.edu (Frank da Cruz)
Newsgroups: comp.unix.sco.misc,comp.protocols.kermit.misc
Subject: Re: Dropping DTR in OSR5
Date: 5 Nov 2001 15:37:18 GMT
Organization: Columbia University
Lines: 79
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References: <9s40rp$fdh$1@newsmaster.cc.columbia.edu> <20011104160917.A13779@mammoth.ca.caldera.com> <9s4qjp$30k$1@newsmaster.cc.columbia.edu> <20011104195143.B13779@mammoth.ca.caldera.com>
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Xref: newsmaster.cc.columbia.edu comp.unix.sco.misc:139901 comp.protocols.kermit.misc:12933
In article <20011104195143.B13779@mammoth.ca.caldera.com>,
Bela Lubkin <belal@caldera.com> wrote:
: ...
: The devsys engineers at SCO (and perhaps today at Caldera) believed that
: if you asked for POSIX compliance, you were asking the devsys to act as
: a filter to prevent you from doing anything that wasn't specified in the
: POSIX standard(s) in question...
:
Right. It's not a criticism of SCO; it's a criticism of POSIX. Most of
the things that communication software needs to do are forbidden by POSIX.
: Hmmm, I would expect Kermit to just work with 3rd party drivers on OSR5.
: Device names? Kermit shouldn't care -- if I tell it "let's talk on
: /dev/ttyi13A" it should say "ok, boss".
:
I don't have my notes handy at the moment, but as I recall the problem
comes when a driver supports hundreds of serial ports, thus stressing the
SCO port-naming conventions and lockfile-name-devising algorithm.
: > In fact DTR comes back on, but RTS stays down, just as without the kludge.
: > The kludge does make a difference in 5.0.5, however: it makes it act like
: > 5.0.2 (without the kludge in 5.0.5, both DTR and RTS stayed down).
:
: Oh well.
:
I tried one last trick this morning. It doesn't work either, but I don't
know why. Maybe somebody can explain it. Last night I said:
: > ...(and of course the problem with closing the device is that you've
: > lost all the myriad setups you've done on it when you reopen it).
But after posting that I realized that in the POSIX environment (unlike in
BSD or System V) everything you need to know about the port is in one place:
the attribute struct. So the following should work:
tcgetattr(ttyfd, &ttcur);
close(ttyfd);
(pause)
ttyfd = open(name,O_RDWR|O_NONBLOCK);
tcsetattr(ttyfd,TCSADRAIN,&ttcur);
Right? Well, it does work insofar as it drops DTR and RTS for the desired
interval and they both come on again. However, any write() to the reopened
device gets error 11, "Resource temporarily unavailable".
: > In short there seems to be no way to do this in OSR5 prior to 5.0.6a.
:
: and you only have John's say-so with regard to 506a...
:
At some point I'd like to get somebody who has 5.0.6a and an external modem
to build and test my working copy of C-Kermit 8.0 to see if:
. The TIOCSDTR code gets included in tthang().
. SET MODEM HANGUP-METHOD RS232 really works.
. SHOW COMM displays the modem signals.
. Kermit automatically pops back to its prompt if CD drops during a
terminal session or file transfer.
The working sources are here:
ftp://kermit.columbia.edu/kermit/test/tar/x.tar.gz (also .Z)
(Is the big difference between 5.0.5 and 5.0.6 or between 5.0.6 and 5.0.6a?)
Ditto for Unixware 7 and Open UNIX 8.
: One more trick you could do -- but which does more firmly tie you to
: "sio". If you're working on tty1a, open and close tty1A. That should
: be sufficient to kick RTS, DTR back to sanity. And if you're working on
: 1A then open/close 1a. None of which is particularly pleasant. I might
: also be wrong in that _opening_ might fix RTS & DTR, but closing might
: screw them up again, so you would need to open and keep open the "other"
: device node. (Then, next time you need to do something to force correct
: RTS & DTR, close and reopen that "other" port.)
:
Opening the "other" port after tcsetattr() makes DTR come on but not RTS.
The behavior is the same if I close it or leave it open.
- Frank