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From: jfh@killer.UUCP
Newsgroups: comp.unix.xenix,comp.unix.questions
Subject: Re: tty watcher
Message-ID: <1551@killer.UUCP>
Date: Thu, 17-Sep-87 18:38:35 EDT
Article-I.D.: killer.1551
Posted: Thu Sep 17 18:38:35 1987
Date-Received: Sat, 19-Sep-87 09:52:51 EDT
References: <4263@ozdaltx.UUCP> <15136@hi.UUCP> <1178@mtune.ATT.COM> <267@spdcc.COM>
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Xref: utgpu comp.unix.xenix:661 comp.unix.questions:3703
Summary: What's wrong with this approach ...

i'm sure this has been thought of before to solve this problem, but what
is wrong with re-writing the /dev/tty driver (i seem to recall the source
is very short and simple) so that the minor device number is passed from
the open/close/read/write/ioctl calls rather than snatched out of the u-page?
you would have your hands on all of the data passed back from the actual
calls (say, dzread()) and would then be able to stuff it into a kernel
structure.  this should be _very_ easy.  my only problem is with the
close routine as closing the ttywatcher would call the real close and
it might not be ready to be closed just yet (although you could finger
through the i-node table for the device)

i forget the calling sequence for device drivers this week, but most of
what you would have to do is pass the same arguments of to the correct
routines, and snatch the returned characters from the users address space
before/after the call.

what am i not seeing?

- john.
-- 
John F. Haugh II		HECI Exploration Co. Inc.
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