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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.sources.bugs
Subject: Re: Bug in MicroEMACS 3.7 (includes fix)
Message-ID: <3732@umcp-cs.UUCP>
Date: Tue, 7-Oct-86 20:24:57 EDT
Article-I.D.: umcp-cs.3732
Posted: Tue Oct  7 20:24:57 1986
Date-Received: Thu, 9-Oct-86 04:52:30 EDT
References: <1923@eagle.ukc.ac.uk>
Distribution: net
Organization: Computer Sci. Dept, U of Maryland, College Park, MD
Lines: 21
Keywords: Sending SIGTSTP to MicroEMACS

It should not be necessary to send SIGTSTP to your process group
after catching one.  (Note the word *should*.)  This is because
everyone in your process group should have received the same keyboard
signal already.  Each should handle the TSTP, then stop itself.

Note that there is a timing problem here as well, at least among
programs that alter and then restore the tty state.  For example,
suppose you run a program that sets the terminal to cbreak mode,
then that program runs another that sets the terminal to nl mode
(CR/LF mapping turned off).  Now you type ^Z.  Which program runs
first?  If it is the cbreak'er that runs first, it will restore
the mode properly, then stop; then the nl'er will run, and `restore'
the mode to cbreak.

Oops.

(There are many solutions, but I am not up to listing them now.)
-- 
In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 1516)
UUCP:	seismo!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@mimsy.umd.edu