bin/161739: top -b does not restore ICANON and ECHO terminal capabilities when exiting

[Alexander Best]

The following reply was made to PR bin/161739; it has been noted by GNATS.

From: Alexander Best <arundel at freebsd.org>
To: Jeremy Chadwick <freebsd at jdc.parodius.com>
Cc: FreeBSD-gnats-submit at FreeBSD.org
Subject: Re: bin/161739: top -b does not restore ICANON and ECHO terminal capabilities when exiting
Date: Mon, 17 Oct 2011 12:08:13 +0000

 On Mon Oct 17 11, Jeremy Chadwick wrote:
 > 
 > >Number:         161739
 > >Category:       bin
 > >Synopsis:       top -b does not restore ICANON and ECHO terminal capabilities when exiting
 > >Confidential:   no
 > >Severity:       non-critical
 > >Priority:       medium
 > >Responsible:    freebsd-bugs
 > >State:          open
 > >Quarter:        
 > >Keywords:       
 > >Date-Required:
 > >Class:          sw-bug
 > >Submitter-Id:   current-users
 > >Arrival-Date:   Mon Oct 17 12:00:24 UTC 2011
 > >Closed-Date:
 > >Last-Modified:
 > >Originator:     Jeremy Chadwick
 > >Release:        FreeBSD 8.2-STABLE amd64
 > >Organization:
 > >Environment:
 > System: FreeBSD icarus.home.lan 8.2-STABLE FreeBSD 8.2-STABLE #0: Wed Sep 28 05:02:05 PDT 2011 root at icarus.home.lan:/usr/obj/usr/src/sys/X7SBA_RELENG_8_amd64 amd64
 > >Description:
 > 	It appears that "top -b" results in top disabling ICANON and
 > 	ECHO the controlling terminal/tty, but upon exit never
 > 	re-enables them.
 > 
 > 	I can confirm this problem on RELENG_7 (7.4-STABLE) and RELENG_8
 > 	(8.2-STABLE).  "top -b" does not work on RELENG_6.
 
 i can also confirm this running a very recent HEAD:
 
 otaku% stty -a > start; top -b ; stty -a > stop ; diff start stop
 
 [...]
 
 2c2
 < lflags: icanon isig iexten echo echoe echok echoke -echonl echoctl
 ---
 > lflags: -icanon isig iexten -echo echoe echok echoke -echonl echoctl
 
 cheers.
 alex
 
 > 
 > 	stty -a after running top -b shows "-icanon" and "-echo", which
 > 	confirms the bug.
 > 
 > 	I have not looked at the top code to find out where the bug
 > 	is, but I do see calls which adjust ICANON and ECHO capabilities
 > 	on the tty, so it's definitely there.
 > >How-To-Repeat:
 > 	1. Run top -b
 > 	2. Attempt to type something into your shell or make use of an
 > 	app which relies on canonical input.
 > >Fix:
 > 	Manually typing "stty echo icanon" after using top -b will
 > 	restore proper bits on the tty.
 > 
 > >Release-Note:
 > >Audit-Trail:
 > >Unformatted: