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

[Jeremy Chadwick]

>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.

	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: