top not restoring terminal echo/icanon correctly

[Jeremy Chadwick]

On Tue, Apr 17, 2012 at 12:51:15PM -0700, Jeremy Chadwick wrote:
> On Tue, Apr 17, 2012 at 11:22:42AM -0700, Jeremy Chadwick wrote:
> > (Please keep me CC'd as I'm not subscribed to the list)
> > 
> > I'd like to request that folks running RELENG_8 (and RELENG_9, though I
> > do not use it) please check the behaviour of their terminal after each
> > of following commands are run (check terminal after each command):
> > 
> > top -a  (press "q" after 1 screen refresh)
> > top -b
> > 
> > If you find that your input characters in your shell aren't being echo'd
> > back after one of the above commands, blindly type "stty icanon echo"
> > and hit <Enter> and things should be back to normal.
> > 
> > What I'm looking for is confirmation from others of the problem.
> > 
> > Also very important: please provide uname -a output, specifically world
> > rebuild date.  It greatly matters, because a commit was recently done
> > where now -b functions fine (was previously busted in this way), but now
> > -a behaves like -b did.  So src/world date matters.
> > 
> > All of this is documented in PR 161739.  I urge anyone experiencing this
> > problem to read that PR in full, as I spent many hours today writing a
> > debug routine to confirm that top is sometimes not calling tcsetattr()
> > with the original terminal parameters when it exits, and what the
> > condition seems to be.
> > 
> > http://www.freebsd.org/cgi/query-pr.cgi?pr=bin/161739
> > 
> > Finally, if anyone want to tackle the problem (work out the logic bug
> > that is in there which causes it), please be my guest.  I have other
> > things going on right now (doctors appointments) so I don't have as much
> > time as I'd like.
> > 
> > Thanks everyone.
> 
> Thanks to all those who have responded, including kib at .
> 
> The problem is very odd and appears specific to the bash shell, but
> only "somewhat".  Below is a part of what I sent kib@ on the matter.
> A chart showing what I've found:
> 
> Location      Username   TERM     Shell                 bug?
> =============================================================
> VGA console   root       cons25   /bin/csh              no
> VGA console   jdc        cons25   /usr/local/bin/bash   no
> SSH (PuTTY)   root       xterm    /bin/csh              no
> SSH (PuTTY)   jdc        xterm    /bin/csh              no
> SSH (PuTTY)   jdc        xterm    /usr/local/bin/bash   yes
> =============================================================
> 
> In the last case (and only that case): if I move my dotfiles (.bashrc
> and .bash_profile) aside and log in (SSH), top behaves normally.
> Naturally this made me think "something is wonky with my dotfiles!"...
> 
> But the problem *doesn't* happen if my dotfiles are intact and I
> log in via VGA console (cons25) as myself with a bash shell.  So it's
> almost like there's some bizarre combination of things that causes this
> problem.
> 
> I'll continue to try and narrow it down.

Boy this is a weird one.

In my .bashrc I've been using the following statement to show all
arguments and set the update interval to 1 second:

export TOP="-a -s 1"

Removing this completely and logging back in results in no problems
when running "top" in any way (top -a, top -s 1, or top -a -s 1).

However, the problem I describe with icanon/echo never getting restored
rears its ugly head when running "top -a -b", but only under bash
(with no dotfiles too).  It never happens under csh.

I can also reproduce this on VGA console when logged in (regardless of
user), e.g. log in as root (get csh shell), run bash, "top -a -b", bam,
issue happens.

I don't know what's different about the two shells at this level that
would cause oddities like this, but um, yeah.....  *blink*

-- 
| Jeremy Chadwick                                 jdc at parodius.com |
| Parodius Networking                     http://www.parodius.com/ |
| UNIX Systems Administrator                 Mountain View, CA, US |
| Making life hard for others since 1977.             PGP 4BD6C0CB |