Support for running xterm within a jail?

[Kostik Belousov]

On Thu, Nov 17, 2011 at 11:44:12AM -0800, David Wolfskill wrote:
> At $WORK, we have recently been reminded that xterm doesn't cope all
> that well with being invoked in an environment that returns ENOENT on
> xterm's attempt to open /dev/tty (in main.c).
> 
> (The environment in question is a jailed 32-bit FreeBSD running on a
> FreeBSD/amd64 host.  Developers need to build in the jail; apparently
> they also want to run things like emacs in the jails.)
> 
> In looking at the xterm sources, I found that there's some code (near
> main.c:3311 - 3329) to take evasive action if the attempt to open
> /dev/tty fails.
> 
> There's even a bit to effectively ignore ENOENT -- if __CYGWIN__ is
> defined.
> 
> But that's not our case -- and we don't want to be defining __CYGWIN__
> when we're building xterm for FreeBSD.
> 
> Given that FreeBSD (with devfs) *can* return ENOENT to the attempt to
> open /dev/tty, it isn't clear to me why that aprticular "error"
> condition isn't ignored unconditionally (in a FreeBSD environment, at
> least).
> 
> Accordingly, I cobbled up a patch (attached), and a colleague has
> verified that it avoids the issue we were encountering: it allows xterm
> to run in the jail.
> 
> Do you think the xterm folks would be receptive to either making the
> "ignore ENOENT" unconditional or conditioning it on (say) "__CYGWIN_"
> being defined or "__FREEBSD__" being defined?
> 
> Failing that (or in the mean time) would you be receptive to a patch to
> the FreeBSD xterm port to patch xterm in a way similar to the attached
> patch?
> 
> (I realize we're approaching 9.0-RELEASE; I'm not asking anyone to make
> changes before that release date.)

I am sure that the issue is a misconfiguration of the jail or attempt to
start xterm from the process that has no control terminal. For jail
misconfiguration, I mean either failure to properly mount devfs into
the jail /dev, or a rule that hides /dev/tty from the jail.

I use very similar configuration (32bit stable/8 jail on amd64 stable/9
kernel) and have no issues starting xterm.

That said, you should diagnose the issue further, otherwise I think the
patch is unneccessary.
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