When attempting an XDMCP-mediated session via VNC to localhost, the
session fails, and the following error is recorded to daemon.log:

    daemon.log:Aug 22 18:33:07 navel wdm: wdm pipe read error with program
    /usr/bin/X11/wdmLogin, wdm terminating

To replicate the problem:

  - Install the xvncviewer, vncserver, and wdm packages.

  - Ensure the wdm display manager is running and will serve a WDM
    greeting on initiated X sessions.

  - Start an X session or use an existing one.

  - Start the vncserver with the following command:

      /usr/bin/X11/Xvnc :2 -query localhost -once -geometry 800x600 -depth 16

  - Start a vncviewer session on the same host:

      /usr/bin/X11/xvncviewer :2

  - Enter userid and password.

Authentication attempts should fail.  The error message indicated above
should be in /var/log/daemon.log and/or /var/log/wdm.log.

Version of xvncviewer: 3.3.3r2-13
Version of vncserver:  3.3.3r2-13
--- Begin /etc/X11/wdm/Xservers (modified conffile)
:0 local /usr/bin/X11/X vt7 -deferglyphs 32 -dpi 100 -nolisten tcp

--- End /etc/X11/wdm/Xservers

--- Begin /etc/X11/wdm/Xsetup_0 (modified conffile)
#!/bin/sh
find /etc/X11/Xresources -maxdepth 1 -type f | xargs xrdb -merge
xmodmap /etc/X11/Xmodmap
if grep -q ^run-xconsole /etc/X11/wdm/wdm.options; then
  xconsole -bg grey70 -geometry 480x62+0-0 -daemon -notify -verbose -fn fixed \
    -exitOnFail -file /dev/xconsole
fi

--- End /etc/X11/wdm/Xsetup_0

--- Begin /etc/X11/wdm/Xstartup_0 (modified conffile)
#!/bin/sh
set -e
if [ -x /etc/X11/wdm/Xstartup ]; then
  /etc/X11/wdm/Xstartup || exit $?
fi
(sleep 10; /usr/local/sbin/xrootconsole-prefered ) &
exit 0

--- End /etc/X11/wdm/Xstartup_0

--- Begin /etc/X11/wdm/wdm-config (modified conffile)
! /etc/X11/wdm/wdm-config
!
! resources specific to wdm itself
DisplayManager.authDir:		/var/state/wdm
DisplayManager.errorLogFile:	/var/log/wdm.log
DisplayManager.pidFile:		/var/run/wdm.pid
DisplayManager.keyFile:		/etc/X11/wdm/wdm-keys
DisplayManager.servers:		/etc/X11/wdm/Xservers
DisplayManager.accessFile:	/etc/X11/wdm/Xaccess
DisplayManager._0.authorize:	true
DisplayManager._0.resources:	/etc/X11/wdm/Xresources_0
DisplayManager._0.setup:	/etc/X11/wdm/Xsetup_0
DisplayManager._0.startup:	/etc/X11/wdm/Xstartup_0
DisplayManager._0.reset:	/etc/X11/wdm/Xreset_0
DisplayManager*resources:	/etc/X11/wdm/Xresources
DisplayManager*setup:		/etc/X11/wdm/Xsetup
DisplayManager*startup:		/etc/X11/wdm/Xstartup
DisplayManager*reset:		/etc/X11/wdm/Xreset
DisplayManager*session:		/etc/X11/wdm/Xsession
DisplayManager*userPath:	/usr/local/bin:/usr/bin:/bin:/usr/bin/X11:/usr/games
DisplayManager*systemPath:	/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/bin/X11
! wdm specific configuration ; documented in wdm(1x)
DisplayManager*wdmLogin:        /usr/bin/X11/wdmLogin
DisplayManager*wdmBg:           solid:darkslategrey
! DisplayManager*wdmLogo:       /usr/share/pixmaps/gnuLogo.xpm
DisplayManager*wdmLogo:		/usr/share/pixmaps/wdmDebianSwirl.xpm
DisplayManager*wdmWm:         blackbox:default:gnome-session:kde2:sawfish:twm:vtwm:wmaker
DisplayManager*wdmReboot:       /sbin/reboot
DisplayManager*wdmHalt:         /sbin/halt
DisplayManager*wdmVerify:       true
DisplayManager*wdmRoot:         true
DisplayManager*wdmAnimations:   true

--- End /etc/X11/wdm/wdm-config

I'll have a go at this this weekend.  Thank you for providing clear
steps to duplicate the bug; I have no prior experience with vnc.  I'll
let you know if I run in to vnc troubles while trying to duplicate the
behavior.

noah

Well, I wish I could call you stupid...  Unfortunately, I had no trouble
at all reproducing your bug.

This is going to be tough, as there doesn't seem to be anybody doing
upstream development on wdm anymore.  I like wdm, and will continue to
use an maintain it, but it will take me a while to familiarize myself
with it enough to properly debug it.

I wish I could say that a fix is forthcoming, but that's not likely the
case.  I'll work on it to whatever extent I am able, though.

noah

Hi,

I am looking at some ancient bug reports for this already orphaned package.
I am aware that original bug report is 9 years old, so you may no longer be
using wdm, but in case you still use it, there is something in above error
message that also appeared in

http://bugs.debian.org/488715
http://bugs.debian.org/547251

and that was fixed in wdm_1.28-3.5, so you may be interested in try again and
see what happens.

Thanks for your feedback.