I had a hard time getting tigervnc service to work on a headless machine. Basically, Xvnc starts but then exits right away. Installing x11-misc/slim as the ebuild recommends "for proper session support" doesn't help either. Reproducible: Always Steps to Reproduce: 1. Start with a system with no X11, no desktop environments. 2. USE="server" emerge -v net-misc/tigervnc x11-wm/awesome (any other WM can be used as well) 3. ln -s tigervnc /etc/init.d/tigervnc.10 4. echo ":10=myuser" >> /etc/tigervnc/vncserver.users 5. mkdir -p /home/myuser/.vnc/ 6. echo "session=awesome" >> /home/myuser/.vnc/config 7. /etc/init.d/tigervnc.10 restart Actual Results: No Xvnc is server running. ~/.xsession-errors contains the following: ``` /etc/X11/Sessions/Xsession: line 112: exec: xsm: not found ``` ~/.vnc/*:10.log doesn't contain anything suspicious -- it just indicates that the server exited right away: ``` Using desktop session awesome New 'myhostname:10 (myuser)' desktop is myhostname:10 Starting desktop session awesome Xvnc TigerVNC 1.13.1 - built Jul 22 2024 03:10:57 Copyright (C) 1999-2022 TigerVNC Team and many others (see README.rst) See https://www.tigervnc.org for information on TigerVNC. Underlying X server release 12101008 Mon Jul 22 03:12:36 2024 vncext: VNC extension running! vncext: Listening for VNC connections on local interface(s), port 5910 vncext: created VNC server for screen 0 [mi] mieq: warning: overriding existing handler (nil) with 0x55f19420dbd0 for event 2 [mi] mieq: warning: overriding existing handler (nil) with 0x55f19420dbd0 for event 3 xinit: XFree86_VT property unexpectedly has 0 items instead of 1 xinit: connection to X server lost waiting for X server to shut down ComparingUpdateTracker: 0 pixels in / 0 pixels out ComparingUpdateTracker: (1:-nan ratio) ``` Expected Results: Xvnc is running, the WM session is launched.
I tracked down what's going on to some extent. `/etc/init.d/tigervnc` calls `/usr/libexec/vncsession-start`, which does a couple of sanity checks. It then calls `/usr/sbin/vncsession`. `/usr/sbin/vncsession` handles PAM and daemonization, sets `XDG_SESSION_CLASS` and `XDG_SESSION_TYPE`, and then calls `/usr/bin/vncserver`. This is where the fun starts -- it reads VNC configs and goes on calling `xinit`. In my case the `xinit` call looks as follows: `xinit /etc/X11/Sessions/Xsession /etc/X11/Sessions/awesome -- /usr/bin/Xvnc :10 -depth 24 -geometry 1280x900 -localhost -auth /home/myuser/.Xauthority -desktop "myhostname:10 (myuser)" -pn -rfbauth /home/myuser/.vnc/passwd -rfbport 5910` Basically, the problem here is that `/etc/X11/Sessions/Xsession` ignores any arguments passed to it (unless the argument is "failsafe"). > Installing x11-misc/slim as the ebuild recommends "for proper session support" doesn't help either. And this doesn't work because `/usr/share/slim/Xsession` is non-executable, so `vncserver` ignores it. Doing `chmod a+x /usr/share/slim/Xsession` fixes the problem and let's the X11 session start normally. I suspect that x11-misc/sddm might have the same problem as it also installs its Xsession under `/usr/share` -- `/usr/share/sddm/scripts/Xsession`.
I don't know the xsession stuff well enough (or rather at all), but I see the following issues: 1. `vncserver` tries to find and start Xsession in order to start a `session=` defined in the config file. At least, on Gentoo, `/etc/X11/Sessions/Xsession` and `/etc/X11/Sessions/awesome` are almost identical (with the latter derived from the former), so it seems like `/etc/X11/Sessions/awesome` can just be run directly instead. 2. `vncserver` wants `Xsession` to be executable, but apparently `xinit` doesn't actually care and runs `/usr/share/slim/Xsession` just fine even if it's not executable. A trivial fix for this would be ```diff --- vncserver.orig 2024-07-22 03:08:31.000000000 +0300 +++ vncserver 2024-07-22 04:32:16.887261909 +0300 @@ -442,7 +442,7 @@ sub SanityCheck $Xsession=$ENV{TIGERVNC_XSESSION_FILE}; if (not defined $Xsession) { foreach $cmd ("/usr/share/sddm/scripts/Xsession", "/etc/gdm/Xsession", "/etc/lightdm/Xsession", "/usr/share/slim/Xsession", "/etc/X11/Sessions/Xsession", "/etc/X11/xinit/Xsession", "/etc/X11/Xsession") { - if (-x "$cmd") { + if (-r "$cmd") { $Xsession = $cmd; last; } ``` 3. `/etc/X11/Sessions/Xsession` basically ignores any arguments passed to it. For comparison, the one from x11-misc/slim ends with `exec $command` (where `command="$@"`). x11-misc/lightdm and x11-misc/sddm also do `exec $command` in the end. A bet this has decades worth of history, so any change can probably break something. But nevertheless, this looks pretty low-risk to me: ```diff --- Xsession.orig 2024-07-22 03:44:43.951197197 +0300 +++ Xsession 2024-07-22 04:46:54.475274950 +0300 @@ -100,15 +100,20 @@ unset XKB_IN_USE +if [ -n "$*" ] ; then + "$@" & +fi + if [ -x "$startup" ]; then - exec "$startup" + "$startup" elif [ -x "$HOME/.Xclients" ]; then - exec "$HOME/.Xclients" + "$HOME/.Xclients" elif [ -x /etc/X11/xinit/Xclients ]; then - exec /etc/X11/xinit/Xclients + /etc/X11/xinit/Xclients elif [ -x /etc/X11/Xclients ]; then - exec /etc/X11/Xclients + /etc/X11/Xclients else - exec xsm + xsm fi +wait true ```
The simplest workaround I've found so far (which doesn't require installing a DM or hacking `/etc/X11/Sessions/Xsession`) is setting `TIGERVNC_XSESSION_FILE="/usr/bin/env"` in `/etc/conf.d/tigervnc`. (or creating a display-specific `/etc/conf.d/tigervnc.10` and setting it there) Setting `TIGERVNC_XSESSION_FILE=/etc/X11/Sessions/awesome` also works, but then the `session=` parameter from `~/.vnc/config` gets ignored essentially.
Thank you for your in-depth analysis. I'll try to test a few of your suggestions and see what I can do without breaking things.
(In reply to Andrey from comment #2) > 2. `vncserver` wants `Xsession` to be executable, > but apparently `xinit` doesn't actually care and runs > `/usr/share/slim/Xsession` just fine even if it's not executable. > > A trivial fix for this would be > ```diff > --- vncserver.orig 2024-07-22 03:08:31.000000000 +0300 > +++ vncserver 2024-07-22 04:32:16.887261909 +0300 > @@ -442,7 +442,7 @@ sub SanityCheck > $Xsession=$ENV{TIGERVNC_XSESSION_FILE}; > if (not defined $Xsession) { > foreach $cmd ("/usr/share/sddm/scripts/Xsession", > "/etc/gdm/Xsession", "/etc/lightdm/Xsession", "/usr/share/slim/Xsession", > "/etc/X11/Sessions/Xsession", "/etc/X11/xinit/Xsession", > "/etc/X11/Xsession") { > - if (-x "$cmd") { > + if (-r "$cmd") { > $Xsession = $cmd; > last; > } > ``` On my system slim's session file is indeed not executable. $ ls -l /usr/share/sddm/scripts/Xsession /etc/gdm/Xsession /etc/lightdm/Xsession /usr/share/slim/Xsession /etc/X11/Sessions/Xsession -rwxr-xr-x 1 root root 6092 mar 31 21:19 /etc/gdm/Xsession -rwxr-xr-x 1 root root 1962 mar 31 05:58 /etc/lightdm/Xsession -rwxr-xr-x 1 root root 2187 mar 30 16:16 /etc/X11/Sessions/Xsession -rwxr-xr-x 1 root root 2852 mai 6 15:22 /usr/share/sddm/scripts/Xsession -rw-r--r-- 1 root root 4045 mar 30 15:33 /usr/share/slim/Xsession Considering I was already patching vncserver, I'll change it to `-r`. > 3. `/etc/X11/Sessions/Xsession` basically ignores any arguments passed to it. > For comparison, the one from x11-misc/slim ends with `exec $command` > (where `command="$@"`). > x11-misc/lightdm and x11-misc/sddm also do `exec $command` in the end. This is exactly why I added that message about installing a proper display manager.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=6f4b28e562378215406f8481c84f1ad95062145c commit 6f4b28e562378215406f8481c84f1ad95062145c Author: Viorel Munteanu <ceamac@gentoo.org> AuthorDate: 2024-07-27 19:21:50 +0000 Commit: Viorel Munteanu <ceamac@gentoo.org> CommitDate: 2024-07-27 19:36:02 +0000 net-misc/tigervnc: add 1.14.0 Add 1.14.0. Small changes to configuration files. Closes: https://bugs.gentoo.org/936442 Closes: https://bugs.gentoo.org/936475 Signed-off-by: Viorel Munteanu <ceamac@gentoo.org> net-misc/tigervnc/Manifest | 1 + .../files/tigervnc-1.14.0-xsession-path.patch | 28 +++ net-misc/tigervnc/files/tigervnc-1.14.0.confd | 13 ++ net-misc/tigervnc/files/tigervnc-1.14.0.initd | 90 ++++++++ net-misc/tigervnc/tigervnc-1.14.0.ebuild | 235 +++++++++++++++++++++ 5 files changed, 367 insertions(+)
