Server: TVNC_USERDBUS config var/command-line opt

Introduce a new turbovncserver.conf variable ($userDBus) and vncserver command-line option (-userdbus) corresponding to the TVNC_USERDBUS environment variable used by xstartup.turbovnc. This allows users to more easily enable the use of the per-user D-Bus session bus instance on a system-wide, per-user, or per-TurboVNC-session basis. The feature is still undocumented except in turbovncserver.conf and xstartup.turbovnc.
TurboVNC · Feb 5, 2025 · 11225f0 · 11225f0
1 parent c6692ed
commit 11225f0
Show file tree

Hide file tree

Showing 3 changed files with 31 additions and 13 deletions.
diff --git a/unix/turbovncserver.conf b/unix/turbovncserver.conf
@@ -29,6 +29,16 @@
 ##                    (passed to Xvnc in the -securitytypes argument)
 ##  $serverArgs  -- additional arguments to pass to Xvnc (refer to the Xvnc man
 ##                  page for a list of accepted arguments)
+##  $userDBus    -- Using a unique D-Bus session bus instance for each TurboVNC
+##                  session is necessary in order to run multiple TurboVNC
+##                  sessions (or a local session and a TurboVNC
+##                  session) simultaneously under the same user account, but
+##                  this also causes issues with Control Group (cgroup) v2 on
+##                  some systems.  If this variable is set to 1, then the
+##                  TurboVNC session will use the per-user D-Bus session bus
+##                  instance provided by systemd rather than a unique D-Bus
+##                  session bus instance.  That improves cgroup v2
+##                  compatibility at the expense of multi-session capability.
 ##  $useUDS      -- listen on a Unix domain socket rather than a TCP port for
 ##                  connections from VNC viewers
 ##                  [equivalent of -uds command-line option]
@@ -65,6 +75,7 @@
 # $noxstartup = 0;
 # $securityTypes = "TLSVnc, TLSOtp, TLSPlain, X509Vnc, X509Otp, X509Plain, VNC, OTP, UnixLogin, Plain";
 # $serverArgs = "";
+# $userDBus = 0;
 # $useUDS = 0;
 # $useVGL = 0;
 # $vncUserDir = "$ENV{HOME}/.vnc";

diff --git a/unix/vncserver.in b/unix/vncserver.in
@@ -1,7 +1,7 @@
 #!/usr/bin/env perl
 #
-# Copyright (C) 2009-2018, 2020-2022, 2024 D. R. Commander.
-#                                          All Rights Reserved.
+# Copyright (C) 2009-2018, 2020-2022, 2024-2025 D. R. Commander.
+#                                               All Rights Reserved.
 # Copyright (C) 2021 Steffen Kieß
 # Copyright (C) 2010 University Corporation for Atmospheric Research.
 #                    All Rights Reserved.
@@ -61,6 +61,7 @@ $autokill = 1;
 $bits = @BITS@;
 $noVNC = "";
 $serverArgs = "";
+$userDBus = 0;
 $useUDS = 0;
 $udsPath = "";
 
@@ -209,7 +210,8 @@ foreach $_registrydir (@registrydirs) {
               "-3dwm", 0, "-vgl", 0, "-debug", 0, "-x509cert", 1,
               "-x509key", 1, "-autokill", 0, "-quiet", 0, "-wm", 1,
               "-sessionlist", 0, "-sessionstart", 0, "-novnc", 1,
-              "-noautokill", 0, "-rfbport", 1, "-rfbunixpath", 1, "-uds", 0);
+              "-noautokill", 0, "-rfbport", 1, "-rfbunixpath", 1, "-uds", 0,
+              "-userdbus", 0);
 
 &Usage() if ($opt{'-help'} || $opt{'-h'} || $opt{'--help'});
 
@@ -267,6 +269,9 @@ if ($opt{'-xstartup'}) {
 if ($opt{'-wm'}) {
   $wm = $opt{'-wm'};
 }
+if ($opt{'-userdbus'}) {
+  $userDBus = 1;
+}
 if ($opt{'-3dwm'} || $opt{'-vgl'}) {
   $useVGL = 1;
 }
@@ -590,6 +595,10 @@ if (!$noxstartup) {
   if ($wm) {
     $ENV{TVNC_WM} = $wm;
   }
+  if ($userDBus) {
+    warn "(Using per-user D-Bus session bus instance)\n";
+    $ENV{TVNC_USERDBUS} = "1";
+  }
   if ($useVGL) {
     warn "(Enabling VirtualGL)\n";
     $ENV{TVNC_VGL} = "1";
@@ -1242,6 +1251,7 @@ sub ReadConfiguration
        passwdFile
        securityTypes
        serverArgs
+       userDBus
        useUDS
        useVGL
        vncUserDir

diff --git a/unix/xstartup.turbovnc b/unix/xstartup.turbovnc
@@ -1,7 +1,7 @@
 #!/bin/sh
 
-#  Copyright (C) 2014-2018, 2021-2022, 2024 D. R. Commander.
-#                                           All Rights Reserved.
+#  Copyright (C) 2014-2018, 2021-2022, 2024-2025 D. R. Commander.
+#                                                All Rights Reserved.
 #  Copyright (C) 2005-2008 Sun Microsystems, Inc.  All Rights Reserved.
 #  Copyright (C) 2002 Constantin Kaplinsky.  All Rights Reserved.
 #
@@ -44,14 +44,11 @@ GDK_BACKEND=x11;  export GDK_BACKEND
 # Ubuntu 18.04+), it is necessary to explicitly create a new session bus
 # instance by invoking dbus-launch.
 #
-# Using a separate D-Bus session bus instance for each TurboVNC session is
-# necessary in order to run multiple TurboVNC sessions (or a local session and
-# a TurboVNC session) simultaneously under the same user account, but this also
-# causes issues with Control Group (cgroup) v2 on some systems.  If
-# TVNC_USERDBUS is set to 1 in the environment (currently undocumented except
-# here), then we forego creating a unique D-Bus session bus instance for the
-# TurboVNC session and use the per-user D-Bus session bus instance provided by
-# systemd instead.  That improves cgroup v2 compatibility at the expense of
+# If TVNC_USERDBUS is set to 1 in the environment (which will be the case if
+# $userDBus = 1 in turbovncserver.conf or -userdbus is passed to vncserver),
+# then we forego creating a unique D-Bus session bus instance for the TurboVNC
+# session and use the per-user D-Bus session bus instance provided by systemd
+# instead.  That improves cgroup v2 compatibility at the expense of
 # multi-session capability.
 case "$DBUS_SESSION_BUS_ADDRESS" in
 unix:path=/run/user/*)