Honor the Xvnc command specified in the config instead of using a hard-coded
default.

Submitted upstream at: https://github.com/canonical/lightdm/pull/265

diff --git a/src/lightdm.c b/src/lightdm.c
index 74f9ff2d..0ccfcd78 100644
--- a/src/lightdm.c
+++ b/src/lightdm.c
@@ -349,27 +349,42 @@ start_display_manager (void)
     /* Start the VNC server */
     if (config_get_boolean (config_get_instance (), "VNCServer", "enabled"))
     {
-        g_autofree gchar *path = g_find_program_in_path ("Xvnc");
-        if (path)
+        /* Validate that a the VNC command is available. */
+        g_autofree gchar *command = config_get_string (config_get_instance (), "VNCServer", "command");
+        if (command)
         {
-            vnc_server = vnc_server_new ();
-            if (config_has_key (config_get_instance (), "VNCServer", "port"))
+            g_auto(GStrv) tokens = g_strsplit (command, " ", 2);
+            if (!g_find_program_in_path (tokens[0]))
             {
-                gint port = config_get_integer (config_get_instance (), "VNCServer", "port");
-                if (port > 0)
-                    vnc_server_set_port (vnc_server, port);
+                g_warning ("Can't start VNC server; command '%s' not found", tokens[0]);
+                return;
             }
-            g_autofree gchar *listen_address = config_get_string (config_get_instance (), "VNCServer", "listen-address");
-            vnc_server_set_listen_address (vnc_server, listen_address);
-            g_signal_connect (vnc_server, VNC_SERVER_SIGNAL_NEW_CONNECTION, G_CALLBACK (vnc_connection_cb), NULL);
-
-            g_debug ("Starting VNC server on TCP/IP port %d", vnc_server_get_port (vnc_server));
-            vnc_server_start (vnc_server);
         }
         else
-            g_warning ("Can't start VNC server, Xvnc is not in the path");
+        {
+            /* Fallback to 'Xvnc'. */
+            if (!g_find_program_in_path ("Xvnc")) {
+                g_warning ("Can't start VNC server; 'Xvnc' command not found");
+                return;
+            }
+        }
+
+        vnc_server = vnc_server_new ();
+        if (config_has_key (config_get_instance (), "VNCServer", "port"))
+        {
+            gint port = config_get_integer (config_get_instance (), "VNCServer", "port");
+            if (port > 0)
+                vnc_server_set_port (vnc_server, port);
+        }
+        g_autofree gchar *listen_address = config_get_string (config_get_instance (), "VNCServer", "listen-address");
+        vnc_server_set_listen_address (vnc_server, listen_address);
+        g_signal_connect (vnc_server, VNC_SERVER_SIGNAL_NEW_CONNECTION, G_CALLBACK (vnc_connection_cb), NULL);
+
+        g_debug ("Starting VNC server on TCP/IP port %d", vnc_server_get_port (vnc_server));
+        vnc_server_start (vnc_server);
     }
 }
+
 static void
 service_ready_cb (DisplayManagerService *service)
 {
td><a href='/guix/commit/gnu/system/examples/vm-image.tmpl?id=65e8472a4b6fc6f66871ba0dad518b7d4c63595e'>system: Remove nss-certs from OS templates, adjust doc.</a><span class='msg-avail'>...<span class='msg-tooltip'>This is a follow-up to commit 86afaadb51 ("system: Add 'nss-certs' to
%base-packages-networking.")

* doc/guix-cookbook.texi (Running Guix on a Linode Server): Remove nss-certs
from operating system's packages field.
(Running Guix on a Kimsufi Server): Likewise.
* doc/guix.texi (Using the Configuration System): Likewise.
(X.509 Certificates): Adjust to mention nss-certs *is* part of %base-packages.
* gnu/installer/services.scm (%system-services): Remove recommendation to
install nss-certs.
* gnu/system/examples/bare-bones.tmpl (host-name): Remove obsolete comments.
* gnu/system/examples/desktop.tmpl (packages): Remove nss-certs.
* gnu/system/examples/lightweight-desktop.tmpl (packages): Likewise.
* gnu/system/examples/plasma.tmpl (packages): Likewise.
* gnu/system/examples/raspberry-pi-64-nfs-root.tmpl (packages): Likewise.
* gnu/system/examples/raspberry-pi-64.tmpl (packages): Likewise.
* gnu/system/examples/vm-image.tmpl (packages): Likewise.
* gnu/system/images/orangepi-r1-plus-lts-rk3328.scm (packages): Likewise.
* gnu/system/images/pine64.scm (packages): Likewise.
* gnu/system/install.scm (installation-os) [packages]: Likewise.

Change-Id: If09123a69b987178bcb0aab61c4570c14fc1286f
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-12-30 00:28:14 -0500'>2023-12-30</span></td><td><a href='/guix/commit/gnu/system/examples/vm-image.tmpl?id=1d4db94bebbaecfd4ddd96f90b8dc3ae3f6bf1a3'>gnu: vm-image.tmpl: Improve SPICE dynamic resizing.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/system/examples/vm-image.tmpl (auto-update-resolution-crutch): Delete
variable.
(operating-system) [packages]: Add x-resize.
[services]: Remove auto-update-resolution-crutch mcron service.

Fixes: https://issues.guix.gnu.org/57068
Reported-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
Change-Id: I45cd3d79b94ece2511d324c7b180f8f37bd9ba49
</span></span></td><td>Maxim Cournoyer</td></tr>
<tr><td><span title='2023-09-11 10:56:03 +0300'>2023-09-11</span></td><td><a href='/guix/commit/gnu/system/examples/vm-image.tmpl?id=ab971e9c1922ae6eeec47401cb589ae15f29e15f'>system: vm-image: Remove duplicate packages.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/system/examples/vm-image.tmpl (use-package-modules): Remove
unneeded modules.
(operating-system)[packages]: Remove nvi, wget.
</span></span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2022-12-16 23:42:17 -0500'>2022-12-16</span></td><td><a href='/guix/commit/gnu/system/examples/vm-image.tmpl?id=491bddfa276cc9775adf325c07e5f82638f330e7'>system: examples: Add mode prop line.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/system/examples/asus-c201.tmpl: Add a mode prop line.
* gnu/system/examples/bare-bones.tmpl: Likewise.
* gnu/system/examples/beaglebone-black.tmpl: Likewise.
* gnu/system/examples/desktop.tmpl: Likewise.
* gnu/system/examples/docker-image.tmpl: Likewise.
* gnu/system/examples/lightweight-desktop.tmpl: Likewise.
* gnu/system/examples/raspberry-pi-64-nfs-root.tmpl: Likewise.
* gnu/system/examples/raspberry-pi-64.tmpl: Likewise.
* gnu/system/examples/vm-image.tmpl: Likewise.
</span></span></td><td>Maxim Cournoyer</td></tr>