Run our session manager as a separate process

compositor/WindowManager.vala

@@ -221,6 +221,7 @@ namespace GreeterCompositor {
                 ShellClientsManager.init (this);
 
                 if (GLib.Environment.get_variable ("DESKTOP_SESSION") != "installer") {
+                    start_command.begin ({ "io.elementary.greeter-session-manager" });
                     start_command.begin ({ "io.elementary.greeter" });
                 }
 

compositor/main.vala

@@ -32,9 +32,6 @@ namespace GreeterCompositor {
             // Ensure we present ourselves as Pantheon so we pick up the right GSettings
             // overrides
             GLib.Environment.set_variable ("XDG_CURRENT_DESKTOP", "Pantheon", true);
-
-            var settings_daemon = new SettingsDaemon ();
-            settings_daemon.start ();
         }
 
         var ctx = new Meta.Context ("Mutter(GreeterCompositor)");

compositor/meson.build

@@ -114,8 +114,6 @@ compositor_files = files(
   'main.vala',
   'MediaFeedback.vala',
   'PointerLocator.vala',
-  'SettingsDaemon.vala',
-  'SubprocessSupervisor.vala',
   'Utils.vala',
   'WindowManager.vala',
   'Zoom.vala'

meson.build

@@ -51,6 +51,7 @@ compositor_resources = gnome.compile_resources(
 subdir('protocol')
 subdir('src')
 subdir('compositor')
+subdir('session-manager')
 subdir('data')
 subdir('po')
 vapigen = find_program('vapigen', required: false)

compositor/SettingsDaemon.vala → session-manager/SessionManager.vala

@@ -1,77 +1,12 @@
-/* -*- Mode:Vala; indent-tabs-mode:nil; tab-width:4 -*-
- *
- * Copyright (C) 2011 Canonical Ltd
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 3 as
- * published by the Free Software Foundation.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- * Authored by: Michael Terry <michael.terry@canonical.com>
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2025 elementary, Inc. (https://elementary.io)
  */
 
-public class GreeterCompositor.SettingsDaemon : Object {
-    private GreeterCompositor.GnomeSessionManager session_manager;
-    private int n_names = 0;
-    private SubprocessSupervisor[] supervisors = {};
-
-    public void start () {
-        /* Pretend to be GNOME session */
-        session_manager = new GreeterCompositor.GnomeSessionManager ();
-        n_names++;
-        GLib.Bus.own_name (BusType.SESSION, "org.gnome.SessionManager", BusNameOwnerFlags.NONE,
-                           (c) => {
-                               try {
-                                   c.register_object ("/org/gnome/SessionManager", session_manager);
-                               } catch (Error e) {
-                                   warning ("Failed to register /org/gnome/SessionManager: %s", e.message);
-                               }
-                           },
-                           () => {
-                               debug ("Acquired org.gnome.SessionManager");
-                               start_settings_daemon ();
-                           },
-                           () => debug ("Failed to acquire name org.gnome.SessionManager"));
-    }
-
-    private void start_settings_daemon () {
-        n_names--;
-        if (n_names != 0) {
-            return;
-        }
-
-        debug ("All bus names acquired, starting gnome-settings-daemon");
-
-        string[] daemons = {
-            "gsd-a11y-settings",
-            "gsd-color",
-            "gsd-media-keys",
-            "gsd-sound",
-            "gsd-power",
-            "gsd-xsettings"
-        };
-
-        foreach (var daemon in daemons) {
-            try {
-                supervisors += new GreeterCompositor.SubprocessSupervisor ({Constants.GSD_DIR + daemon});
-            } catch (GLib.Error e) {
-                critical ("Could not start %s: %s", daemon, e.message);
-            }
-        }
-    }
-}
-
 [DBus (name="org.gnome.SessionManager")]
-public class GreeterCompositor.GnomeSessionManager : GLib.Object {
-    private Gee.ArrayList<GreeterCompositor.GnomeSessionManagerClient> clients;
-    private Gee.ArrayList<unowned GreeterCompositor.GnomeSessionManagerClient> inhibitors;
+public class GreeterSessionManager.GnomeSessionManager : GLib.Object {
+    private Gee.ArrayList<GnomeSessionManagerClient> clients;
+    private Gee.ArrayList<unowned GnomeSessionManagerClient> inhibitors;
 
     public string session_name { owned get; set; default = "pantheon"; }
     public string renderer { owned get; set; default = ""; }
@@ -86,8 +21,8 @@ public class GreeterCompositor.GnomeSessionManager : GLib.Object {
     public signal void session_over ();
 
     construct {
-        clients = new Gee.ArrayList<GreeterCompositor.GnomeSessionManagerClient> ();
-        inhibitors = new Gee.ArrayList<unowned GreeterCompositor.GnomeSessionManagerClient> ();
+        clients = new Gee.ArrayList<GnomeSessionManagerClient> ();
+        inhibitors = new Gee.ArrayList<unowned GnomeSessionManagerClient> ();
     }
 
     public void setenv (string variable, string value) throws GLib.Error {
@@ -188,7 +123,7 @@ public class GreeterCompositor.GnomeSessionManager : GLib.Object {
 }
 
 [DBus (name = "org.gnome.SessionManager.Client")]
-public class GreeterCompositor.GnomeSessionManagerClient : GLib.Object {
+public class GreeterSessionManager.GnomeSessionManagerClient : GLib.Object {
     static uint32 serial_id = 0;
 
     private string app_id;
@@ -203,7 +138,7 @@ public class GreeterCompositor.GnomeSessionManagerClient : GLib.Object {
 
         try {
             var session_bus = GLib.Bus.get_sync (GLib.BusType.SESSION);
-            session_bus.register_object<GreeterCompositor.GnomeSessionManagerClient> (object_path, this);
+            session_bus.register_object<GnomeSessionManagerClient> (object_path, this);
         } catch (Error e) {
             critical (e.message);
         }

session-manager/SettingsDaemon.vala

@@ -0,0 +1,51 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2011 Canonical Ltd
+ *                         2025 elementary, Inc. (https://elementary.io)
+ */
+
+public class GreeterSessionManager.SettingsDaemon : GLib.Object {
+    private const string[] DAEMONS = {
+        "gsd-a11y-settings",
+        "gsd-color",
+        "gsd-media-keys",
+        "gsd-sound",
+        "gsd-power",
+        "gsd-xsettings"
+    };
+
+    private SubprocessSupervisor[] supervisors = {};
+
+    construct {
+        /* Pretend to be GNOME session */
+        GLib.Bus.own_name (
+            BusType.SESSION, "org.gnome.SessionManager", BusNameOwnerFlags.NONE,
+            (connection) => {
+                try {
+                    connection.register_object ("/org/gnome/SessionManager", new GnomeSessionManager ());
+                } catch (Error e) {
+                    critical ("Failed to register /org/gnome/SessionManager: %s", e.message);
+                }
+            },
+            () => {
+                debug ("Acquired org.gnome.SessionManager");
+                start_settings_daemon ();
+            },
+            () => {
+                critical ("Lost org.gnome.SessionManager");
+            }
+        );
+    }
+
+    private void start_settings_daemon () {
+        debug ("All bus names acquired, starting gnome-settings-daemon");
+
+        foreach (unowned var daemon in DAEMONS) {
+            try {
+                supervisors += new SubprocessSupervisor ({ Constants.GSD_DIR + daemon });
+            } catch (Error e) {
+                critical ("Could not start %s: %s", daemon, e.message);
+            }
+        }
+    }
+}

session-manager/SubprocessSupervisor.vala

@@ -0,0 +1,37 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * SPDX-FileCopyrightText: 2018, 2025 elementary, Inc. (https://elementary.io)
+ * Authors: Corentin Noël <corentin@elementary.io>
+ */
+
+public class GreeterSessionManager.SubprocessSupervisor : GLib.Object {
+    public string[] exec { get; construct; }
+
+    private GLib.Subprocess? subprocess = null;
+
+    public SubprocessSupervisor (string[] exec) throws GLib.Error {
+        Object (exec: exec);
+    }
+
+    construct {
+        ensure_run.begin ();
+    }
+
+    ~SubprocessSupervisor () {
+        if (subprocess != null) {
+            subprocess.force_exit ();
+        }
+    }
+
+    private async void ensure_run () {
+        try {
+            subprocess = new GLib.Subprocess.newv (exec, GLib.SubprocessFlags.STDIN_INHERIT | GLib.SubprocessFlags.STDERR_MERGE);
+
+            if (!yield subprocess.wait_check_async ()) {
+                ensure_run.begin ();
+            }
+        } catch (Error e) {
+            critical ("Couldn't create subprocess: %s", e.message);
+        }
+    }
+}

session-manager/main.vala

@@ -0,0 +1,15 @@
+/*
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ * SPDX-FileCopyrightText: 2025 elementary, Inc. (https://elementary.io)
+ */
+
+public class GreeterSessionManager.Application : GLib.Object {
+    public static int main (string[] args) {
+        new SettingsDaemon ();
+
+        var loop = new GLib.MainLoop (GLib.MainContext.default (), true);
+        loop.run ();
+
+        return 0;
+	}
+}

session-manager/meson.build

@@ -0,0 +1,22 @@
+gee_dep = dependency('gee-0.8')
+gio_dep = dependency('gio-2.0')
+glib_dep = dependency('glib-2.0')
+gobject_dep = dependency('gobject-2.0')
+
+install_path = join_paths(get_option('prefix'), get_option('sbindir'))
+
+files = files(
+    'main.vala',
+    'SessionManager.vala',
+    'SettingsDaemon.vala',
+    'SubprocessSupervisor.vala'
+)
+
+executable(
+    meson.project_name()+'-session-manager',
+    files,
+    config_header,
+    dependencies: [ gee_dep, gio_dep, glib_dep, gobject_dep ],
+    install : true,
+    install_dir: install_path
+)