Add native screensaver (#13432)

* Implement a screensaver.

- Functional in wayland or x11
- Add a native 'away message' dialog
- Unify 'switch-to-greeter' code from multiple sources
- Add systemd/consolekit support for session states
- Provide cinnamon-screensaver-command (still utilized by csd-
  power for pre-power-event activation).
- Remove cinnamon-screensaver as a required session component.
- Allow disabling of the internal screensaver to continue using
  cinnamon-screensaver.
- Unify mpris code for the sound applet and albumArtWidget.js
- Unify power code for the power applet and powerWidget.js

TODO:
- Wallpaper in wayland sessions (postponed until there is layer-
  shell support in muffin).

Imported from cinnamon-screensaver:
- PAM-related files, cinnamon-screensaver-pam-helper
- cinnamon-screensaver-command and cinnamon-unlock-desktop: Both
  remain compatible with cinnamon-screensaver (> 6.7).

The screenShield actor contains all other related widgets like the
unlock dialog, and is placed in the new screenShieldGroup, the top-
most child of the global.stage.

Requires:
linuxmint/muffin#797
linuxmint/cinnamon-screensaver#491
linuxmint/cinnamon-settings-daemon#442

* Add backup-locker support for screensaver.

Imported from cinnamon-screensaver, but improved...

- Relies on dbus-activation now, which allows easier interaction
  between cinnamon and the locker process to coordinate grabs.
- Add a simple dbus service to cinnamon-launcher, to allow restart
  from the backup locker (still falling back to tty instructions
  if the launcher isn't available).
- Re-use event-grabber and event-filter from cinnamon-screensaver

The backup window spawns when the screensaver shows, and is placed
in global.top_window_group (where other override-redirect/POPUP-type
windows are placed automatically).

In the event of a crash/restart, the backup window will try to raise
itself to the top, and will continue to until Cinnamon restarts.

When Cinnamon restarts, if its stored state (gsettings) shows it
should be locked, it will negotiate the modal grab from the backup
locker, and immediately lock the screensaver again.

* debian/control: Add Breaks/Replaces cinnamon-screensaver.

* Restrict access to screenShield instance and screensaver service.

Author: mtwebster

.github/workflows/build.yml

@@ -28,7 +28,6 @@ jobs:
         linuxmint/cinnamon-control-center,
         linuxmint/cinnamon-desktop,
         linuxmint/cinnamon-menus,
-        linuxmint/cinnamon-screensaver,
         linuxmint/cinnamon-session,
         linuxmint/cinnamon-settings-daemon,
         linuxmint/cinnamon-translations,

cinnamon.session.in

@@ -1,6 +1,6 @@
 [Cinnamon Session]
 Name=Cinnamon
-RequiredComponents=cinnamon;org.cinnamon.ScreenSaver;nemo-autostart;@REQUIRED@cinnamon-killer-daemon;
+RequiredComponents=cinnamon;nemo-autostart;@REQUIRED@cinnamon-killer-daemon;
 DesktopName=X-Cinnamon
 
 

cinnamon2d.session.in

@@ -1,6 +1,6 @@
 [Cinnamon Session]
 Name=Cinnamon (Software Rendering)
-RequiredComponents=cinnamon2d;org.cinnamon.ScreenSaver;nemo-autostart;@REQUIRED@cinnamon-killer-daemon;
+RequiredComponents=cinnamon2d;nemo-autostart;@REQUIRED@cinnamon-killer-daemon;
 DesktopName=X-Cinnamon
 
 

data/meson.build

@@ -62,3 +62,5 @@ gnome.compile_resources(
     install: true,
     install_dir: pkgdatadir
 )
+
+subdir('pam')

data/org.cinnamon.gschema.xml

@@ -521,6 +521,24 @@
       <description>If true, the pointer will be set to the center of the new monitor when using pointer next/previous shortcuts.</description>
     </key>
 
+    <key type="b" name="internal-screensaver-enabled">
+      <default>true</default>
+      <summary>Use internal screensaver implementation. Requires cinnamon restart if changed.</summary>
+      <description>If true, use Cinnamon's internal screensaver for locking instead of the external cinnamon-screensaver daemon.</description>
+    </key>
+
+    <key type="b" name="session-locked-state">
+      <default>false</default>
+      <summary>Whether the session is currently locked</summary>
+      <description>Persists the screensaver locked state so it can be restored after a Cinnamon restart. This key is managed internally and should not be modified manually.</description>
+    </key>
+
+    <key type="b" name="debug-screensaver">
+      <default>false</default>
+      <summary>Enable screensaver debug logging</summary>
+      <description>If true, enables verbose debug logging for the screensaver, unlock dialog, and backup-locker.</description>
+    </key>
+
     <child name="theme" schema="org.cinnamon.theme"/>
     <child name="recorder" schema="org.cinnamon.recorder"/>
     <child name="keyboard" schema="org.cinnamon.keyboard"/>

data/pam/cinnamon.pam

@@ -0,0 +1,16 @@
+#%PAM-1.0
+
+# Fedora & Arch
+-auth      sufficient   pam_selinux_permit.so
+auth       include      system-auth
+-auth       optional     pam_gnome_keyring.so
+account    include      system-auth
+password   include      system-auth
+session    include      system-auth
+
+# SuSE/Novell
+#auth       include      common-auth
+#auth       optional     pam_gnome_keyring.so
+#account    include      common-account
+#password   include      common-password
+#session    include      common-session

data/pam/cinnamon.pam.debian

@@ -0,0 +1,2 @@
+@include common-auth
+auth optional pam_gnome_keyring.so

data/pam/meson.build

@@ -0,0 +1,18 @@
+pamdir = get_option('pam_prefix')
+if pamdir == ''
+  pamdir = sysconfdir
+endif
+
+if get_option('use_debian_pam')
+  install_data(
+    'cinnamon.pam.debian',
+    rename: 'cinnamon',
+    install_dir: join_paths(pamdir, 'pam.d')
+  )
+else
+  install_data(
+    'cinnamon.pam',
+    rename: 'cinnamon',
+    install_dir: join_paths(pamdir, 'pam.d')
+  )
+endif

data/services/meson.build

@@ -1,4 +1,5 @@
 service_files = [
+  'org.cinnamon.BackupLocker.service',
   'org.cinnamon.CalendarServer.service',
   'org.Cinnamon.HotplugSniffer.service',
   'org.Cinnamon.Melange.service',

data/services/org.cinnamon.BackupLocker.service.in

@@ -0,0 +1,3 @@
+[D-BUS Service]
+Name=org.cinnamon.BackupLocker
+Exec=@libexecdir@/cinnamon-backup-locker