session: Leave to meson the duty of keeping the lists in sync

Don't leave to humans what machines can do, the gnome-login.session list
is filled with an hard-to-maintain single-line semicolon separated list of
components, that then are repeated in the gnome systemd session.conf.
And these are meant to be kept in sync.

Meson can help us in this, so let's just keep a single list in meson and
use it to generate the various formats we need.

4 files changed, 44 insertions, 25 deletions

diff --git a/data/gnome-login.session.in b/data/gnome-login.session.in
index fd9d45aa..63470962 100644
--- a/data/gnome-login.session.in
+++ b/data/gnome-login.session.in
@@ -1,4 +1,3 @@
 [GNOME Session]
 Name=Display Manager
-# Keep in sync with gnome-session@gnome-login.target.d/session.conf
-RequiredComponents=org.gnome.Shell;org.gnome.SettingsDaemon.A11ySettings;org.gnome.SettingsDaemon.Color;org.gnome.SettingsDaemon.Datetime;org.gnome.SettingsDaemon.Housekeeping;org.gnome.SettingsDaemon.Keyboard;org.gnome.SettingsDaemon.MediaKeys;org.gnome.SettingsDaemon.Power;org.gnome.SettingsDaemon.PrintNotifications;org.gnome.SettingsDaemon.Rfkill;org.gnome.SettingsDaemon.ScreensaverProxy;org.gnome.SettingsDaemon.Sharing;org.gnome.SettingsDaemon.Smartcard;org.gnome.SettingsDaemon.Sound;org.gnome.SettingsDaemon.Wacom;
+RequiredComponents=@gnome_required_components@;
diff --git a/data/meson.build b/data/meson.build
index bbcad589..cf068599 100644
--- a/data/meson.build
+++ b/data/meson.build
@@ -61,12 +61,38 @@ gdm_schema = configure_file(
 install_data('locale.alias',
   install_dir: get_option('datadir') / 'gdm',
 )
+
+gdm_gnome_shell_component = 'org.gnome.Shell'
+gdm_gnome_session_required_components = [
+  'org.gnome.SettingsDaemon.A11ySettings',
+  'org.gnome.SettingsDaemon.Color',
+  'org.gnome.SettingsDaemon.Datetime',
+  'org.gnome.SettingsDaemon.Housekeeping',
+  'org.gnome.SettingsDaemon.Keyboard',
+  'org.gnome.SettingsDaemon.MediaKeys',
+  'org.gnome.SettingsDaemon.Power',
+  'org.gnome.SettingsDaemon.PrintNotifications',
+  'org.gnome.SettingsDaemon.Rfkill',
+  'org.gnome.SettingsDaemon.ScreensaverProxy',
+  'org.gnome.SettingsDaemon.Sharing',
+  'org.gnome.SettingsDaemon.Smartcard',
+  'org.gnome.SettingsDaemon.Sound',
+  'org.gnome.SettingsDaemon.Wacom',
+]
+
+gdm_gnome_user_session_wanted_components = gdm_gnome_session_required_components
+gdm_gnome_user_session_wanted_components += [
+  'org.gnome.SettingsDaemon.XSettings',
+]
+
 configure_file(
   input: 'gnome-login.session.in',
   output: '@BASENAME@',
   configuration: {
     'libexecdir': gdm_prefix / get_option('libexecdir'),
     'check_accelerated_dir': check_accelerated_dir,
+    'gnome_required_components': ';'.join(
+      [ gdm_gnome_shell_component ] + gdm_gnome_session_required_components),
   },
   install_dir: get_option('datadir') / 'gnome-session' / 'sessions',
 )
@@ -165,10 +191,19 @@ configure_file(
   format: 'cmake'
 )
 
-install_data(
-  'session.conf',
-  rename: join_paths('gnome-session@gnome-login.target.d', 'session.conf'),
-  install_dir: systemd_userunitdir,
+gdm_gnome_session_wanted_targets = []
+foreach component: gdm_gnome_user_session_wanted_components
+  gdm_gnome_session_wanted_targets += 'Wants=@0@.target'.format(component)
+endforeach
+
+configure_file(
+  input: 'session.conf.in',
+  output: 'session.conf',
+  configuration: {
+    'requires_component': gdm_gnome_shell_component,
+    'wants_required_components': '\n'.join(gdm_gnome_session_wanted_targets),
+  },
+  install_dir: systemd_userunitdir / 'gnome-session@gnome-login.target.d',
 )
 
 # XSession
diff --git a/data/session.conf b/data/session.conf
deleted file mode 100644
index 560f8dce..00000000
--- a/data/session.conf
+++ /dev/null
@@ -1,19 +0,0 @@
-[Unit]
-# Keep in sync with gnome-login.session
-Wants=org.gnome.SettingsDaemon.A11ySettings.target
-Wants=org.gnome.SettingsDaemon.Color.target
-Wants=org.gnome.SettingsDaemon.Datetime.target
-Wants=org.gnome.SettingsDaemon.Housekeeping.target
-Wants=org.gnome.SettingsDaemon.Keyboard.target
-Wants=org.gnome.SettingsDaemon.MediaKeys.target
-Wants=org.gnome.SettingsDaemon.Power.target
-Wants=org.gnome.SettingsDaemon.PrintNotifications.target
-Wants=org.gnome.SettingsDaemon.Rfkill.target
-Wants=org.gnome.SettingsDaemon.ScreensaverProxy.target
-Wants=org.gnome.SettingsDaemon.Sharing.target
-Wants=org.gnome.SettingsDaemon.Smartcard.target
-Wants=org.gnome.SettingsDaemon.Sound.target
-Wants=org.gnome.SettingsDaemon.Wacom.target
-Wants=org.gnome.SettingsDaemon.XSettings.target
-
-Requires=org.gnome.Shell.target
diff --git a/data/session.conf.in b/data/session.conf.in
new file mode 100644
index 00000000..7bfa3652
--- /dev/null
+++ b/data/session.conf.in
@@ -0,0 +1,4 @@
+[Unit]
+@wants_required_components@
+
+Requires=@requires_component@.target