systemd: add service file to start Plasma

Used in postmarketOS but probably also useful for others, this service
file can be used to start Plasma Mobile using systemd

CMakeLists.txt

@@ -18,6 +18,8 @@ set(KDE_COMPILERSETTINGS_LEVEL "5.82")
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
+option(INSTALL_SYSTEMD_SERVICE "Install a systemd service file to start the session" OFF)
+
 find_package(ECM ${KF6_MIN_VERSION} REQUIRED NO_MODULE)
 set(CMAKE_MODULE_PATH ${ECM_MODULE_PATH})
 
@@ -137,3 +139,10 @@ kde_clang_format(${ALL_CLANG_FORMAT_SOURCE_FILES})
 kde_configure_git_pre_commit_hook(CHECKS CLANG_FORMAT)
 
 ki18n_install(po)
+
+if (INSTALL_SYSTEMD_SERVICE)
+    install(FILES
+        ${CMAKE_CURRENT_SOURCE_DIR}/plasma-mobile.service
+        DESTINATION ${KDE_INSTALL_SYSTEMDUNITDIR}
+    )
+endif()

plasma-mobile.service

@@ -0,0 +1,59 @@
+[Unit]
+Description=Open-source user interface for phones, based on Plasma technologies
+Documentation=https://invent.kde.org/plasma-mobile
+
+# replaces the getty
+Conflicts=getty@tty7.service
+After=getty@tty7.service
+
+# Needs all the dependencies of the services it's replacing
+# (currently getty@tty1.service):
+After=rc-local.service plymouth-quit-wait.service systemd-user-sessions.service
+
+OnFailure=getty@tty7.service
+
+# D-Bus is necessary for contacting logind. Logind is required.
+Wants=dbus.socket
+After=dbus.socket
+
+# This scope is created by pam_systemd when logging in as the user.
+# This directive is a workaround to a systemd bug, where the setup of the
+# user session by PAM has some race condition, possibly leading to a failure.
+After=session-c1.scope
+
+# Since we are part of the graphical session, make sure we are started before
+# it is complete.
+Before=graphical.target
+
+# Prevent starting on systems without virtual consoles
+ConditionPathExists=/dev/tty0
+
+[Service]
+Environment=LANG=C.UTF-8
+Environment=XDG_SEAT=seat0
+Environment=XDG_VTNR=tty7
+ExecStart=/usr/bin/startplasmamobile
+TimeoutStartSec=30
+User=1000
+PAMName=login
+WorkingDirectory=~
+Restart=always
+RestartSec=5s
+
+# A virtual terminal is needed.
+TTYPath=/dev/tty7
+TTYReset=yes
+TTYVHangup=yes
+TTYVTDisallocate=yes
+
+# Fail to start if not controlling the tty.
+StandardInput=tty-fail
+StandardOutput=journal
+StandardError=journal
+
+# Log this user with utmp, letting it show up with commands 'w' and 'who'.
+UtmpIdentifier=tty7
+UtmpMode=user
+
+[Install]
+Alias=display-manager.service

plasma-mobile.service.license

@@ -0,0 +1,2 @@
+Copyright None
+SPDX-License-Identifier: CC0-1.0