[calamares] Switch over to DBus unique activation

- By default, try to use DBus service to keep Calamares unique
- The older implementation via KDSingleApplicationGuard is still
  available, just not used by default.

CMakeLists.txt

@@ -54,6 +54,7 @@ option( BUILD_TESTING "Build the testing tree." ON )
 option( WITH_PYTHON "Enable Python modules API (requires Boost.Python)." ON )
 option( WITH_PYTHONQT "Enable next generation Python modules API (experimental, requires PythonQt)." OFF )
 option( WITH_KF5Crash "Enable crash reporting with KCrash." ON )
+option( WITH_KF5DBus "Use DBus service for unique-application." ON )
 
 # Possible debugging flags are:
 #  - DEBUG_TIMEZONES draws latitude and longitude lines on the timezone
@@ -290,7 +291,7 @@ if( ECM_FOUND )
     include(KDEInstallDirs)
 endif()
 
-find_package( KF5 QUIET COMPONENTS CoreAddons Crash )
+find_package( KF5 QUIET COMPONENTS CoreAddons Crash DBusAddons )
 set_package_properties(
     KF5::CoreAddons PROPERTIES
     TYPE REQUIRED
@@ -299,8 +300,17 @@ set_package_properties(
     PURPOSE "About Calamares"
 )
 if( NOT KF5Crash_FOUND )
+    if( WITH_KF5Crash )
+        message(WARNING "WITH_KF5Crash is set, but KF5::Crash is not available.")
+    endif()
     set( WITH_KF5Crash OFF )
 endif()
+if( NOT KF5DBusAddons_FOUND )
+    if( WITH_KF5DBus )
+        message(WARNING "WITH_KF5DBus is set, but KF5::DBusAddons is not available.")
+    endif()
+    set( WITH_KF5DBus OFF )
+endif()
 
 if( BUILD_TESTING )
     enable_testing()
@@ -520,6 +530,7 @@ add_feature_info(Python ${WITH_PYTHON} "Python job modules")
 add_feature_info(PythonQt ${WITH_PYTHONQT} "Python view modules")
 add_feature_info(Config ${INSTALL_CONFIG} "Install Calamares configuration")
 add_feature_info(KCrash ${WITH_KF5Crash} "Crash dumps via KCrash")
+add_feature_info(KDBusAddons ${WITH_KF5DBus} "Unique-application via DBus")
 
 # Add all targets to the build-tree export set
 set( CMAKE_INSTALL_CMAKEDIR "${CMAKE_INSTALL_LIBDIR}/cmake/Calamares" CACHE PATH  "Installation directory for CMake files" )

src/calamares/CMakeLists.txt

@@ -41,12 +41,13 @@ target_link_libraries( calamares_bin
         KF5::CoreAddons
 )
 if( WITH_KF5Crash )
-    target_link_libraries( calamares_bin
-        PRIVATE
-            KF5::Crash
-    )
+    target_link_libraries( calamares_bin PRIVATE KF5::Crash )
     target_compile_definitions( calamares_bin PRIVATE WITH_KF5Crash )
 endif()
+if( WITH_KF5DBus )
+    target_link_libraries( calamares_bin PRIVATE KF5::DBusAddons )
+    target_compile_definitions( calamares_bin PRIVATE WITH_KF5DBus )
+endif()
 
 install( TARGETS calamares_bin
     BUNDLE DESTINATION .

src/calamares/main.cpp

@@ -25,9 +25,15 @@
 #include "utils/Logger.h"
 #include "utils/Retranslator.h"
 
+#ifndef WITH_KF5DBus
+#warning "KDSingleApplicationGuard is deprecated"
 #include "3rdparty/kdsingleapplicationguard/kdsingleapplicationguard.h"
+#endif
 
 #include <KCoreAddons/KAboutData>
+#ifdef WITH_KF5DBus
+#include <KDBusAddons/KDBusService>
+#endif
 #ifdef WITH_KF5Crash
 #include <KCrash/KCrash>
 #endif
@@ -137,11 +143,12 @@ main( int argc, char* argv[] )
 
     bool is_debug = handle_args( a );
 
-    if ( !is_debug )
-    {
-        KDSingleApplicationGuard guard( KDSingleApplicationGuard::AutoKillOtherInstances );
-
-        if ( !guard.isPrimaryInstance() )
+#ifdef WITH_KF5DBus
+    KDBusService service( is_debug ? KDBusService::Multiple : KDBusService::Unique );
+#else
+    KDSingleApplicationGuard guard( is_debug ? KDSingleApplicationGuard::NoPolicy
+                                             : KDSingleApplicationGuard::AutoKillOtherInstances );
+    if ( !is_debug && !guard.isPrimaryInstance() )
     {
         // Here we have not yet set-up the logger system, so qDebug() is ok
         auto instancelist = guard.instances();
@@ -156,7 +163,7 @@ main( int argc, char* argv[] )
         }
         return 69;  // EX_UNAVAILABLE on FreeBSD
     }
-    }
+#endif
 
     Calamares::Settings::init( is_debug );
     a.init();