system-upgrade: misc fixes

dnf5.spec

@@ -262,8 +262,6 @@ It supports RPM packages, modulemd modules, and comps groups & environments.
 %dir %{_datadir}/dnf5
 %dir %{_datadir}/dnf5/aliases.d
 %config %{_datadir}/dnf5/aliases.d/compatibility.conf
-%config %{_unitdir}/dnf5-offline-transaction.service
-%config %{_unitdir}/dnf5-offline-transaction-cleanup.service
 %dir %{_libdir}/dnf5
 %dir %{_libdir}/dnf5/plugins
 %dir %{_datadir}/dnf5/dnf5-plugins
@@ -317,6 +315,12 @@ It supports RPM packages, modulemd modules, and comps groups & environments.
 %{_mandir}/man5/dnf5.conf-todo.5.*
 %{_mandir}/man5/dnf5.conf-deprecated.5.*
 
+%if %{with systemd}
+%{_unitdir}/dnf5-offline-transaction.service
+%{_unitdir}/dnf5-offline-transaction-cleanup.service
+%{_unitdir}/system-update.target.wants/dnf5-offline-transaction.service
+%endif
+
 # ========== libdnf5 ==========
 %package -n libdnf5
 Summary:        Package management library

dnf5/CMakeLists.txt

@@ -2,7 +2,8 @@ if(NOT WITH_DNF5)
     return()
 endif()
 
-set(SYSTEMD_SYSTEM_UNIT_DIR /usr/lib/systemd/system)
+pkg_check_modules(SYSTEMD REQUIRED systemd)
+pkg_get_variable(SYSTEMD_SYSTEM_UNIT_DIR systemd systemdsystemunitdir)
 
 find_package(Threads)
 
@@ -56,11 +57,14 @@ install(FILES bash-completion/dnf5 DESTINATION ${BASH_COMPLETION_COMPLETIONSDIR}
 install(FILES "README.plugins" DESTINATION "${CMAKE_INSTALL_FULL_LIBDIR}/dnf5/plugins" RENAME "README")
 install(DIRECTORY "config/usr/" DESTINATION "${CMAKE_INSTALL_PREFIX}" PATTERN ".gitkeep" EXCLUDE)
 install(DIRECTORY "config/etc/" DESTINATION "${CMAKE_INSTALL_FULL_SYSCONFDIR}" PATTERN ".gitkeep" EXCLUDE)
-install(DIRECTORY "config/systemd/system/" DESTINATION "${SYSTEMD_SYSTEM_UNIT_DIR}" PATTERN ".gitkeep" EXCLUDE)
-install(CODE "execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink
-    ${SYSTEMD_SYSTEM_UNIT_DIR}/dnf5-offline-transaction.service
-    ${SYSTEMD_SYSTEM_UNIT_DIR}/system-update.target.wants/dnf5-offline-transaction.service)"
-)
+
+if(WITH_SYSTEMD)
+  install(DIRECTORY "config/systemd/system/" DESTINATION "${SYSTEMD_SYSTEM_UNIT_DIR}" PATTERN ".gitkeep" EXCLUDE)
+  install(CODE "execute_process(COMMAND ${CMAKE_COMMAND} -E create_symlink
+      ${SYSTEMD_SYSTEM_UNIT_DIR}/dnf5-offline-transaction.service
+      ${SYSTEMD_SYSTEM_UNIT_DIR}/system-update.target.wants/dnf5-offline-transaction.service)"
+  )
+endif()
 
 # Makes an empty directory for dnf5-plugins configuration files
 install(DIRECTORY DESTINATION "${CMAKE_INSTALL_FULL_SYSCONFDIR}/dnf/dnf5-plugins")

dnf5/commands/offline/offline.cpp

@@ -45,6 +45,12 @@ using namespace libdnf5::cli;
 
 const std::string & ID_TO_IDENTIFY_BOOTS = dnf5::offline::OFFLINE_STARTED_ID;
 
+const std::string SYSTEMD_DESTINATION_NAME{"org.freedesktop.systemd1"};
+const std::string SYSTEMD_OBJECT_PATH{"/org/freedesktop/systemd1"};
+const std::string SYSTEMD_MANAGER_INTERFACE{"org.freedesktop.systemd1.Manager"};
+const std::string SYSTEMD_UNIT_INTERFACE{"org.freedesktop.systemd1.Unit"};
+const std::string SYSTEMD_SERVICE_NAME{"dnf5-offline-transaction.service"};
+
 int call(const std::string & command, const std::vector<std::string> & args) {
     std::vector<char *> c_args;
     c_args.emplace_back(const_cast<char *>(command.c_str()));
@@ -192,6 +198,9 @@ OfflineSubcommand::OfflineSubcommand(Context & context, const std::string & name
 
 void OfflineSubcommand::configure() {
     auto & ctx = get_context();
+    // This value comes from systemd, see
+    // https://www.freedesktop.org/wiki/Software/systemd/SystemUpdates or
+    // systemd.offline-updates(7).
     magic_symlink = "/system-update";
 
     const std::filesystem::path installroot = ctx.base.get_config().get_installroot_option().get_value();
@@ -223,10 +232,6 @@ void check_state(const dnf5::offline::OfflineTransactionState & state) {
 }
 
 void reboot([[maybe_unused]] bool poweroff = false) {
-    const std::string systemd_destination_name{"org.freedesktop.systemd1"};
-    const std::string systemd_object_path{"/org/freedesktop/systemd1"};
-    const std::string systemd_manager_interface{"org.freedesktop.systemd1.Manager"};
-
     if (std::getenv("DNF_SYSTEM_UPGRADE_NO_REBOOT")) {
         std::cerr << "DNF_SYSTEM_UPGRADE_NO_REBOOT is set, not rebooting." << std::endl;
         return;
@@ -241,11 +246,11 @@ void reboot([[maybe_unused]] bool poweroff = false) {
         const std::string error_message{ex.what()};
         throw libdnf5::cli::CommandExitError(1, M_("Couldn't connect to D-Bus: {}"), error_message);
     }
-    auto proxy = sdbus::createProxy(systemd_destination_name, systemd_object_path);
+    auto proxy = sdbus::createProxy(SYSTEMD_DESTINATION_NAME, SYSTEMD_OBJECT_PATH);
     if (poweroff) {
-        proxy->callMethod("Poweroff").onInterface(systemd_manager_interface);
+        proxy->callMethod("Poweroff").onInterface(SYSTEMD_MANAGER_INTERFACE);
     } else {
-        proxy->callMethod("Reboot").onInterface(systemd_manager_interface);
+        proxy->callMethod("Reboot").onInterface(SYSTEMD_MANAGER_INTERFACE);
     }
 #else
     std::cerr << "Can't connect to D-Bus; this build of DNF 5 does not support D-Bus." << std::endl;
@@ -290,9 +295,33 @@ void OfflineRebootCommand::run() {
         throw libdnf5::cli::CommandExitError(1, M_("System is not ready for offline transaction."));
     }
     if (!std::filesystem::is_directory(get_datadir())) {
-        throw libdnf5::cli::CommandExitError(1, M_("data directory {} does not exist"), get_datadir().string());
+        throw libdnf5::cli::CommandExitError(1, M_("Data directory {} does not exist."), get_datadir().string());
     }
 
+#ifdef WITH_SYSTEMD
+    // Check that dnf5-offline-transaction.service is present and wanted by system-update.target
+    std::unique_ptr<sdbus::IConnection> connection;
+    try {
+        connection = sdbus::createSystemBusConnection();
+    } catch (const sdbus::Error & ex) {
+        const std::string error_message{ex.what()};
+        throw libdnf5::cli::CommandExitError(1, M_("Couldn't connect to D-Bus: {}"), error_message);
+    }
+    auto systemd_proxy = sdbus::createProxy(SYSTEMD_DESTINATION_NAME, SYSTEMD_OBJECT_PATH);
+
+    sdbus::ObjectPath unit_object_path;
+    systemd_proxy->callMethod("LoadUnit")
+        .onInterface(SYSTEMD_MANAGER_INTERFACE)
+        .withArguments("system-update.target")
+        .storeResultsTo(unit_object_path);
+
+    auto unit_proxy = sdbus::createProxy(SYSTEMD_DESTINATION_NAME, unit_object_path);
+    const std::vector<std::string> & wants = unit_proxy->getProperty("Wants").onInterface(SYSTEMD_UNIT_INTERFACE);
+    if (std::find(wants.begin(), wants.end(), SYSTEMD_SERVICE_NAME) == wants.end()) {
+        throw libdnf5::cli::CommandExitError(1, M_("{} is not wanted by system-update.target."), SYSTEMD_SERVICE_NAME);
+    }
+#endif
+
     if (state->get_data().verb == "system-upgrade download") {
         std::cout << _("The system will now reboot to upgrade to release version ")
                   << state->get_data().target_releasever << "." << std::endl;
@@ -396,8 +425,7 @@ void OfflineExecuteCommand::run() {
         throw libdnf5::cli::CommandExitError(0, M_("Trigger file does not exist. Exiting."));
     }
 
-    const auto & symlinked_path = std::filesystem::read_symlink(get_magic_symlink());
-    if (symlinked_path != get_datadir()) {
+    if (!std::filesystem::equivalent(get_magic_symlink(), get_datadir())) {
         throw libdnf5::cli::CommandExitError(0, M_("Another offline transaction tool is running. Exiting."));
     }
 

dnf5/commands/system-upgrade/system-upgrade.cpp

@@ -123,9 +123,7 @@ void SystemUpgradeDownloadCommand::run() {
     ctx.set_should_store_offline(true);
     ctx.download_and_run(transaction);
 
-    std::cout << _("Download complete! Use `dnf5 system-upgrade reboot` to start the upgrade.\n"
-                   "To cancel the upgrade and delete the downloaded upgrade files, use `dnf5 system-upgrade clean`.")
-              << std::endl;
+    std::cout << _("Download complete!") << std::endl;
 
     dnf5::offline::log_status(
         ctx, "Download finished.", dnf5::offline::DOWNLOAD_FINISHED_ID, system_releasever, target_releasever);

dnf5/context.cpp

@@ -451,7 +451,8 @@ void Context::download_and_run(libdnf5::base::Transaction & transaction) {
     if (should_store_offline) {
         store_offline(transaction);
         std::cout << "Transaction stored to be performed offline. Run `dnf5 offline reboot` to reboot and run the "
-                     "transaction."
+                     "transaction. To cancel the transaction and delete the downloaded files, use `dnf5 "
+                     "offline clean`."
                   << std::endl;
     }
 }