dnfdaemon: Add new API for offline transactions

- Goal::offline_transaction_pending - check whether there is an offline
  update scheduled for the next reboot

- Goal:: offline_transaction_clean - cancel the scheduled offline update

dnf5daemon-server/dbus/interfaces/org.rpm.dnf.v0.Goal.xml

@@ -94,6 +94,36 @@ along with libdnf.  If not, see <https://www.gnu.org/licenses/>.
         <arg name="options" type="a{sv}" direction="in" />
     </method>
 
+
+    <!--
+        offline_transaction_pending:
+        @pending: boolean, true if there is a pending offline transaction
+
+        Check whether there is an offline transaction configured for the next reboot (i.e. checks the /system-update symlink existence).
+    -->
+    <method name="offline_transaction_pending">
+        <arg name="pending" type="b" direction="out" />
+    </method>
+
+
+    <!--
+        offline_transaction_clean:
+        @options: an array of key/value pairs
+        @transaction_cleaned: boolean, returns `false` if there was an error during the transaction cleanup. Returns `true` if the offline transaction was successfully cleaned or if no offline transaction was configured.
+
+        Clean the offline transaction configured for the next reboot by removing the /system-update symlink (see systemd.offline-updates(7)).
+
+        Following @options are supported:
+            - clean_datadir: boolean, default true
+                If true, all stored offline transaction data, including downloaded packages, will be removed along with the system-update symlink.
+
+        Unknown options are ignored.
+    -->
+    <method name="do_transaction">
+        <arg name="options" type="a{sv}" direction="in" />
+        <arg name="transaction_cleaned" type="b" direction="out" />
+    </method>
+
 </interface>
 
 </node>

dnf5daemon-server/services/goal/goal.cpp

@@ -105,6 +105,28 @@ void Goal::dbus_register() {
         [this](sdbus::MethodCall call) -> void {
             session.get_threads_manager().handle_method(*this, &Goal::do_transaction, call, session.session_locale);
         });
+    dbus_object->registerMethod(
+        dnfdaemon::INTERFACE_GOAL,
+        "offline_transaction_pending",
+        {},
+        {},
+        "b",
+        {"pending"},
+        [this](sdbus::MethodCall call) -> void {
+            session.get_threads_manager().handle_method(
+                *this, &Goal::offline_transaction_pending, call, session.session_locale);
+        });
+    dbus_object->registerMethod(
+        dnfdaemon::INTERFACE_GOAL,
+        "offline_transaction_clean",
+        "a{sv}",
+        {"options"},
+        "b",
+        {"transaction_cleaned"},
+        [this](sdbus::MethodCall call) -> void {
+            session.get_threads_manager().handle_method(
+                *this, &Goal::offline_transaction_clean, call, session.session_locale);
+        });
 }
 
 sdbus::MethodReply Goal::resolve(sdbus::MethodCall & call) {
@@ -307,3 +329,33 @@ sdbus::MethodReply Goal::do_transaction(sdbus::MethodCall & call) {
     auto reply = call.createReply();
     return reply;
 }
+
+sdbus::MethodReply Goal::offline_transaction_pending(sdbus::MethodCall & call) {
+    // check the presence of the magic symlink
+    auto reply = call.createReply();
+    std::error_code ec;
+    reply << std::filesystem::exists(libdnf5::offline::MAGIC_SYMLINK, ec);
+    return reply;
+}
+
+sdbus::MethodReply Goal::offline_transaction_clean(sdbus::MethodCall & call) {
+    dnfdaemon::KeyValueMap options;
+    call >> options;
+    bool clean_datadir = dnfdaemon::key_value_map_get<bool>(options, "clean_datadir", true);
+    bool cleaned = true;
+    std::error_code ec;
+    if (!std::filesystem::remove(libdnf5::offline::MAGIC_SYMLINK, ec) && ec) {
+        cleaned = false;
+    }
+    if (clean_datadir) {
+        auto base = session.get_base();
+        const auto & installroot = base->get_config().get_installroot_option().get_value();
+        std::filesystem::path datadir = installroot / libdnf5::offline::DEFAULT_DATADIR.relative_path();
+        for (const auto & entry : std::filesystem::directory_iterator(datadir)) {
+            std::filesystem::remove_all(entry.path(), ec);
+        }
+    }
+    auto reply = call.createReply();
+    reply << cleaned;
+    return reply;
+}

dnf5daemon-server/services/goal/goal.hpp

@@ -36,6 +36,8 @@ class Goal : public IDbusSessionService {
     sdbus::MethodReply get_transaction_problems_string(sdbus::MethodCall & call);
     sdbus::MethodReply get_transaction_problems(sdbus::MethodCall & call);
     sdbus::MethodReply do_transaction(sdbus::MethodCall & call);
+    sdbus::MethodReply offline_transaction_pending(sdbus::MethodCall & call);
+    sdbus::MethodReply offline_transaction_clean(sdbus::MethodCall & call);
 };
 
 #endif