Endpoint to set arbitrary settings

kittens/desktop_ui/main.go

@@ -71,6 +71,37 @@ func EntryPoint(root *cli.Command) {
 			return utils.IfElse(err == nil, 0, 1), err
 		},
 	})
+	st := parent.AddSubCommand(&cli.Command{
+		Name:             "set-setting",
+		ShortDescription: "Change an arbitrary setting",
+		Usage:            " key [value]",
+		HelpText:         "Set an arbitrary setting. If you want to set the color-scheme use the dedicated command for it. Use this command with care as it does no validation for the type of value. The syntax for specifying values is described at: :link:`the glib docs <https://docs.gtk.org/glib/gvariant-text-format.html>`. Leaving out the value or specifying an empty value, will delete the setting.",
+		Run: func(cmd *cli.Command, args []string) (rc int, err error) {
+			val := ""
+			if len(args) < 1 {
+				cmd.ShowHelp()
+				return 1, fmt.Errorf("must specify the key")
+			}
+			if len(args) > 1 {
+				val = args[1]
+			}
+			opts := SetOptions{}
+			if err = cmd.GetOptionValues(&opts); err == nil {
+				err = set_setting(args[0], val, &opts)
+			}
+			return utils.IfElse(err == nil, 0, 1), err
+		},
+	})
+	st.Add(cli.OptionSpec{
+		Name:    "--namespace -n",
+		Help:    "The namespace in which to change the setting.",
+		Default: PORTAL_APPEARANCE_NAMESPACE,
+	})
+	st.Add(cli.OptionSpec{
+		Name: "--data-type",
+		Help: "The DBUS data type signature of the value. The default is to guess from the textual representation, see :link:`the glib docs <https://docs.gtk.org/glib/gvariant-text-format.html>` for details.",
+	})
+
 	ss := parent.AddSubCommand(&cli.Command{
 		Name:             "show-settings",
 		ShortDescription: "Print the current values of the desktop settings",

kittens/desktop_ui/portal.go

@@ -171,6 +171,7 @@ func (self *Portal) Start() (err error) {
 	}
 	methods = MethodSpec{
 		"ChangeSetting": {{"namespace", "s", false}, {"key", "s", false}, {"value", "v", false}},
+		"RemoveSetting": {{"namespace", "s", false}, {"key", "s", false}},
 	}
 	props["version"].Value = uint32(1)
 	if err = ExportInterface(self.bus, self, CHANGE_SETTINGS_INTERFACE, CHANGE_SETTINGS_OBJECT_PATH, methods, props, nil); err != nil {
@@ -189,7 +190,10 @@ func ParseValueWithSignature(value, value_type_signature string) (v dbus.Variant
 	}
 	v, err = dbus.ParseVariant(value, s)
 	if err != nil {
-		return dbus.Variant{}, fmt.Errorf("%s is not a valid value for signature: %s with error: %w", value, value_type_signature, err)
+		if value_type_signature == "" {
+			return dbus.Variant{}, fmt.Errorf("could not guess the data type of: %s with error: %w", value, err)
+		}
+		return dbus.Variant{}, fmt.Errorf("%s is not a valid value for signature: %#v with error: %w", value, value_type_signature, err)
 	}
 	return v, nil
 }
@@ -414,6 +418,35 @@ Exec=kitten run-server
 
 // }}}
 
+type SetOptions struct {
+	Namespace, DataType string
+}
+
+func set_setting(key, value string, opts *SetOptions) (err error) {
+	conn, err := dbus.SessionBus()
+	if err != nil {
+		return fmt.Errorf("failed to connect to system bus with error: %w", err)
+	}
+	defer conn.Close()
+	method := "ChangeSetting"
+	var vals = []any{opts.Namespace, key}
+	if value == "" {
+		method = "RemoveSetting"
+	} else {
+		v, err := ParseValueWithSignature(value, opts.DataType)
+		if err != nil {
+			return err
+		}
+		vals = append(vals, v)
+	}
+	obj := conn.Object(PORTAL_BUS_NAME, dbus.ObjectPath(CHANGE_SETTINGS_OBJECT_PATH))
+	call := obj.Call(CHANGE_SETTINGS_INTERFACE+"."+method, dbus.FlagNoAutoStart, vals...)
+	if err = call.Store(); err != nil {
+		return fmt.Errorf("failed to call %s with error: %w", method, err)
+	}
+	return
+}
+
 func set_color_scheme(which string) (err error) {
 	conn, err := dbus.SessionBus()
 	if err != nil {
@@ -479,6 +512,20 @@ func (self *Portal) ChangeSetting(namespace, key string, value dbus.Variant) *db
 	return nil
 }
 
+func (self *Portal) RemoveSetting(namespace, key string) *dbus.Error {
+	self.lock.Lock()
+	defer self.lock.Unlock()
+	existed := false
+	if m := self.settings[namespace]; m != nil {
+		_, existed = m[key]
+	}
+	if !existed {
+		return nil
+	}
+	delete(self.settings[namespace], key)
+	return nil
+}
+
 func (self *Portal) Read(namespace, key string) (dbus.Variant, *dbus.Error) {
 	self.lock.Lock()
 	defer self.lock.Unlock()