core: device: implement storing to disk for Device.SetManaged()

If the NM_DEVICE_MANAGED_FLAGS_PERMANENT flag is used, the value will be
stored to disk, to the NetworkManager-intern.conf file, in a [device-*]
section.

To modify the runtime value, the NM_DEVICE_MANAGED_FLAGS_RUNTIME must be
passed. This allows to control independently whether to modify only one
or both.

introspection/org.freedesktop.NetworkManager.Device.xml

@@ -397,10 +397,11 @@
     <!--
         SetManaged:
         @managed: Whether the device is managed.
-        @flags: Flags which would modify the behavior of the SetManaged call. Invalid flags are rejected.
+        @flags: (<link linkend="NMDeviceManagedFlags">NMDeviceManagedFlags</link>) flags.
         @since: 1.58
 
-        Set the managed state of the device.
+        Set the managed state of the device. With the flags argument different
+        behaviors can be achieved, like storing the new managed state to disk.
     -->
     <method name="SetManaged">
       <arg name="managed" type="b" direction="in"/>

po/POTFILES.in

@@ -5,6 +5,7 @@ src/core/NetworkManagerUtils.c
 src/core/devices/adsl/nm-device-adsl.c
 src/core/devices/bluetooth/nm-bluez-manager.c
 src/core/devices/bluetooth/nm-device-bt.c
+src/core/devices/nm-device.c
 src/core/devices/nm-device-6lowpan.c
 src/core/devices/nm-device-bond.c
 src/core/devices/nm-device-bridge.c

src/core/devices/nm-device.c

@@ -14942,16 +14942,67 @@ typedef struct {
     NMDeviceManagedFlags managed_flags;
 } SetManagedData;
 
+/**
+ * set_managed:
+ * @self: the device
+ * @managed: the new managed state to set.
+ * @flags: flags to select different behaviors like storing to disk.
+ * @error: return location for a #GError, or %NULL
+ *
+ * Sets the managed state of the device. It can affect the runtime managed state
+ * if the %NM_DEVICE_MANAGED_FLAGS_RUNTIME is set, and to the value stored on disk
+ * (persistent across reboots) state if the %NM_DEVICE_MANAGED_FLAGS_PERMANENT is set.
+ *
+ * Returns: %TRUE if the managed state was set successfully, %FALSE otherwise.
+ */
 static gboolean
 set_managed(NMDevice *self, gboolean managed, NMDeviceManagedFlags flags, GError **error)
 {
-    gboolean old;
+    NMDevicePrivate *priv = NM_DEVICE_GET_PRIVATE(self);
+    gboolean         managed_old;
+    NMTernary        managed_to_disk_old;
 
-    g_object_get(self, NM_DEVICE_MANAGED, &old, NULL);
-    g_object_set(self, NM_DEVICE_MANAGED, managed, NULL);
-    g_object_get(self, NM_DEVICE_MANAGED, &managed, NULL);
-    if (old != managed)
-        _notify(self, PROP_MANAGED);
+    if (flags & NM_DEVICE_MANAGED_FLAGS_PERMANENT) {
+        managed_to_disk_old = nm_config_get_device_managed(nm_manager_get_config(priv->manager),
+                                                           nm_device_get_iface(self));
+
+        if (!nm_config_set_device_managed(nm_manager_get_config(priv->manager),
+                                          self,
+                                          managed,
+                                          flags & NM_DEVICE_MANAGED_FLAGS_BY_MAC,
+                                          error))
+            return FALSE;
+
+        /* Update the unmanaged flags after the change on disk */
+        nm_device_set_unmanaged_by_user_conf(self);
+
+        if (!!nm_device_get_unmanaged_flags(self, NM_UNMANAGED_USER_CONF) != !managed) {
+            /* We failed to make the new state effective on disk. Maybe the new config
+             * collides with other config. Try to revert and return error. Otherwise,
+             * we would set the runtime state correctly, but get an unexpected state
+             * after a reboot. */
+            nm_config_set_device_managed(nm_manager_get_config(priv->manager),
+                                         self,
+                                         managed_to_disk_old,
+                                         flags & NM_DEVICE_MANAGED_FLAGS_BY_MAC,
+                                         error);
+            g_set_error(error,
+                        NM_DEVICE_ERROR,
+                        NM_DEVICE_ERROR_FAILED,
+                        _("failed to persist 'managed=%d' on disk, other configurations may be "
+                          "overriding it"),
+                        managed);
+            return FALSE;
+        }
+    }
+
+    if (flags & NM_DEVICE_MANAGED_FLAGS_RUNTIME) {
+        g_object_get(self, NM_DEVICE_MANAGED, &managed_old, NULL);
+        g_object_set(self, NM_DEVICE_MANAGED, !!managed, NULL);
+        g_object_get(self, NM_DEVICE_MANAGED, &managed, NULL);
+        if (managed_old != managed)
+            _notify(self, PROP_MANAGED);
+    }
 
     return TRUE;
 }

src/libnm-core-public/nm-dbus-interface.h

@@ -1248,13 +1248,20 @@ typedef enum /*< flags >*/ {
 /**
  * NMDeviceManagedFlags:
  * @NM_DEVICE_MANAGED_FLAGS_NONE: no flag set.
+ * @NM_DEVICE_MANAGED_FLAGS_RUNTIME: to set the device managed state to the runtime value.
+ * @NM_DEVICE_MANAGED_FLAGS_PERMANENT: to set the device managed state to the permanent (on disk) value.
+ * @NM_DEVICE_MANAGED_FLAGS_BY_MAC: to match the device by MAC address, not by name.
+ *   This option only makes sense together with %NM_DEVICE_MANAGED_FLAGS_PERMANENT.
  *
  * Flags for the SetManaged() D-Bus call of a device and nm_device_set_managed_async().
  *
  * Since: 1.58
  */
 typedef enum /*< flags >*/ {
-    NM_DEVICE_MANAGED_FLAGS_NONE = 0,
+    NM_DEVICE_MANAGED_FLAGS_NONE      = 0,
+    NM_DEVICE_MANAGED_FLAGS_RUNTIME   = 0x1,
+    NM_DEVICE_MANAGED_FLAGS_PERMANENT = 0x2,
+    NM_DEVICE_MANAGED_FLAGS_BY_MAC    = 0x4,
 } NMDeviceManagedFlags;
 
 /**