platform: drop nm_platform_free() and register weak-ref

Instead of having a nm_platform_free() function, use NM_DEFINE_SINGLETON_WEAK_REF()
and register a weak reference. That way, users who want to free the platform
instance can just unref it.

src/platform/nm-platform.c

@@ -58,7 +58,9 @@ static guint signals[LAST_SIGNAL] = { 0 };
 /******************************************************************/
 
 /* Singleton NMPlatform subclass instance and cached class object */
-static NMPlatform *singleton_instance = NULL;
+NM_DEFINE_SINGLETON_INSTANCE (NMPlatform);
+
+NM_DEFINE_SINGLETON_WEAK_REF (NMPlatform);
 
 /* Just always initialize a @klass instance. NM_PLATFORM_GET_CLASS()
  * is only a plain read on the self instance, which the compiler
@@ -90,8 +92,7 @@ static NMPlatform *singleton_instance = NULL;
  *
  * NetworkManager will typically use only one platform object during
  * its run. Test programs might want to switch platform implementations,
- * though. This is done with a combination of nm_platform_free() and
- * nm_*_platform_setup().
+ * though.
  */
 void
 nm_platform_setup (NMPlatform *instance)
@@ -100,20 +101,10 @@ nm_platform_setup (NMPlatform *instance)
 	g_return_if_fail (!singleton_instance);
 
 	singleton_instance = instance;
-}
 
-/**
- * nm_platform_free:
- *
- * Free #NMPlatform singleton created by nm_*_platform_setup().
- */
-void
-nm_platform_free (void)
-{
-	g_assert (singleton_instance);
+	nm_singleton_instance_weak_ref_register ();
 
-	g_object_unref (singleton_instance);
-	singleton_instance = NULL;
+	nm_log_dbg (LOGD_CORE, "setup NMPlatform singleton (%p, %s)", instance,  G_OBJECT_TYPE_NAME (instance));
 }
 
 /**
@@ -121,8 +112,7 @@ nm_platform_free (void)
  * @self: platform instance
  *
  * Retrieve #NMPlatform singleton. Use this whenever you want to connect to
- * #NMPlatform signals. It is an error to call it before nm_*_platform_setup()
- * or after nm_platform_free().
+ * #NMPlatform signals. It is an error to call it before nm_platform_setup().
  *
  * Returns: (transfer none): The #NMPlatform singleton reference.
  */

src/platform/nm-platform.h

@@ -490,7 +490,6 @@ GType nm_platform_get_type (void);
 
 void nm_platform_setup (NMPlatform *instance);
 NMPlatform *nm_platform_get (void);
-void nm_platform_free (void);
 
 #define NM_PLATFORM_GET (nm_platform_get ())
 

src/platform/tests/test-common.c

@@ -287,6 +287,6 @@ main (int argc, char **argv)
 
 	nm_platform_link_delete (NM_PLATFORM_GET, nm_platform_link_get_ifindex (NM_PLATFORM_GET, DEVICE_NAME));
 
-	nm_platform_free ();
+	g_object_unref (nm_platform_get ());
 	return result;
 }