libnm/vpn: add nm_vpn_editor_plugin_get_editor_load() to load the editor pluginth/vpn-editor-split-bgo765732

Currently, libnm-core allows to load the NMVpnEditorPlugin interface
by loading the shared library from the libnm.plugin setting.

NMVpnEditorPlugin has a method nm_vpn_editor_plugin_get_editor(), which
returns a NMVpnEditor interface, which in turn can return a GtkWidged
via nm_vpn_editor_get_widget(). So, although NMVpnEditor itself has no
direct GTK dependency, it is strongly related to the GUI and GTK.

On the other hand, NMVpnEditorPlugin interface is more generic and
lives in libnm-core. It can and should contain only parts that are
independent from the GUI and not drag in the entire GTK dependency.

Extend nm_vpn_editor_plugin_get_editor() to allow for a new generation
of plugins that split their implementation of NMVpnEditorPlugin and
NMVpnEditor in two different libraries. Only the latter has a dependency
on GTK.

New plugins no longer overwrite NMVpnEditorPluginInterface::get_editor.
Instead, their .name file specifies a library path in GNOME.editor-plugin.
This path is passed ot NMVpnEditorPlugin, and used to create to load the
editor-plugin.

Also expose a low-level function nm_vpn_editor_plugin_get_editor_load()
which allows for more control when loading the library.

3 files changed, 170 insertions, 4 deletions

diff --git a/libnm-core/nm-vpn-editor-plugin.c b/libnm-core/nm-vpn-editor-plugin.c
index 5bf72b0cdd..5a2bfa49a0 100644
--- a/libnm-core/nm-vpn-editor-plugin.c
+++ b/libnm-core/nm-vpn-editor-plugin.c
@@ -403,21 +403,152 @@ nm_vpn_editor_plugin_set_editor_library_path (NMVpnEditorPlugin *self,
 }
 
 /**
+ * nm_vpn_editor_plugin_get_editor_load:
+ * @self: the #NMVpnEditorPlugin instance
+ * @editor_library_path: (allow-none): the library path to load. If %NULL,
+ *   fallback to nm_vpn_editor_plugin_get_editor_library_path().
+ * @connection: the #NMConnection instance passed to the factory method.
+ * @do_file_checks: if %TRUE, check that the file is valid and has proper
+ *   permissions before loading the library. Otherwise, the path is passed
+ *   directly to dlopen.
+ * @check_owner: if positive, only allow plugins owned by this owner.
+ *   This argument is ignored if @do_file_checks is %FALSE.
+ * @check_file: (allow-none): a predicate to test whether the file is valid
+ *   before loading the shared library. This argument is ignored if @do_file_checks
+ *   is %FALSE.
+ * @user_data: the user-data for @check_file callback.
+ * @load_data: the data passed to the factory method. Currently %NMVpnEditorLoadData
+ *   is an opaque type that contains no fields. In the future we might extend this
+ *   structure to pass additional arguments to the factory method.
+ * @error: %GError with the error reason
+ *
+ * This loads the shared library from @editor_library_path, optionally performs some checks
+ * on the file before dlopen(), looks up the factory method "nm_vpn_editor_factory"
+ * and calls it to create an NMVpnEditor instance.
+ *
+ * Returns: (transfer-full): a #NMVpnEditor instance of %NULL in case of error.
+ *
+ * Since: 1.4
+ **/
+NMVpnEditor *
+nm_vpn_editor_plugin_get_editor_load (NMVpnEditorPlugin *self,
+                                      const char *editor_library_path,
+                                      NMConnection *connection,
+                                      gboolean do_file_checks,
+                                      int check_owner,
+                                      NMUtilsCheckFilePredicate check_file,
+                                      gpointer user_data,
+                                      NMVpnEditorLoadData *load_data,
+                                      GError **error)
+{
+	GModule *module = NULL;
+	NMVpnEditorFactory factory = NULL;
+	NMVpnEditor *editor = NULL;
+	gs_free char *editor_library_path_free  = NULL;
+
+	g_return_val_if_fail (NM_IS_VPN_EDITOR_PLUGIN (self), NULL);
+
+	if (!editor_library_path) {
+		editor_library_path_free = nm_vpn_editor_plugin_get_editor_library_path (self, TRUE);
+		editor_library_path = editor_library_path_free;
+	} else if (do_file_checks) {
+		editor_library_path_free = _get_editor_library_path_validate_and_absolute (editor_library_path);
+		editor_library_path = editor_library_path_free;
+	}
+
+	if (!editor_library_path) {
+		g_set_error_literal (error,
+		                     NM_VPN_PLUGIN_ERROR,
+		                     NM_VPN_PLUGIN_ERROR_FAILED,
+		                     _("Cannot create VPN editor due to missing editor-library-path"));
+		return NULL;
+	}
+
+	if (do_file_checks) {
+		if (!_nm_utils_check_module_file (editor_library_path,
+		                                  check_owner,
+		                                  check_file,
+		                                  user_data,
+		                                  error))
+			return NULL;
+	}
+
+	module = g_module_open (editor_library_path, G_MODULE_BIND_LAZY | G_MODULE_BIND_LOCAL);
+	if (!module) {
+		g_set_error (error,
+		             NM_VPN_PLUGIN_ERROR,
+		             NM_VPN_PLUGIN_ERROR_FAILED,
+		             _("cannot load plugin %s"), editor_library_path);
+		return NULL;
+	}
+
+	if (g_module_symbol (module, "nm_vpn_editor_factory", (gpointer) &factory)) {
+		gs_free_error GError *factory_error = NULL;
+
+		editor = factory (self,
+		                  connection,
+		                  load_data,
+		                  &factory_error);
+
+		g_assert (!editor || G_IS_OBJECT (editor));
+
+		if (editor) {
+			g_object_set_data_full (G_OBJECT (editor), "gmodule", module,
+			                        (GDestroyNotify) g_module_close);
+		} else {
+			if (factory_error) {
+				g_propagate_error (error, factory_error);
+				factory_error = NULL;
+			} else {
+				g_set_error (error,
+				             NM_VPN_PLUGIN_ERROR,
+				             NM_VPN_PLUGIN_ERROR_FAILED,
+				             _("unknown error initializing editor plugin %s"), editor_library_path);
+			}
+			g_module_close (module);
+		}
+	} else {
+		g_set_error (error,
+		             NM_VPN_PLUGIN_ERROR,
+		             NM_VPN_PLUGIN_ERROR_FAILED,
+		             _("failed to load nm_vpn_editor_factory() from %s (%s)"),
+		             g_module_name (module), g_module_error ());
+		g_module_close (module);
+	}
+
+	return editor;
+}
+
+/**
  * nm_vpn_editor_plugin_get_editor:
- * @plugin: the #NMVpnEditorPlugin
+ * @self: the #NMVpnEditorPlugin
  * @connection: the #NMConnection to be edited
  * @error: on return, an error or %NULL
  *
  * Returns: (transfer full): a new #NMVpnEditor or %NULL on error
  */
 NMVpnEditor *
-nm_vpn_editor_plugin_get_editor (NMVpnEditorPlugin *plugin,
+nm_vpn_editor_plugin_get_editor (NMVpnEditorPlugin *self,
                                  NMConnection *connection,
                                  GError **error)
 {
-	g_return_val_if_fail (NM_IS_VPN_EDITOR_PLUGIN (plugin), NULL);
+	NMVpnEditorPluginInterface *interface;
+
+	g_return_val_if_fail (NM_IS_VPN_EDITOR_PLUGIN (self), NULL);
 
-	return NM_VPN_EDITOR_PLUGIN_GET_INTERFACE (plugin)->get_editor (plugin, connection, error);
+	interface = NM_VPN_EDITOR_PLUGIN_GET_INTERFACE (self);
+	if (interface->get_editor)
+		return interface->get_editor (self, connection, error);
+
+	return nm_vpn_editor_plugin_get_editor_load (self,
+	                                             NULL,
+	                                             connection,
+	                                             TRUE,
+	                                             getuid (),
+	                                             NULL,
+	                                             NULL,
+	                                             NULL,
+	                                             error);
 }
 
 NMVpnEditorPluginCapability
diff --git a/libnm-core/nm-vpn-editor-plugin.h b/libnm-core/nm-vpn-editor-plugin.h
index ffddf72f34..51e43473a0 100644
--- a/libnm-core/nm-vpn-editor-plugin.h
+++ b/libnm-core/nm-vpn-editor-plugin.h
@@ -37,12 +37,32 @@ G_BEGIN_DECLS
 typedef struct _NMVpnEditorPlugin NMVpnEditorPlugin;
 typedef struct _NMVpnEditor NMVpnEditor;
 
+/**
+ * NMVpnEditorLoadData:
+ *
+ * Used to pass addtional arguments to the nm_vpn_editor_factory method
+ * of the library and nm_vpn_editor_plugin_get_editor_load(). Currently
+ * no values are defined. This structure is used for future extensions.
+ *
+ * Since: 1.4
+ **/
+typedef struct _NMVpnEditorLoadData NMVpnEditorLoadData;
+
 /* Plugin's factory function that returns a GObject that implements
  * NMVpnEditorPlugin.
  */
 #ifndef __GI_SCANNER__
 typedef NMVpnEditorPlugin * (*NMVpnEditorPluginFactory) (GError **error);
 NMVpnEditorPlugin *nm_vpn_editor_plugin_factory (GError **error);
+
+typedef NMVpnEditor *(*NMVpnEditorFactory) (NMVpnEditorPlugin *editor_plugin,
+                                            NMConnection *connection,
+                                            NMVpnEditorLoadData *load_data,
+                                            GError **error);
+NMVpnEditor *nm_vpn_editor_factory (NMVpnEditorPlugin *editor_plugin,
+                                    NMConnection *connection,
+                                    NMVpnEditorLoadData *load_data,
+                                    GError **error);
 #endif
 
 
@@ -85,6 +105,11 @@ typedef enum /*< flags >*/ {
  * @g_iface: the parent interface
  * @get_editor: returns an #NMVpnEditor, pre-filled with values from @connection
  *   if non-%NULL.
+ *   This #NMVpnEditor is a GUI class and usually includes gtk dependencies. Newer
+ *   VPN plugins allow to split the base VPN plugin from the GUI dependency. In this
+ *   case they leave get_editor plugin unset and specify GNOME.editor-plugin path
+ *   in the name file. In that case, nm_vpn_editor_plugin_get_editor() will load
+ *   the module and return the editor plugin from there.
  * @get_capabilities: returns a bitmask of capabilities.
  * @import_from_file: Try to import a connection from the specified path.  On
  *   success, return a partial #NMConnection object.  On error, return %NULL and
@@ -131,6 +156,15 @@ void nm_vpn_editor_plugin_set_editor_library_path (NMVpnEditorPlugin *self,
 NMVpnEditor *nm_vpn_editor_plugin_get_editor (NMVpnEditorPlugin *plugin,
                                               NMConnection *connection,
                                               GError **error);
+NMVpnEditor *nm_vpn_editor_plugin_get_editor_load (NMVpnEditorPlugin *self,
+                                                   const char *editor_library_path,
+                                                   NMConnection *connection,
+                                                   gboolean do_file_checks,
+                                                   int check_owner,
+                                                   NMUtilsCheckFilePredicate check_file,
+                                                   gpointer user_data,
+                                                   NMVpnEditorLoadData *load_data,
+                                                   GError **error);
 
 NMVpnEditorPluginCapability nm_vpn_editor_plugin_get_capabilities (NMVpnEditorPlugin *plugin);
 
diff --git a/libnm/libnm.ver b/libnm/libnm.ver
index 1d5c125f6c..1f89a53b6b 100644
--- a/libnm/libnm.ver
+++ b/libnm/libnm.ver
@@ -1062,6 +1062,7 @@ global:
 libnm_1_4_0 {
 global:
 	nm_vpn_editor_plugin_get_editor_library_path;
+	nm_vpn_editor_plugin_get_editor_load;
 	nm_vpn_editor_plugin_load;
 	nm_vpn_editor_plugin_set_editor_library_path;
 	nm_vpn_plugin_info_get_auth_dialog;