cli: fix crash when edited profile was removed by another client (rh #1011942)

Use g_weak_ref_get() that either returns an object with reference increment or
returns NULL.
That fixes the problem.  However, in the long run we should rework the editor
loop trying to merge that with GMainLoop, which could help for various issues.

https://bugzilla.redhat.com/show_bug.cgi?id=1011942

cli/src/connections.c

@@ -6112,6 +6112,21 @@ editor_show_status_line (NMConnection *connection, gboolean dirty)
 	        con_type, con_id, con_uuid, dirty ? _("yes") : _("no"));
 }
 
+static gboolean
+refresh_remote_connection (GWeakRef *weak, NMRemoteConnection **remote)
+{
+	gboolean previous;
+
+	g_return_val_if_fail (remote != NULL, FALSE);
+
+	previous = (*remote != NULL);
+	if (*remote)
+		g_object_unref (*remote);
+	*remote = g_weak_ref_get (weak);
+
+	return (previous && !*remote);
+}
+
 /*
  * Submenu for detailed property editing
  * Return: TRUE - continue;  FALSE - should quit
@@ -6119,7 +6134,8 @@ editor_show_status_line (NMConnection *connection, gboolean dirty)
 static gboolean
 property_edit_submenu (NmCli *nmc,
                        NMConnection *connection,
-                       NMRemoteConnection *rem_con,
+                       NMRemoteConnection **rem_con,
+                       GWeakRef *rem_con_weak,
                        NMSetting *curr_setting,
                        const char *prop_name)
 {
@@ -6132,6 +6148,7 @@ property_edit_submenu (NmCli *nmc,
 	char *prompt;
 	gboolean dirty;
 	GValue prop_g_value = G_VALUE_INIT;
+	gboolean removed;
 
 	prompt = nmc_colorize (nmc->editor_prompt_color, "nmcli %s.%s> ",
 	                       nm_setting_get_name (curr_setting), prop_name);
@@ -6140,9 +6157,15 @@ property_edit_submenu (NmCli *nmc,
 		char *cmd_property_user;
 		char *cmd_property_arg;
 
+		/* Get the remote connection again, it may have disapeared */
+		removed = refresh_remote_connection (rem_con_weak, rem_con);
+		if (removed)
+			printf (_("The connection profile has been removed from another client. "
+			          "You may type 'save' in the main menu to restore it.\n"));
+
 		/* Connection is dirty? (not saved or differs from the saved) */
 		dirty = !nm_connection_compare (connection,
-		                                rem_con ? NM_CONNECTION (rem_con) : NULL,
+		                                *rem_con ? NM_CONNECTION (*rem_con) : NULL,
 		                                NM_SETTING_COMPARE_FLAG_EXACT);
 
 		if (nmc->editor_status_line)
@@ -6507,7 +6530,10 @@ menu_switch_to_level1 (NmcEditorMenuContext *menu_ctx,
 static gboolean
 editor_menu_main (NmCli *nmc, NMConnection *connection, const char *connection_type)
 {
-	NMRemoteConnection *rem_con = NULL;
+	NMRemoteConnection *rem_con;
+	NMRemoteConnection *con_tmp;
+	GWeakRef weak = { { NULL } };
+	gboolean removed;
 	NmcEditorMainCmd cmd;
 	char *cmd_user;
 	gboolean cmd_loop = TRUE;
@@ -6531,11 +6557,13 @@ editor_menu_main (NmCli *nmc, NMConnection *connection, const char *connection_t
 	menu_ctx.valid_props = NULL;
 	menu_ctx.valid_props_str = NULL;
 
-	while (cmd_loop) {
+	/* Get remote connection */
-		if (!rem_con)
+	con_tmp = nm_remote_settings_get_connection_by_uuid (nmc->system_settings,
-			rem_con = nm_remote_settings_get_connection_by_uuid (nmc->system_settings,
 	                                                     nm_connection_get_uuid (connection));
+	g_weak_ref_init (&weak, con_tmp);
+	rem_con = g_weak_ref_get (&weak);
 
+	while (cmd_loop) {
 		/* Connection is dirty? (not saved or differs from the saved) */
 		dirty = !nm_connection_compare (connection,
 		                                rem_con ? NM_CONNECTION (rem_con) : NULL,
@@ -6543,7 +6571,15 @@ editor_menu_main (NmCli *nmc, NMConnection *connection, const char *connection_t
 		if (nmc->editor_status_line)
 			editor_show_status_line (connection, dirty);
 
+		/* Read user input */
 		cmd_user = readline_x (menu_ctx.main_prompt);
+
+		/* Get the remote connection again, it may have disapeared */
+		removed = refresh_remote_connection (&weak, &rem_con);
+		if (removed)
+			printf (_("The connection profile has been removed from another client. "
+			          "You may type 'save' to restore it.\n"));
+
 		if (!cmd_user || *cmd_user == '\0')
 			continue;
 		cmd = parse_editor_main_cmd (g_strstrip (cmd_user), &cmd_arg);
@@ -6693,7 +6729,12 @@ editor_menu_main (NmCli *nmc, NMConnection *connection, const char *connection_t
 					break;
 
 				/* submenu - level 2 - editing properties */
-				cmd_loop = property_edit_submenu (nmc, connection, rem_con, menu_ctx.curr_setting, prop_name);
+				cmd_loop = property_edit_submenu (nmc,
+				                                  connection,
+				                                  &rem_con,
+				                                  &weak,
+				                                  menu_ctx.curr_setting,
+				                                  prop_name);
 			}
 			break;
 
@@ -6933,18 +6974,19 @@ editor_menu_main (NmCli *nmc, NMConnection *connection, const char *connection_t
 
 					g_error_free (nmc_editor_error);
 				} else {
-					NMRemoteConnection *con_tmp;
-
 					printf (_("Connection '%s' (%s) successfully saved.\n"),
 					        nm_connection_get_id (connection),
 					        nm_connection_get_uuid (connection));
 
+					con_tmp = nm_remote_settings_get_connection_by_uuid (nmc->system_settings,
+					                                                     nm_connection_get_uuid (connection));
+					g_weak_ref_set (&weak, con_tmp);
+					refresh_remote_connection (&weak, &rem_con);
+
 					/* Replace local connection with the remote one to be sure they are equal.
 					 * This mitigates problems with plugins not preserving some properties or
 					 * adding ipv{4,6} settings when not present.
 					 */
-					con_tmp = nm_remote_settings_get_connection_by_uuid (nmc->system_settings,
-					                                                     nm_connection_get_uuid (connection));
 					if (con_tmp) {
 						char *s_name = NULL;
 						if (menu_ctx.curr_setting)
@@ -7128,6 +7170,9 @@ editor_menu_main (NmCli *nmc, NMConnection *connection, const char *connection_t
 	g_free (menu_ctx.main_prompt);
 	g_strfreev (menu_ctx.valid_props);
 	g_free (menu_ctx.valid_props_str);
+	if (rem_con)
+		g_object_unref (rem_con);
+	g_weak_ref_clear (&weak);
 
 	/* Save history file */
 	save_history_cmds (nm_connection_get_uuid (connection));