3 files changed, 31 insertions, 48 deletions

diff --git a/include/osmocom/vty/vty.h b/include/osmocom/vty/vty.h
index 03a29248..9acaa7d2 100644
--- a/include/osmocom/vty/vty.h
+++ b/include/osmocom/vty/vty.h
@@ -178,9 +178,14 @@ struct vty_app_info {
 	const char *copyright;
 	/*! \ref talloc context */
 	void *tall_ctx;
-	/*! call-back for returning to parent n ode */
+	/*! Call-back for taking actions upon exiting a node.
+	 * The return value is ignored, and changes to vty->node and vty->index made in this callback are ignored.
+	 * Implicit parent node tracking always sets the correct parent node and vty->index after this callback exits,
+	 * so this callback can handle only those nodes that should take specific actions upon node exit, or can be left
+	 * NULL entirely. */
 	int (*go_parent_cb)(struct vty *vty);
-	/*! call-back to determine if node is config node */
+	/*! OBSOLETED: Implicit parent node tracking has replaced the use of this callback. This callback is no longer
+	 * called, ever, and can be left NULL. */
 	int (*is_config_node)(struct vty *vty, int node);
 	/*! Check if the config is consistent before write */
 	int (*config_is_consistent)(struct vty *vty);
diff --git a/src/vty/command.c b/src/vty/command.c
index 6a9d18af..daee5c5a 100644
--- a/src/vty/command.c
+++ b/src/vty/command.c
@@ -200,18 +200,6 @@ static int cmp_desc(const void *p, const void *q)
 	return strcmp(a->cmd, b->cmd);
 }
 
-static int is_config_child(struct vty *vty)
-{
-	if (vty->node <= CONFIG_NODE)
-		return 0;
-	else if (vty->node > CONFIG_NODE && vty->node < _LAST_OSMOVTY_NODE)
-		return 1;
-	else if (host.app_info->is_config_node)
-		return host.app_info->is_config_node(vty, vty->node);
-	else
-		return vty->node > CONFIG_NODE;
-}
-
 /*! Sort each node's command element according to command string. */
 void sort_node(void)
 {
@@ -2187,25 +2175,10 @@ int vty_go_parent(struct vty *vty)
 			vty_clear_parents(vty);
 			break;
 
-		case CFG_LOG_NODE:
-		case VTY_NODE:
-			vty->node = CONFIG_NODE;
-			vty_clear_parents(vty);
-			break;
-
 		default:
-			if (host.app_info->go_parent_cb) {
+			if (host.app_info->go_parent_cb)
 				host.app_info->go_parent_cb(vty);
-				vty_pop_parent(vty);
-			}
-			else if (is_config_child(vty)) {
-				vty->node = CONFIG_NODE;
-				vty_clear_parents(vty);
-			}
-			else {
-				vty->node = VIEW_NODE;
-				vty_clear_parents(vty);
-			}
+			vty_pop_parent(vty);
 			break;
 	}
 
@@ -2365,9 +2338,30 @@ cmd_execute_command_real(vector vline, struct vty *vty,
 
 	if (matched_element->daemon)
 		rc = CMD_SUCCESS_DAEMON;
-	else	/* Execute matched command. */
+	else {
+		/* Execute matched command. */
+		struct vty_parent_node this_node = {
+				.node = vty->node,
+				.priv = vty->priv,
+				.indent = vty->indent,
+			};
+		struct vty_parent_node *parent = vty_parent(vty);
 		rc = (*matched_element->func) (matched_element, vty, argc, argv);
 
+		/* If we have stepped down into a child node, push a parent frame.
+		 * The causality is such: we don't expect every single node entry implementation to push
+		 * a parent node entry onto vty->parent_nodes. Instead we expect vty_go_parent() to *pop*
+		 * a parent node. Hence if the node changed without the parent node changing, we must
+		 * have stepped into a child node. */
+		if (vty->node != this_node.node && parent == vty_parent(vty)
+		    && vty->node > CONFIG_NODE) {
+			/* Push the parent node. */
+			parent = talloc_zero(vty, struct vty_parent_node);
+			*parent = this_node;
+			llist_add(&parent->entry, &vty->parent_nodes);
+		}
+	}
+
 rc_free_deopt_ctx:
 	/* Now after we called the command func, we can free temporary strings */
 	talloc_free(cmd_deopt_ctx);
diff --git a/tests/vty/vty_test.c b/tests/vty/vty_test.c
index 1139638d..9627b6d2 100644
--- a/tests/vty/vty_test.c
+++ b/tests/vty/vty_test.c
@@ -482,27 +482,11 @@ void test_is_cmd_ambiguous()
 	destroy_test_vty(&test, vty);
 }
 
-static int go_parent_cb(struct vty *vty)
-{
-	/*
-	 * - For the interactive VTY tests above, it is expected to bounce back to
-	 *   the CONFIG_NODE. Hence do so in go_parent_cb().
-	 * - In the config file parsing tests, setting vty->node in go_parent_cb() has no
-	 *   effect, because we will subsequently pop a parent node from the parent stack
-	 *   and override to go to the node that was recorded as the actual parent.
-	 */
-	vty->node = CONFIG_NODE;
-	vty->index = NULL;
-	return 0;
-}
-
 int main(int argc, char **argv)
 {
 	struct vty_app_info vty_info = {
 		.name		= "VtyTest",
 		.version	= 0,
-		.go_parent_cb	= go_parent_cb,
-		.is_config_node	= NULL,
 	};
 
 	const struct log_info_cat default_categories[] = {};