[PATCH 3/9 v3] libsepol/cil: Add cil_tree_node_remove function

[James Carter <jwcart2@gmail.com>]

Add the function cil_tree_node_remove() which takes a node pointer
as an input, finds the parent, walks the list of nodes to the node
prior to the given node, updates that node's next pointer to remove
the given node from the tree, and then destroys the node.

Signed-off-by: James Carter <jwcart2@gmail.com>
---
v3:
 - Check for cl_tail pointing to the node
 - Destroy the node before returning if cl_head points to the node

 libsepol/cil/src/cil_tree.c | 35 +++++++++++++++++++++++++++++++++++
 libsepol/cil/src/cil_tree.h |  1 +
 2 files changed, 36 insertions(+)

diff --git a/libsepol/cil/src/cil_tree.c b/libsepol/cil/src/cil_tree.c
index 6376c208..1155e311 100644
--- a/libsepol/cil/src/cil_tree.c
+++ b/libsepol/cil/src/cil_tree.c
@@ -248,6 +248,41 @@ void cil_tree_node_destroy(struct cil_tree_node **node)
 	*node = NULL;
 }
 
+void cil_tree_node_remove(struct cil_tree_node *node)
+{
+	struct cil_tree_node *parent, *curr;
+
+	if (node == NULL || node->parent == NULL) {
+		return;
+	}
+
+	parent = node->parent;
+
+	if (parent->cl_head == node) {
+		if (parent->cl_tail == node) {
+			parent->cl_tail = NULL;
+		}
+		parent->cl_head = node->next;
+		cil_tree_node_destroy(&node);
+		return;
+	}
+
+	curr = parent->cl_head;
+	while (curr && curr->next != node) {
+		curr = curr->next;
+	}
+
+	if (curr == NULL) {
+		return;
+	}
+
+	if (parent->cl_tail == node) {
+		parent->cl_tail = curr;
+	}
+	curr->next = node->next;
+	cil_tree_node_destroy(&node);
+}
+
 /* Perform depth-first walk of the tree
    Parameters:
    start_node:          root node to start walking from
diff --git a/libsepol/cil/src/cil_tree.h b/libsepol/cil/src/cil_tree.h
index 5a98da55..cb6a0d24 100644
--- a/libsepol/cil/src/cil_tree.h
+++ b/libsepol/cil/src/cil_tree.h
@@ -63,6 +63,7 @@ void cil_tree_children_destroy(struct cil_tree_node *node);
 
 void cil_tree_node_init(struct cil_tree_node **node);
 void cil_tree_node_destroy(struct cil_tree_node **node);
+void cil_tree_node_remove(struct cil_tree_node *node);
 
 //finished values
 #define CIL_TREE_SKIP_NOTHING	0
-- 
2.39.2