dtoc: Allow deleting nodes and adding them in the same sync

This does not work at present, since the current algorithm assumes that
either there are no nodes or all nodes have an offset. If a node is new,
but an old node is still in the tree, then syncing fails due to this
assumption.

Fix it and add a test.

Signed-off-by: Simon Glass <sjg@chromium.org>

tools/dtoc/fdt.py

@@ -356,6 +356,8 @@ class Node:
 
         offset = fdt_obj.first_subnode(self._offset, QUIET_NOTFOUND)
         for subnode in self.subnodes:
+            if subnode._offset is None:
+                continue
             if subnode.name != fdt_obj.get_name(offset):
                 raise ValueError('Internal error, node name mismatch %s != %s' %
                                  (subnode.name, fdt_obj.get_name(offset)))

tools/dtoc/test_fdt.py

@@ -272,6 +272,17 @@ class TestNode(unittest.TestCase):
 
         self.dtb.Sync(auto_resize=True)
 
+    def testAddOneNode(self):
+        """Testing deleting and adding a subnode before syncing"""
+        subnode = self.node.AddSubnode('subnode')
+        self.node.AddSubnode('subnode2')
+        self.dtb.Sync(auto_resize=True)
+
+        # Delete a node and add a new one
+        subnode.Delete()
+        self.node.AddSubnode('subnode3')
+        self.dtb.Sync()
+
     def testRefreshNameMismatch(self):
         """Test name mismatch when syncing nodes and properties"""
         prop = self.node.AddInt('integer-a', 12)