From ddd48d34a05fb540f40fd81c61a25f99f0d7f741 Mon Sep 17 00:00:00 2001
From: Walter Bender <walter@sugarlabs.org>
Date: Fri, 15 Oct 2010 19:19:07 +0000
Subject: more rigorous connection checking to prevent crashing on reading bad project data (#2447)

---
diff --git a/TurtleArt/tablock.py b/TurtleArt/tablock.py
index b797ada..344f2da 100644
--- a/TurtleArt/tablock.py
+++ b/TurtleArt/tablock.py
@@ -367,7 +367,7 @@ class Block:
                 n = len(BLOCK_NAMES[self.name])
             else:
                 _logger.debug("WARNING: unknown block name %s" % (self.name))
-            n = 0
+                n = 0
         for i in range(n):
             if i == 1: # top
                 self.spr.set_label_attributes(int(self._font_size[1] + 0.5),
diff --git a/TurtleArt/tautils.py b/TurtleArt/tautils.py
index 7565c4e..025c4f4 100644
--- a/TurtleArt/tautils.py
+++ b/TurtleArt/tautils.py
@@ -121,10 +121,9 @@ def _tuplify(tup):
 
 def get_id(connection):
     """ Get a connection block ID. """
-    if connection is None:
-        return None
-    return connection.id
-
+    if connection is not None and hasattr(connection, 'id'):
+        return connection.id
+    return None
 
 def json_dump(data):
     """ Save data using available JSON tools. """
diff --git a/TurtleArt/tawindow.py b/TurtleArt/tawindow.py
index f620958..1bc7ab8 100644
--- a/TurtleArt/tawindow.py
+++ b/TurtleArt/tawindow.py
@@ -1067,11 +1067,15 @@ class TurtleArtWindow():
             cons = []
             # Normally, it is simply a matter of copying the connections.
             if blocks[i].connections is None:
-                for c in block_data[i][4]:
-                    if c is None:
-                        cons.append(None)
-                    else:
-                        cons.append(blocks[c])
+                if block_data[i][4] is not None:
+                    for c in block_data[i][4]:
+                        if c is None or c > (len(blocks) - 1):
+                            cons.append(None)
+                        else:
+                            cons.append(blocks[c])
+                else:
+                    _logger.debug("connection error %s" % (str(block_data[i])))
+                    cons.append(None)
             elif blocks[i].connections == 'check':
                 # Convert old-style boolean and arithmetic blocks
                 cons.append(None) # Add an extra connection.
@@ -1145,7 +1149,7 @@ class TurtleArtWindow():
             if i > 0 and c is not None:
                 bdock = blk.docks[i]
                 for j in range(len(c.docks)):
-                    if c.connections[j] == blk:
+                    if j < len(c.connections) and c.connections[j] == blk:
                         cdock = c.docks[j]
                         nx = sx + bdock[2] - cdock[2]
                         ny = sy + bdock[3] - cdock[3]
@@ -1651,8 +1655,9 @@ class TurtleArtWindow():
             best_destination.connections[best_destination_dockn] = \
                 selected_block
             if selected_block.connections is not None:
-                selected_block.connections[best_selected_block_dockn] = \
-                    best_destination
+                if best_selected_block_dockn < len(selected_block.connections):
+                    selected_block.connections[best_selected_block_dockn] = \
+                        best_destination
 
             if best_destination.name in BOOLEAN_STYLE:
                 if best_destination_dockn == 2 and \
@@ -1688,8 +1693,9 @@ class TurtleArtWindow():
         if collapsed(blk):
             return
         blk2 = blk.connections[0]
-        c = blk2.connections.index(blk)
-        blk2.connections[c] = None
+        if blk in blk2.connections:
+            c = blk2.connections.index(blk)
+            blk2.connections[c] = None
 
         if blk2.name in BOOLEAN_STYLE:
             if c == 2 and blk2.ey > 0:
@@ -2312,7 +2318,7 @@ class TurtleArtWindow():
                 _name = (_blk.name, self.block_scale)
             else:
                 _name = (_blk.name)
-            if hasattr(_blk, 'connections'):
+            if hasattr(_blk, 'connections') and _blk.connections is not None:
                 connections = [get_id(_cblk) for _cblk in _blk.connections]
             else:
                 connections = None
--
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