fix segfault from unpredictable GC ordering

We cannot guarantee GC will mark valid nodes when the tree
the node belongs to is destroyed, so we have to allocate
a new node that is a copy of the original node whenever
we create Patricia::Node objects

2 files changed, 14 insertions, 3 deletions

diff --git a/ext/rpatricia/rpatricia.c b/ext/rpatricia/rpatricia.c
index 1c81ba1..ae018af 100644
--- a/ext/rpatricia/rpatricia.c
+++ b/ext/rpatricia/rpatricia.c
@@ -33,10 +33,13 @@ p_node_mark (void *ptr)
 }
 
 static VALUE
-wrap_node(patricia_node_t *node)
+wrap_node(patricia_node_t *orig)
 {
-  /* node will be freed when parent is freed */
-  return Data_Wrap_Struct(cNode, p_node_mark, 0, node);
+  patricia_node_t *node = ALLOC(patricia_node_t);
+
+  memcpy(node, orig, sizeof(patricia_node_t));
+
+  return Data_Wrap_Struct(cNode, p_node_mark, -1, node);
 }
 
 static prefix_t *
diff --git a/test/test_old_segfaults.rb b/test/test_old_segfaults.rb
index 5e7ec3e..96f1b43 100644
--- a/test/test_old_segfaults.rb
+++ b/test/test_old_segfaults.rb
@@ -30,4 +30,12 @@ class TestOldSegfaults < Test::Unit::TestCase
     t = Patricia.new
     assert_equal 0, t.num_nodes
   end
+
+  def test_gc_ordering_segfault
+    added = []
+    100000.times do
+      tmp = Patricia.new
+      added << tmp.add('8.8.8.8')
+    end
+  end
 end