Fixed BSON (de)serialization of object ids. New test that saves/restores oid to the database.

lib/mongo/util/bson.rb

@@ -184,10 +184,7 @@ class BSON
   end
 
   def deserialize_oid_data(buf)
-    high_bytes = buf.get_long
-    low_bytes = buf.get_int
-    hexval = (high_bytes << 32) + low_bytes
-    XGen::Mongo::Driver::ObjectID.new('%012x' % hexval)
+    XGen::Mongo::Driver::ObjectID.new(buf.get(12))
   end
 
   def serialize_eoo_element(buf)
@@ -254,11 +251,7 @@ class BSON
     buf.put(OID)
     self.class.serialize_cstr(buf, key)
 
-    hexval = val.to_s.hex
-    high_bytes = hexval >> 32
-    low_bytes = hexval && 0xffffffff
-    buf.put_long(high_bytes)
-    buf.put_int(low_bytes)
+    buf.put_array(val.to_a)
   end
 
   def serialize_string_element(buf, key, val, type)

tests/test_objectid.rb

@@ -51,4 +51,18 @@ class ObjectIDTest < Test::Unit::TestCase
     assert_equal 24, $1.length
   end
 
+  def test_save_and_restore
+    host = ENV['MONGO_RUBY_DRIVER_HOST'] || 'localhost'
+    port = ENV['MONGO_RUBY_DRIVER_PORT'] || XGen::Mongo::Driver::Mongo::DEFAULT_PORT
+    db = XGen::Mongo::Driver::Mongo.new(host, port).db('ruby-mongo-test')
+    coll = db.collection('test')
+
+    coll.clear
+    coll << {'a' => 1, '_id' => @o}
+
+    row = coll.find().collect.first
+    assert_equal 1, row['a']
+    assert_equal @o, row['_id']
+  end
+
 end