found bug when to/fromwiring empty lists

added unittest


git-svn-id: svn://bind10.isc.org/svn/bind10/branches/jelte-configuration@809 e5f2f494-b856-4b98-b285-d166d9295462

src/lib/cc/cpp/data.cc

@@ -829,13 +829,19 @@ ListElement::toWire(std::stringstream& ss, int omit_length)
         (*it)->toWire(ss2, 0);
     }
 
+
     if (omit_length) {
-        ss << ss2.rdbuf();
+        stringbuf *ss2_buf = ss2.rdbuf();
+        if (ss2_buf->in_avail() > 0) {
+            ss << ss2_buf;
+        }
     } else {
         stringbuf *ss2_buf = ss2.rdbuf();
         ss2_buf->pubseekpos(0);
         ss << encode_length(ss2_buf->in_avail(), ITEM_LIST);
-        ss << ss2_buf;
+        if (ss2_buf->in_avail() > 0) {
+            ss << ss2_buf;
+        }
     }
 }
 
@@ -873,13 +879,17 @@ MapElement::toWire(std::stringstream& ss, int omit_length)
     // add length if needed
     //
     if (omit_length) {
-        ss << ss2.rdbuf();
+        stringbuf *ss2_buf = ss2.rdbuf();
+        if (ss2_buf->in_avail() > 0) {
+            ss << ss2_buf;
+        }
     } else {
-        
         stringbuf *ss2_buf = ss2.rdbuf();
         ss2_buf->pubseekpos(0);
         ss << encode_length(ss2_buf->in_avail(), ITEM_HASH);
-        ss << ss2_buf;
+        if (ss2_buf->in_avail() > 0) {
+            ss << ss2_buf;
+        }
     }
 }
 

src/lib/cc/cpp/data_unittests.cc

@@ -266,5 +266,13 @@ TEST(Element, to_and_from_wire) {
 
     //EXPECT_EQ("\047\0031.2", Element::create(1.2)->toWire(0));
     EXPECT_EQ("\046\0011", Element::createFromString("[ 1 ]")->toWire(1));
+
+    std::string ddef = "{\"data_specification\": {\"config_data\": [ {\"item_default\": \"Hello, world!\", \"item_name\": \"default_name\", \"item_optional\": False, \"item_type\": \"string\"}, {\"item_default\": [  ], \"item_name\": \"zone_list\", \"item_optional\": False, \"item_type\": \"list\", \"list_item_spec\": {\"item_name\": \"zone_name\", \"item_optional\": True, \"item_type\": \"string\"}} ], \"module_name\": \"Auth\"}}";
+    //std::string ddef = "{\"aaa\": 123, \"test\": [  ], \"zzz\": 123}";
+    ElementPtr ddef_el = Element::createFromString(ddef);
+    std::string ddef_wire = ddef_el->toWire();
+    ElementPtr ddef_el2 = Element::fromWire(ddef_wire);
+    std::string ddef2 = ddef_el2->str();
+    EXPECT_EQ(ddef, ddef2);
 }