Enhance handling of circular references

It's now an error to try to add an object or array to itself. The
encoder checks for circular references and fails with an error status
if one is detected.

1 files changed, 29 insertions, 0 deletions

diff --git a/test/testprogs/test_object.c b/test/testprogs/test_object.c
index 3be49e5..657a9c6 100644
--- a/test/testprogs/test_object.c
+++ b/test/testprogs/test_object.c
@@ -139,6 +139,34 @@ static void test_update()
     json_decref(object);
 }
 
+static void test_circular()
+{
+    json_t *object1, *object2;
+
+    object1 = json_object();
+    object2 = json_object();
+    if(!object1 || !object2)
+        fail("unable to create object");
+
+    /* the simple case is checked */
+    if(json_object_set(object1, "a", object1) == 0)
+        fail("able to set self");
+
+    /* create circular references */
+    if(json_object_set(object1, "a", object2) ||
+       json_object_set(object2, "a", object1))
+        fail("unable to set value");
+
+    /* circularity is detected when dumping */
+    if(json_dumps(object1, 0) != NULL)
+        fail("able to dump circulars");
+
+    /* decref twice to deal with the circular references */
+    json_decref(object1);
+    json_decref(object2);
+    json_decref(object1);
+}
+
 static void test_misc()
 {
     json_t *object, *string, *other_string, *value;
@@ -264,6 +292,7 @@ int main()
     test_misc();
     test_clear();
     test_update();
+    test_circular();
 
     return 0;
 }