add the loop key length macro for circular reference detect

src/dump.c

@@ -296,8 +296,7 @@ static int do_dump(const json_t *json, size_t flags, int depth,
             void *iter;
             const char *separator;
             int separator_length;
-            /* Space for "0x", double the sizeof a pointer for the hex and a terminator. */
-            char loop_key[2 + (sizeof(json) * 2) + 1];
+            char loop_key[LOOP_KEY_LEN];
 
             if(flags & JSON_COMPACT) {
                 separator = ":";

src/jansson_private.h

@@ -91,6 +91,8 @@ char *jsonp_strdup(const char *str) JANSSON_ATTRS(warn_unused_result);
 char *jsonp_strndup(const char *str, size_t len) JANSSON_ATTRS(warn_unused_result);
 
 /* Circular reference check*/
+/* Space for "0x", double the sizeof a pointer for the hex and a terminator. */
+#define LOOP_KEY_LEN (2 + (sizeof(json_t *) * 2) + 1)
 int jsonp_loop_check(hashtable_t *parents, const json_t *json, char *key, size_t key_size);
 
 

src/value.c

@@ -322,10 +322,10 @@ static json_t *json_object_deep_copy(const json_t *object, hashtable_t *parents)
 {
     json_t *result;
     void *iter;
-    char loop_key[2 + (sizeof(object) * 2) + 1];
+    char loop_key[LOOP_KEY_LEN];
 
     if (jsonp_loop_check(parents, object, loop_key, sizeof(loop_key)))
-            return NULL;
+        return NULL;
 
     result = json_object();
     if(!result)
@@ -641,7 +641,7 @@ static json_t *json_array_deep_copy(const json_t *array, hashtable_t *parents)
 {
     json_t *result;
     size_t i;
-    char loop_key[2 + (sizeof(array) * 2) + 1];
+    char loop_key[LOOP_KEY_LEN];
 
     if (jsonp_loop_check(parents, array, loop_key, sizeof(loop_key)))
         return NULL;