From: Haffon <31226194+Haffon@users.noreply.github.com>
Date: Thu, 7 Sep 2017 01:33:07 +0000 (+0800)
Subject: Merge pull request #2 from json-c/master
X-Git-Tag: json-c-0.13-20171207~53^2~3
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=86a3a6475fd42ef999a3c0e205e097c62f8a1e65;p=thirdparty%2Fjson-c.git

Merge pull request #2 from json-c/master

merge upstream
---

86a3a6475fd42ef999a3c0e205e097c62f8a1e65
diff --cc json_object.c
index 3cecc43e,ec4e2b6e..5edcd7e8
--- a/json_object.c
+++ b/json_object.c
@@@ -161,27 -161,39 +161,39 @@@ static int json_escape_str(struct print
  
  /* reference counting */
  
 -extern struct json_object* json_object_get(struct json_object *jso)
 +extern struct json_object* json_object_retain(struct json_object *jso)
  {
- 	if (jso)
- 		jso->_ref_count++;
+ 	if (!jso) return jso;
+ 
+ #if defined(HAVE_ATOMIC_BUILTINS) && defined(ENABLE_THREADING)
+ 	__sync_add_and_fetch(&jso->_ref_count, 1);
+ #else
+ 	++jso->_ref_count;
+ #endif        
+ 
  	return jso;
  }
  
 -int json_object_put(struct json_object *jso)
 +int json_object_release(struct json_object *jso)
  {
- 	if(jso)
- 	{
- 		jso->_ref_count--;
- 		if(!jso->_ref_count)
- 		{
- 			if (jso->_user_delete)
- 				jso->_user_delete(jso, jso->_userdata);
- 			jso->_delete(jso);
- 			return 1;
- 		}
- 	}
- 	return 0;
+ 	if(!jso) return 0;
+ 
+ #if defined(HAVE_ATOMIC_BUILTINS) && defined(ENABLE_THREADING)
+ 	/* Note: this only allow the refcount to remain correct
+ 	 * when multiple threads are adjusting it.  It is still an error 
+ 	 * for a thread to decrement the refcount if it doesn't "own" it,
+ 	 * as that can result in the thread that loses the race to 0
+ 	 * operating on an already-freed object.
+ 	 */
+ 	if (__sync_sub_and_fetch(&jso->_ref_count, 1) > 0) return 0;
+ #else
+ 	if (--jso->_ref_count > 0) return 0;
+ #endif
+ 
+ 	if (jso->_user_delete)
+ 		jso->_user_delete(jso, jso->_userdata);
+ 	jso->_delete(jso);
+ 	return 1;
  }