Valgrind: invalid read after json_object_array_del_idx.

[louandutoit]

Hi,
I need to clear an array and add some new elements, but using json_object_array_del_idx is raising a possible issue, when adding new values after deleting.
Below is a snippet of code to reproduce the error. I can work around this by deleting the array object, and recreating, but that is a more time consuming process.

int32_t doSomeArrayStuff() {
	json_object * opContainer = json_object_new_object();
	json_object * opArray = json_object_new_array();
	json_object_array_add(opArray, json_object_new_string("string1"));
	json_object_array_add(opArray, json_object_new_string("string2")); //block allocated here
	json_object_array_add(opArray, json_object_new_string("string3")); //block allocated here
	json_object_array_add(opArray, json_object_new_string("string4"));
	json_object_object_add(opContainer, "myarray", opArray);

	if(json_object_array_del_idx(opArray, 0, 3) != 0) { //block free here
		return 1;
	}

	json_object_array_add(opArray, json_object_new_string("string5")); //invalid read of size 4
	json_object_array_add(opArray, json_object_new_string("string6")); //invalid read of size 4
	json_object_put(opContainer);

	return 0;
}

Running this through valgrind raises:
Invalid read of size 4

At the position as indicated in the comments. I'm using version "json-c 0.12.99".

[hawicz]

hmm... your code looks fine, seems like a bug somewhere in json-c. I'll see what I can figure out.

[hawicz]

Sometimes you wonder how it ever worked. It should be fixed now, please try again with the most recent code.

[louandutoit]

Thanks

[elbaraka]

Hi I have exactely the same problem ! any solution please !

[hawicz]

@elbaraka, what problem are you talking about? If you're still getting a valgrind error even after the fix from fd9b3b2 then please open an issue with the details.

[elbaraka]

I set this but always the same problem ! it destroys the structure of objects after deletion

[hawicz]

I'll be happy to help you, but I don't understand what you're trying to explain. Please create a separate issue with an example of the problem that you are seeing.