cJSON_PrintUnformatted err = -ENOMEM;

RE: cJSON_PrintUnformatted err = -ENOMEM;

Marte Myrvold — Wed, 19 Jun 2024 07:54:15 GMT

Hi,

The Asset Tracker v2 uses the QoS module to retransmit payloads (the allocated JSON strings) until they have been acked. Once that happens, it is freed here: https://github.com/nrfconnect/sdk-nrf/blob/v2.6.1/applications/asset_tracker_v2/src/modules/cloud_module.c#L812.

Best regards,
Marte

RE: cJSON_PrintUnformatted err = -ENOMEM;

zsn — Thu, 13 Jun 2024 11:46:27 GMT

hi Marte Myrvold thanks for your feedback. Ill correct all those issues. FYI, It seems nrf asset tracker app also has the same problem. I tried to explain here above in my previous comment:

[quote userid="117272" url="~/f/nordic-q-a/112086/cjson_printunformatted-err--enomem/488652"]

but it was surprising to me, I took nrf applications as a reference to create my own sample and I didnt see anywhere nrf developers call cJSON_free functions. Except here

Fullscreen

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if (IS_ENABLED(CONFIG_CLOUD_CODEC_LOG_LEVEL_DBG)) {
 json_print_obj("Encoded message:\n", root_obj);
 }
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

if (IS_ENABLED(CONFIG_CLOUD_CODEC_LOG_LEVEL_DBG)) {
 json_print_obj("Encoded message:\n", root_obj);
 }

But this is not enough, if a user doesnt enable the CONFIG_CLOUD_CODEC_LOG_LEVEL_DBG,
the application doesnt free the memory. So seems this is a problem,

Am I right?

https://github.com/nrfconnect/sdk-nrf/blob/main/applications/asset_tracker_v2/src/cloud/cloud_codec/aws_iot/aws_iot_codec.c#L371

[/quote]

RE: cJSON_PrintUnformatted err = -ENOMEM;

Marte Myrvold — Thu, 13 Jun 2024 11:40:25 GMT

Hi,

It seems like you have some memory leaks in your application.

First of all, buffers allocated by cJSON_PrintUnformatted() must be freed. In your code, it is not freed before the usb_log structure is re-initialized, which means that every time encode_json() is called, a new buffer is allocated, and the old one is lost without being freed. You can free it with cJSON_free():

char *buffer = cJSON_PrintUnformatted(root_obj);

...

exit:
	cJSON_Delete(root_obj);
    cJSON_free(json_str);
	printk("%d %s\n", __LINE__, FILE_NAME);

return;

Another issue is that if any of the error checks fail before sub_obj and data_obj are added as child objects to root_obj, then sub_obj and data_obj will not be deleted when root_obj is deleted. So you should also make sure that these objects are deleted in the exit as well.

Best regards,
Marte

RE: cJSON_PrintUnformatted err = -ENOMEM;

zsn — Thu, 13 Jun 2024 11:09:21 GMT

it seems I fixed the issue by following this ticket: https://github.com/DaveGamble/cJSON/issues/297

this is the fix:

const char * jsonString = cJSON_PrintUnformatted(root);
//...
cJSON_free(jsonString);
cJSON_Delete(root);

but it was surprising to me, I took nrf applications as a reference to create my own sample and I didnt see anywhere nrf developers call cJSON_free functions. Except here

if (IS_ENABLED(CONFIG_CLOUD_CODEC_LOG_LEVEL_DBG)) {
 json_print_obj("Encoded message:\n", root_obj);
 }

But this is not enough, if a user doesnt enable the CONFIG_CLOUD_CODEC_LOG_LEVEL_DBG,
the application doesnt free the memory. So seems this is a problem,

Am I right?

https://github.com/nrfconnect/sdk-nrf/blob/main/applications/asset_tracker_v2/src/cloud/cloud_codec/aws_iot/aws_iot_codec.c#L371