Codec issue when transferring lists with size 0

[burgerkingorama]

When transferring an empty list, the codec will be confused and all following structs are corrupted.

IDL:

interface Test {
	getData(out list<uint8>) -> void
}

The client shim code looks like this:

static void read_list_uint8_1_t_struct(erpc::Codec * codec, list_uint8_1_t * data) {
	codec->startReadList(&data->elementsCount);
	data->elements = (uint8_t *) erpc_malloc(data->elementsCount * sizeof(uint8_t));
	if (data->elements == NULL)
	{
		codec->updateStatus(kErpcStatus_MemoryError);
	}
[...]

Depending on the implementation of erpc_malloc the function may return NULL if the size to malloc is zero.

In the NULL case, which is our case is not an error the codec updates its state to error and all following struct are corrupted then.

[MichalPrincNXP]

Hello @burgerkingorama , thanks for reporting this, providing the fix and sorry for not being responded yet. This seems to me like a valid use case but need the confirmation from @Hadatko . Is it allowed to use lists as out parameters? If so, we should handle the use case with empty list being parsed as proposed in #72 . @Hadatko , could you briefly comment, please? Thank you.

[Hadatko]

I think the condition if (data->elements == NULL) should be changed to
if (data->elements == NULL && data->elementsCount>0)

[Hadatko]

Also need be confirmed that if if elementsCount is set to 0 then write list struct will send 0 to other side and nothing more. I would suggest to add tests for binary/list type for this cases.