Error when trying to access TEE_ObjectHandle attribute: dereferencing pointer to incomplete type 'struct __TEE_ObjectHandle'

[cezane]

I would like to know why I can not just access some ObjectHandle attribute like in this code:

void prepare_rsa_operation(TEE_OperationHandle *handle, uint32_t alg, TEE_OperationMode mode, TEE_ObjectHandle key) {
    (....)
    ret = TEE_AllocateOperation(&handle, alg, mode, key->dataLen);

The key->dataLen part is returning the following error:

rsa_crypto.c:25:64: error: dereferencing pointer to incomplete type 'struct __TEE_ObjectHandle'
ret = TEE_AllocateOperation(&handle, alg, mode, (uint32_t) key->dataLen);
^~

Can anyone explain me why, please?
Thank you.

[lorc]

Hi @cezane,

You don't need to take address of handle. Try in this way:

ret = TEE_AllocateOperation(handle, alg, mode, key->dataLen);

[jforissier]

TEE_ObjectHandle is an opaque type, which means the application cannot access its internal representation. A TEE_ObjectHandle value may only be manipulated using the API.

Perhaps what you're after is TEE_GetObjectInfo1(TEE_ObjectHandle object, TEE_ObjectInfo *objectInfo); then access objectInfo->dataSize?

[cezane]

Hi, @lorc . Can you explain me why your suggestion? For me, if I pass like you are suggesting (ret = TEE_AllocateOperation(handle, alg, mode, key->dataLen);), I will be passing handle by value; but, instead, I want it passed by reference, since I want the changes reflect outside that function also. Am I wrong with this thought?

[cezane]

Thank you by explanation, @jforissier . In this case, as you said, I have to use TEE_GetObjectInfo1 to do what I want.

[lorc]

Hi, @cezane,

I was partly mistaken. This is not related to your question, but looks like you have an another bug there.

If I got your code snippet right, you have a function

void prepare_rsa_operation(TEE_OperationHandle *handle, uint32_t alg, TEE_OperationMode mode, TEE_ObjectHandle key)

And inside this function you invoke TEE_AllocateOperation(TEE_OperationHandle *operation, uint32_t algorithm, uint32_t mode, uint32_t maxKeySize)

As you can see, first parameter is a pointer to TEE_OperationHandle. This is exactly what you receive in your prepare_rsa_operation() as a first parameter. But, you want to call TEE_AllocateOperation() with &handle. This will have a type TEE_OperationHandle ** and compiler must at least warn you there.

You are already passing pointer to TEE_OperationHandle in prepare_rsa_operation, you will see changes outside it. Pointers in C is not the same thing as references in C++ or Java. You can't create reference to reference in C++, but you can easily create a pointer to pointer to pointer in C. So I recommend you to compile your code with -Wall -Werror options, so compiler will stop you from using dubious constructions.

[cezane]

Yes. Sure, @lorc . You are right. Understood, now, what you said and my mistake, since I was already receiving a pointer in the function.

Thank you.