Hi,
Thanks so much for your patience while we looked into this issue.
As you rightfully said, you should use [out, count=len] instead of [out, size=len], but that does not solve the problem.
Short answer:
Remove the line p_return_ptr = (int*)malloc(len*sizeof(int)); in your Enclave.cpp and you program works as expected.
More details:
The function sgx_returns_int_ptr generated for you in the file Enclave/Enclave_t.c already does the memory allocation (inside enclave memory) in the line _in_p_return_ptr = (int*)malloc(_len_p_return_ptr);.
It then passes the pointer _in_p_return_ptr to your function returns_int_ptr with returns_int_ptr(_in_p_return_ptr, _tmp_len);.
As a result, the pointer p_return_ptr in your function does point to the space allocated before.
Note, however, that _in_p_return_ptr and p_return_ptr are two independent pointers (i.e., both pointers are stored at different memory locations) that point to the same memory location allocated before.
At this point, you currently perform another allocation and change the pointer p_return_ptr to this new location.
As _in_p_return_ptr and p_return_ptr are independent pointers, the former does still point to the memory location allocated by sgx_returns_int_ptr, and p_return_ptr does point to the newly allocated memory.
Then, you do changes to the newly allocated memory.
After your function returns, sgx_returns_int_ptr does copy data from the memory location allocated before (and pointed to by sgx_returns_int_ptr) to space allocated outside of the enclave with memcpy_s(_tmp_p_return_ptr, _len_p_return_ptr, _in_p_return_ptr, _len_p_return_ptr).
As you never did anything with this memory location, your result is not as expected.
Side note: you currently have a memory leak in your code, because p_return_ptr is never freed.
Please let us know if you have any further questions.
Sincerely,
Sahira
