How do you load a model from Assets on Android in C++?

[ChthonicOne]

I am attempting to incorporate onnx into our application, but I can't even get the session started. It's returning an ORT_ILLEGAL_ARGUMENT error. After some debugging it seems to be failing right after it checks the argument for the SessionOptions, and the only arguments left are those for the model file. I can't seem to figure out what argument is the problem here, so I will post the minimum code example of the issue so you can see. Maybe you can help.

public:
Model_Wrapper() : env() {}

Model_Wrapper::load(AAssetManager* mgr, const char* modeltype) {

   Ort::SessionOptions so; //Also tried <Ort::SessionOptions so{nullptr};> but this segfaults 2 lines later
   uint32_t nnapi_flags = 0;
   Ort::ThrowOnError(OrtSessionOptionsAppendExecutionProvider_Nnapi(so, nnapi_flags));

   AAsset* asset = AAssetManager_open(mgr, modeltype, 0);

   // session_ = Ort::Session{env, AAsset_getBuffer(asset), static_cast<size_t>(AAsset_getLength(asset)), so}; // This is where I get the ORT_ILLEGAL_ARGUMENT
   Ort::Session session_temp(env, AAsset_getBuffer(asset), static_cast<size_t>(AAsset_getLength(asset)), so); // Just tried this it still gives the error
   session_ = std::move(session_tmp);

   AAsset_close(asset);

   return 0;
}
private:
    Ort::Session session_{nullptr};
    Ort::Env env{ORT_LOGGING_LEVEL_WARNING, "test"};

I have also tried just giving the file name to Ort::Session as well, but switched to this method in case it was because it couldn't find the model file in question. I have based my wrapper design on #7790 but in this issue there was no mention of this Illegal Argument at all and I can see no reason why my code should produce one.

[ChthonicOne]

Also, I would like to point out that this model has been successfully been converted to NCNN and used in our application through the C++ interface for the last 9 months. This exact model file in fact has been successfully converted and used, so corrupted model file is not likely.

[ChthonicOne]

I did some more digging into the API, and now I believe that this is caused by the API returning a mismatched API for some reason. Could this be a project setup problem?

If it is, there really needs to be a better error message and more information about the problem to allow for easier debugging of this issue. Once I confirm this I'll be converting this into an issue.

[ChthonicOne]

Ok, this is really odd. I just traced back to where the OrtStatus is being created. If it is created with a nullptr it is considered a success. However, if it is created with anything else, it is considered a failure.

In this case it is being created with a NULL, which is not a nullptr, and thus I fail with an empty useless status. Something is wrong, and it is likely because I'm running native code in a Java environment.