uwp-native-stream.cpp

void GLTF_Parser::ParseFile(StorageFile^ storageFile)
{
	// try to get an IStorageItemHandleAccess interface from the StorageFile 
	ComPtr<IUnknown> unknown(reinterpret_cast<IUnknown*>(storageFile));
	ComPtr<IStorageItemHandleAccess> fileAccessor;
	ThrowIfFailed(unknown.As(&fileAccessor));

	// Use the IStorageItemHandleAccess::Create method to retrieve an OS HANDLE
	shared_ptr<void> fileHandle;
	HANDLE file = nullptr;
	ThrowIfFailed(fileAccessor->Create(HANDLE_ACCESS_OPTIONS::HAO_READ,
		HANDLE_SHARING_OPTIONS::HSO_SHARE_NONE,
		HANDLE_OPTIONS::HO_RANDOM_ACCESS,
		nullptr,
		&file));

	// Use RAII-style to ensure that CloseHandle is called when appropriate
	bool closed = false;
	fileHandle.reset(file, [&closed](HANDLE f) { if (!closed) { CloseHandle(f); closed = true; }});

	// Associates a C run-time file descriptor with an existing operating-system file handle.
	// https://msdn.microsoft.com/en-us/library/bdts1c9x.aspx
	int fd = _open_osfhandle((intptr_t)file, _O_RDONLY);
	if (fd == -1)
	{
		throw std::exception("Unable to open file descriptor!");
	}

	// Use RAII-style to ensure that _close is called when appropriate
	unique_ptr<int, function<int(int*)>> osHandle(&fd,
		[&closed](int *fd)
	{
		int ret = -1;
		if (!closed)
		{
			ret = _close(*fd);
			closed = true;
		}
		return ret;
	});

	// Open the file descriptor to get a FILE pointer
	unique_ptr<FILE, function<int(FILE *)>> fileDescriptor(_fdopen(fd, "r"),
		[&closed](FILE *fp)
	{
		int ret = -1;
		if (!closed)
		{
			ret = fclose(fp);
			closed = true;
		}
		return ret;
	});

	// wrap our istream in a shared pointer for sharing with the glTF library..
	auto str = make_shared<ifstream>(fileDescriptor.get());