Android File read from assets

androidfilereader

	class FileReaderAndroidImpl : public bx::FileReaderI
	{
	public:
		FileReaderAndroidImpl(AAssetManager *assetManager, AAsset* _file)
			: m_assetManager(assetManager)
			, m_file(_file)
			, m_open(false)
		{
		}

		virtual ~FileReaderAndroidImpl()
		{
			close();
		}

		virtual bool open(const bx::FilePath& _filePath, bx::Error* _err) override
		{
			BX_CHECK(NULL != _err, "Reader/Writer interface calling functions must handle errors.");

			if (NULL != m_file)
			{
				BX_ERROR_SET(_err, BX_ERROR_READERWRITER_ALREADY_OPEN, "FileReader: File is already open.");
				return false;
			}

			m_file = AAssetManager_open(m_assetManager, _filePath.get(), AASSET_MODE_RANDOM);
			if (NULL == m_file)
			{
				BX_ERROR_SET(_err, BX_ERROR_READERWRITER_OPEN, "FileReader: Failed to open file.");
				return false;
			}

			m_open = true;
			return true;
		}

		virtual void close() override
		{
			if (m_open
			&&  NULL != m_file)
			{
				AAsset_close(m_file);
				m_file = NULL;
			}
		}

		virtual int64_t seek(int64_t _offset, bx::Whence::Enum _whence) override
		{
			BX_CHECK(NULL != m_file, "Reader/Writer file is not open.");
			return AAsset_seek64(m_file, _offset, _whence);
			
		}

		virtual int32_t read(void* _data, int32_t _size, bx::Error* _err) override
		{
			BX_CHECK(NULL != m_file, "Reader/Writer file is not open.");
			BX_CHECK(NULL != _err, "Reader/Writer interface calling functions must handle errors.");

			int32_t size = (int32_t)AAsset_read(m_file, _data, _size);
			if (size != _size)
			{
				if (0 == AAsset_getRemainingLength(m_file) )
				{
					BX_ERROR_SET(_err, BX_ERROR_READERWRITER_EOF, "FileReader: EOF.");
				}

				return size >= 0 ? size : 0;
			}

			return size;
		}

	private:
		AAssetManager	*m_assetManager;
		AAsset* m_file;
		bool  m_open;
	};