firmware: start implementing open

Start implementing the open command for the firmware handler.

Change-Id: I8426e397b182bfe76625918a4148b1b6d1003f43
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/firmware_handler.hpp b/firmware_handler.hpp
index 9d57b63..18b04fc 100644
--- a/firmware_handler.hpp
+++ b/firmware_handler.hpp
@@ -72,8 +72,14 @@
     static const std::string activeHashBlobID;
 
   private:
+    /** Active list of blobIDs. */
     std::vector<std::string> blobIDs;
+
+    /** The bits set indicate what transport mechanisms are supported. */
     std::uint16_t transports;
+
+    /** Temporary variable to track whether a blob is open. */
+    bool fileOpen = false;
 };
 
 } // namespace blobs