ItemUpdater: Validate PNOR squashfs image

- Validate the image dir by checking its content.
- Set Activation to "Ready" if validation passed or
  else set it to "Invalid".

Resolves openbmc/openbmc#1356

Change-Id: Ica73ae5604e74db11cd58c223d82265309ea76a6
Signed-off-by: Saqib Khan <khansa@us.ibm.com>
diff --git a/item_updater.hpp b/item_updater.hpp
index 5afb96d..8e79d1d 100755
--- a/item_updater.hpp
+++ b/item_updater.hpp
@@ -61,6 +61,14 @@
          */
         static std::string getExtendedVersion(const std::string&
                                                manifestFilePath);
+        /**
+         * @brief Validates the presence of SquashFS iamge in the image dir.
+         *
+         * @param[in]  versionId - The software version ID.
+         * @param[out] result    - 0 --> if validation was successful
+         *                       - -1--> Otherwise
+         */
+        static int validateSquashFSImage(const std::string& versionId);
 
         /** @brief Persistent sdbusplus DBus bus connection. */
         sdbusplus::bus::bus& busItem;