Application Isolation and access control

I want to prevent an app from knowing whether certain files or directories exist on a device. For instance, if the application have some code like: if (/system/lib/libJohnDoe.so){ print("yes") } else{ print("no") } I want this to always evaluate to "no" even if the file does exist. I was thinking of completely changing the directory tree that the application sees but I do not know if this is even possible. What I would like even more is to only allow applications to see specific directories and files rather than hiding existing ones from them.