Is there a way to hook into the windows file system so that for a particular directory I controlled every bit with custom code?

Question

I'm interested to know if there's any method/mechanism to roll my own virtual file system that will run on modern windows. The idea would be that no matter what part of the operating system tried to access files under the directory I "control", all of the operations are filtered through some kind of callback code. If not, is there a fundamental reason why?

Answer 1

You absolutely can do this, it's called a "reparse point". See MSDN for the details.

Answer 2

Take a look at the TrueCrypt source code its open source and it does something very close to what you want: "# Creates a virtual encrypted disk within a file and mounts it as a real disk."