I know that the invalid value returned by CreateFile is INVALID_HANDLE_VALUE. But since I also like to use RAII it's very tempting to just stick the HANDLE in a shared_ptr (like this:
shared_ptr<void> handle (CreateFile(args),&CloseHandle))
to make sure that the handle is closed.
My only concern with this quick and easy way to do RAII is if CreateFile can return NULL as the HANDLE value.
NULL is not a valid handle value. You can discern this from the fact that some Windows API functions return NULL to indicate a failure. Since there is a single function to dispose of handles, CloseHandle, it follows that NULL is not a valid HANDLE value. Hence CreateFile cannot ever return NULL.
Raymond Chen wrote a blog article touching on this topic: Why are HANDLE return values so inconsistent?.
Now, I know nothing about shared_ptr<> so would like to make no comment on whether or not your idea is appropriate. I am merely answering the direct question that you asked.