Anybody got a good way to ATOMICALLY create a temporary directory in .net managed code?

Question

The .net framework has GetTempFileName, which goes straight to the Windows API procedure of the same name, and as far as I know is a threadsafe way to create a temporary file with a name not previously in use. It's hilariously outdated and limited, but as far as I know it works, as long as you keep your temp directory from filling up.

But I don't see anything that'll work even that well for creating temporary folders. In a contentious parallel environment such as a web server, I don't see any way to avoid race conditions between testing whether a folder name is in use, and creating it. This could I suppose be doable with unmanaged API code, but there may be institutional resistance to such a solution. Is there a better way?

And if there is, can it be extended back to temp file creation, so I don't have to use GetTempFileName with its four hex digits of variation?

-- To those who think this is a duplicate: the linked other question did not really address thread safety. And I have to develop for a situation where thread safety is a very serious concern -- we could have 32 cores running with every one of them attempting to create batches of a hundred or a thousand temp files apiece.

-- UPDATE: the book Secure Programming with Static Analysis by Chess and West says that GetTempFileName “suffers from an inherent underlying race condition”. So maybe that ain't safe either.

Answer 1

@paul-kienitz FWIW: according to the documentation of CreateDirectory(), the function returns ERROR_ALREADY_EXISTS if the directory already existed, which gives you an atomic check for collisions. So you can safely create a new temp directory if you combine the random name approach (using CoCreateGuid()) with a limited number of retries (e.g. 9 retries), after which you fail. The retries will exponentially lower the collision probability to a value which even satisfies paranoids.