[mjevans]

Some (but probably not an exhaustive list) of pitfalls:

    * Filename: Either force random data or only allow a whitelist through.  Do not trust unknown character ranges.
    * File-existence: Never over-write files, resumed uploads should be handled VERY carefully (it's easier to just not).
    * File-extension: (I) do not care; security design should never trust this data anyway.
    * File-size: You don't have control of this on the host?
    * Disk space: It might be a good idea to reserve at least some of this, or set a maximum ingress pool size.