Create creates the named file with mode 0666 (before umask), truncating it if it already exists.

Open opens the named file for reading.

PreAllocate the file for performance reasons.

SetSparse makes the file be a sparse file.

UNCPath converts an absolute Windows path to a UNC long path.

PreallocateImplemented is a constant indicating whether the implementation of Preallocate actually does anything.

SetSparseImplemented is a constant indicating whether the implementation of SetSparse actually does anything.

OpenFile is the generalized open call; most users will use Open or Create instead.