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

FindUnusedDriveLetter does nothing except on Windows.

IsReserved checks if path contains a reserved name.

MkdirAll just calls os.MkdirAll on non-Windows.

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.

ErrDiskFull is returned from PreAllocate when it detects disk full.

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