
  -spec allocate(File, Offset, Length) -> ok | {error, posix()}
                    when
                        File :: io_device(),
                        Offset :: non_neg_integer(),
                        Length :: non_neg_integer().

Since:
  OTP R16B

  allocate/3 can be used to preallocate space for a file.

  This function only succeeds in platforms that provide this
  feature.
