# symlink.rb
require 'ffi'

class Windows
  extend FFI::Library
  ffi_lib :kernel32

  attach_function :CreateSymbolicLinkA, [:string, :string, :ulong], :bool

  def self.symlink(old_name, new_name)
    # Flip the arguments to match File.symlink
    unless CreateSymbolicLinkA(new_name, old_name, 0) # Assume file
      raise SystemCallError.new('CreateSymbolicLink', FFI.errno)
    end
  end
end

# Please run with elevated privileges.

# Here assume 'bogus.txt' does not exist
Windows.symlink('bogus.txt', 'test_link.txt')
File.delete('test_link.txt') # Works with MRI, fails with JRuby.