Getting the ShadowHashData object in OS X 10.7 and 10.8

gistfile1.rb

require 'puppet'
require 'facter/util/plist'
require 'pp'
@@users_plist_dir    = '/var/db/dslocal/nodes/Default/users'
resource_name = 'glarizza'
users_plist = Plist::parse_xml(`plutil -convert xml1 -o /dev/stdout #{@@users_plist_dir}/#{resource_name}.plist`)
password_hash_plist = users_plist['ShadowHashData'][0].string
IO.popen('plutil -convert xml1 -o - -', mode='r+') do |io|
  io.write password_hash_plist
  io.close_write
  @converted_plist = io.read
end
@plist_hash = Plist::parse_xml(@converted_plist)

@plist_hash['SALTED-SHA512'].class # (StringIO in 10.7 or Nil in 10.8)