def self.tmpdir
  if $SAFE > 0
    @@systmpdir.dup
  else
    tmp = nil
    # Search a directory which isn't world-writable first. In JRuby,
    # FileUtils.remove_entry_secure(dir) crashes when a dir is under
    # a world-writable directory because it tries to open directory.
    # Opening directory is not allowed in Java.
    dirs = [ENV['TMPDIR'], ENV['TMP'], ENV['TEMP'], @@systmpdir, '/tmp', '.']
    for dir in dirs
      if dir and stat = File.stat(dir) and stat.directory? and stat.writable? and !stat.world_writable?
        return File.expand_path(dir)
      end
    end

    # Some OS sets the environment variables to '/tmp', which we may reject.
    warn "Unable to find a non world-writable directory for #{__method__}. Consider setting ENV['TMPDIR'], ENV['TMP'] or ENV['TEMP'] to a non world-writable directory."

    [ENV['TMPDIR'], ENV['TMP'], ENV['TEMP'], @@systmpdir, '/tmp', '.'].each do |dir|
      next if !dir
      dir = File.expand_path(dir)
      if stat = File.stat(dir) and stat.directory? and stat.writable? and
          (!stat.world_writable? or stat.sticky?)
        tmp = dir
        break
      end rescue nil
    end
    raise ArgumentError, "could not find a temporary directory" unless tmp
    tmp
  end
end

def self.tmpdir
  if $SAFE > 0
    @@systmpdir.dup
  else
    tmp = nil
    [ENV['TMPDIR'], ENV['TMP'], ENV['TEMP'], @@systmpdir, '/tmp', '.'].each do |dir|
      next if !dir
      dir = File.expand_path(dir)
      if stat = File.stat(dir) and stat.directory? and stat.writable? and
          (!stat.world_writable? or stat.sticky?)
        tmp = dir
        break
      end rescue nil
    end
    raise ArgumentError, "could not find a temporary directory" unless tmp
    tmp
  end
end