# File lib/rubygems/format.rb, line 57
    def self.from_io(io, gem_path="(io)", security_policy = nil)
      format = self.new(gem_path)
      Package.open_from_io(io, 'r', security_policy) do |pkg|
        format.spec = pkg.metadata
        format.file_entries = []
        pkg.each do |entry|
          format.file_entries << [{"size", entry.size, "mode", entry.mode,
              "path", entry.full_name}, entry.read]
        end
      end
      format
    end