require 'zip/filesystem'

filename = 'test'
zipfile = 'test.zip'

Zip::File.open(zipfile, create: true) do |z|
  z.file.open(filename, "w") { |f| f.write "created by rubyzip" }
  z.file.chmod(0o755, filename)
end

Zip::File.open(zipfile) do |z|
  puts "perms: %o" % z.file.stat(filename).mode
end