[IMPROVEMENT] Cmd Size and exotic filesystem

[anykeyh]

The command SIZE is calling read method of the file driver. Which is bad in the case your driver is not a file system.

For example, I ftpd with google bucket and it works perfectly except for this command.

For informations, we monkey-patched the method internally for our tool, like that:

( PS: I'm not gonna open a pull request as it's not just debugging feature, and better idea of implementation would exists )

# frozen_string_literal: true

require_relative 'command_handler'

module Ftpd

  class CmdSize < CommandHandler

    def cmd_size(path)
      ensure_logged_in
      ensure_file_system_supports :read
      syntax_error unless path
      path = File.expand_path(path, name_prefix)
      ensure_accessible(path)
      ensure_exists(path)
      if file_system.respond_to?(:size)
        size = file_system.size(path, data_type).to_i
        reply "213 #{size}"
      else
        file_system.read(path) do |file|
          if data_type == 'A'
            output = StringIO.new
            io = Ftpd::Stream.new(output, data_type)
            io.write(file)
            size = output.size
          else
            size = file.size
          end
          reply "213 #{size}"
        end

      end

    end

  end

end