Sheller

class CommandError < RuntimeError
end
 
class BaseCmd
  attr_accessor :uid, :done, :status
end
 
class Sheller
  attr_accessor :continious
 
  def initialize(bin = "bash")
    @sleep_time = 0.001
    @input_pipe = IO.pipe
    @output_pipe = IO.pipe
    @error_pipe = IO.pipe
    @invalid = false
 
    fork do
      @input_pipe[1].close
      @output_pipe[0].close
      @error_pipe[0].close
 
      $stdin.reopen(@input_pipe[0])
      $stdout.reopen(@output_pipe[1])
      $stderr.reopen(@error_pipe[1])
 
      exec(bin)
    end
 
    @input_pipe[0].close
    @output_pipe[1].close
    @error_pipe[1].close
  end
 
  def low_write(data)
    printf "#{data}" if $DEBUG
    @input_pipe[1].write(data)
  end
 
  def write(data)
    low_write(data)
    low_write("echo -e \"\027:$?\" > /dev/stderr\n")
  end
 
  def poll
    clean = true
 
    if svrs = IO.select([@output_pipe[0]], nil, nil, 0)
      svrs[0].each { |io|
        clean = false
        line = io.readline.chomp
        got_stdout(line)
      }
    end
 
    if svrs = IO.select([@error_pipe[0]], nil, nil, 0)
      svrs[0].each { |io|
        clean = false
        line = io.readline
 
        if line[0] == 23
          md = line.match(/^.:(\d+)$/)
          if md
            @pending_cmd.status = md[1].to_i
            raise CommandError if @pending_cmd.status != 0 && @continious
          end
        else
          got_stderr(line)
        end
      }
    end
 
    if @pending_cmd.status and clean
      @pending_cmd.done = true
    end
  end
 
  def read_loop
    while !@pending_cmd.done
      poll
      sleep(@sleep_time)
    end
  end
 
  def do(string)
    @pending_cmd = BaseCmd.new
    begin
      write("%s\n" % string)
      read_loop
    rescue EOFError,Errno::EPIPE => error
      Process.wait
      # $?.exitstatus
      @invalid = true
      return nil
    end
    return @pending_cmd
  end
 
  def info(string)
    puts "# %s" % [string]
  end
 
  def got_stdout(line)
  end
 
  def got_stderr(line)
  end
 
end