Share input within multiple terminals

share-input.rb

#!/usr/bin/ruby
# share-input.rb: share input within multiple terminals
# Author: NeoCat
require 'socket'
require 'pty'
require "thread"
require "curses"

def server(sock, sock_name)
  puts "relay server started."
  $sock_name = sock_name
  $clients = []
  
  def stop_client(client)
    client.close
    $mutex.synchronize {
      $clients.delete client
      #p $clients
      quit if $clients.empty?
    }
  end
  
  def quit
    puts "relay server stopped."
    File.unlink $sock_name
    exit
  end
  
  Signal.trap(:CHLD, 'IGNORE')
  Signal.trap(:HUP)  { quit }
  Signal.trap(:INT)  { quit }
  Signal.trap(:TERM) { quit }

  $mutex = Mutex.new
  while new_client = sock.accept
    $mutex.synchronize { $clients << new_client }
    #p $clients
    Thread.new(new_client) do |client|
      begin
        while data = client.readpartial(4096)
          $clients.each do |c|
            begin
              c.write data
            rescue
              #puts "error on write: #$!"
              stop_client c
            end
          end
        end
      rescue
        #puts "error on read: #$!"
        stop_client client
      end
    end
  end
end


def make_connection(sock_id)
  sock_name = "/tmp/sock.pty-relay."+sock_id.to_s
  
  # launch a server unless it already exists
  sock = nil
  begin
    sock = UNIXServer.open(sock_name)
  rescue
  end
  if sock
    fork { server(sock, sock_name) }
  end
  
  # client mode
  return UNIXSocket.open(sock_name)
end

def relay_pty(sock, cmd)
  $child_pid = nil
  
  def quit
    Curses::noraw
    exit
  end
  
  Signal.trap(:CHLD, 'IGNORE')
  Signal.trap(:HUP)  { quit }
  Signal.trap(:INT)  { quit }
  Signal.trap(:TERM) { quit }
  
  Curses::init_screen
  Curses::raw
  p = PTY.spawn "export PTY_RELAY=#$$; stty rows #{Curses::lines} columns #{Curses::cols}; " + (cmd || "exec $SHELL")
  $child_pid = p[2]
  $p = p
  
  single_mode = false
  
  until p[0].closed? || STDIN.closed? || sock.closed?
    s = IO.select [p[0], STDIN, sock]
    if s0 = s[0][0]
      out = nil
      
      if single_mode
        out = s0 === sock ? p[1] : s0 === STDIN ? p[1] : STDOUT
      else
        out = s0 === sock ? p[1] : s0 === STDIN ? sock : STDOUT
      end
      
      begin
        if s0 === STDIN
          data = s0.readpartial(1)
          if !single_mode and data == "\C-]"
            single_mode = true
          elsif single_mode and data == "\r"
            single_mode = false
            out.write data
          else
            out.write data
          end
        else
          out.write s0.readpartial(4096)
          out.flush
        end
      rescue
        #puts "error on relay: #$!"
        p[0].close
        p[1].close
      end
    end
  end
  
  quit
end


if ARGV[0] == '-h'
  puts <<-EOD
#$0: share input within multiple terminals
  
usage: #$0 [server-id] [command]
  
  - Execute #$0 in multiple terminal to share the input.
  - The login shell or the specified command is started.
  - If you hit ^], the input is not shared until you hit Enter key
    and only applied to current terminal.
  EOD
  exit
end

if ENV['PTY_RELAY']
  STDERR.puts "Cannot launch #$0 inside another #$0 !"
  exit 1
end

sock_id = 0
if ARGV[0] =~ /^\d+$/
  sock_id = ARGV[0].to_i
  ARGV.shift
end
if sock = make_connection(sock_id)
  relay_pty(sock, ARGV[0] && ARGV * " ")
end