text: # coding: utf-8
  """A tornado based Jupyter notebook server."""
  
  # Copyright (c) Jupyter Development Team.
  # Distributed under the terms of the Modified BSD License.
  
  from __future__ import absolute_import, print_function
  
  import base64
  import datetime
  import errno
  import importlib
  import io
  import json
  import logging
  import os
  import random
  import re
  import select
  import signal
  import socket
  import ssl
  import sys
  import threading
  import webbrowser
  
  
  from jinja2 import Environment, FileSystemLoader
  
  # Install the pyzmq ioloop. This has to be done before anything else from
  # tornado is imported.
  from zmq.eventloop import ioloop
  ioloop.install()
  
  # check for tornado 3.1.0
  msg = "The Jupyter Notebook requires tornado >= 4.0"
  try:
      import tornado
  except ImportError:
      raise ImportError(msg)
  try:
      version_info = tornado.version_info
  except AttributeError:
      raise ImportError(msg + ", but you have < 1.1.0")
  if version_info < (4,0):
      raise ImportError(msg + ", but you have %s" % tornado.version)
  
  from tornado import httpserver
  from tornado import web
  from tornado.log import LogFormatter, app_log, access_log, gen_log
  
  from notebook import (
      DEFAULT_STATIC_FILES_PATH,
      DEFAULT_TEMPLATE_PATH_LIST,
      __version__,
  )
  from .base.handlers import Template404
  from .log import log_request
  from .services.kernels.kernelmanager import MappingKernelManager
  from .services.config import ConfigManager
  from .services.contents.manager import ContentsManager
  from .services.contents.filemanager import FileContentsManager
  from .services.sessions.sessionmanager import SessionManager
  
  from .auth.login import LoginHandler
  from .auth.logout import LogoutHandler
  from .base.handlers import FileFindHandler, IPythonHandler
  
  from traitlets.config import Config
  from traitlets.config.application import catch_config_error, boolean_flag
  from jupyter_core.application import (
      JupyterApp, base_flags, base_aliases,
  )
  from jupyter_client import KernelManager
  from jupyter_client.kernelspec import KernelSpecManager, NoSuchKernel, NATIVE_KERNEL_NAME
  from jupyter_client.session import Session
  from nbformat.sign import NotebookNotary
  from traitlets import (
      Dict, Unicode, Integer, List, Bool, Bytes, Instance,
      TraitError, Type,
  )
  from ipython_genutils import py3compat
  from jupyter_core.paths import jupyter_runtime_dir, jupyter_path
  from notebook._sysinfo import get_sys_info
  
  from .utils import url_path_join, check_pid, url_escape
  
  #-----------------------------------------------------------------------------
  # Module globals
  #-----------------------------------------------------------------------------
  
  _examples = """
  jupyter notebook                       # start the notebook
  jupyter notebook --certfile=mycert.pem # use SSL/TLS certificate
  """
  
  #-----------------------------------------------------------------------------
  # Helper functions
  #-----------------------------------------------------------------------------
  
  def random_ports(port, n):
      """Generate a list of n random ports near the given port.
  
      The first 5 ports will be sequential, and the remaining n-5 will be
      randomly selected in the range [port-2*n, port+2*n].
      """
      for i in range(min(5, n)):
          yield port + i
      for i in range(n-5):
          yield max(1, port + random.randint(-2*n, 2*n))
  
  def load_handlers(name):
      """Load the (URL pattern, handler) tuples for each component."""
      name = 'notebook.' + name
      mod = __import__(name, fromlist=['default_handlers'])
      return mod.default_handlers
  
  
  class DeprecationHandler(IPythonHandler):
      def get(self, url_path):
          self.set_header("Content-Type", 'text/javascript')
          self.finish("""
              console.warn('`/static/widgets/js` is deprecated.  Use `nbextensions/widgets/widgets/js` instead.');
              define(['%s'], function(x) { return x; });
          """ % url_path_join('nbextensions', 'widgets', 'widgets', url_path.rstrip('.js')))
          self.log.warn('Deprecated widget Javascript path /static/widgets/js/*.js was used')
  
  #-----------------------------------------------------------------------------
  # The Tornado web application
  #-----------------------------------------------------------------------------
  
  class NotebookWebApplication(web.Application):
  
      def __init__(self, ipython_app, kernel_manager, contents_manager,
                   session_manager, kernel_spec_manager,
                   config_manager, log,
                   base_url, default_url, settings_overrides, jinja_env_options):
  
          settings = self.init_settings(
              ipython_app, kernel_manager, contents_manager,
              session_manager, kernel_spec_manager, config_manager, log, base_url,
              default_url, settings_overrides, jinja_env_options)
          handlers = self.init_handlers(settings)
  
          super(NotebookWebApplication, self).__init__(handlers, **settings)
  
      def init_settings(self, ipython_app, kernel_manager, contents_manager,
                        session_manager, kernel_spec_manager,
                        config_manager,
                        log, base_url, default_url, settings_overrides,
                        jinja_env_options=None):
  
          _template_path = settings_overrides.get(
              "template_path",
              ipython_app.template_file_path,
          )
          if isinstance(_template_path, py3compat.string_types):
              _template_path = (_template_path,)
          template_path = [os.path.expanduser(path) for path in _template_path]
  
          jenv_opt = {"autoescape": True}
          jenv_opt.update(jinja_env_options if jinja_env_options else {})
  
          env = Environment(loader=FileSystemLoader(template_path), **jenv_opt)
          
          sys_info = get_sys_info()
          if sys_info['commit_source'] == 'repository':
              # don't cache (rely on 304) when working from master
              version_hash = ''
          else:
              # reset the cache on server restart
              version_hash = datetime.datetime.now().strftime("%Y%m%d%H%M%S")
  
          settings = dict(
              # basics
              log_function=log_request,
              base_url=base_url,
              default_url=default_url,
              template_path=template_path,
              static_path=ipython_app.static_file_path,
              static_custom_path=ipython_app.static_custom_path,
              static_handler_class = FileFindHandler,
              static_url_prefix = url_path_join(base_url,'/static/'),
              static_handler_args = {
                  # don't cache custom.js
                  'no_cache_paths': [url_path_join(base_url, 'static', 'custom')],
              },
              version_hash=version_hash,
              ignore_minified_js=ipython_app.ignore_minified_js,
              
              # authentication
              cookie_secret=ipython_app.cookie_secret,
              login_url=url_path_join(base_url,'/login'),
              login_handler_class=ipython_app.login_handler_class,
              logout_handler_class=ipython_app.logout_handler_class,
              password=ipython_app.password,
  
              # managers
              kernel_manager=kernel_manager,
              contents_manager=contents_manager,
              session_manager=session_manager,
              kernel_spec_manager=kernel_spec_manager,
              config_manager=config_manager,
  
              # IPython stuff
              jinja_template_vars=ipython_app.jinja_template_vars,
              nbextensions_path=ipython_app.nbextensions_path,
              websocket_url=ipython_app.websocket_url,
              mathjax_url=ipython_app.mathjax_url,
              config=ipython_app.config,
              config_dir=ipython_app.config_dir,
              jinja2_env=env,
              terminals_available=False,  # Set later if terminals are available
          )
  
          # allow custom overrides for the tornado web app.
          settings.update(settings_overrides)
          return settings
  
      def init_handlers(self, settings):
          """Load the (URL pattern, handler) tuples for each component."""
          
          # Order matters. The first handler to match the URL will handle the request.
          handlers = []
          handlers.append((r'/deprecatedwidgets/(.*)', DeprecationHandler))
          handlers.extend(load_handlers('tree.handlers'))
          handlers.extend([(r"/login", settings['login_handler_class'])])
          handlers.extend([(r"/logout", settings['logout_handler_class'])])
          handlers.extend(load_handlers('files.handlers'))
          handlers.extend(load_handlers('notebook.handlers'))
          handlers.extend(load_handlers('nbconvert.handlers'))
          handlers.extend(load_handlers('kernelspecs.handlers'))
          handlers.extend(load_handlers('edit.handlers'))
          handlers.extend(load_handlers('services.api.handlers'))
          handlers.extend(load_handlers('services.config.handlers'))
          handlers.extend(load_handlers('services.kernels.handlers'))
          handlers.extend(load_handlers('services.contents.handlers'))
          handlers.extend(load_handlers('services.sessions.handlers'))
          handlers.extend(load_handlers('services.nbconvert.handlers'))
          handlers.extend(load_handlers('services.kernelspecs.handlers'))
          handlers.extend(load_handlers('services.security.handlers'))
          
          # BEGIN HARDCODED WIDGETS HACK
          try:
              import ipywidgets
              handlers.append(
                  (r"/nbextensions/widgets/(.*)", FileFindHandler, {
                      'path': ipywidgets.find_static_assets(),
                      'no_cache_paths': ['/'], # don't cache anything in nbextensions
                  }),
              )
          except:
              app_log.warn('ipywidgets package not installed.  Widgets are unavailable.')
          # END HARDCODED WIDGETS HACK
          
          handlers.append(
              (r"/nbextensions/(.*)", FileFindHandler, {
                  'path': settings['nbextensions_path'],
                  'no_cache_paths': ['/'], # don't cache anything in nbextensions
              }),
          )
          handlers.append(
              (r"/custom/(.*)", FileFindHandler, {
                  'path': settings['static_custom_path'],
                  'no_cache_paths': ['/'], # don't cache anything in custom
              })
          )
          # register base handlers last
          handlers.extend(load_handlers('base.handlers'))
          # set the URL that will be redirected from `/`
          handlers.append(
              (r'/?', web.RedirectHandler, {
                  'url' : settings['default_url'],
                  'permanent': False, # want 302, not 301
              })
          )
  
          # prepend base_url onto the patterns that we match
          new_handlers = []
          for handler in handlers:
              pattern = url_path_join(settings['base_url'], handler[0])
              new_handler = tuple([pattern] + list(handler[1:]))
              new_handlers.append(new_handler)
          # add 404 on the end, which will catch everything that falls through
          new_handlers.append((r'(.*)', Template404))
          return new_handlers
  
  
  class NbserverListApp(JupyterApp):
      version = __version__
      description="List currently running notebook servers."
      
      flags = dict(
          json=({'NbserverListApp': {'json': True}},
                "Produce machine-readable JSON output."),
      )
      
      json = Bool(False, config=True,
            help="If True, each line of output will be a JSON object with the "
                    "details from the server info file.")
  
      def start(self):
          if not self.json:
              print("Currently running servers:")
          for serverinfo in list_running_servers(self.runtime_dir):
              if self.json:
                  print(json.dumps(serverinfo))
              else:
                  print(serverinfo['url'], "::", serverinfo['notebook_dir'])
  
  #-----------------------------------------------------------------------------
  # Aliases and Flags
  #-----------------------------------------------------------------------------
  
  flags = dict(base_flags)
  flags['no-browser']=(
      {'NotebookApp' : {'open_browser' : False}},
      "Don't open the notebook in a browser after startup."
  )
  flags['pylab']=(
      {'NotebookApp' : {'pylab' : 'warn'}},
      "DISABLED: use %pylab or %matplotlib in the notebook to enable matplotlib."
  )
  flags['no-mathjax']=(
      {'NotebookApp' : {'enable_mathjax' : False}},
      """Disable MathJax
      
      MathJax is the javascript library Jupyter uses to render math/LaTeX. It is
      very large, so you may want to disable it if you have a slow internet
      connection, or for offline use of the notebook.
      
      When disabled, equations etc. will appear as their untransformed TeX source.
      """
  )
  
  # Add notebook manager flags
  flags.update(boolean_flag('script', 'FileContentsManager.save_script',
                 'DEPRECATED, IGNORED',
                 'DEPRECATED, IGNORED'))
  
  aliases = dict(base_aliases)
  
  aliases.update({
      'ip': 'NotebookApp.ip',
      'port': 'NotebookApp.port',
      'port-retries': 'NotebookApp.port_retries',
      'transport': 'KernelManager.transport',
      'keyfile': 'NotebookApp.keyfile',
      'certfile': 'NotebookApp.certfile',
      'client-ca': 'NotebookApp.client_ca',
      'notebook-dir': 'NotebookApp.notebook_dir',
      'browser': 'NotebookApp.browser',
      'pylab': 'NotebookApp.pylab',
  })
  
  #-----------------------------------------------------------------------------
  # NotebookApp
  #-----------------------------------------------------------------------------
  
  class NotebookApp(JupyterApp):
  
      name = 'jupyter-notebook'
      version = __version__
      description = """
          The Jupyter HTML Notebook.
          
          This launches a Tornado based HTML Notebook Server that serves up an
          HTML5/Javascript Notebook client.
      """
      examples = _examples
      aliases = aliases
      flags = flags
      
      classes = [
          KernelManager, Session, MappingKernelManager,
          ContentsManager, FileContentsManager, NotebookNotary,
          KernelSpecManager,
      ]
      flags = Dict(flags)
      aliases = Dict(aliases)
      
      subcommands = dict(
          list=(NbserverListApp, NbserverListApp.description.splitlines()[0]),
      )
  
      _log_formatter_cls = LogFormatter
  
      def _log_level_default(self):
          return logging.INFO
  
      def _log_datefmt_default(self):
          """Exclude date from default date format"""
          return "%H:%M:%S"
      
      def _log_format_default(self):
          """override default log format to include time"""
          return u"%(color)s[%(levelname)1.1s %(asctime)s.%(msecs).03d %(name)s]%(end_color)s %(message)s"
  
      ignore_minified_js = Bool(False,
              config=True,
              help='Use minified JS file or not, mainly use during dev to avoid JS recompilation', 
              )
  
      # file to be opened in the notebook server
      file_to_run = Unicode('', config=True)
  
      # Network related information
      
      allow_origin = Unicode('', config=True,
          help="""Set the Access-Control-Allow-Origin header
          
          Use '*' to allow any origin to access your server.
          
          Takes precedence over allow_origin_pat.
          """
      )
      
      allow_origin_pat = Unicode('', config=True,
          help="""Use a regular expression for the Access-Control-Allow-Origin header
          
          Requests from an origin matching the expression will get replies with:
          
              Access-Control-Allow-Origin: origin
          
          where `origin` is the origin of the request.
          
          Ignored if allow_origin is set.
          """
      )
      
      allow_credentials = Bool(False, config=True,
          help="Set the Access-Control-Allow-Credentials: true header"
      )
      
      default_url = Unicode('/tree', config=True,
          help="The default URL to redirect to from `/`"
      )
      
      ip = Unicode('localhost', config=True,
          help="The IP address the notebook server will listen on."
      )
      def _ip_default(self):
          """Return localhost if available, 127.0.0.1 otherwise.
          
          On some (horribly broken) systems, localhost cannot be bound.
          """
          s = socket.socket()
          try:
              s.bind(('localhost', 0))
          except socket.error as e:
              self.log.warn("Cannot bind to localhost, using 127.0.0.1 as default ip\n%s", e)
              return '127.0.0.1'
          else:
              s.close()
              return 'localhost'
  
      def _ip_changed(self, name, old, new):
          if new == u'*': self.ip = u''
  
      port = Integer(8888, config=True,
          help="The port the notebook server will listen on."
      )
      port_retries = Integer(50, config=True,
          help="The number of additional ports to try if the specified port is not available."
      )
  
      certfile = Unicode(u'', config=True, 
          help="""The full path to an SSL/TLS certificate file."""
      )
      
      keyfile = Unicode(u'', config=True, 
          help="""The full path to a private key file for usage with SSL/TLS."""
      )
      
      client_ca = Unicode(u'', config=True,
          help="""The full path to a certificate authority certifificate for SSL/TLS client authentication."""
      )
      
      cookie_secret_file = Unicode(config=True,
          help="""The file where the cookie secret is stored."""
      )
      def _cookie_secret_file_default(self):
          return os.path.join(self.runtime_dir, 'notebook_cookie_secret')
      
      cookie_secret = Bytes(b'', config=True,
          help="""The random bytes used to secure cookies.
          By default this is a new random number every time you start the Notebook.
          Set it to a value in a config file to enable logins to persist across server sessions.
          
          Note: Cookie secrets should be kept private, do not share config files with
          cookie_secret stored in plaintext (you can read the value from a file).
          """
      )
      def _cookie_secret_default(self):
          if os.path.exists(self.cookie_secret_file):
              with io.open(self.cookie_secret_file, 'rb') as f:
                  return f.read()
          else:
              secret = base64.encodestring(os.urandom(1024))
              self._write_cookie_secret_file(secret)
              return secret
      
      def _write_cookie_secret_file(self, secret):
          """write my secret to my secret_file"""
          self.log.info("Writing notebook server cookie secret to %s", self.cookie_secret_file)
          with io.open(self.cookie_secret_file, 'wb') as f:
              f.write(secret)
          try:
              os.chmod(self.cookie_secret_file, 0o600)
          except OSError:
              self.log.warn(
                  "Could not set permissions on %s",
                  self.cookie_secret_file
              )
  
      password = Unicode(u'', config=True,
                        help="""Hashed password to use for web authentication.
  
                        To generate, type in a python/IPython shell:
  
                          from notebook.auth import passwd; passwd()
  
                        The string should be of the form type:salt:hashed-password.
                        """
      )
  
      open_browser = Bool(True, config=True,
                          help="""Whether to open in a browser after starting.
                          The specific browser used is platform dependent and
                          determined by the python standard library `webbrowser`
                          module, unless it is overridden using the --browser
                          (NotebookApp.browser) configuration option.
                          """)
  
      browser = Unicode(u'', config=True,
                        help="""Specify what command to use to invoke a web
                        browser when opening the notebook. If not specified, the
                        default browser will be determined by the `webbrowser`
                        standard library module, which allows setting of the
                        BROWSER environment variable to override it.
                        """)
      
      webapp_settings = Dict(config=True,
          help="DEPRECATED, use tornado_settings"
      )
      def _webapp_settings_changed(self, name, old, new):
          self.log.warn("\n    webapp_settings is deprecated, use tornado_settings.\n")
          self.tornado_settings = new
      
      tornado_settings = Dict(config=True,
              help="Supply overrides for the tornado.web.Application that the "
                   "Jupyter notebook uses.")
      
      ssl_options = Dict(config=True,
              help="""Supply SSL options for the tornado HTTPServer.
              See the tornado docs for details.""")
      
      jinja_environment_options = Dict(config=True, 
              help="Supply extra arguments that will be passed to Jinja environment.")
  
      jinja_template_vars = Dict(
          config=True,
          help="Extra variables to supply to jinja templates when rendering.",
      )
      
      enable_mathjax = Bool(True, config=True,
          help="""Whether to enable MathJax for typesetting math/TeX
  
          MathJax is the javascript library Jupyter uses to render math/LaTeX. It is
          very large, so you may want to disable it if you have a slow internet
          connection, or for offline use of the notebook.
  
          When disabled, equations etc. will appear as their untransformed TeX source.
          """
      )
      def _enable_mathjax_changed(self, name, old, new):
          """set mathjax url to empty if mathjax is disabled"""
          if not new:
              self.mathjax_url = u''
  
      base_url = Unicode('/', config=True,
                                 help='''The base URL for the notebook server.
  
                                 Leading and trailing slashes can be omitted,
                                 and will automatically be added.
                                 ''')
      def _base_url_changed(self, name, old, new):
          if not new.startswith('/'):
              self.base_url = '/'+new
          elif not new.endswith('/'):
              self.base_url = new+'/'
      
      base_project_url = Unicode('/', config=True, help="""DEPRECATED use base_url""")
      def _base_project_url_changed(self, name, old, new):
          self.log.warn("base_project_url is deprecated, use base_url")
          self.base_url = new
  
      extra_static_paths = List(Unicode(), config=True,
          help="""Extra paths to search for serving static files.
          
          This allows adding javascript/css to be available from the notebook server machine,
          or overriding individual files in the IPython"""
      )
      
      @property
      def static_file_path(self):
          """return extra paths + the default location"""
          return self.extra_static_paths + [DEFAULT_STATIC_FILES_PATH]
      
      static_custom_path = List(Unicode(),
          help="""Path to search for custom.js, css"""
      )
      def _static_custom_path_default(self):
          return [
              os.path.join(d, 'custom') for d in (
                  self.config_dir,
                  DEFAULT_STATIC_FILES_PATH)
          ]
  
      extra_template_paths = List(Unicode(), config=True,
          help="""Extra paths to search for serving jinja templates.
  
          Can be used to override templates from notebook.templates."""
      )
  
      @property
      def template_file_path(self):
          """return extra paths + the default locations"""
          return self.extra_template_paths + DEFAULT_TEMPLATE_PATH_LIST
  
      extra_nbextensions_path = List(Unicode(), config=True,
          help="""extra paths to look for Javascript notebook extensions"""
      )
      
      @property
      def nbextensions_path(self):
          """The path to look for Javascript notebook extensions"""
          path = self.extra_nbextensions_path + jupyter_path('nbextensions')
          # FIXME: remove IPython nbextensions path after a migration period
          try:
              from IPython.paths import get_ipython_dir
          except ImportError:
              pass
          else:
              path.append(os.path.join(get_ipython_dir(), 'nbextensions'))
          return path
  
      websocket_url = Unicode("", config=True,
          help="""The base URL for websockets,
          if it differs from the HTTP server (hint: it almost certainly doesn't).
          
          Should be in the form of an HTTP origin: ws[s]://hostname[:port]
          """
      )
      mathjax_url = Unicode("", config=True,
          help="""The url for MathJax.js."""
      )
      def _mathjax_url_default(self):
          if not self.enable_mathjax:
              return u''
          static_url_prefix = self.tornado_settings.get("static_url_prefix", "static")
          return url_path_join(static_url_prefix, 'components', 'MathJax', 'MathJax.js')
      
      def _mathjax_url_changed(self, name, old, new):
          if new and not self.enable_mathjax:
              # enable_mathjax=False overrides mathjax_url
              self.mathjax_url = u''
          else:
              self.log.info("Using MathJax: %s", new)
  
      contents_manager_class = Type(
          default_value=FileContentsManager,
          klass=ContentsManager,
          config=True,
          help='The notebook manager class to use.'
      )
      kernel_manager_class = Type(
          default_value=MappingKernelManager,
          config=True,
          help='The kernel manager class to use.'
      )
      session_manager_class = Type(
          default_value=SessionManager,
          config=True,
          help='The session manager class to use.'
      )
  
      config_manager_class = Type(
          default_value=ConfigManager,
          config = True,
          help='The config manager class to use'
      )
  
      kernel_spec_manager = Instance(KernelSpecManager, allow_none=True)
  
      kernel_spec_manager_class = Type(
          default_value=KernelSpecManager,
          config=True,
          help="""
          The kernel spec manager class to use. Should be a subclass
          of `jupyter_client.kernelspec.KernelSpecManager`.
  
          The Api of KernelSpecManager is provisional and might change
          without warning between this version of Jupyter and the next stable one.
          """
      )
  
      login_handler_class = Type(
          default_value=LoginHandler,
          klass=web.RequestHandler,
          config=True,
          help='The login handler class to use.',
      )
  
      logout_handler_class = Type(
          default_value=LogoutHandler,
          klass=web.RequestHandler,
          config=True,
          help='The logout handler class to use.',
      )
  
      trust_xheaders = Bool(False, config=True,
          help=("Whether to trust or not X-Scheme/X-Forwarded-Proto and X-Real-Ip/X-Forwarded-For headers"
                "sent by the upstream reverse proxy. Necessary if the proxy handles SSL")
      )
  
      info_file = Unicode()
  
      def _info_file_default(self):
          info_file = "nbserver-%s.json" % os.getpid()
          return os.path.join(self.runtime_dir, info_file)
      
      pylab = Unicode('disabled', config=True,
          help="""
          DISABLED: use %pylab or %matplotlib in the notebook to enable matplotlib.
          """
      )
      def _pylab_changed(self, name, old, new):
          """when --pylab is specified, display a warning and exit"""
          if new != 'warn':
              backend = ' %s' % new
          else:
              backend = ''
          self.log.error("Support for specifying --pylab on the command line has been removed.")
          self.log.error(
              "Please use `%pylab{0}` or `%matplotlib{0}` in the notebook itself.".format(backend)
          )
          self.exit(1)
  
      notebook_dir = Unicode(config=True,
          help="The directory to use for notebooks and kernels."
      )
  
      def _notebook_dir_default(self):
          if self.file_to_run:
              return os.path.dirname(os.path.abspath(self.file_to_run))
          else:
              return py3compat.getcwd()
  
      def _notebook_dir_validate(self, value, trait):
          # Strip any trailing slashes
          value = value.rstrip(os.sep)
  
          if not os.path.isabs(value):
              # If we receive a non-absolute path, make it absolute.
              value = os.path.abspath(value)
          if not os.path.isdir(value):
              raise TraitError("No such notebook dir: %r" % value)
          return value
  
      def _notebook_dir_changed(self, name, old, new):
          """Do a bit of validation of the notebook dir."""
          # setting App.notebook_dir implies setting notebook and kernel dirs as well
          self.config.FileContentsManager.root_dir = new
          self.config.MappingKernelManager.root_dir = new
  
      server_extensions = List(Unicode(), config=True,
          help=("Python modules to load as notebook server extensions. "
                "This is an experimental API, and may change in future releases.")
      )
  
      reraise_server_extension_failures = Bool(
          False,
          config=True,
          help="Reraise exceptions encountered loading server extensions?",
      )
  
      def parse_command_line(self, argv=None):
          super(NotebookApp, self).parse_command_line(argv)
          
          if self.extra_args:
              arg0 = self.extra_args[0]
              f = os.path.abspath(arg0)
              self.argv.remove(arg0)
              if not os.path.exists(f):
                  self.log.critical("No such file or directory: %s", f)
                  self.exit(1)
              
              # Use config here, to ensure that it takes higher priority than
              # anything that comes from the config dirs.
              c = Config()
              if os.path.isdir(f):
                  c.NotebookApp.notebook_dir = f
              elif os.path.isfile(f):
                  c.NotebookApp.file_to_run = f
              self.update_config(c)
  
      def init_configurables(self):
          self.kernel_spec_manager = self.kernel_spec_manager_class(
              parent=self,
          )
          self.kernel_manager = self.kernel_manager_class(
              parent=self,
              log=self.log,
              connection_dir=self.runtime_dir,
              kernel_spec_manager=self.kernel_spec_manager,
          )
          self.contents_manager = self.contents_manager_class(
              parent=self,
              log=self.log,
          )
          self.session_manager = self.session_manager_class(
              parent=self,
              log=self.log,
              kernel_manager=self.kernel_manager,
              contents_manager=self.contents_manager,
          )
          self.config_manager = self.config_manager_class(
              parent=self,
              log=self.log,
              config_dir=os.path.join(self.config_dir, 'nbconfig'),
          )
  
      def init_logging(self):
          # This prevents double log messages because tornado use a root logger that
          # self.log is a child of. The logging module dipatches log messages to a log
          # and all of its ancenstors until propagate is set to False.
          self.log.propagate = False
          
          for log in app_log, access_log, gen_log:
              # consistent log output name (NotebookApp instead of tornado.access, etc.)
              log.name = self.log.name
          # hook up tornado 3's loggers to our app handlers
          logger = logging.getLogger('tornado')
          logger.propagate = True
          logger.parent = self.log
          logger.setLevel(self.log.level)
      
      def init_webapp(self):
          """initialize tornado webapp and httpserver"""
          self.tornado_settings['allow_origin'] = self.allow_origin
          if self.allow_origin_pat:
              self.tornado_settings['allow_origin_pat'] = re.compile(self.allow_origin_pat)
          self.tornado_settings['allow_credentials'] = self.allow_credentials
          # ensure default_url starts with base_url
          if not self.default_url.startswith(self.base_url):
              self.default_url = url_path_join(self.base_url, self.default_url)
          
          self.web_app = NotebookWebApplication(
              self, self.kernel_manager, self.contents_manager,
              self.session_manager, self.kernel_spec_manager,
              self.config_manager,
              self.log, self.base_url, self.default_url, self.tornado_settings,
              self.jinja_environment_options
          )
          ssl_options = self.ssl_options
          if self.certfile:
              ssl_options['certfile'] = self.certfile
          if self.keyfile:
              ssl_options['keyfile'] = self.keyfile
          if self.client_ca:
              ssl_options['ca_certs'] = self.client_ca
              ssl_options['cert_reqs'] = ssl.CERT_REQUIRED
          if not ssl_options:
              # None indicates no SSL config
              ssl_options = None
          else:
              # Disable SSLv3, since its use is discouraged.
              ssl_options['ssl_version']=ssl.PROTOCOL_TLSv1
          self.login_handler_class.validate_security(self, ssl_options=ssl_options)
          self.http_server = httpserver.HTTPServer(self.web_app, ssl_options=ssl_options,
                                                   xheaders=self.trust_xheaders)
  
          success = None
          for port in random_ports(self.port, self.port_retries+1):
              try:
                  self.http_server.listen(port, self.ip)
              except socket.error as e:
                  if e.errno == errno.EADDRINUSE:
                      self.log.info('The port %i is already in use, trying another random port.' % port)
                      continue
                  elif e.errno in (errno.EACCES, getattr(errno, 'WSAEACCES', errno.EACCES)):
                      self.log.warn("Permission to listen on port %i denied" % port)
                      continue
                  else:
                      raise
              else:
                  self.port = port
                  success = True
                  break
          if not success:
              self.log.critical('ERROR: the notebook server could not be started because '
                                'no available port could be found.')
              self.exit(1)
      
      @property
      def display_url(self):
          ip = self.ip if self.ip else '[all ip addresses on your system]'
          return self._url(ip)
  
      @property
      def connection_url(self):
          ip = self.ip if self.ip else 'localhost'
          return self._url(ip)
  
      def _url(self, ip):
          proto = 'https' if self.certfile else 'http'
          return "%s://%s:%i%s" % (proto, ip, self.port, self.base_url)
  
      def init_terminals(self):
          try:
              from .terminal import initialize
              initialize(self.web_app, self.notebook_dir, self.connection_url)
              self.web_app.settings['terminals_available'] = True
          except ImportError as e:
              log = self.log.debug if sys.platform == 'win32' else self.log.warn
              log("Terminals not available (error was %s)", e)
  
      def init_signal(self):
          if not sys.platform.startswith('win') and sys.stdin.isatty():
              signal.signal(signal.SIGINT, self._handle_sigint)
          signal.signal(signal.SIGTERM, self._signal_stop)
          if hasattr(signal, 'SIGUSR1'):
              # Windows doesn't support SIGUSR1
              signal.signal(signal.SIGUSR1, self._signal_info)
          if hasattr(signal, 'SIGINFO'):
              # only on BSD-based systems
              signal.signal(signal.SIGINFO, self._signal_info)
      
      def _handle_sigint(self, sig, frame):
          """SIGINT handler spawns confirmation dialog"""
          # register more forceful signal handler for ^C^C case
          signal.signal(signal.SIGINT, self._signal_stop)
          # request confirmation dialog in bg thread, to avoid
          # blocking the App
          thread = threading.Thread(target=self._confirm_exit)
          thread.daemon = True
          thread.start()
      
      def _restore_sigint_handler(self):
          """callback for restoring original SIGINT handler"""
          signal.signal(signal.SIGINT, self._handle_sigint)
      
      def _confirm_exit(self):
          """confirm shutdown on ^C
          
          A second ^C, or answering 'y' within 5s will cause shutdown,
          otherwise original SIGINT handler will be restored.
          
          This doesn't work on Windows.
          """
          info = self.log.info
          info('interrupted')
          print(self.notebook_info())
          sys.stdout.write("Shutdown this notebook server (y/[n])? ")
          sys.stdout.flush()
          r,w,x = select.select([sys.stdin], [], [], 5)
          if r:
              line = sys.stdin.readline()
              if line.lower().startswith('y') and 'n' not in line.lower():
                  self.log.critical("Shutdown confirmed")
                  ioloop.IOLoop.current().stop()
                  return
          else:
              print("No answer for 5s:", end=' ')
          print("resuming operation...")
          # no answer, or answer is no:
          # set it back to original SIGINT handler
          # use IOLoop.add_callback because signal.signal must be called
          # from main thread
          ioloop.IOLoop.current().add_callback(self._restore_sigint_handler)
      
      def _signal_stop(self, sig, frame):
          self.log.critical("received signal %s, stopping", sig)
          ioloop.IOLoop.current().stop()
  
      def _signal_info(self, sig, frame):
          print(self.notebook_info())
      
      def init_components(self):
          """Check the components submodule, and warn if it's unclean"""
          # TODO: this should still check, but now we use bower, not git submodule
          pass
  
      def init_server_extensions(self):
          """Load any extensions specified by config.
  
          Import the module, then call the load_jupyter_server_extension function,
          if one exists.
          
          The extension API is experimental, and may change in future releases.
          """
          for modulename in self.server_extensions:
              try:
                  mod = importlib.import_module(modulename)
                  func = getattr(mod, 'load_jupyter_server_extension', None)
                  if func is not None:
                      func(self)
              except Exception:
                  if self.reraise_server_extension_failures:
                      raise
                  self.log.warn("Error loading server extension %s", modulename,
                                exc_info=True)
      
      @catch_config_error
      def initialize(self, argv=None):
          super(NotebookApp, self).initialize(argv)
          self.init_logging()
          if self._dispatching:
              return
          self.init_configurables()
          self.init_components()
          self.init_webapp()
          self.init_terminals()
          self.init_signal()
          self.init_server_extensions()
  
      def cleanup_kernels(self):
          """Shutdown all kernels.
          
          The kernels will shutdown themselves when this process no longer exists,
          but explicit shutdown allows the KernelManagers to cleanup the connection files.
          """
          self.log.info('Shutting down kernels')
          self.kernel_manager.shutdown_all()
  
      def notebook_info(self):
          "Return the current working directory and the server url information"
          info = self.contents_manager.info_string() + "\n"
          info += "%d active kernels \n" % len(self.kernel_manager._kernels)
          return info + "The Jupyter Notebook is running at: %s" % self.display_url
  
      def server_info(self):
          """Return a JSONable dict of information about this server."""
          return {'url': self.connection_url,
                  'hostname': self.ip if self.ip else 'localhost',
                  'port': self.port,
                  'secure': bool(self.certfile),
                  'base_url': self.base_url,
                  'notebook_dir': os.path.abspath(self.notebook_dir),
                  'pid': os.getpid()
                 }
  
      def write_server_info_file(self):
          """Write the result of server_info() to the JSON file info_file."""
          with open(self.info_file, 'w') as f:
              json.dump(self.server_info(), f, indent=2)
  
      def remove_server_info_file(self):
          """Remove the nbserver-<pid>.json file created for this server.
          
          Ignores the error raised when the file has already been removed.
          """
          try:
              os.unlink(self.info_file)
          except OSError as e:
              if e.errno != errno.ENOENT:
                  raise
  
      def start(self):
          """ Start the Notebook server app, after initialization
          
          This method takes no arguments so all configuration and initialization
          must be done prior to calling this method."""
          super(NotebookApp, self).start()
  
          info = self.log.info
          for line in self.notebook_info().split("\n"):
              info(line)
          info("Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).")
  
          self.write_server_info_file()
  
          if self.open_browser or self.file_to_run:
              try:
                  browser = webbrowser.get(self.browser or None)
              except webbrowser.Error as e:
                  self.log.warn('No web browser found: %s.' % e)
                  browser = None
              
              if self.file_to_run:
                  if not os.path.exists(self.file_to_run):
                      self.log.critical("%s does not exist" % self.file_to_run)
                      self.exit(1)
  
                  relpath = os.path.relpath(self.file_to_run, self.notebook_dir)
                  uri = url_escape(url_path_join('notebooks', *relpath.split(os.sep)))
              else:
                  uri = 'tree'
              if browser:
                  b = lambda : browser.open(url_path_join(self.connection_url, uri),
                                            new=2)
                  threading.Thread(target=b).start()
          
          self.io_loop = ioloop.IOLoop.current()
          if sys.platform.startswith('win'):
              # add no-op to wake every 5s
              # to handle signals that may be ignored by the inner loop
              pc = ioloop.PeriodicCallback(lambda : None, 5000)
              pc.start()
          try:
              self.io_loop.start()
          except KeyboardInterrupt:
              info("Interrupted...")
          finally:
              self.cleanup_kernels()
              self.remove_server_info_file()
      
      def stop(self):
          def _stop():
              self.http_server.stop()
              self.io_loop.stop()
          self.io_loop.add_callback(_stop)
  
  
  def list_running_servers(runtime_dir=None):
      """Iterate over the server info files of running notebook servers.
      
      Given a runtime directory, find nbserver-* files in the security directory,
      and yield dicts of their information, each one pertaining to
      a currently running notebook server instance.
      """
      if runtime_dir is None:
          runtime_dir = jupyter_runtime_dir()
  
      # The runtime dir might not exist
      if not os.path.isdir(runtime_dir):
          return
  
      for file in os.listdir(runtime_dir):
          if file.startswith('nbserver-'):
              with io.open(os.path.join(runtime_dir, file), encoding='utf-8') as f:
                  info = json.load(f)
  
              # Simple check whether that process is really still running
              # Also remove leftover files from IPython 2.x without a pid field
              if ('pid' in info) and check_pid(info['pid']):
                  yield info
              else:
                  # If the process has died, try to delete its info file
                  try:
                      os.unlink(file)
                  except OSError:
                      pass  # TODO: This should warn or log or something
  #-----------------------------------------------------------------------------
  # Main entry point
  #-----------------------------------------------------------------------------
  
  main = launch_new_instance = NotebookApp.launch_instance
  
  