"""Tornado handlers for the notebook.
Authors:
* Brian Granger
"""
#-----------------------------------------------------------------------------
# Copyright (C) 2008-2011 The IPython Development Team
#
# Distributed under the terms of the BSD License. The full license is in
# the file COPYING, distributed as part of this software.
#-----------------------------------------------------------------------------
#-----------------------------------------------------------------------------
# Imports
#-----------------------------------------------------------------------------
import Cookie
import datetime
import email.utils
import hashlib
import logging
import mimetypes
import os
import stat
import threading
import time
import uuid
from tornado.escape import url_escape
from tornado import web
from tornado import websocket
from zmq.eventloop import ioloop
from zmq.utils import jsonapi
from IPython.external.decorator import decorator
from IPython.kernel.zmq.session import Session
from IPython.lib.security import passwd_check
from IPython.utils.jsonutil import date_default
from IPython.utils.path import filefind
from IPython.utils.py3compat import PY3
try:
from docutils.core import publish_string
except ImportError:
publish_string = None
#-----------------------------------------------------------------------------
# Monkeypatch for Tornado <= 2.1.1 - Remove when no longer necessary!
#-----------------------------------------------------------------------------
# Google Chrome, as of release 16, changed its websocket protocol number. The
# parts tornado cares about haven't really changed, so it's OK to continue
# accepting Chrome connections, but as of Tornado 2.1.1 (the currently released
# version as of Oct 30/2011) the version check fails, see the issue report:
# https://github.com/facebook/tornado/issues/385
# This issue has been fixed in Tornado post 2.1.1:
# https://github.com/facebook/tornado/commit/84d7b458f956727c3b0d6710
# Here we manually apply the same patch as above so that users of IPython can
# continue to work with an officially released Tornado. We make the
# monkeypatch version check as narrow as possible to limit its effects; once
# Tornado 2.1.1 is no longer found in the wild we'll delete this code.
import tornado
if tornado.version_info <= (2,1,1):
def _execute(self, transforms, *args, **kwargs):
from tornado.websocket import WebSocketProtocol8, WebSocketProtocol76
self.open_args = args
self.open_kwargs = kwargs
# The difference between version 8 and 13 is that in 8 the
# client sends a "Sec-Websocket-Origin" header and in 13 it's
# simply "Origin".
if self.request.headers.get("Sec-WebSocket-Version") in ("7", "8", "13"):
self.ws_connection = WebSocketProtocol8(self)
self.ws_connection.accept_connection()
elif self.request.headers.get("Sec-WebSocket-Version"):
self.stream.write(tornado.escape.utf8(
"HTTP/1.1 426 Upgrade Required\r\n"
"Sec-WebSocket-Version: 8\r\n\r\n"))
self.stream.close()
else:
self.ws_connection = WebSocketProtocol76(self)
self.ws_connection.accept_connection()
websocket.WebSocketHandler._execute = _execute
del _execute
#-----------------------------------------------------------------------------
# Decorator for disabling read-only handlers
#-----------------------------------------------------------------------------
@decorator
def not_if_readonly(f, self, *args, **kwargs):
if self.application.read_only:
raise web.HTTPError(403, "Notebook server is read-only")
else:
return f(self, *args, **kwargs)
@decorator
def authenticate_unless_readonly(f, self, *args, **kwargs):
"""authenticate this page *unless* readonly view is active.
In read-only mode, the notebook list and print view should
be accessible without authentication.
"""
@web.authenticated
def auth_f(self, *args, **kwargs):
return f(self, *args, **kwargs)
if self.application.read_only:
return f(self, *args, **kwargs)
else:
return auth_f(self, *args, **kwargs)
def urljoin(*pieces):
"""Join componenet of url into a relative url
Use to prevent double slash when joining subpath
"""
striped = [s.strip('/') for s in pieces]
return '/'.join(s for s in striped if s)
#-----------------------------------------------------------------------------
# Top-level handlers
#-----------------------------------------------------------------------------
class RequestHandler(web.RequestHandler):
"""RequestHandler with default variable setting."""
def render(*args, **kwargs):
kwargs.setdefault('message', '')
return web.RequestHandler.render(*args, **kwargs)
class AuthenticatedHandler(RequestHandler):
"""A RequestHandler with an authenticated user."""
def get_current_user(self):
user_id = self.get_secure_cookie(self.settings['cookie_name'])
# For now the user_id should not return empty, but it could eventually
if user_id == '':
user_id = 'anonymous'
if user_id is None:
# prevent extra Invalid cookie sig warnings:
self.clear_cookie(self.settings['cookie_name'])
if not self.application.password and not self.application.read_only:
user_id = 'anonymous'
return user_id
@property
def logged_in(self):
"""Is a user currently logged in?
"""
user = self.get_current_user()
return (user and not user == 'anonymous')
@property
def login_available(self):
"""May a user proceed to log in?
This returns True if login capability is available, irrespective of
whether the user is already logged in or not.
"""
return bool(self.application.password)
@property
def read_only(self):
"""Is the notebook read-only?
"""
return self.application.read_only
@property
def use_less(self):
"""Use less instead of css in templates"""
return self.application.use_less
@property
def ws_url(self):
"""websocket url matching the current request
turns http[s]://host[:port] into
ws[s]://host[:port]
"""
proto = self.request.protocol.replace('http', 'ws')
host = self.application.ipython_app.websocket_host # default to config value
if host == '':
host = self.request.host # get from request
return "%s://%s" % (proto, host)
class AuthenticatedFileHandler(AuthenticatedHandler, web.StaticFileHandler):
"""static files should only be accessible when logged in"""
@authenticate_unless_readonly
def get(self, path):
return web.StaticFileHandler.get(self, path)
class ProjectDashboardHandler(AuthenticatedHandler):
@authenticate_unless_readonly
def get(self):
nbm = self.application.notebook_manager
project = nbm.notebook_dir
template = self.application.jinja2_env.get_template('projectdashboard.html')
self.write( template.render(
project=project,
project_component=project.split('/'),
base_project_url=self.application.ipython_app.base_project_url,
base_kernel_url=self.application.ipython_app.base_kernel_url,
read_only=self.read_only,
logged_in=self.logged_in,
use_less=self.use_less,
login_available=self.login_available))
class LoginHandler(AuthenticatedHandler):
def _render(self, message=None):
template = self.application.jinja2_env.get_template('login.html')
self.write( template.render(
next=url_escape(self.get_argument('next', default=self.application.ipython_app.base_project_url)),
read_only=self.read_only,
logged_in=self.logged_in,
login_available=self.login_available,
base_project_url=self.application.ipython_app.base_project_url,
message=message
))
def get(self):
if self.current_user:
self.redirect(self.get_argument('next', default=self.application.ipython_app.base_project_url))
else:
self._render()
def post(self):
pwd = self.get_argument('password', default=u'')
if self.application.password:
if passwd_check(self.application.password, pwd):
self.set_secure_cookie(self.settings['cookie_name'], str(uuid.uuid4()))
else:
self._render(message={'error': 'Invalid password'})
return
self.redirect(self.get_argument('next', default=self.application.ipython_app.base_project_url))
class LogoutHandler(AuthenticatedHandler):
def get(self):
self.clear_cookie(self.settings['cookie_name'])
if self.login_available:
message = {'info': 'Successfully logged out.'}
else:
message = {'warning': 'Cannot log out. Notebook authentication '
'is disabled.'}
template = self.application.jinja2_env.get_template('logout.html')
self.write( template.render(
read_only=self.read_only,
logged_in=self.logged_in,
login_available=self.login_available,
base_project_url=self.application.ipython_app.base_project_url,
message=message))
class NewHandler(AuthenticatedHandler):
@web.authenticated
def get(self):
nbm = self.application.notebook_manager
project = nbm.notebook_dir
notebook_id = nbm.new_notebook()
self.redirect('/'+urljoin(self.application.ipython_app.base_project_url, notebook_id))
class NamedNotebookHandler(AuthenticatedHandler):
@authenticate_unless_readonly
def get(self, notebook_id):
nbm = self.application.notebook_manager
project = nbm.notebook_dir
if not nbm.notebook_exists(notebook_id):
raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
template = self.application.jinja2_env.get_template('notebook.html')
self.write( template.render(
project=project,
notebook_id=notebook_id,
base_project_url=self.application.ipython_app.base_project_url,
base_kernel_url=self.application.ipython_app.base_kernel_url,
kill_kernel=False,
read_only=self.read_only,
logged_in=self.logged_in,
login_available=self.login_available,
mathjax_url=self.application.ipython_app.mathjax_url,
use_less=self.use_less
)
)
class PrintNotebookHandler(AuthenticatedHandler):
@authenticate_unless_readonly
def get(self, notebook_id):
nbm = self.application.notebook_manager
project = nbm.notebook_dir
if not nbm.notebook_exists(notebook_id):
raise web.HTTPError(404, u'Notebook does not exist: %s' % notebook_id)
template = self.application.jinja2_env.get_template('printnotebook.html')
self.write( template.render(
project=project,
notebook_id=notebook_id,
base_project_url=self.application.ipython_app.base_project_url,
base_kernel_url=self.application.ipython_app.base_kernel_url,
kill_kernel=False,
read_only=self.read_only,
logged_in=self.logged_in,
login_available=self.login_available,
mathjax_url=self.application.ipython_app.mathjax_url,
))
#-----------------------------------------------------------------------------
# Kernel handlers
#-----------------------------------------------------------------------------
class MainKernelHandler(AuthenticatedHandler):
@web.authenticated
def get(self):
km = self.application.kernel_manager
self.finish(jsonapi.dumps(km.list_kernel_ids()))
@web.authenticated
def post(self):
km = self.application.kernel_manager
nbm = self.application.notebook_manager
notebook_id = self.get_argument('notebook', default=None)
kernel_id = km.start_kernel(notebook_id, cwd=nbm.notebook_dir)
data = {'ws_url':self.ws_url,'kernel_id':kernel_id}
self.set_header('Location', '/'+kernel_id)
self.finish(jsonapi.dumps(data))
class KernelHandler(AuthenticatedHandler):
SUPPORTED_METHODS = ('DELETE')
@web.authenticated
def delete(self, kernel_id):
km = self.application.kernel_manager
km.shutdown_kernel(kernel_id)
self.set_status(204)
self.finish()
class KernelActionHandler(AuthenticatedHandler):
@web.authenticated
def post(self, kernel_id, action):
km = self.application.kernel_manager
if action == 'interrupt':
km.interrupt_kernel(kernel_id)
self.set_status(204)
if action == 'restart':
km.restart_kernel(kernel_id)
data = {'ws_url':self.ws_url, 'kernel_id':kernel_id}
self.set_header('Location', '/'+kernel_id)
self.write(jsonapi.dumps(data))
self.finish()
class ZMQStreamHandler(websocket.WebSocketHandler):
def _reserialize_reply(self, msg_list):
"""Reserialize a reply message using JSON.
This takes the msg list from the ZMQ socket, unserializes it using
self.session and then serializes the result using JSON. This method
should be used by self._on_zmq_reply to build messages that can
be sent back to the browser.
"""
idents, msg_list = self.session.feed_identities(msg_list)
msg = self.session.unserialize(msg_list)
try:
msg['header'].pop('date')
except KeyError:
pass
try:
msg['parent_header'].pop('date')
except KeyError:
pass
msg.pop('buffers')
return jsonapi.dumps(msg, default=date_default)
def _on_zmq_reply(self, msg_list):
try:
msg = self._reserialize_reply(msg_list)
except Exception:
self.application.log.critical("Malformed message: %r" % msg_list, exc_info=True)
else:
self.write_message(msg)
def allow_draft76(self):
"""Allow draft 76, until browsers such as Safari update to RFC 6455.
This has been disabled by default in tornado in release 2.2.0, and
support will be removed in later versions.
"""
return True
class AuthenticatedZMQStreamHandler(ZMQStreamHandler):
def open(self, kernel_id):
self.kernel_id = kernel_id.decode('ascii')
try:
cfg = self.application.config
except AttributeError:
# protect from the case where this is run from something other than
# the notebook app:
cfg = None
self.session = Session(config=cfg)
self.save_on_message = self.on_message
self.on_message = self.on_first_message
def get_current_user(self):
user_id = self.get_secure_cookie(self.settings['cookie_name'])
if user_id == '' or (user_id is None and not self.application.password):
user_id = 'anonymous'
return user_id
def _inject_cookie_message(self, msg):
"""Inject the first message, which is the document cookie,
for authentication."""
if not PY3 and isinstance(msg, unicode):
# Cookie constructor doesn't accept unicode strings
# under Python 2.x for some reason
msg = msg.encode('utf8', 'replace')
try:
self.request._cookies = Cookie.SimpleCookie(msg)
except:
logging.warn("couldn't parse cookie string: %s",msg, exc_info=True)
def on_first_message(self, msg):
self._inject_cookie_message(msg)
if self.get_current_user() is None:
logging.warn("Couldn't authenticate WebSocket connection")
raise web.HTTPError(403)
self.on_message = self.save_on_message
class IOPubHandler(AuthenticatedZMQStreamHandler):
def initialize(self, *args, **kwargs):
self._kernel_alive = True
self._beating = False
self.iopub_stream = None
self.hb_stream = None
def on_first_message(self, msg):
try:
super(IOPubHandler, self).on_first_message(msg)
except web.HTTPError:
self.close()
return
km = self.application.kernel_manager
self.time_to_dead = km.time_to_dead
self.first_beat = km.first_beat
kernel_id = self.kernel_id
try:
self.iopub_stream = km.create_iopub_stream(kernel_id)
self.hb_stream = km.create_hb_stream(kernel_id)
except web.HTTPError:
# WebSockets don't response to traditional error codes so we
# close the connection.
if not self.stream.closed():
self.stream.close()
self.close()
else:
self.iopub_stream.on_recv(self._on_zmq_reply)
self.start_hb(self.kernel_died)
def on_message(self, msg):
pass
def on_close(self):
# This method can be called twice, once by self.kernel_died and once
# from the WebSocket close event. If the WebSocket connection is
# closed before the ZMQ streams are setup, they could be None.
self.stop_hb()
if self.iopub_stream is not None and not self.iopub_stream.closed():
self.iopub_stream.on_recv(None)
self.iopub_stream.close()
if self.hb_stream is not None and not self.hb_stream.closed():
self.hb_stream.close()
def start_hb(self, callback):
"""Start the heartbeating and call the callback if the kernel dies."""
if not self._beating:
self._kernel_alive = True
def ping_or_dead():
self.hb_stream.flush()
if self._kernel_alive:
self._kernel_alive = False
self.hb_stream.send(b'ping')
# flush stream to force immediate socket send
self.hb_stream.flush()
else:
try:
callback()
except:
pass
finally:
self.stop_hb()
def beat_received(msg):
self._kernel_alive = True
self.hb_stream.on_recv(beat_received)
loop = ioloop.IOLoop.instance()
self._hb_periodic_callback = ioloop.PeriodicCallback(ping_or_dead, self.time_to_dead*1000, loop)
loop.add_timeout(time.time()+self.first_beat, self._really_start_hb)
self._beating= True
def _really_start_hb(self):
"""callback for delayed heartbeat start
Only start the hb loop if we haven't been closed during the wait.
"""
if self._beating and not self.hb_stream.closed():
self._hb_periodic_callback.start()
def stop_hb(self):
"""Stop the heartbeating and cancel all related callbacks."""
if self._beating:
self._beating = False
self._hb_periodic_callback.stop()
if not self.hb_stream.closed():
self.hb_stream.on_recv(None)
def _delete_kernel_data(self):
"""Remove the kernel data and notebook mapping."""
self.application.kernel_manager.delete_mapping_for_kernel(self.kernel_id)
def kernel_died(self):
self._delete_kernel_data()
self.application.log.error("Kernel died: %s" % self.kernel_id)
self.write_message(
{'header': {'msg_type': 'status'},
'parent_header': {},
'content': {'execution_state':'dead'}
}
)
self.on_close()
class ShellHandler(AuthenticatedZMQStreamHandler):
def initialize(self, *args, **kwargs):
self.shell_stream = None
def on_first_message(self, msg):
try:
super(ShellHandler, self).on_first_message(msg)
except web.HTTPError:
self.close()
return
km = self.application.kernel_manager
self.max_msg_size = km.max_msg_size
kernel_id = self.kernel_id
try:
self.shell_stream = km.create_shell_stream(kernel_id)
except web.HTTPError:
# WebSockets don't response to traditional error codes so we
# close the connection.
if not self.stream.closed():
self.stream.close()
self.close()
else:
self.shell_stream.on_recv(self._on_zmq_reply)
def on_message(self, msg):
if len(msg) < self.max_msg_size:
msg = jsonapi.loads(msg)
self.session.send(self.shell_stream, msg)
def on_close(self):
# Make sure the stream exists and is not already closed.
if self.shell_stream is not None and not self.shell_stream.closed():
self.shell_stream.close()
#-----------------------------------------------------------------------------
# Notebook web service handlers
#-----------------------------------------------------------------------------
class NotebookRootHandler(AuthenticatedHandler):
@authenticate_unless_readonly
def get(self):
nbm = self.application.notebook_manager
km = self.application.kernel_manager
files = nbm.list_notebooks()
for f in files :
f['kernel_id'] = km.kernel_for_notebook(f['notebook_id'])
self.finish(jsonapi.dumps(files))
@web.authenticated
def post(self):
nbm = self.application.notebook_manager
body = self.request.body.strip()
format = self.get_argument('format', default='json')
name = self.get_argument('name', default=None)
if body:
notebook_id = nbm.save_new_notebook(body, name=name, format=format)
else:
notebook_id = nbm.new_notebook()
self.set_header('Location', '/'+notebook_id)
self.finish(jsonapi.dumps(notebook_id))
class NotebookHandler(AuthenticatedHandler):
SUPPORTED_METHODS = ('GET', 'PUT', 'DELETE')
@authenticate_unless_readonly
def get(self, notebook_id):
nbm = self.application.notebook_manager
format = self.get_argument('format', default='json')
last_mod, name, data = nbm.get_notebook(notebook_id, format)
if format == u'json':
self.set_header('Content-Type', 'application/json')
self.set_header('Content-Disposition','attachment; filename="%s.ipynb"' % name)
elif format == u'py':
self.set_header('Content-Type', 'application/x-python')
self.set_header('Content-Disposition','attachment; filename="%s.py"' % name)
self.set_header('Last-Modified', last_mod)
self.finish(data)
@web.authenticated
def put(self, notebook_id):
nbm = self.application.notebook_manager
format = self.get_argument('format', default='json')
name = self.get_argument('name', default=None)
nbm.save_notebook(notebook_id, self.request.body, name=name, format=format)
self.set_status(204)
self.finish()
@web.authenticated
def delete(self, notebook_id):
nbm = self.application.notebook_manager
nbm.delete_notebook(notebook_id)
self.set_status(204)
self.finish()
class NotebookCopyHandler(AuthenticatedHandler):
@web.authenticated
def get(self, notebook_id):
nbm = self.application.notebook_manager
project = nbm.notebook_dir
notebook_id = nbm.copy_notebook(notebook_id)
self.redirect('/'+urljoin(self.application.ipython_app.base_project_url, notebook_id))
#-----------------------------------------------------------------------------
# Cluster handlers
#-----------------------------------------------------------------------------
class MainClusterHandler(AuthenticatedHandler):
@web.authenticated
def get(self):
cm = self.application.cluster_manager
self.finish(jsonapi.dumps(cm.list_profiles()))
class ClusterProfileHandler(AuthenticatedHandler):
@web.authenticated
def get(self, profile):
cm = self.application.cluster_manager
self.finish(jsonapi.dumps(cm.profile_info(profile)))
class ClusterActionHandler(AuthenticatedHandler):
@web.authenticated
def post(self, profile, action):
cm = self.application.cluster_manager
if action == 'start':
n = self.get_argument('n',default=None)
if n is None:
data = cm.start_cluster(profile)
else:
data = cm.start_cluster(profile,int(n))
if action == 'stop':
data = cm.stop_cluster(profile)
self.finish(jsonapi.dumps(data))
#-----------------------------------------------------------------------------
# RST web service handlers
#-----------------------------------------------------------------------------
class RSTHandler(AuthenticatedHandler):
@web.authenticated
def post(self):
if publish_string is None:
raise web.HTTPError(503, u'docutils not available')
body = self.request.body.strip()
source = body
# template_path=os.path.join(os.path.dirname(__file__), u'templates', u'rst_template.html')
defaults = {'file_insertion_enabled': 0,
'raw_enabled': 0,
'_disable_config': 1,
'stylesheet_path': 0
# 'template': template_path
}
try:
html = publish_string(source, writer_name='html',
settings_overrides=defaults
)
except:
raise web.HTTPError(400, u'Invalid RST')
print html
self.set_header('Content-Type', 'text/html')
self.finish(html)
# to minimize subclass changes:
HTTPError = web.HTTPError
class FileFindHandler(web.StaticFileHandler):
"""subclass of StaticFileHandler for serving files from a search path"""
_static_paths = {}
# _lock is needed for tornado < 2.2.0 compat
_lock = threading.Lock() # protects _static_hashes
def initialize(self, path, default_filename=None):
if isinstance(path, basestring):
path = [path]
self.roots = tuple(
os.path.abspath(os.path.expanduser(p)) + os.path.sep for p in path
)
self.default_filename = default_filename
@classmethod
def locate_file(cls, path, roots):
"""locate a file to serve on our static file search path"""
with cls._lock:
if path in cls._static_paths:
return cls._static_paths[path]
try:
abspath = os.path.abspath(filefind(path, roots))
except IOError:
# empty string should always give exists=False
return ''
# os.path.abspath strips a trailing /
# it needs to be temporarily added back for requests to root/
if not (abspath + os.path.sep).startswith(roots):
raise HTTPError(403, "%s is not in root static directory", path)
cls._static_paths[path] = abspath
return abspath
def get(self, path, include_body=True):
path = self.parse_url_path(path)
# begin subclass override
abspath = self.locate_file(path, self.roots)
# end subclass override
if os.path.isdir(abspath) and self.default_filename is not None:
# need to look at the request.path here for when path is empty
# but there is some prefix to the path that was already
# trimmed by the routing
if not self.request.path.endswith("/"):
self.redirect(self.request.path + "/")
return
abspath = os.path.join(abspath, self.default_filename)
if not os.path.exists(abspath):
raise HTTPError(404)
if not os.path.isfile(abspath):
raise HTTPError(403, "%s is not a file", path)
stat_result = os.stat(abspath)
modified = datetime.datetime.fromtimestamp(stat_result[stat.ST_MTIME])
self.set_header("Last-Modified", modified)
mime_type, encoding = mimetypes.guess_type(abspath)
if mime_type:
self.set_header("Content-Type", mime_type)
cache_time = self.get_cache_time(path, modified, mime_type)
if cache_time > 0:
self.set_header("Expires", datetime.datetime.utcnow() + \
datetime.timedelta(seconds=cache_time))
self.set_header("Cache-Control", "max-age=" + str(cache_time))
else:
self.set_header("Cache-Control", "public")
self.set_extra_headers(path)
# Check the If-Modified-Since, and don't send the result if the
# content has not been modified
ims_value = self.request.headers.get("If-Modified-Since")
if ims_value is not None:
date_tuple = email.utils.parsedate(ims_value)
if_since = datetime.datetime.fromtimestamp(time.mktime(date_tuple))
if if_since >= modified:
self.set_status(304)
return
with open(abspath, "rb") as file:
data = file.read()
hasher = hashlib.sha1()
hasher.update(data)
self.set_header("Etag", '"%s"' % hasher.hexdigest())
if include_body:
self.write(data)
else:
assert self.request.method == "HEAD"
self.set_header("Content-Length", len(data))
@classmethod
def get_version(cls, settings, path):
"""Generate the version string to be used in static URLs.
This method may be overridden in subclasses (but note that it
is a class method rather than a static method). The default
implementation uses a hash of the file's contents.
``settings`` is the `Application.settings` dictionary and ``path``
is the relative location of the requested asset on the filesystem.
The returned value should be a string, or ``None`` if no version
could be determined.
"""
# begin subclass override:
static_paths = settings['static_path']
if isinstance(static_paths, basestring):
static_paths = [static_paths]
roots = tuple(
os.path.abspath(os.path.expanduser(p)) + os.path.sep for p in static_paths
)
try:
abs_path = filefind(path, roots)
except IOError:
logging.error("Could not find static file %r", path)
return None
# end subclass override
with cls._lock:
hashes = cls._static_hashes
if abs_path not in hashes:
try:
f = open(abs_path, "rb")
hashes[abs_path] = hashlib.md5(f.read()).hexdigest()
f.close()
except Exception:
logging.error("Could not open static file %r", path)
hashes[abs_path] = None
hsh = hashes.get(abs_path)
if hsh:
return hsh[:5]
return None
def parse_url_path(self, url_path):
"""Converts a static URL path into a filesystem path.
``url_path`` is the path component of the URL with
``static_url_prefix`` removed. The return value should be
filesystem path relative to ``static_path``.
"""
if os.path.sep != "/":
url_path = url_path.replace("/", os.path.sep)
return url_path