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Diffstat (limited to 'websdk/flask/helpers.py')
| -rw-r--r-- | websdk/flask/helpers.py | 649 |
1 files changed, 649 insertions, 0 deletions
diff --git a/websdk/flask/helpers.py b/websdk/flask/helpers.py new file mode 100644 index 0000000..72c8f17 --- /dev/null +++ b/websdk/flask/helpers.py @@ -0,0 +1,649 @@ +# -*- coding: utf-8 -*- +""" + flask.helpers + ~~~~~~~~~~~~~ + + Implements various helpers. + + :copyright: (c) 2011 by Armin Ronacher. + :license: BSD, see LICENSE for more details. +""" + +from __future__ import with_statement + +import os +import sys +import posixpath +import mimetypes +from time import time +from zlib import adler32 +from threading import RLock + +# try to load the best simplejson implementation available. If JSON +# is not installed, we add a failing class. +json_available = True +json = None +try: + import simplejson as json +except ImportError: + try: + import json + except ImportError: + try: + # Google Appengine offers simplejson via django + from django.utils import simplejson as json + except ImportError: + json_available = False + + +from werkzeug.datastructures import Headers +from werkzeug.exceptions import NotFound + +# this was moved in 0.7 +try: + from werkzeug.wsgi import wrap_file +except ImportError: + from werkzeug.utils import wrap_file + +from jinja2 import FileSystemLoader + +from .globals import session, _request_ctx_stack, current_app, request + + +def _assert_have_json(): + """Helper function that fails if JSON is unavailable.""" + if not json_available: + raise RuntimeError('simplejson not installed') + +# figure out if simplejson escapes slashes. This behaviour was changed +# from one version to another without reason. +if not json_available or '\\/' not in json.dumps('/'): + + def _tojson_filter(*args, **kwargs): + if __debug__: + _assert_have_json() + return json.dumps(*args, **kwargs).replace('/', '\\/') +else: + _tojson_filter = json.dumps + + +# sentinel +_missing = object() + + +# what separators does this operating system provide that are not a slash? +# this is used by the send_from_directory function to ensure that nobody is +# able to access files from outside the filesystem. +_os_alt_seps = list(sep for sep in [os.path.sep, os.path.altsep] + if sep not in (None, '/')) + + +def _endpoint_from_view_func(view_func): + """Internal helper that returns the default endpoint for a given + function. This always is the function name. + """ + assert view_func is not None, 'expected view func if endpoint ' \ + 'is not provided.' + return view_func.__name__ + + +def jsonify(*args, **kwargs): + """Creates a :class:`~flask.Response` with the JSON representation of + the given arguments with an `application/json` mimetype. The arguments + to this function are the same as to the :class:`dict` constructor. + + Example usage:: + + @app.route('/_get_current_user') + def get_current_user(): + return jsonify(username=g.user.username, + email=g.user.email, + id=g.user.id) + + This will send a JSON response like this to the browser:: + + { + "username": "admin", + "email": "admin@localhost", + "id": 42 + } + + This requires Python 2.6 or an installed version of simplejson. For + security reasons only objects are supported toplevel. For more + information about this, have a look at :ref:`json-security`. + + .. versionadded:: 0.2 + """ + if __debug__: + _assert_have_json() + return current_app.response_class(json.dumps(dict(*args, **kwargs), + indent=None if request.is_xhr else 2), mimetype='application/json') + + +def make_response(*args): + """Sometimes it is necessary to set additional headers in a view. Because + views do not have to return response objects but can return a value that + is converted into a response object by Flask itself, it becomes tricky to + add headers to it. This function can be called instead of using a return + and you will get a response object which you can use to attach headers. + + If view looked like this and you want to add a new header:: + + def index(): + return render_template('index.html', foo=42) + + You can now do something like this:: + + def index(): + response = make_response(render_template('index.html', foo=42)) + response.headers['X-Parachutes'] = 'parachutes are cool' + return response + + This function accepts the very same arguments you can return from a + view function. This for example creates a response with a 404 error + code:: + + response = make_response(render_template('not_found.html'), 404) + + The other use case of this function is to force the return value of a + view function into a response which is helpful with view + decorators:: + + response = make_response(view_function()) + response.headers['X-Parachutes'] = 'parachutes are cool' + + Internally this function does the following things: + + - if no arguments are passed, it creates a new response argument + - if one argument is passed, :meth:`flask.Flask.make_response` + is invoked with it. + - if more than one argument is passed, the arguments are passed + to the :meth:`flask.Flask.make_response` function as tuple. + + .. versionadded:: 0.6 + """ + if not args: + return current_app.response_class() + if len(args) == 1: + args = args[0] + return current_app.make_response(args) + + +def url_for(endpoint, **values): + """Generates a URL to the given endpoint with the method provided. + + Variable arguments that are unknown to the target endpoint are appended + to the generated URL as query arguments. If the value of a query argument + is `None`, the whole pair is skipped. In case blueprints are active + you can shortcut references to the same blueprint by prefixing the + local endpoint with a dot (``.``). + + This will reference the index function local to the current blueprint:: + + url_for('.index') + + For more information, head over to the :ref:`Quickstart <url-building>`. + + :param endpoint: the endpoint of the URL (name of the function) + :param values: the variable arguments of the URL rule + :param _external: if set to `True`, an absolute URL is generated. + """ + ctx = _request_ctx_stack.top + blueprint_name = request.blueprint + if not ctx.request._is_old_module: + if endpoint[:1] == '.': + if blueprint_name is not None: + endpoint = blueprint_name + endpoint + else: + endpoint = endpoint[1:] + else: + # TODO: get rid of this deprecated functionality in 1.0 + if '.' not in endpoint: + if blueprint_name is not None: + endpoint = blueprint_name + '.' + endpoint + elif endpoint.startswith('.'): + endpoint = endpoint[1:] + external = values.pop('_external', False) + ctx.app.inject_url_defaults(endpoint, values) + return ctx.url_adapter.build(endpoint, values, force_external=external) + + +def get_template_attribute(template_name, attribute): + """Loads a macro (or variable) a template exports. This can be used to + invoke a macro from within Python code. If you for example have a + template named `_cider.html` with the following contents: + + .. sourcecode:: html+jinja + + {% macro hello(name) %}Hello {{ name }}!{% endmacro %} + + You can access this from Python code like this:: + + hello = get_template_attribute('_cider.html', 'hello') + return hello('World') + + .. versionadded:: 0.2 + + :param template_name: the name of the template + :param attribute: the name of the variable of macro to acccess + """ + return getattr(current_app.jinja_env.get_template(template_name).module, + attribute) + + +def flash(message, category='message'): + """Flashes a message to the next request. In order to remove the + flashed message from the session and to display it to the user, + the template has to call :func:`get_flashed_messages`. + + .. versionchanged: 0.3 + `category` parameter added. + + :param message: the message to be flashed. + :param category: the category for the message. The following values + are recommended: ``'message'`` for any kind of message, + ``'error'`` for errors, ``'info'`` for information + messages and ``'warning'`` for warnings. However any + kind of string can be used as category. + """ + session.setdefault('_flashes', []).append((category, message)) + + +def get_flashed_messages(with_categories=False): + """Pulls all flashed messages from the session and returns them. + Further calls in the same request to the function will return + the same messages. By default just the messages are returned, + but when `with_categories` is set to `True`, the return value will + be a list of tuples in the form ``(category, message)`` instead. + + Example usage: + + .. sourcecode:: html+jinja + + {% for category, msg in get_flashed_messages(with_categories=true) %} + <p class=flash-{{ category }}>{{ msg }} + {% endfor %} + + .. versionchanged:: 0.3 + `with_categories` parameter added. + + :param with_categories: set to `True` to also receive categories. + """ + flashes = _request_ctx_stack.top.flashes + if flashes is None: + _request_ctx_stack.top.flashes = flashes = session.pop('_flashes') \ + if '_flashes' in session else [] + if not with_categories: + return [x[1] for x in flashes] + return flashes + + +def send_file(filename_or_fp, mimetype=None, as_attachment=False, + attachment_filename=None, add_etags=True, + cache_timeout=60 * 60 * 12, conditional=False): + """Sends the contents of a file to the client. This will use the + most efficient method available and configured. By default it will + try to use the WSGI server's file_wrapper support. Alternatively + you can set the application's :attr:`~Flask.use_x_sendfile` attribute + to ``True`` to directly emit an `X-Sendfile` header. This however + requires support of the underlying webserver for `X-Sendfile`. + + By default it will try to guess the mimetype for you, but you can + also explicitly provide one. For extra security you probably want + to send certain files as attachment (HTML for instance). The mimetype + guessing requires a `filename` or an `attachment_filename` to be + provided. + + Please never pass filenames to this function from user sources without + checking them first. Something like this is usually sufficient to + avoid security problems:: + + if '..' in filename or filename.startswith('/'): + abort(404) + + .. versionadded:: 0.2 + + .. versionadded:: 0.5 + The `add_etags`, `cache_timeout` and `conditional` parameters were + added. The default behaviour is now to attach etags. + + .. versionchanged:: 0.7 + mimetype guessing and etag support for file objects was + deprecated because it was unreliable. Pass a filename if you are + able to, otherwise attach an etag yourself. This functionality + will be removed in Flask 1.0 + + :param filename_or_fp: the filename of the file to send. This is + relative to the :attr:`~Flask.root_path` if a + relative path is specified. + Alternatively a file object might be provided + in which case `X-Sendfile` might not work and + fall back to the traditional method. Make sure + that the file pointer is positioned at the start + of data to send before calling :func:`send_file`. + :param mimetype: the mimetype of the file if provided, otherwise + auto detection happens. + :param as_attachment: set to `True` if you want to send this file with + a ``Content-Disposition: attachment`` header. + :param attachment_filename: the filename for the attachment if it + differs from the file's filename. + :param add_etags: set to `False` to disable attaching of etags. + :param conditional: set to `True` to enable conditional responses. + :param cache_timeout: the timeout in seconds for the headers. + """ + mtime = None + if isinstance(filename_or_fp, basestring): + filename = filename_or_fp + file = None + else: + from warnings import warn + file = filename_or_fp + filename = getattr(file, 'name', None) + + # XXX: this behaviour is now deprecated because it was unreliable. + # removed in Flask 1.0 + if not attachment_filename and not mimetype \ + and isinstance(filename, basestring): + warn(DeprecationWarning('The filename support for file objects ' + 'passed to send_file is now deprecated. Pass an ' + 'attach_filename if you want mimetypes to be guessed.'), + stacklevel=2) + if add_etags: + warn(DeprecationWarning('In future flask releases etags will no ' + 'longer be generated for file objects passed to the send_file ' + 'function because this behaviour was unreliable. Pass ' + 'filenames instead if possible, otherwise attach an etag ' + 'yourself based on another value'), stacklevel=2) + + if filename is not None: + if not os.path.isabs(filename): + filename = os.path.join(current_app.root_path, filename) + if mimetype is None and (filename or attachment_filename): + mimetype = mimetypes.guess_type(filename or attachment_filename)[0] + if mimetype is None: + mimetype = 'application/octet-stream' + + headers = Headers() + if as_attachment: + if attachment_filename is None: + if filename is None: + raise TypeError('filename unavailable, required for ' + 'sending as attachment') + attachment_filename = os.path.basename(filename) + headers.add('Content-Disposition', 'attachment', + filename=attachment_filename) + + if current_app.use_x_sendfile and filename: + if file is not None: + file.close() + headers['X-Sendfile'] = filename + data = None + else: + if file is None: + file = open(filename, 'rb') + mtime = os.path.getmtime(filename) + data = wrap_file(request.environ, file) + + rv = current_app.response_class(data, mimetype=mimetype, headers=headers, + direct_passthrough=True) + + # if we know the file modification date, we can store it as the + # the time of the last modification. + if mtime is not None: + rv.last_modified = int(mtime) + + rv.cache_control.public = True + if cache_timeout: + rv.cache_control.max_age = cache_timeout + rv.expires = int(time() + cache_timeout) + + if add_etags and filename is not None: + rv.set_etag('flask-%s-%s-%s' % ( + os.path.getmtime(filename), + os.path.getsize(filename), + adler32( + filename.encode('utf8') if isinstance(filename, unicode) + else filename + ) & 0xffffffff + )) + if conditional: + rv = rv.make_conditional(request) + # make sure we don't send x-sendfile for servers that + # ignore the 304 status code for x-sendfile. + if rv.status_code == 304: + rv.headers.pop('x-sendfile', None) + return rv + + +def safe_join(directory, filename): + """Safely join `directory` and `filename`. + + Example usage:: + + @app.route('/wiki/<path:filename>') + def wiki_page(filename): + filename = safe_join(app.config['WIKI_FOLDER'], filename) + with open(filename, 'rb') as fd: + content = fd.read() # Read and process the file content... + + :param directory: the base directory. + :param filename: the untrusted filename relative to that directory. + :raises: :class:`~werkzeug.exceptions.NotFound` if the resulting path + would fall out of `directory`. + """ + filename = posixpath.normpath(filename) + for sep in _os_alt_seps: + if sep in filename: + raise NotFound() + if os.path.isabs(filename) or filename.startswith('../'): + raise NotFound() + return os.path.join(directory, filename) + + +def send_from_directory(directory, filename, **options): + """Send a file from a given directory with :func:`send_file`. This + is a secure way to quickly expose static files from an upload folder + or something similar. + + Example usage:: + + @app.route('/uploads/<path:filename>') + def download_file(filename): + return send_from_directory(app.config['UPLOAD_FOLDER'], + filename, as_attachment=True) + + .. admonition:: Sending files and Performance + + It is strongly recommended to activate either `X-Sendfile` support in + your webserver or (if no authentication happens) to tell the webserver + to serve files for the given path on its own without calling into the + web application for improved performance. + + .. versionadded:: 0.5 + + :param directory: the directory where all the files are stored. + :param filename: the filename relative to that directory to + download. + :param options: optional keyword arguments that are directly + forwarded to :func:`send_file`. + """ + filename = safe_join(directory, filename) + if not os.path.isfile(filename): + raise NotFound() + return send_file(filename, conditional=True, **options) + + +def get_root_path(import_name): + """Returns the path to a package or cwd if that cannot be found. This + returns the path of a package or the folder that contains a module. + + Not to be confused with the package path returned by :func:`find_package`. + """ + __import__(import_name) + try: + directory = os.path.dirname(sys.modules[import_name].__file__) + return os.path.abspath(directory) + except AttributeError: + # this is necessary in case we are running from the interactive + # python shell. It will never be used for production code however + return os.getcwd() + + +def find_package(import_name): + """Finds a package and returns the prefix (or None if the package is + not installed) as well as the folder that contains the package or + module as a tuple. The package path returned is the module that would + have to be added to the pythonpath in order to make it possible to + import the module. The prefix is the path below which a UNIX like + folder structure exists (lib, share etc.). + """ + __import__(import_name) + root_mod = sys.modules[import_name.split('.')[0]] + package_path = getattr(root_mod, '__file__', None) + if package_path is None: + # support for the interactive python shell + package_path = os.getcwd() + else: + package_path = os.path.abspath(os.path.dirname(package_path)) + if hasattr(root_mod, '__path__'): + package_path = os.path.dirname(package_path) + + # leave the egg wrapper folder or the actual .egg on the filesystem + test_package_path = package_path + if os.path.basename(test_package_path).endswith('.egg'): + test_package_path = os.path.dirname(test_package_path) + + site_parent, site_folder = os.path.split(test_package_path) + py_prefix = os.path.abspath(sys.prefix) + if test_package_path.startswith(py_prefix): + return py_prefix, package_path + elif site_folder.lower() == 'site-packages': + parent, folder = os.path.split(site_parent) + # Windows like installations + if folder.lower() == 'lib': + base_dir = parent + # UNIX like installations + elif os.path.basename(parent).lower() == 'lib': + base_dir = os.path.dirname(parent) + else: + base_dir = site_parent + return base_dir, package_path + return None, package_path + + +class locked_cached_property(object): + """A decorator that converts a function into a lazy property. The + function wrapped is called the first time to retrieve the result + and then that calculated result is used the next time you access + the value. Works like the one in Werkzeug but has a lock for + thread safety. + """ + + def __init__(self, func, name=None, doc=None): + self.__name__ = name or func.__name__ + self.__module__ = func.__module__ + self.__doc__ = doc or func.__doc__ + self.func = func + self.lock = RLock() + + def __get__(self, obj, type=None): + if obj is None: + return self + with self.lock: + value = obj.__dict__.get(self.__name__, _missing) + if value is _missing: + value = self.func(obj) + obj.__dict__[self.__name__] = value + return value + + +class _PackageBoundObject(object): + + def __init__(self, import_name, template_folder=None): + #: The name of the package or module. Do not change this once + #: it was set by the constructor. + self.import_name = import_name + + #: location of the templates. `None` if templates should not be + #: exposed. + self.template_folder = template_folder + + #: Where is the app root located? + self.root_path = get_root_path(self.import_name) + + self._static_folder = None + self._static_url_path = None + + def _get_static_folder(self): + if self._static_folder is not None: + return os.path.join(self.root_path, self._static_folder) + def _set_static_folder(self, value): + self._static_folder = value + static_folder = property(_get_static_folder, _set_static_folder) + del _get_static_folder, _set_static_folder + + def _get_static_url_path(self): + if self._static_url_path is None: + if self.static_folder is None: + return None + return '/' + os.path.basename(self.static_folder) + return self._static_url_path + def _set_static_url_path(self, value): + self._static_url_path = value + static_url_path = property(_get_static_url_path, _set_static_url_path) + del _get_static_url_path, _set_static_url_path + + @property + def has_static_folder(self): + """This is `True` if the package bound object's container has a + folder named ``'static'``. + + .. versionadded:: 0.5 + """ + return self.static_folder is not None + + @locked_cached_property + def jinja_loader(self): + """The Jinja loader for this package bound object. + + .. versionadded:: 0.5 + """ + if self.template_folder is not None: + return FileSystemLoader(os.path.join(self.root_path, + self.template_folder)) + + def send_static_file(self, filename): + """Function used internally to send static files from the static + folder to the browser. + + .. versionadded:: 0.5 + """ + if not self.has_static_folder: + raise RuntimeError('No static folder for this object') + return send_from_directory(self.static_folder, filename) + + def open_resource(self, resource, mode='rb'): + """Opens a resource from the application's resource folder. To see + how this works, consider the following folder structure:: + + /myapplication.py + /schema.sql + /static + /style.css + /templates + /layout.html + /index.html + + If you want to open the `schema.sql` file you would do the + following:: + + with app.open_resource('schema.sql') as f: + contents = f.read() + do_something_with(contents) + + :param resource: the name of the resource. To access resources within + subfolders use forward slashes as separator. + """ + if mode not in ('r', 'rb'): + raise ValueError('Resources can only be opened for reading') + return open(os.path.join(self.root_path, resource), mode) |