624 lines
22 KiB
Python
624 lines
22 KiB
Python
# -*- coding: utf-8 -*-
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"""
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werkzeug.utils
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~~~~~~~~~~~~~~
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This module implements various utilities for WSGI applications. Most of
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them are used by the request and response wrappers but especially for
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middleware development it makes sense to use them without the wrappers.
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:copyright: (c) 2014 by the Werkzeug Team, see AUTHORS for more details.
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:license: BSD, see LICENSE for more details.
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"""
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import re
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import os
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import sys
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import pkgutil
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try:
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from html.entities import name2codepoint
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except ImportError:
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from htmlentitydefs import name2codepoint
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from werkzeug._compat import unichr, text_type, string_types, iteritems, \
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reraise, PY2
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from werkzeug._internal import _DictAccessorProperty, \
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_parse_signature, _missing
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_format_re = re.compile(r'\$(?:(%s)|\{(%s)\})' % (('[a-zA-Z_][a-zA-Z0-9_]*',) * 2))
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_entity_re = re.compile(r'&([^;]+);')
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_filename_ascii_strip_re = re.compile(r'[^A-Za-z0-9_.-]')
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_windows_device_files = ('CON', 'AUX', 'COM1', 'COM2', 'COM3', 'COM4', 'LPT1',
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'LPT2', 'LPT3', 'PRN', 'NUL')
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class cached_property(object):
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"""A decorator that converts a function into a lazy property. The
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function wrapped is called the first time to retrieve the result
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and then that calculated result is used the next time you access
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the value::
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class Foo(object):
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@cached_property
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def foo(self):
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# calculate something important here
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return 42
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The class has to have a `__dict__` in order for this property to
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work.
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"""
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# implementation detail: this property is implemented as non-data
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# descriptor. non-data descriptors are only invoked if there is
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# no entry with the same name in the instance's __dict__.
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# this allows us to completely get rid of the access function call
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# overhead. If one choses to invoke __get__ by hand the property
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# will still work as expected because the lookup logic is replicated
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# in __get__ for manual invocation.
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def __init__(self, func, name=None, doc=None):
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self.__name__ = name or func.__name__
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self.__module__ = func.__module__
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self.__doc__ = doc or func.__doc__
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self.func = func
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def __get__(self, obj, type=None):
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if obj is None:
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return self
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value = obj.__dict__.get(self.__name__, _missing)
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if value is _missing:
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value = self.func(obj)
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obj.__dict__[self.__name__] = value
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return value
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class environ_property(_DictAccessorProperty):
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"""Maps request attributes to environment variables. This works not only
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for the Werzeug request object, but also any other class with an
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environ attribute:
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>>> class Test(object):
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... environ = {'key': 'value'}
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... test = environ_property('key')
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>>> var = Test()
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>>> var.test
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'value'
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If you pass it a second value it's used as default if the key does not
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exist, the third one can be a converter that takes a value and converts
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it. If it raises :exc:`ValueError` or :exc:`TypeError` the default value
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is used. If no default value is provided `None` is used.
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Per default the property is read only. You have to explicitly enable it
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by passing ``read_only=False`` to the constructor.
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"""
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read_only = True
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def lookup(self, obj):
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return obj.environ
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class header_property(_DictAccessorProperty):
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"""Like `environ_property` but for headers."""
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def lookup(self, obj):
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return obj.headers
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class HTMLBuilder(object):
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"""Helper object for HTML generation.
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Per default there are two instances of that class. The `html` one, and
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the `xhtml` one for those two dialects. The class uses keyword parameters
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and positional parameters to generate small snippets of HTML.
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Keyword parameters are converted to XML/SGML attributes, positional
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arguments are used as children. Because Python accepts positional
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arguments before keyword arguments it's a good idea to use a list with the
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star-syntax for some children:
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>>> html.p(class_='foo', *[html.a('foo', href='foo.html'), ' ',
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... html.a('bar', href='bar.html')])
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u'<p class="foo"><a href="foo.html">foo</a> <a href="bar.html">bar</a></p>'
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This class works around some browser limitations and can not be used for
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arbitrary SGML/XML generation. For that purpose lxml and similar
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libraries exist.
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Calling the builder escapes the string passed:
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>>> html.p(html("<foo>"))
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u'<p><foo></p>'
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"""
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_entity_re = re.compile(r'&([^;]+);')
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_entities = name2codepoint.copy()
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_entities['apos'] = 39
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_empty_elements = set([
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'area', 'base', 'basefont', 'br', 'col', 'command', 'embed', 'frame',
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'hr', 'img', 'input', 'keygen', 'isindex', 'link', 'meta', 'param',
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'source', 'wbr'
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])
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_boolean_attributes = set([
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'selected', 'checked', 'compact', 'declare', 'defer', 'disabled',
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'ismap', 'multiple', 'nohref', 'noresize', 'noshade', 'nowrap'
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])
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_plaintext_elements = set(['textarea'])
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_c_like_cdata = set(['script', 'style'])
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def __init__(self, dialect):
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self._dialect = dialect
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def __call__(self, s):
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return escape(s)
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def __getattr__(self, tag):
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if tag[:2] == '__':
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raise AttributeError(tag)
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def proxy(*children, **arguments):
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buffer = '<' + tag
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for key, value in iteritems(arguments):
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if value is None:
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continue
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if key[-1] == '_':
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key = key[:-1]
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if key in self._boolean_attributes:
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if not value:
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continue
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if self._dialect == 'xhtml':
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value = '="' + key + '"'
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else:
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value = ''
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else:
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value = '="' + escape(value) + '"'
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buffer += ' ' + key + value
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if not children and tag in self._empty_elements:
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if self._dialect == 'xhtml':
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buffer += ' />'
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else:
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buffer += '>'
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return buffer
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buffer += '>'
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children_as_string = ''.join([text_type(x) for x in children
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if x is not None])
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if children_as_string:
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if tag in self._plaintext_elements:
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children_as_string = escape(children_as_string)
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elif tag in self._c_like_cdata and self._dialect == 'xhtml':
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children_as_string = '/*<![CDATA[*/' + \
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children_as_string + '/*]]>*/'
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buffer += children_as_string + '</' + tag + '>'
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return buffer
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return proxy
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def __repr__(self):
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return '<%s for %r>' % (
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self.__class__.__name__,
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self._dialect
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)
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html = HTMLBuilder('html')
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xhtml = HTMLBuilder('xhtml')
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def get_content_type(mimetype, charset):
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"""Returns the full content type string with charset for a mimetype.
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If the mimetype represents text the charset will be appended as charset
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parameter, otherwise the mimetype is returned unchanged.
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:param mimetype: the mimetype to be used as content type.
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:param charset: the charset to be appended in case it was a text mimetype.
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:return: the content type.
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"""
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if mimetype.startswith('text/') or \
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mimetype == 'application/xml' or \
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(mimetype.startswith('application/') and
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mimetype.endswith('+xml')):
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mimetype += '; charset=' + charset
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return mimetype
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def format_string(string, context):
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"""String-template format a string:
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>>> format_string('$foo and ${foo}s', dict(foo=42))
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'42 and 42s'
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This does not do any attribute lookup etc. For more advanced string
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formattings have a look at the `werkzeug.template` module.
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:param string: the format string.
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:param context: a dict with the variables to insert.
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"""
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def lookup_arg(match):
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x = context[match.group(1) or match.group(2)]
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if not isinstance(x, string_types):
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x = type(string)(x)
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return x
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return _format_re.sub(lookup_arg, string)
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def secure_filename(filename):
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r"""Pass it a filename and it will return a secure version of it. This
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filename can then safely be stored on a regular file system and passed
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to :func:`os.path.join`. The filename returned is an ASCII only string
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for maximum portability.
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On windows systems the function also makes sure that the file is not
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named after one of the special device files.
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>>> secure_filename("My cool movie.mov")
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'My_cool_movie.mov'
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>>> secure_filename("../../../etc/passwd")
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'etc_passwd'
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>>> secure_filename(u'i contain cool \xfcml\xe4uts.txt')
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'i_contain_cool_umlauts.txt'
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The function might return an empty filename. It's your responsibility
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to ensure that the filename is unique and that you generate random
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filename if the function returned an empty one.
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.. versionadded:: 0.5
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:param filename: the filename to secure
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"""
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if isinstance(filename, text_type):
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from unicodedata import normalize
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filename = normalize('NFKD', filename).encode('ascii', 'ignore')
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if not PY2:
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filename = filename.decode('ascii')
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for sep in os.path.sep, os.path.altsep:
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if sep:
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filename = filename.replace(sep, ' ')
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filename = str(_filename_ascii_strip_re.sub('', '_'.join(
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filename.split()))).strip('._')
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# on nt a couple of special files are present in each folder. We
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# have to ensure that the target file is not such a filename. In
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# this case we prepend an underline
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if os.name == 'nt' and filename and \
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filename.split('.')[0].upper() in _windows_device_files:
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filename = '_' + filename
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return filename
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def escape(s, quote=None):
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"""Replace special characters "&", "<", ">" and (") to HTML-safe sequences.
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There is a special handling for `None` which escapes to an empty string.
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.. versionchanged:: 0.9
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`quote` is now implicitly on.
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:param s: the string to escape.
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:param quote: ignored.
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"""
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if s is None:
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return ''
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elif hasattr(s, '__html__'):
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return text_type(s.__html__())
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elif not isinstance(s, string_types):
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s = text_type(s)
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if quote is not None:
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from warnings import warn
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warn(DeprecationWarning('quote parameter is implicit now'), stacklevel=2)
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s = s.replace('&', '&').replace('<', '<') \
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.replace('>', '>').replace('"', """)
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return s
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def unescape(s):
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"""The reverse function of `escape`. This unescapes all the HTML
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entities, not only the XML entities inserted by `escape`.
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:param s: the string to unescape.
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"""
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def handle_match(m):
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name = m.group(1)
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if name in HTMLBuilder._entities:
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return unichr(HTMLBuilder._entities[name])
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try:
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if name[:2] in ('#x', '#X'):
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return unichr(int(name[2:], 16))
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elif name.startswith('#'):
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return unichr(int(name[1:]))
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except ValueError:
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pass
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return u''
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return _entity_re.sub(handle_match, s)
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def redirect(location, code=302, Response=None):
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"""Returns a response object (a WSGI application) that, if called,
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redirects the client to the target location. Supported codes are 301,
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302, 303, 305, and 307. 300 is not supported because it's not a real
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redirect and 304 because it's the answer for a request with a request
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with defined If-Modified-Since headers.
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.. versionadded:: 0.6
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The location can now be a unicode string that is encoded using
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the :func:`iri_to_uri` function.
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.. versionadded:: 0.10
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The class used for the Response object can now be passed in.
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:param location: the location the response should redirect to.
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:param code: the redirect status code. defaults to 302.
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:param class Response: a Response class to use when instantiating a
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response. The default is :class:`werkzeug.wrappers.Response` if
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unspecified.
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"""
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if Response is None:
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from werkzeug.wrappers import Response
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display_location = escape(location)
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if isinstance(location, text_type):
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# Safe conversion is necessary here as we might redirect
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# to a broken URI scheme (for instance itms-services).
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from werkzeug.urls import iri_to_uri
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location = iri_to_uri(location, safe_conversion=True)
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response = Response(
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'<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">\n'
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'<title>Redirecting...</title>\n'
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'<h1>Redirecting...</h1>\n'
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'<p>You should be redirected automatically to target URL: '
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'<a href="%s">%s</a>. If not click the link.' %
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(escape(location), display_location), code, mimetype='text/html')
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response.headers['Location'] = location
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return response
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def append_slash_redirect(environ, code=301):
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"""Redirects to the same URL but with a slash appended. The behavior
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of this function is undefined if the path ends with a slash already.
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:param environ: the WSGI environment for the request that triggers
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the redirect.
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:param code: the status code for the redirect.
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"""
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new_path = environ['PATH_INFO'].strip('/') + '/'
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query_string = environ.get('QUERY_STRING')
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if query_string:
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new_path += '?' + query_string
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return redirect(new_path, code)
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def import_string(import_name, silent=False):
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"""Imports an object based on a string. This is useful if you want to
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use import paths as endpoints or something similar. An import path can
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be specified either in dotted notation (``xml.sax.saxutils.escape``)
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or with a colon as object delimiter (``xml.sax.saxutils:escape``).
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If `silent` is True the return value will be `None` if the import fails.
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:param import_name: the dotted name for the object to import.
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:param silent: if set to `True` import errors are ignored and
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`None` is returned instead.
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:return: imported object
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"""
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# force the import name to automatically convert to strings
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# __import__ is not able to handle unicode strings in the fromlist
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# if the module is a package
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import_name = str(import_name).replace(':', '.')
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try:
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try:
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__import__(import_name)
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except ImportError:
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if '.' not in import_name:
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raise
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else:
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return sys.modules[import_name]
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module_name, obj_name = import_name.rsplit('.', 1)
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try:
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module = __import__(module_name, None, None, [obj_name])
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except ImportError:
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# support importing modules not yet set up by the parent module
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# (or package for that matter)
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module = import_string(module_name)
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try:
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return getattr(module, obj_name)
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except AttributeError as e:
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raise ImportError(e)
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except ImportError as e:
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if not silent:
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reraise(
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ImportStringError,
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ImportStringError(import_name, e),
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sys.exc_info()[2])
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def find_modules(import_path, include_packages=False, recursive=False):
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"""Finds all the modules below a package. This can be useful to
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automatically import all views / controllers so that their metaclasses /
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function decorators have a chance to register themselves on the
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application.
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Packages are not returned unless `include_packages` is `True`. This can
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also recursively list modules but in that case it will import all the
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packages to get the correct load path of that module.
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:param import_name: the dotted name for the package to find child modules.
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:param include_packages: set to `True` if packages should be returned, too.
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:param recursive: set to `True` if recursion should happen.
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:return: generator
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"""
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module = import_string(import_path)
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path = getattr(module, '__path__', None)
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if path is None:
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raise ValueError('%r is not a package' % import_path)
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basename = module.__name__ + '.'
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for importer, modname, ispkg in pkgutil.iter_modules(path):
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modname = basename + modname
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if ispkg:
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if include_packages:
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yield modname
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if recursive:
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for item in find_modules(modname, include_packages, True):
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yield item
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else:
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yield modname
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def validate_arguments(func, args, kwargs, drop_extra=True):
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"""Checks if the function accepts the arguments and keyword arguments.
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Returns a new ``(args, kwargs)`` tuple that can safely be passed to
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the function without causing a `TypeError` because the function signature
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is incompatible. If `drop_extra` is set to `True` (which is the default)
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any extra positional or keyword arguments are dropped automatically.
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The exception raised provides three attributes:
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`missing`
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A set of argument names that the function expected but where
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missing.
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`extra`
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A dict of keyword arguments that the function can not handle but
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where provided.
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`extra_positional`
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A list of values that where given by positional argument but the
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function cannot accept.
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This can be useful for decorators that forward user submitted data to
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a view function::
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from werkzeug.utils import ArgumentValidationError, validate_arguments
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def sanitize(f):
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def proxy(request):
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data = request.values.to_dict()
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try:
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args, kwargs = validate_arguments(f, (request,), data)
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except ArgumentValidationError:
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raise BadRequest('The browser failed to transmit all '
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'the data expected.')
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return f(*args, **kwargs)
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return proxy
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:param func: the function the validation is performed against.
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:param args: a tuple of positional arguments.
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:param kwargs: a dict of keyword arguments.
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:param drop_extra: set to `False` if you don't want extra arguments
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to be silently dropped.
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:return: tuple in the form ``(args, kwargs)``.
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"""
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parser = _parse_signature(func)
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args, kwargs, missing, extra, extra_positional = parser(args, kwargs)[:5]
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if missing:
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raise ArgumentValidationError(tuple(missing))
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|
elif (extra or extra_positional) and not drop_extra:
|
|
raise ArgumentValidationError(None, extra, extra_positional)
|
|
return tuple(args), kwargs
|
|
|
|
|
|
def bind_arguments(func, args, kwargs):
|
|
"""Bind the arguments provided into a dict. When passed a function,
|
|
a tuple of arguments and a dict of keyword arguments `bind_arguments`
|
|
returns a dict of names as the function would see it. This can be useful
|
|
to implement a cache decorator that uses the function arguments to build
|
|
the cache key based on the values of the arguments.
|
|
|
|
:param func: the function the arguments should be bound for.
|
|
:param args: tuple of positional arguments.
|
|
:param kwargs: a dict of keyword arguments.
|
|
:return: a :class:`dict` of bound keyword arguments.
|
|
"""
|
|
args, kwargs, missing, extra, extra_positional, \
|
|
arg_spec, vararg_var, kwarg_var = _parse_signature(func)(args, kwargs)
|
|
values = {}
|
|
for (name, has_default, default), value in zip(arg_spec, args):
|
|
values[name] = value
|
|
if vararg_var is not None:
|
|
values[vararg_var] = tuple(extra_positional)
|
|
elif extra_positional:
|
|
raise TypeError('too many positional arguments')
|
|
if kwarg_var is not None:
|
|
multikw = set(extra) & set([x[0] for x in arg_spec])
|
|
if multikw:
|
|
raise TypeError('got multiple values for keyword argument ' +
|
|
repr(next(iter(multikw))))
|
|
values[kwarg_var] = extra
|
|
elif extra:
|
|
raise TypeError('got unexpected keyword argument ' +
|
|
repr(next(iter(extra))))
|
|
return values
|
|
|
|
|
|
class ArgumentValidationError(ValueError):
|
|
"""Raised if :func:`validate_arguments` fails to validate"""
|
|
|
|
def __init__(self, missing=None, extra=None, extra_positional=None):
|
|
self.missing = set(missing or ())
|
|
self.extra = extra or {}
|
|
self.extra_positional = extra_positional or []
|
|
ValueError.__init__(self, 'function arguments invalid. ('
|
|
'%d missing, %d additional)' % (
|
|
len(self.missing),
|
|
len(self.extra) + len(self.extra_positional)
|
|
))
|
|
|
|
|
|
class ImportStringError(ImportError):
|
|
"""Provides information about a failed :func:`import_string` attempt."""
|
|
|
|
#: String in dotted notation that failed to be imported.
|
|
import_name = None
|
|
#: Wrapped exception.
|
|
exception = None
|
|
|
|
def __init__(self, import_name, exception):
|
|
self.import_name = import_name
|
|
self.exception = exception
|
|
|
|
msg = (
|
|
'import_string() failed for %r. Possible reasons are:\n\n'
|
|
'- missing __init__.py in a package;\n'
|
|
'- package or module path not included in sys.path;\n'
|
|
'- duplicated package or module name taking precedence in '
|
|
'sys.path;\n'
|
|
'- missing module, class, function or variable;\n\n'
|
|
'Debugged import:\n\n%s\n\n'
|
|
'Original exception:\n\n%s: %s')
|
|
|
|
name = ''
|
|
tracked = []
|
|
for part in import_name.replace(':', '.').split('.'):
|
|
name += (name and '.') + part
|
|
imported = import_string(name, silent=True)
|
|
if imported:
|
|
tracked.append((name, getattr(imported, '__file__', None)))
|
|
else:
|
|
track = ['- %r found in %r.' % (n, i) for n, i in tracked]
|
|
track.append('- %r not found.' % name)
|
|
msg = msg % (import_name, '\n'.join(track),
|
|
exception.__class__.__name__, str(exception))
|
|
break
|
|
|
|
ImportError.__init__(self, msg)
|
|
|
|
def __repr__(self):
|
|
return '<%s(%r, %r)>' % (self.__class__.__name__, self.import_name,
|
|
self.exception)
|
|
|
|
|
|
# circular dependencies
|
|
from werkzeug.http import quote_header_value, unquote_header_value, \
|
|
cookie_date
|
|
|
|
# DEPRECATED
|
|
# these objects were previously in this module as well. we import
|
|
# them here for backwards compatibility with old pickles.
|
|
from werkzeug.datastructures import MultiDict, CombinedMultiDict, \
|
|
Headers, EnvironHeaders
|
|
from werkzeug.http import parse_cookie, dump_cookie
|