523 lines
21 KiB
Python
523 lines
21 KiB
Python
# -*- coding: utf-8 -*-
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"""
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werkzeug.formparser
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~~~~~~~~~~~~~~~~~~~
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This module implements the form parsing. It supports url-encoded forms
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as well as non-nested multipart uploads.
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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 codecs
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from io import BytesIO
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from tempfile import TemporaryFile
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from itertools import chain, repeat, tee
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from functools import update_wrapper
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from werkzeug._compat import to_native, text_type
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from werkzeug.urls import url_decode_stream
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from werkzeug.wsgi import make_line_iter, \
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get_input_stream, get_content_length
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from werkzeug.datastructures import Headers, FileStorage, MultiDict
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from werkzeug.http import parse_options_header
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#: an iterator that yields empty strings
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_empty_string_iter = repeat('')
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#: a regular expression for multipart boundaries
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_multipart_boundary_re = re.compile('^[ -~]{0,200}[!-~]$')
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#: supported http encodings that are also available in python we support
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#: for multipart messages.
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_supported_multipart_encodings = frozenset(['base64', 'quoted-printable'])
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def default_stream_factory(total_content_length, filename, content_type,
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content_length=None):
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"""The stream factory that is used per default."""
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if total_content_length > 1024 * 500:
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return TemporaryFile('wb+')
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return BytesIO()
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def parse_form_data(environ, stream_factory=None, charset='utf-8',
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errors='replace', max_form_memory_size=None,
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max_content_length=None, cls=None,
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silent=True):
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"""Parse the form data in the environ and return it as tuple in the form
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``(stream, form, files)``. You should only call this method if the
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transport method is `POST`, `PUT`, or `PATCH`.
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If the mimetype of the data transmitted is `multipart/form-data` the
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files multidict will be filled with `FileStorage` objects. If the
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mimetype is unknown the input stream is wrapped and returned as first
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argument, else the stream is empty.
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This is a shortcut for the common usage of :class:`FormDataParser`.
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Have a look at :ref:`dealing-with-request-data` for more details.
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.. versionadded:: 0.5
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The `max_form_memory_size`, `max_content_length` and
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`cls` parameters were added.
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.. versionadded:: 0.5.1
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The optional `silent` flag was added.
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:param environ: the WSGI environment to be used for parsing.
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:param stream_factory: An optional callable that returns a new read and
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writeable file descriptor. This callable works
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the same as :meth:`~BaseResponse._get_file_stream`.
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:param charset: The character set for URL and url encoded form data.
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:param errors: The encoding error behavior.
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:param max_form_memory_size: the maximum number of bytes to be accepted for
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in-memory stored form data. If the data
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exceeds the value specified an
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:exc:`~exceptions.RequestEntityTooLarge`
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exception is raised.
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:param max_content_length: If this is provided and the transmitted data
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is longer than this value an
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:exc:`~exceptions.RequestEntityTooLarge`
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exception is raised.
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:param cls: an optional dict class to use. If this is not specified
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or `None` the default :class:`MultiDict` is used.
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:param silent: If set to False parsing errors will not be caught.
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:return: A tuple in the form ``(stream, form, files)``.
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"""
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return FormDataParser(stream_factory, charset, errors,
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max_form_memory_size, max_content_length,
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cls, silent).parse_from_environ(environ)
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def exhaust_stream(f):
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"""Helper decorator for methods that exhausts the stream on return."""
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def wrapper(self, stream, *args, **kwargs):
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try:
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return f(self, stream, *args, **kwargs)
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finally:
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exhaust = getattr(stream, 'exhaust', None)
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if exhaust is not None:
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exhaust()
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else:
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while 1:
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chunk = stream.read(1024 * 64)
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if not chunk:
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break
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return update_wrapper(wrapper, f)
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class FormDataParser(object):
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"""This class implements parsing of form data for Werkzeug. By itself
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it can parse multipart and url encoded form data. It can be subclassed
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and extended but for most mimetypes it is a better idea to use the
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untouched stream and expose it as separate attributes on a request
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object.
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.. versionadded:: 0.8
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:param stream_factory: An optional callable that returns a new read and
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writeable file descriptor. This callable works
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the same as :meth:`~BaseResponse._get_file_stream`.
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:param charset: The character set for URL and url encoded form data.
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:param errors: The encoding error behavior.
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:param max_form_memory_size: the maximum number of bytes to be accepted for
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in-memory stored form data. If the data
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exceeds the value specified an
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:exc:`~exceptions.RequestEntityTooLarge`
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exception is raised.
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:param max_content_length: If this is provided and the transmitted data
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is longer than this value an
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:exc:`~exceptions.RequestEntityTooLarge`
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exception is raised.
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:param cls: an optional dict class to use. If this is not specified
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or `None` the default :class:`MultiDict` is used.
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:param silent: If set to False parsing errors will not be caught.
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"""
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def __init__(self, stream_factory=None, charset='utf-8',
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errors='replace', max_form_memory_size=None,
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max_content_length=None, cls=None,
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silent=True):
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if stream_factory is None:
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stream_factory = default_stream_factory
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self.stream_factory = stream_factory
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self.charset = charset
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self.errors = errors
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self.max_form_memory_size = max_form_memory_size
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self.max_content_length = max_content_length
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if cls is None:
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cls = MultiDict
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self.cls = cls
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self.silent = silent
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def get_parse_func(self, mimetype, options):
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return self.parse_functions.get(mimetype)
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def parse_from_environ(self, environ):
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"""Parses the information from the environment as form data.
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:param environ: the WSGI environment to be used for parsing.
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:return: A tuple in the form ``(stream, form, files)``.
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"""
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content_type = environ.get('CONTENT_TYPE', '')
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content_length = get_content_length(environ)
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mimetype, options = parse_options_header(content_type)
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return self.parse(get_input_stream(environ), mimetype,
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content_length, options)
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def parse(self, stream, mimetype, content_length, options=None):
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"""Parses the information from the given stream, mimetype,
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content length and mimetype parameters.
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:param stream: an input stream
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:param mimetype: the mimetype of the data
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:param content_length: the content length of the incoming data
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:param options: optional mimetype parameters (used for
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the multipart boundary for instance)
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:return: A tuple in the form ``(stream, form, files)``.
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"""
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if self.max_content_length is not None and \
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content_length is not None and \
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content_length > self.max_content_length:
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raise exceptions.RequestEntityTooLarge()
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if options is None:
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options = {}
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parse_func = self.get_parse_func(mimetype, options)
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if parse_func is not None:
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try:
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return parse_func(self, stream, mimetype,
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content_length, options)
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except ValueError:
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if not self.silent:
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raise
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return stream, self.cls(), self.cls()
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@exhaust_stream
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def _parse_multipart(self, stream, mimetype, content_length, options):
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parser = MultiPartParser(self.stream_factory, self.charset, self.errors,
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max_form_memory_size=self.max_form_memory_size,
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cls=self.cls)
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boundary = options.get('boundary')
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if boundary is None:
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raise ValueError('Missing boundary')
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if isinstance(boundary, text_type):
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boundary = boundary.encode('ascii')
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form, files = parser.parse(stream, boundary, content_length)
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return stream, form, files
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@exhaust_stream
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def _parse_urlencoded(self, stream, mimetype, content_length, options):
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if self.max_form_memory_size is not None and \
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content_length is not None and \
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content_length > self.max_form_memory_size:
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raise exceptions.RequestEntityTooLarge()
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form = url_decode_stream(stream, self.charset,
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errors=self.errors, cls=self.cls)
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return stream, form, self.cls()
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#: mapping of mimetypes to parsing functions
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parse_functions = {
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'multipart/form-data': _parse_multipart,
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'application/x-www-form-urlencoded': _parse_urlencoded,
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'application/x-url-encoded': _parse_urlencoded
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}
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def is_valid_multipart_boundary(boundary):
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"""Checks if the string given is a valid multipart boundary."""
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return _multipart_boundary_re.match(boundary) is not None
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def _line_parse(line):
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"""Removes line ending characters and returns a tuple (`stripped_line`,
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`is_terminated`).
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"""
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if line[-2:] in ['\r\n', b'\r\n']:
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return line[:-2], True
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elif line[-1:] in ['\r', '\n', b'\r', b'\n']:
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return line[:-1], True
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return line, False
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def parse_multipart_headers(iterable):
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"""Parses multipart headers from an iterable that yields lines (including
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the trailing newline symbol). The iterable has to be newline terminated.
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The iterable will stop at the line where the headers ended so it can be
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further consumed.
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:param iterable: iterable of strings that are newline terminated
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"""
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result = []
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for line in iterable:
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line = to_native(line)
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line, line_terminated = _line_parse(line)
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if not line_terminated:
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raise ValueError('unexpected end of line in multipart header')
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if not line:
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break
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elif line[0] in ' \t' and result:
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key, value = result[-1]
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result[-1] = (key, value + '\n ' + line[1:])
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else:
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parts = line.split(':', 1)
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if len(parts) == 2:
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result.append((parts[0].strip(), parts[1].strip()))
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# we link the list to the headers, no need to create a copy, the
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# list was not shared anyways.
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return Headers(result)
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_begin_form = 'begin_form'
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_begin_file = 'begin_file'
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_cont = 'cont'
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_end = 'end'
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class MultiPartParser(object):
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def __init__(self, stream_factory=None, charset='utf-8', errors='replace',
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max_form_memory_size=None, cls=None, buffer_size=64 * 1024):
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self.stream_factory = stream_factory
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self.charset = charset
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self.errors = errors
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self.max_form_memory_size = max_form_memory_size
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if stream_factory is None:
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stream_factory = default_stream_factory
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if cls is None:
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cls = MultiDict
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self.cls = cls
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# make sure the buffer size is divisible by four so that we can base64
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# decode chunk by chunk
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assert buffer_size % 4 == 0, 'buffer size has to be divisible by 4'
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# also the buffer size has to be at least 1024 bytes long or long headers
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# will freak out the system
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assert buffer_size >= 1024, 'buffer size has to be at least 1KB'
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self.buffer_size = buffer_size
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def _fix_ie_filename(self, filename):
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"""Internet Explorer 6 transmits the full file name if a file is
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uploaded. This function strips the full path if it thinks the
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filename is Windows-like absolute.
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"""
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if filename[1:3] == ':\\' or filename[:2] == '\\\\':
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return filename.split('\\')[-1]
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return filename
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def _find_terminator(self, iterator):
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"""The terminator might have some additional newlines before it.
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There is at least one application that sends additional newlines
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before headers (the python setuptools package).
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"""
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for line in iterator:
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if not line:
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break
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line = line.strip()
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if line:
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return line
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return b''
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def fail(self, message):
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raise ValueError(message)
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def get_part_encoding(self, headers):
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transfer_encoding = headers.get('content-transfer-encoding')
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if transfer_encoding is not None and \
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transfer_encoding in _supported_multipart_encodings:
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return transfer_encoding
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def get_part_charset(self, headers):
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# Figure out input charset for current part
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content_type = headers.get('content-type')
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if content_type:
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mimetype, ct_params = parse_options_header(content_type)
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return ct_params.get('charset', self.charset)
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return self.charset
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def start_file_streaming(self, filename, headers, total_content_length):
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if isinstance(filename, bytes):
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filename = filename.decode(self.charset, self.errors)
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filename = self._fix_ie_filename(filename)
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content_type = headers.get('content-type')
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try:
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content_length = int(headers['content-length'])
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except (KeyError, ValueError):
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content_length = 0
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container = self.stream_factory(total_content_length, content_type,
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filename, content_length)
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return filename, container
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def in_memory_threshold_reached(self, bytes):
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raise exceptions.RequestEntityTooLarge()
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def validate_boundary(self, boundary):
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if not boundary:
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self.fail('Missing boundary')
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if not is_valid_multipart_boundary(boundary):
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self.fail('Invalid boundary: %s' % boundary)
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if len(boundary) > self.buffer_size: # pragma: no cover
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# this should never happen because we check for a minimum size
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# of 1024 and boundaries may not be longer than 200. The only
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# situation when this happens is for non debug builds where
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# the assert is skipped.
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self.fail('Boundary longer than buffer size')
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def parse_lines(self, file, boundary, content_length):
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"""Generate parts of
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``('begin_form', (headers, name))``
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``('begin_file', (headers, name, filename))``
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``('cont', bytestring)``
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``('end', None)``
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Always obeys the grammar
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parts = ( begin_form cont* end |
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begin_file cont* end )*
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"""
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next_part = b'--' + boundary
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last_part = next_part + b'--'
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iterator = chain(make_line_iter(file, limit=content_length,
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buffer_size=self.buffer_size),
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_empty_string_iter)
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terminator = self._find_terminator(iterator)
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if terminator == last_part:
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return
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elif terminator != next_part:
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self.fail('Expected boundary at start of multipart data')
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while terminator != last_part:
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headers = parse_multipart_headers(iterator)
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disposition = headers.get('content-disposition')
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if disposition is None:
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self.fail('Missing Content-Disposition header')
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disposition, extra = parse_options_header(disposition)
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transfer_encoding = self.get_part_encoding(headers)
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name = extra.get('name')
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filename = extra.get('filename')
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# if no content type is given we stream into memory. A list is
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# used as a temporary container.
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if filename is None:
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yield _begin_form, (headers, name)
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# otherwise we parse the rest of the headers and ask the stream
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# factory for something we can write in.
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else:
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yield _begin_file, (headers, name, filename)
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buf = b''
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for line in iterator:
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if not line:
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self.fail('unexpected end of stream')
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if line[:2] == b'--':
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terminator = line.rstrip()
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if terminator in (next_part, last_part):
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break
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if transfer_encoding is not None:
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if transfer_encoding == 'base64':
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transfer_encoding = 'base64_codec'
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try:
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line = codecs.decode(line, transfer_encoding)
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except Exception:
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self.fail('could not decode transfer encoded chunk')
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# we have something in the buffer from the last iteration.
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# this is usually a newline delimiter.
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if buf:
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yield _cont, buf
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buf = b''
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# If the line ends with windows CRLF we write everything except
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# the last two bytes. In all other cases however we write
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# everything except the last byte. If it was a newline, that's
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# fine, otherwise it does not matter because we will write it
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# the next iteration. this ensures we do not write the
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# final newline into the stream. That way we do not have to
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# truncate the stream. However we do have to make sure that
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# if something else than a newline is in there we write it
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# out.
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if line[-2:] == b'\r\n':
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buf = b'\r\n'
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cutoff = -2
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else:
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buf = line[-1:]
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cutoff = -1
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yield _cont, line[:cutoff]
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else: # pragma: no cover
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raise ValueError('unexpected end of part')
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# if we have a leftover in the buffer that is not a newline
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# character we have to flush it, otherwise we will chop of
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# certain values.
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if buf not in (b'', b'\r', b'\n', b'\r\n'):
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yield _cont, buf
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yield _end, None
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def parse_parts(self, file, boundary, content_length):
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"""Generate ``('file', (name, val))`` and
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``('form', (name, val))`` parts.
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"""
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in_memory = 0
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for ellt, ell in self.parse_lines(file, boundary, content_length):
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if ellt == _begin_file:
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headers, name, filename = ell
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is_file = True
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guard_memory = False
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filename, container = self.start_file_streaming(
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filename, headers, content_length)
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_write = container.write
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elif ellt == _begin_form:
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headers, name = ell
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is_file = False
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container = []
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_write = container.append
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guard_memory = self.max_form_memory_size is not None
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elif ellt == _cont:
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_write(ell)
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# if we write into memory and there is a memory size limit we
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# count the number of bytes in memory and raise an exception if
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# there is too much data in memory.
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if guard_memory:
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in_memory += len(ell)
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if in_memory > self.max_form_memory_size:
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self.in_memory_threshold_reached(in_memory)
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elif ellt == _end:
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if is_file:
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container.seek(0)
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yield ('file',
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(name, FileStorage(container, filename, name,
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headers=headers)))
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else:
|
|
part_charset = self.get_part_charset(headers)
|
|
yield ('form',
|
|
(name, b''.join(container).decode(
|
|
part_charset, self.errors)))
|
|
|
|
def parse(self, file, boundary, content_length):
|
|
formstream, filestream = tee(
|
|
self.parse_parts(file, boundary, content_length), 2)
|
|
form = (p[1] for p in formstream if p[0] == 'form')
|
|
files = (p[1] for p in filestream if p[0] == 'file')
|
|
return self.cls(form), self.cls(files)
|
|
|
|
|
|
from werkzeug import exceptions
|