163 lines
4.6 KiB
Python
163 lines
4.6 KiB
Python
# Copyright 2013 by Rackspace Hosting, Inc.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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"""Utilities for the Request class."""
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import io
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def header_property(wsgi_name):
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"""Creates a read-only header property.
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Args:
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wsgi_name (str): Case-sensitive name of the header as it would
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appear in the WSGI environ ``dict`` (i.e., 'HTTP_*')
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Returns:
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A property instance than can be assigned to a class variable.
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"""
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def fget(self):
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try:
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return self.env[wsgi_name] or None
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except KeyError:
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return None
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return property(fget)
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class BoundedStream(io.IOBase):
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"""Wrap *wsgi.input* streams to make them more robust.
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``socket._fileobject`` and ``io.BufferedReader`` are sometimes used
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to implement *wsgi.input*. However, app developers are often burned
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by the fact that the `read()` method for these objects block
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indefinitely if either no size is passed, or a size greater than
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the request's content length is passed to the method.
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This class normalizes *wsgi.input* behavior between WSGI servers
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by implementing non-blocking behavior for the cases mentioned
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above.
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Args:
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stream: Instance of ``socket._fileobject`` from
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``environ['wsgi.input']``
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stream_len: Expected content length of the stream.
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"""
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def __init__(self, stream, stream_len):
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self.stream = stream
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self.stream_len = stream_len
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self._bytes_remaining = self.stream_len
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def __iter__(self):
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return self
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def __next__(self):
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return next(self.stream)
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next = __next__
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def _read(self, size, target):
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"""Helper function for proxing reads to the underlying stream.
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Args:
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size (int): Maximum number of bytes to read. Will be
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coerced, if None or -1, to the number of remaining bytes
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in the stream. Will likewise be coerced if greater than
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the number of remaining bytes, to avoid making a
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blocking call to the wrapped stream.
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target (callable): Once `size` has been fixed up, this function
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will be called to actually do the work.
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Returns:
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bytes: Data read from the stream, as returned by `target`.
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"""
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# NOTE(kgriffs): Default to reading all remaining bytes if the
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# size is not specified or is out of bounds. This behaves
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# similarly to the IO streams passed in by non-wsgiref servers.
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if (size is None or size == -1 or size > self._bytes_remaining):
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size = self._bytes_remaining
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self._bytes_remaining -= size
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return target(size)
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def readable(self):
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"""Always returns ``True``."""
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return True
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def seekable(self):
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"""Always returns ``False``."""
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return False
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def writeable(self):
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"""Always returns ``False``."""
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return False
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def read(self, size=None):
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"""Read from the stream.
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Args:
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size (int): Maximum number of bytes/characters to read.
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Defaults to reading until EOF.
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Returns:
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bytes: Data read from the stream.
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"""
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return self._read(size, self.stream.read)
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def readline(self, limit=None):
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"""Read a line from the stream.
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Args:
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limit (int): Maximum number of bytes/characters to read.
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Defaults to reading until EOF.
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Returns:
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bytes: Data read from the stream.
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"""
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return self._read(limit, self.stream.readline)
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def readlines(self, hint=None):
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"""Read lines from the stream.
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Args:
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hint (int): Maximum number of bytes/characters to read.
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Defaults to reading until EOF.
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Returns:
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bytes: Data read from the stream.
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"""
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return self._read(hint, self.stream.readlines)
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def write(self, data):
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"""Always raises IOError; writing is not supported."""
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raise IOError('Stream is not writeable')
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# NOTE(kgriffs): Alias for backwards-compat
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Body = BoundedStream
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