"""Marks a function as responder. Decorate a function with it and it

will automatically call the return value as WSGI application.

Example::

@responder

def application(environ, start_response):

return Response('Hello World!')

"""

host_only=False, trusted_hosts=None):

"""A handy helper function that recreates the full URL for the current

request or parts of it. Here an example:

>>> from werkzeug.test import create_environ

>>> env = create_environ("/?param=foo", "http://localhost/script")

>>> get_current_url(env)

'http://localhost/script/?param=foo'

>>> get_current_url(env, root_only=True)

'http://localhost/script/'

>>> get_current_url(env, host_only=True)

'http://localhost/'

>>> get_current_url(env, strip_querystring=True)

'http://localhost/script/'

This optionally it verifies that the host is in a list of trusted hosts.

If the host is not in there it will raise a

:exc:`~werkzeug.exceptions.SecurityError`.

:param environ: the WSGI environment to get the current URL from.

:param root_only: set `True` if you only want the root URL.

:param strip_querystring: set to `True` if you don't want the querystring.

:param host_only: set to `True` if the host URL should be returned.

:param trusted_hosts: a list of trusted hosts, see :func:`host_is_trusted`

for more information.

"""

tmp = [environ['wsgi.url_scheme'], '://', get_host(environ, trusted_hosts)]

cat = tmp.append

if host_only:

return uri_to_iri(''.join(tmp) + '/')

cat(url_quote(wsgi_get_bytes(environ.get('SCRIPT_NAME', ''))).rstrip('/'))

cat('/')

if not root_only:

cat(url_quote(wsgi_get_bytes(environ.get('PATH_INFO', '')).lstrip(b'/')))

if not strip_querystring:

qs = get_query_string(environ)

if qs:

cat('?' + qs)

"""Checks if a host is trusted against a list. This also takes care

of port normalization.

.. versionadded:: 0.9

:param hostname: the hostname to check

:param trusted_list: a list of hostnames to check against. If a

hostname starts with a dot it will match against

all subdomains as well.

"""

if not hostname:

return False

if isinstance(trusted_list, string_types):

trusted_list = [trusted_list]

def _normalize(hostname):

if ':' in hostname:

hostname = hostname.rsplit(':', 1)[0]

return _encode_idna(hostname)

hostname = _normalize(hostname)

for ref in trusted_list:

if ref.startswith('.'):

ref = ref[1:]

suffix_match = True

else:

suffix_match = False

ref = _normalize(ref)

if ref == hostname:

return True

if suffix_match and hostname.endswith('.' + ref):

return True

"""Return the real host for the given WSGI environment. This takes care

of the `X-Forwarded-Host` header. Optionally it verifies that the host

is in a list of trusted hosts. If the host is not in there it will raise

a :exc:`~werkzeug.exceptions.SecurityError`.

:param environ: the WSGI environment to get the host of.

:param trusted_hosts: a list of trusted hosts, see :func:`host_is_trusted`

for more information.

"""

if 'HTTP_X_FORWARDED_HOST' in environ:

rv = environ['HTTP_X_FORWARDED_HOST'].split(',')[0].strip()

elif 'HTTP_HOST' in environ:

rv = environ['HTTP_HOST']

else:

rv = environ['SERVER_NAME']

if (environ['wsgi.url_scheme'], environ['SERVER_PORT']) not \

in (('https', '443'), ('http', '80')):

rv += ':' + environ['SERVER_PORT']

if trusted_hosts is not None:

if not host_is_trusted(rv, trusted_hosts):

from werkzeug.exceptions import SecurityError

raise SecurityError('Host "%s" is not trusted' % rv)

"""Returns the content length from the WSGI environment as

integer. If it's not available `None` is returned.

.. versionadded:: 0.9

:param environ: the WSGI environ to fetch the content length from.

"""

content_length = environ.get('CONTENT_LENGTH')

if content_length is not None:

try:

return int(content_length)

except (ValueError, TypeError):

"""Returns the input stream from the WSGI environment and wraps it

in the most sensible way possible. The stream returned is not the

raw WSGI stream in most cases but one that is safe to read from

without taking into account the content length.

.. versionadded:: 0.9

:param environ: the WSGI environ to fetch the stream from.

:param safe: indicates weather the function should use an empty

stream as safe fallback or just return the original

WSGI input stream if it can't wrap it safely. The

default is to return an empty string in those cases.

"""

stream = environ['wsgi.input']

content_length = get_content_length(environ)

# If the content length is negative we're dealing with a WSGI

# server that gives us a chunked response already dechunked which

# however means we don't know the actual content length.

#

# XXX: check this behavior against gunicorn/mod_wsgi and other

# WSGI servers to make a better decision

if content_length == -1:

return stream

if content_length is None:

return safe_fallback and _empty_stream or stream

# Otherwise limit the stream to the content length

"""Returns the `QUERY_STRING` from the WSGI environment. This also takes

care about the WSGI decoding dance on Python 3 environments as a

native string. The string returned will be restricted to ASCII

characters.

.. versionadded:: 0.9

:param environ: the WSGI environment object to get the query string from.

"""

qs = wsgi_get_bytes(environ.get('QUERY_STRING', ''))

# QUERY_STRING really should be ascii safe but some browsers

# will send us some unicode stuff (I am looking at you IE).

# In that case we want to urllib quote it badly.

"""Returns the `PATH_INFO` from the WSGI environment and properly

decodes it. This also takes care about the WSGI decoding dance

on Python 3 environments. if the `charset` is set to `None` a

bytestring is returned.

.. versionadded:: 0.9

:param environ: the WSGI environment object to get the path from.

:param charset: the charset for the path info, or `None` if no

decoding should be performed.

:param errors: the decoding error handling.

"""

path = wsgi_get_bytes(environ.get('PATH_INFO', ''))

"""Returns the `SCRIPT_NAME` from the WSGI environment and properly

decodes it. This also takes care about the WSGI decoding dance

on Python 3 environments. if the `charset` is set to `None` a

bytestring is returned.

.. versionadded:: 0.9

:param environ: the WSGI environment object to get the path from.

:param charset: the charset for the path, or `None` if no

decoding should be performed.

:param errors: the decoding error handling.

"""

path = wsgi_get_bytes(environ.get('SCRIPT_NAME', ''))

"""Removes and returns the next segment of `PATH_INFO`, pushing it onto

`SCRIPT_NAME`. Returns `None` if there is nothing left on `PATH_INFO`.

If the `charset` is set to `None` a bytestring is returned.

If there are empty segments (``'/foo//bar``) these are ignored but

properly pushed to the `SCRIPT_NAME`:

>>> env = {'SCRIPT_NAME': '/foo', 'PATH_INFO': '/a/b'}

>>> pop_path_info(env)

'a'

>>> env['SCRIPT_NAME']

'/foo/a'

>>> pop_path_info(env)

'b'

>>> env['SCRIPT_NAME']

'/foo/a/b'

.. versionadded:: 0.5

.. versionchanged:: 0.9

The path is now decoded and a charset and encoding

parameter can be provided.

:param environ: the WSGI environment that is modified.

"""

path = environ.get('PATH_INFO')

if not path:

return None

script_name = environ.get('SCRIPT_NAME', '')

# shift multiple leading slashes over

old_path = path

path = path.lstrip('/')

if path != old_path:

script_name += '/' * (len(old_path) - len(path))

if '/' not in path:

environ['PATH_INFO'] = ''

environ['SCRIPT_NAME'] = script_name + path

rv = wsgi_get_bytes(path)

else:

segment, path = path.split('/', 1)

environ['PATH_INFO'] = '/' + path

environ['SCRIPT_NAME'] = script_name + segment

rv = wsgi_get_bytes(segment)

"""Returns the next segment on the `PATH_INFO` or `None` if there

is none. Works like :func:`pop_path_info` without modifying the

environment:

>>> env = {'SCRIPT_NAME': '/foo', 'PATH_INFO': '/a/b'}

>>> peek_path_info(env)

'a'

>>> peek_path_info(env)

'a'

If the `charset` is set to `None` a bytestring is returned.

.. versionadded:: 0.5

.. versionchanged:: 0.9

The path is now decoded and a charset and encoding

parameter can be provided.

:param environ: the WSGI environment that is checked.

"""

segments = environ.get('PATH_INFO', '').lstrip('/').split('/', 1)

if segments:

return to_unicode(wsgi_get_bytes(segments[0]),

errors='replace', collapse_http_schemes=True):

"""Extracts the path info from the given URL (or WSGI environment) and

path. The path info returned is a unicode string, not a bytestring

suitable for a WSGI environment. The URLs might also be IRIs.

If the path info could not be determined, `None` is returned.

Some examples:

>>> extract_path_info('http://example.com/app', '/app/hello')

u'/hello'

>>> extract_path_info('http://example.com/app',

... 'https://example.com/app/hello')

u'/hello'

>>> extract_path_info('http://example.com/app',

... 'https://example.com/app/hello',

... collapse_http_schemes=False) is None

True

Instead of providing a base URL you can also pass a WSGI environment.

.. versionadded:: 0.6

:param environ_or_baseurl: a WSGI environment dict, a base URL or

base IRI. This is the root of the

application.

:param path_or_url: an absolute path from the server root, a

relative path (in which case it's the path info)

or a full URL. Also accepts IRIs and unicode

parameters.

:param charset: the charset for byte data in URLs

:param errors: the error handling on decode

:param collapse_http_schemes: if set to `False` the algorithm does

not assume that http and https on the

same server point to the same

resource.

"""

def _normalize_netloc(scheme, netloc):

parts = netloc.split(u'@', 1)[-1].split(u':', 1)

if len(parts) == 2:

netloc, port = parts

if (scheme == u'http' and port == u'80') or \

(scheme == u'https' and port == u'443'):

port = None

else:

netloc = parts[0]

port = None

if port is not None:

netloc += u':' + port

return netloc

# make sure whatever we are working on is a IRI and parse it

path = uri_to_iri(path_or_url, charset, errors)

if isinstance(environ_or_baseurl, dict):

environ_or_baseurl = get_current_url(environ_or_baseurl,

root_only=True)

base_iri = uri_to_iri(environ_or_baseurl, charset, errors)

base_scheme, base_netloc, base_path = url_parse(base_iri)[:3]

cur_scheme, cur_netloc, cur_path, = \

url_parse(url_join(base_iri, path))[:3]

# normalize the network location

base_netloc = _normalize_netloc(base_scheme, base_netloc)

cur_netloc = _normalize_netloc(cur_scheme, cur_netloc)

# is that IRI even on a known HTTP scheme?

if collapse_http_schemes:

for scheme in base_scheme, cur_scheme:

if scheme not in (u'http', u'https'):

return None

else:

if not (base_scheme in (u'http', u'https') and \

base_scheme == cur_scheme):

return None

# are the netlocs compatible?

if base_netloc != cur_netloc:

return None

# are we below the application path?

base_path = base_path.rstrip(u'/')

if not cur_path.startswith(base_path):

return None

"""A WSGI middleware that provides static content for development

environments or simple server setups. Usage is quite simple::

import os

from werkzeug.wsgi import SharedDataMiddleware

app = SharedDataMiddleware(app, {

'/shared': os.path.join(os.path.dirname(__file__), 'shared')

})

The contents of the folder ``./shared`` will now be available on

``http://example.com/shared/``. This is pretty useful during development

because a standalone media server is not required. One can also mount

files on the root folder and still continue to use the application because

the shared data middleware forwards all unhandled requests to the

application, even if the requests are below one of the shared folders.

If `pkg_resources` is available you can also tell the middleware to serve

files from package data::

app = SharedDataMiddleware(app, {

'/shared': ('myapplication', 'shared_files')

})

This will then serve the ``shared_files`` folder in the `myapplication`

Python package.

The optional `disallow` parameter can be a list of :func:`~fnmatch.fnmatch`

rules for files that are not accessible from the web. If `cache` is set to

`False` no caching headers are sent.

Currently the middleware does not support non ASCII filenames. If the

encoding on the file system happens to be the encoding of the URI it may

work but this could also be by accident. We strongly suggest using ASCII

only file names for static files.

The middleware will guess the mimetype using the Python `mimetype`

module. If it's unable to figure out the charset it will fall back

to `fallback_mimetype`.

.. versionchanged:: 0.5

The cache timeout is configurable now.

.. versionadded:: 0.6

The `fallback_mimetype` parameter was added.

:param app: the application to wrap. If you don't want to wrap an

application you can pass it :exc:`NotFound`.

:param exports: a dict of exported files and folders.

:param disallow: a list of :func:`~fnmatch.fnmatch` rules.

:param fallback_mimetype: the fallback mimetype for unknown files.

:param cache: enable or disable caching headers.

:Param cache_timeout: the cache timeout in seconds for the headers.

"""

def __init__(self, app, exports, disallow=None, cache=True,

cache_timeout=60 * 60 * 12, fallback_mimetype='text/plain'):

self.app = app

self.exports = {}

self.cache = cache

self.cache_timeout = cache_timeout

for key, value in iteritems(exports):

if isinstance(value, tuple):

loader = self.get_package_loader(*value)

elif isinstance(value, string_types):

if os.path.isfile(value):

loader = self.get_file_loader(value)

else:

loader = self.get_directory_loader(value)

else:

raise TypeError('unknown def %r' % value)

self.exports[key] = loader

if disallow is not None:

from fnmatch import fnmatch

self.is_allowed = lambda x: not fnmatch(x, disallow)

self.fallback_mimetype = fallback_mimetype

def is_allowed(self, filename):

"""Subclasses can override this method to disallow the access to

certain files. However by providing `disallow` in the constructor

this method is overwritten.

"""

return True

def _opener(self, filename):

return lambda: (

open(filename, 'rb'),

datetime.utcfromtimestamp(os.path.getmtime(filename)),

int(os.path.getsize(filename))

)

def get_file_loader(self, filename):

return lambda x: (os.path.basename(filename), self._opener(filename))

def get_package_loader(self, package, package_path):

from pkg_resources import DefaultProvider, ResourceManager, \

get_provider

loadtime = datetime.utcnow()

provider = get_provider(package)

manager = ResourceManager()

filesystem_bound = isinstance(provider, DefaultProvider)

def loader(path):

if path is None:

return None, None

path = posixpath.join(package_path, path)

if not provider.has_resource(path):

return None, None

basename = posixpath.basename(path)

if filesystem_bound:

return basename, self._opener(

provider.get_resource_filename(manager, path))

return basename, lambda: (

provider.get_resource_stream(manager, path),

loadtime,

0

)

return loader

def get_directory_loader(self, directory):

def loader(path):

if path is not None:

path = os.path.join(directory, path)

else:

path = directory

if os.path.isfile(path):

return os.path.basename(path), self._opener(path)

return None, None

return loader

def generate_etag(self, mtime, file_size, real_filename):

return 'wzsdm-%d-%s-%s' % (

mktime(mtime.timetuple()),

file_size,

adler32(real_filename.encode(sys.getfilesystemencoding())) & 0xffffffff

)

def __call__(self, environ, start_response):

# sanitize the path for non unix systems

cleaned_path = environ.get('PATH_INFO', '').strip('/')

for sep in os.sep, os.altsep:

if sep and sep != '/':

cleaned_path = cleaned_path.replace(sep, '/')

path = '/'.join([''] + [x for x in cleaned_path.split('/')

if x and x != '..'])

file_loader = None

for search_path, loader in iteritems(self.exports):

if search_path == path:

real_filename, file_loader = loader(None)

if file_loader is not None:

break

if not search_path.endswith('/'):

search_path += '/'

if path.startswith(search_path):

real_filename, file_loader = loader(path[len(search_path):])

if file_loader is not None:

break

if file_loader is None or not self.is_allowed(real_filename):

return self.app(environ, start_response)

guessed_type = mimetypes.guess_type(real_filename)

mime_type = guessed_type[0] or self.fallback_mimetype

f, mtime, file_size = file_loader()

headers = [('Date', http_date())]

if self.cache:

timeout = self.cache_timeout

etag = self.generate_etag(mtime, file_size, real_filename)

headers += [

('Etag', '"%s"' % etag),

('Cache-Control', 'max-age=%d, public' % timeout)

]

if not is_resource_modified(environ, etag, last_modified=mtime):

f.close()

start_response('304 Not Modified', headers)

return []

headers.append(('Expires', http_date(time() + timeout)))

else:

headers.append(('Cache-Control', 'public'))

headers.extend((

('Content-Type', mime_type),

('Content-Length', str(file_size)),

('Last-Modified', http_date(mtime))

))

start_response('200 OK', headers)

"""Allows one to mount middlewares or applications in a WSGI application.

This is useful if you want to combine multiple WSGI applications::

app = DispatcherMiddleware(app, {

'/app2': app2,

'/app3': app3

})

"""

def __init__(self, app, mounts=None):

self.app = app

self.mounts = mounts or {}

def __call__(self, environ, start_response):

script = environ.get('PATH_INFO', '')

path_info = ''

while '/' in script:

if script in self.mounts:

app = self.mounts[script]

break

items = script.split('/')

script = '/'.join(items[:-1])

path_info = '/%s%s' % (items[-1], path_info)

else:

app = self.mounts.get(script, self.app)

original_script_name = environ.get('SCRIPT_NAME', '')

environ['SCRIPT_NAME'] = original_script_name + script

environ['PATH_INFO'] = path_info

"""The WSGI specification requires that all middlewares and gateways

respect the `close` callback of an iterator. Because it is useful to add

another close action to a returned iterator and adding a custom iterator

is a boring task this class can be used for that::

return ClosingIterator(app(environ, start_response), [cleanup_session,

cleanup_locals])

If there is just one close function it can be passed instead of the list.

A closing iterator is not needed if the application uses response objects

and finishes the processing if the response is started::

try:

return response(environ, start_response)

finally:

cleanup_session()

cleanup_locals()

"""

def __init__(self, iterable, callbacks=None):

iterator = iter(iterable)

self._next = partial(next, iterator)

if callbacks is None:

callbacks = []

elif callable(callbacks):

callbacks = [callbacks]

else:

callbacks = list(callbacks)

iterable_close = getattr(iterator, 'close', None)

if iterable_close:

callbacks.insert(0, iterable_close)

self._callbacks = callbacks

def __iter__(self):

return self

def __next__(self):

return self._next()

def close(self):

for callback in self._callbacks:

"""Wraps a file. This uses the WSGI server's file wrapper if available

or otherwise the generic :class:`FileWrapper`.

.. versionadded:: 0.5

If the file wrapper from the WSGI server is used it's important to not

iterate over it from inside the application but to pass it through

unchanged. If you want to pass out a file wrapper inside a response

object you have to set :attr:`~BaseResponse.direct_passthrough` to `True`.

More information about file wrappers are available in :pep:`333`.

:param file: a :class:`file`-like object with a :meth:`~file.read` method.

:param buffer_size: number of bytes for one iteration.

"""

"""This class can be used to convert a :class:`file`-like object into

an iterable. It yields `buffer_size` blocks until the file is fully

read.

You should not use this class directly but rather use the

:func:`wrap_file` function that uses the WSGI server's file wrapper

support if it's available.

.. versionadded:: 0.5

If you're using this object together with a :class:`BaseResponse` you have

to use the `direct_passthrough` mode.

:param file: a :class:`file`-like object with a :meth:`~file.read` method.

:param buffer_size: number of bytes for one iteration.

"""

def __init__(self, file, buffer_size=8192):

self.file = file

self.buffer_size = buffer_size

def close(self):

if hasattr(self.file, 'close'):

self.file.close()

def __iter__(self):

return self

def __next__(self):

data = self.file.read(self.buffer_size)

if data:

return data

"""Helper for the line and chunk iter functions."""

if isinstance(stream, (bytes, bytearray, text_type)):

raise TypeError('Passed a string or byte object instead of '

'true iterator or stream.')

if not hasattr(stream, 'read'):

for item in stream:

if item:

yield item

return

if not isinstance(stream, LimitedStream) and limit is not None:

stream = LimitedStream(stream, limit)

_read = stream.read

while 1:

item = _read(buffer_size)

if not item:

break

"""Safely iterates line-based over an input stream. If the input stream

is not a :class:`LimitedStream` the `limit` parameter is mandatory.

This uses the stream's :meth:`~file.read` method internally as opposite

to the :meth:`~file.readline` method that is unsafe and can only be used

in violation of the WSGI specification. The same problem applies to the

`__iter__` function of the input stream which calls :meth:`~file.readline`

without arguments.

If you need line-by-line processing it's strongly recommended to iterate

over the input stream using this helper function.

.. versionchanged:: 0.8

This function now ensures that the limit was reached.

.. versionadded:: 0.9

added support for iterators as input stream.

:param stream: the stream or iterate to iterate over.

:param limit: the limit in bytes for the stream. (Usually

content length. Not necessary if the `stream`

is a :class:`LimitedStream`.

:param buffer_size: The optional buffer size.

"""

_iter = _make_chunk_iter(stream, limit, buffer_size)

first_item = next(_iter, '')

if not first_item:

return

s = make_literal_wrapper(first_item)

empty = s('')

cr = s('\r')

lf = s('\n')

crlf = s('\r\n')

_iter = chain((first_item,), _iter)

def _iter_basic_lines():

_join = empty.join

buffer = []

while 1:

new_data = next(_iter, '')

if not new_data:

break

new_buf = []

for item in chain(buffer, new_data.splitlines(True)):

new_buf.append(item)

if item and item[-1:] in crlf:

yield _join(new_buf)

new_buf = []

buffer = new_buf

if buffer:

yield _join(buffer)

# This hackery is necessary to merge 'foo\r' and '\n' into one item

# of 'foo\r\n' if we were unlucky and we hit a chunk boundary.

previous = empty

for item in _iter_basic_lines():

if item == lf and previous[-1:] == cr:

previous += item

item = empty

if previous:

yield previous

previous = item

if previous:

"""Works like :func:`make_line_iter` but accepts a separator

which divides chunks. If you want newline based processing

you should use :func:`make_line_iter` instead as it

supports arbitrary newline markers.

.. versionadded:: 0.8

.. versionadded:: 0.9

added support for iterators as input stream.

:param stream: the stream or iterate to iterate over.

:param separator: the separator that divides chunks.

:param limit: the limit in bytes for the stream. (Usually

content length. Not necessary if the `stream`

is otherwise already limited).

:param buffer_size: The optional buffer size.

"""

_iter = _make_chunk_iter(stream, limit, buffer_size)

first_item = next(_iter, '')

if not first_item:

return

_iter = chain((first_item,), _iter)

if isinstance(first_item, text_type):

separator = to_unicode(separator)

_split = re.compile(r'(%s)' % re.escape(separator)).split

_join = u''.join

else:

separator = to_bytes(separator)

_split = re.compile(b'(' + re.escape(separator) + b')').split

_join = b''.join

buffer = []

while 1:

new_data = next(_iter, '')

if not new_data:

break

chunks = _split(new_data)

new_buf = []

for item in chain(buffer, chunks):

if item == separator:

yield _join(new_buf)

new_buf = []

else:

new_buf.append(item)

buffer = new_buf

if buffer:

"""Wraps a stream so that it doesn't read more than n bytes. If the

stream is exhausted and the caller tries to get more bytes from it

:func:`on_exhausted` is called which by default returns an empty

string. The return value of that function is forwarded

to the reader function. So if it returns an empty string

:meth:`read` will return an empty string as well.

The limit however must never be higher than what the stream can

output. Otherwise :meth:`readlines` will try to read past the

limit.

.. admonition:: Note on WSGI compliance

calls to :meth:`readline` and :meth:`readlines` are not

WSGI compliant because it passes a size argument to the

readline methods. Unfortunately the WSGI PEP is not safely

implementable without a size argument to :meth:`readline`

because there is no EOF marker in the stream. As a result

of that the use of :meth:`readline` is discouraged.

For the same reason iterating over the :class:`LimitedStream`

is not portable. It internally calls :meth:`readline`.

We strongly suggest using :meth:`read` only or using the

:func:`make_line_iter` which safely iterates line-based

over a WSGI input stream.

:param stream: the stream to wrap.

:param limit: the limit for the stream, must not be longer than

what the string can provide if the stream does not

end with `EOF` (like `wsgi.input`)

"""

def __init__(self, stream, limit):

self._read = stream.read

self._readline = stream.readline

self._pos = 0

self.limit = limit

def __iter__(self):

return self

@property

def is_exhausted(self):

"""If the stream is exhausted this attribute is `True`."""

return self._pos >= self.limit

def on_exhausted(self):

"""This is called when the stream tries to read past the limit.

The return value of this function is returned from the reading

function.

"""

# Read null bytes from the stream so that we get the

# correct end of stream marker.

return self._read(0)

def on_disconnect(self):

"""What should happen if a disconnect is detected? The return

value of this function is returned from read functions in case

the client went away. By default a

:exc:`~werkzeug.exceptions.ClientDisconnected` exception is raised.

"""

from werkzeug.exceptions import ClientDisconnected

raise ClientDisconnected()

def exhaust(self, chunk_size=1024 * 16):

"""Exhaust the stream. This consumes all the data left until the

limit is reached.

:param chunk_size: the size for a chunk. It will read the chunk

until the stream is exhausted and throw away

the results.

"""

to_read = self.limit - self._pos

chunk = chunk_size

while to_read > 0:

chunk = min(to_read, chunk)

self.read(chunk)

to_read -= chunk

def read(self, size=None):

"""Read `size` bytes or if size is not provided everything is read.

:param size: the number of bytes read.

"""

if self._pos >= self.limit:

return self.on_exhausted()

if size is None or size == -1: # -1 is for consistence with file

size = self.limit

to_read = min(self.limit - self._pos, size)

try:

read = self._read(to_read)

except (IOError, ValueError):

return self.on_disconnect()

if to_read and len(read) != to_read:

return self.on_disconnect()

self._pos += len(read)

return read

def readline(self, size=None):

"""Reads one line from the stream."""

if self._pos >= self.limit:

return self.on_exhausted()

if size is None:

size = self.limit - self._pos

else:

size = min(size, self.limit - self._pos)

try:

line = self._readline(size)

except (ValueError, IOError):

return self.on_disconnect()

if size and not line:

return self.on_disconnect()

self._pos += len(line)

return line

def readlines(self, size=None):

"""Reads a file into a list of strings. It calls :meth:`readline`