[Repoze-dev] [issue184] repoze.who raises an exception when the WSGI response iterator is empty.

[Tres Seaver]

Tres Seaver  added the comment:

Fixed for 2.3 release:

 
https://github.com/repoze/repoze.who/commit/19d2190b6240a7b7a9fdfc536e6ec865cd5ddf07

--
status: unread -> resolved

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[Repoze-dev] [issue184] repoze.who raises an exception when the WSGI response iterator is empty.

[Olly]

New submission from Olly :

repoze.who middleware raises an exception when the WSGI response iterator is
empty. This
causes responses with no content body (eg 304 not modified) to fail::

2012-07-15 20:49:36,759 ERROR [gunicorn.error] Error handling request
Traceback (most recent call last):
File "gunicorn/workers/sync.py", line 107, in handle_request
for item in respiter:
File "util/wsgi.py", line 132, in next
return self._next()
File "eggs/repoze.who-2.0-py2.7.egg/repoze/who/middleware.py", line 145, in
wrapper
yield first
NameError: free variable 'first' referenced before assignment in enclosing 
scope


I think the bug is in repoze/who/middleware.py:wrap_generator, which only
assigns a value to `first` if there is at least one iteration::

def wrap_generator(result):
"""\
This function returns a generator that behaves exactly the same as the
original.  It's only difference is it pulls the first iteration off and
caches it to trigger any immediate side effects (in a WSGI world, this
ensures start_response is called).
"""
# PEP 333 requires that we call the original iterator's
# 'close' method, if it exists, before releasing it.
close = getattr(result, 'close', lambda: None)
# Neat trick to pull the first iteration only. We need to do this 
outside
# of the generator function to ensure it is called.
for iter in result:
first = iter
break

# Wrapper yields the first iteration, then passes result's iterations
# directly up.
def wrapper():
yield first
for iter in result:
# We'll let result's StopIteration bubble up directly.
yield iter
close()
return wrapper()

--
messages: 541
nosy: olly
priority: bug
status: unread
title: repoze.who raises an exception when the WSGI response iterator is empty.
topic: repoze.who

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