Merge pull request #3029 from mmerickel/clear-request.exception

Michael Merickel

2017-05-03 2edbd967ef8f017f53a565d913556c38f545bbaf

Merge pull request #3029 from mmerickel/clear-request.exception

clear request.exception if the excview fails to handle the error

 pyramid/tests/test_tweens.py

@@ -22,6 +22,8 @@
        request = DummyRequest()
        result = tween(request)
        self.assertTrue(result is dummy_response)
        self.assertIsNone(request.exception)
        self.assertIsNone(request.exc_info)

    def test_it_catches_notfound(self):
        from pyramid.request import Request
@@ -31,8 +33,11 @@
            raise HTTPNotFound
        tween = self._makeOne(handler)
        request = Request.blank('/')
        request.registry = self.config.registry
        result = tween(request)
        self.assertEqual(result.status, '404 Not Found')
        self.assertIsInstance(request.exception, HTTPNotFound)
        self.assertEqual(request.exception, request.exc_info[1])

    def test_it_catches_with_predicate(self):
        from pyramid.request import Request
@@ -44,8 +49,11 @@
            raise ValueError
        tween = self._makeOne(handler)
        request = Request.blank('/')
        request.registry = self.config.registry
        result = tween(request)
        self.assertTrue(b'foo' in result.body)
        self.assertIsInstance(request.exception, ValueError)
        self.assertEqual(request.exception, request.exc_info[1])

    def test_it_reraises_on_mismatch(self):
        from pyramid.request import Request
@@ -55,8 +63,11 @@
            raise ValueError
        tween = self._makeOne(handler)
        request = Request.blank('/')
        request.registry = self.config.registry
        request.method = 'POST'
        self.assertRaises(ValueError, lambda: tween(request))
        self.assertIsNone(request.exception)
        self.assertIsNone(request.exc_info)

    def test_it_reraises_on_no_match(self):
        from pyramid.request import Request
@@ -64,10 +75,14 @@
            raise ValueError
        tween = self._makeOne(handler)
        request = Request.blank('/')
        request.registry = self.config.registry
        self.assertRaises(ValueError, lambda: tween(request))
        self.assertIsNone(request.exception)
        self.assertIsNone(request.exc_info)

class DummyRequest:
    pass
    exception = None
    exc_info = None

class DummyResponse:
    pass

 pyramid/tweens.py

@@ -10,6 +10,50 @@
from zope.interface import providedBy
from pyramid.view import _call_view

def _error_handler(request, exc):
    # NOTE: we do not need to delete exc_info because this function
    # should never be in the call stack of the exception
    exc_info = sys.exc_info()

    attrs = request.__dict__
    attrs['exc_info'] = exc_info
    attrs['exception'] = exc
    # clear old generated request.response, if any; it may
    # have been mutated by the view, and its state is not
    # sane (e.g. caching headers)
    if 'response' in attrs:
        del attrs['response']
    # we use .get instead of .__getitem__ below due to
    # https://github.com/Pylons/pyramid/issues/700
    request_iface = attrs.get('request_iface', IRequest)
    provides = providedBy(exc)
    try:
        response = _call_view(
            request.registry,
            request,
            exc,
            provides,
            '',
            view_classifier=IExceptionViewClassifier,
            request_iface=request_iface.combined
            )

    # if views matched but did not pass predicates then treat the
    # same as not finding any matching views
    except PredicateMismatch:
        response = None

    # re-raise the original exception as no exception views were
    # able to handle the error
    if response is None:
        if 'exception' in attrs:
            del attrs['exception']
        if 'exc_info' in attrs:
            del attrs['exc_info']
        reraise(*exc_info)

    return response

def excview_tween_factory(handler, registry):
    """ A :term:`tween` factory which produces a tween that catches an
    exception raised by downstream tweens (or the main Pyramid request
@@ -17,50 +61,10 @@
    :term:`exception view`."""

    def excview_tween(request):
        attrs = request.__dict__
        try:
            response = handler(request)
        except Exception as exc:
            # WARNING: do not assign the result of sys.exc_info() to a local
            # var here, doing so will cause a leak.  We used to actually
            # explicitly delete both "exception" and "exc_info" from ``attrs``
            # in a ``finally:`` clause below, but now we do not because these
            # attributes are useful to upstream tweens.  This actually still
            # apparently causes a reference cycle, but it is broken
            # successfully by the garbage collector (see
            # https://github.com/Pylons/pyramid/issues/1223).
            attrs['exc_info'] = sys.exc_info()
            attrs['exception'] = exc
            # clear old generated request.response, if any; it may
            # have been mutated by the view, and its state is not
            # sane (e.g. caching headers)
            if 'response' in attrs:
                del attrs['response']
            # we use .get instead of .__getitem__ below due to
            # https://github.com/Pylons/pyramid/issues/700
            request_iface = attrs.get('request_iface', IRequest)
            provides = providedBy(exc)
            try:
                response = _call_view(
                    registry,
                    request,
                    exc,
                    provides,
                    '',
                    view_classifier=IExceptionViewClassifier,
                    request_iface=request_iface.combined
                    )

            # if views matched but did not pass predicates, squash the error
            # and re-raise the original exception
            except PredicateMismatch:
                response = None

            # re-raise the original exception as no exception views were
            # able to handle the error
            if response is None:
                reraise(*attrs['exc_info'])

            response = _error_handler(request, exc)
        return response

    return excview_tween