From 7c59362a15dfce538512ff1fce4e07d33a925cfb Mon Sep 17 00:00:00 2001
From: Berker Peksag <berker.peksag@gmail.com>
Date: Sun, 19 May 2019 18:56:15 +0300
Subject: [PATCH] bpo-29183: Fix double exceptions in
wsgiref.handlers.BaseHandler (GH-12914)
---
Lib/test/test_wsgiref.py | 25 +++++++++++++++++++
Lib/wsgiref/handlers.py | 11 +++++++-
.../2019-04-22-22-55-29.bpo-29183.MILvsk.rst | 3 +++
3 files changed, 38 insertions(+), 1 deletion(-)
create mode 100644 Misc/NEWS.d/next/Library/2019-04-22-22-55-29.bpo-29183.MILvsk.rst
diff --git a/Lib/test/test_wsgiref.py b/Lib/test/test_wsgiref.py
index 46f88a9443..42432bfbd2 100644
--- a/Lib/test/test_wsgiref.py
+++ b/Lib/test/test_wsgiref.py
@@ -806,6 +806,31 @@ class HandlerTests(TestCase):
self.assertFalse(stderr.getvalue())
+ def testDontResetInternalStateOnException(self):
+ class CustomException(ValueError):
+ pass
+
+ # We are raising CustomException here to trigger an exception
+ # during the execution of SimpleHandler.finish_response(), so
+ # we can easily test that the internal state of the handler is
+ # preserved in case of an exception.
+ class AbortingWriter:
+ def write(self, b):
+ raise CustomException
+
+ stderr = StringIO()
+ environ = {"SERVER_PROTOCOL": "HTTP/1.0"}
+ h = SimpleHandler(BytesIO(), AbortingWriter(), stderr, environ)
+ h.run(hello_app)
+
+ self.assertIn("CustomException", stderr.getvalue())
+
+ # Test that the internal state of the handler is preserved.
+ self.assertIsNotNone(h.result)
+ self.assertIsNotNone(h.headers)
+ self.assertIsNotNone(h.status)
+ self.assertIsNotNone(h.environ)
+
if __name__ == "__main__":
unittest.main()
diff --git a/Lib/wsgiref/handlers.py b/Lib/wsgiref/handlers.py
index 834073d500..31360e5878 100644
--- a/Lib/wsgiref/handlers.py
+++ b/Lib/wsgiref/handlers.py
@@ -183,7 +183,16 @@ class BaseHandler:
for data in self.result:
self.write(data)
self.finish_content()
- finally:
+ except:
+ # Call close() on the iterable returned by the WSGI application
+ # in case of an exception.
+ if hasattr(self.result, 'close'):
+ self.result.close()
+ raise
+ else:
+ # We only call close() when no exception is raised, because it
+ # will set status, result, headers, and environ fields to None.
+ # See bpo-29183 for more details.
self.close()
diff --git a/Misc/NEWS.d/next/Library/2019-04-22-22-55-29.bpo-29183.MILvsk.rst b/Misc/NEWS.d/next/Library/2019-04-22-22-55-29.bpo-29183.MILvsk.rst
new file mode 100644
index 0000000000..1d19f191ee
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-04-22-22-55-29.bpo-29183.MILvsk.rst
@@ -0,0 +1,3 @@
+Fix double exceptions in :class:`wsgiref.handlers.BaseHandler` by calling
+its :meth:`~wsgiref.handlers.BaseHandler.close` method only when no
+exception is raised.
--
2.40.0