Merge pull request #41 from bukzor/buck-less-deadlock

avoid infinite regress in __getattr__

cachecontrol/filewrapper.py

@@ -19,7 +19,11 @@ def __init__(self, fp, callback):
         self.__callback = callback
 
     def __getattr__(self, name):
-        return getattr(self.__fp, name)
+        # The vaguaries of garbage collection means that self.__fp is not always set.
+        # This strange style lets us throw AttributeError in that case, rather than
+        # recursing infinitely
+        fp = self.__getattribute__('_CallbackFileWrapper__fp')
+        return getattr(fp, name)
 
     def __is_fp_closed(self):
         try:

tests/test_regressions.py

@@ -4,6 +4,7 @@
 
 from cachecontrol import CacheControl
 from cachecontrol.caches.file_cache import FileCache
+from cachecontrol.filewrapper import CallbackFileWrapper
 from requests import Session
 
 
@@ -16,3 +17,15 @@ def test_file_cache_recognizes_consumed_file_handle(self):
         s.get('http://httpbin.org/cache/60')
         r = s.get('http://httpbin.org/cache/60')
         assert r.from_cache
+
+
+def test_getattr_during_gc():
+    s = CallbackFileWrapper(None, None)
+    # normal behavior:
+    with pytest.raises(AttributeError):
+        s.x
+
+    # this previously had caused an infinite recursion
+    vars(s).clear()  # gc does this.
+    with pytest.raises(AttributeError):
+        s.x