bpo-30441: Fix bug when modifying os.environ while iterating over it (#2409)
diff --git a/Lib/os.py b/Lib/os.py
index e293eca..807ddb5 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -697,7 +697,9 @@
raise KeyError(key) from None
def __iter__(self):
- for key in self._data:
+ # list() from dict object is an atomic operation
+ keys = list(self._data)
+ for key in keys:
yield self.decodekey(key)
def __len__(self):
diff --git a/Lib/test/test_os.py b/Lib/test/test_os.py
index d069270..49e5a37 100644
--- a/Lib/test/test_os.py
+++ b/Lib/test/test_os.py
@@ -835,6 +835,30 @@
self.assertIs(cm.exception.args[0], missing)
self.assertTrue(cm.exception.__suppress_context__)
+ def _test_environ_iteration(self, collection):
+ iterator = iter(collection)
+ new_key = "__new_key__"
+
+ next(iterator) # start iteration over os.environ.items
+
+ # add a new key in os.environ mapping
+ os.environ[new_key] = "test_environ_iteration"
+
+ try:
+ next(iterator) # force iteration over modified mapping
+ self.assertEqual(os.environ[new_key], "test_environ_iteration")
+ finally:
+ del os.environ[new_key]
+
+ def test_iter_error_when_changing_os_environ(self):
+ self._test_environ_iteration(os.environ)
+
+ def test_iter_error_when_changing_os_environ_items(self):
+ self._test_environ_iteration(os.environ.items())
+
+ def test_iter_error_when_changing_os_environ_values(self):
+ self._test_environ_iteration(os.environ.values())
+
class WalkTests(unittest.TestCase):
"""Tests for os.walk()."""
diff --git a/Misc/ACKS b/Misc/ACKS
index 910f819..3455c1b 100644
--- a/Misc/ACKS
+++ b/Misc/ACKS
@@ -1088,6 +1088,7 @@
Tony Nelson
Trent Nelson
Andrew Nester
+Osvaldo Santana Neto
Chad Netzer
Max Neunhöffer
Anthon van der Neut
diff --git a/Misc/NEWS.d/next/Library/2017-06-29-14-25-14.bpo-30441.3Wh9kc.rst b/Misc/NEWS.d/next/Library/2017-06-29-14-25-14.bpo-30441.3Wh9kc.rst
new file mode 100644
index 0000000..55dd613
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2017-06-29-14-25-14.bpo-30441.3Wh9kc.rst
@@ -0,0 +1 @@
+Fix bug when modifying os.environ while iterating over it