[Python-checkins] cpython: Fix crash in itertools.cycle.setstate() caused by lack of type checking.

Sat Aug 15 22:52:07 CEST 2015

https://hg.python.org/cpython/rev/a4d5ef7fdec3
changeset: 97390:a4d5ef7fdec3
user: Raymond Hettinger <python at rcn.com>
date: Sat Aug 15 13:51:59 2015 -0700
summary:
 Fix crash in itertools.cycle.__setstate__() caused by lack of type checking.
Will backport after the 3.6 release is done.
files:
 Lib/test/test_itertools.py | 33 ++++++++++++++++++++++++++
 Misc/NEWS | 3 ++
 Modules/itertoolsmodule.c | 2 +-
 3 files changed, 37 insertions(+), 1 deletions(-)

diff --git a/Lib/test/test_itertools.py b/Lib/test/test_itertools.py
--- a/Lib/test/test_itertools.py
+++ b/Lib/test/test_itertools.py
@@ -613,6 +613,39 @@
 for proto in range(pickle.HIGHEST_PROTOCOL + 1):
 self.pickletest(proto, cycle('abc'))
 
+ def test_cycle_setstate(self):
+ # Verify both modes for restoring state
+
+ # Mode 0 is efficient. It uses an incompletely consumed input
+ # iterator to build a cycle object and then passes in state with
+ # a list of previously consumed values. There is no data
+ # overlap bewteen the two.
+ c = cycle('defg')
+ c.__setstate__((list('abc'), 0))
+ self.assertEqual(take(20, c), list('defgabcdefgabcdefgab'))
+
+ # Mode 1 is inefficient. It starts with a cycle object built
+ # from an iterator over the remaining elements in a partial
+ # cycle and then passes in state with all of the previously
+ # seen values (this overlaps values included in the iterator).
+ c = cycle('defg')
+ c.__setstate__((list('abcdefg'), 1))
+ self.assertEqual(take(20, c), list('defgabcdefgabcdefgab'))
+
+ # The first argument to setstate needs to be a tuple
+ with self.assertRaises(SystemError):
+ cycle('defg').__setstate__([list('abcdefg'), 0])
+
+ # The first argument in the setstate tuple must be a list
+ with self.assertRaises(TypeError):
+ c = cycle('defg')
+ c.__setstate__((dict.fromkeys('defg'), 0))
+ take(20, c)
+
+ # The first argument in the setstate tuple must be a list
+ with self.assertRaises(TypeError):
+ cycle('defg').__setstate__((list('abcdefg'), 'x'))
+
 def test_groupby(self):
 # Check whether it accepts arguments correctly
 self.assertEqual([], list(groupby([])))
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -25,6 +25,9 @@
 - Issue #21159: Improve message in configparser.InterpolationMissingOptionError.
 Patch from Łukasz Langa.
 
+- Fix crash in itertools.cycle.__setstate__() when the first argument wasn't
+ a list.
+
 - Issue #20059: urllib.parse raises ValueError on all invalid ports.
 Patch by Martin Panter.
 
diff --git a/Modules/itertoolsmodule.c b/Modules/itertoolsmodule.c
--- a/Modules/itertoolsmodule.c
+++ b/Modules/itertoolsmodule.c
@@ -973,7 +973,7 @@
 {
 PyObject *saved=NULL;
 int firstpass;
- if (!PyArg_ParseTuple(state, "Oi", &saved, &firstpass))
+ if (!PyArg_ParseTuple(state, "O!i", &PyList_Type, &saved, &firstpass))
 return NULL;
 Py_CLEAR(lz->saved);
 lz->saved = saved;
-- 
Repository URL: https://hg.python.org/cpython


[Python-checkins] cpython: Fix crash in itertools.cycle.__setstate__() caused by lack of type checking.

[Python-checkins] cpython: Fix crash in itertools.cycle.setstate() caused by lack of type checking.