[Python-checkins] cpython (2.7): Backport issue #12973 list_repeat fix from 3.x.

[mark.dickinson]

http://hg.python.org/cpython/rev/f8280cf63d9e
changeset:   72419:f8280cf63d9e
branch:      2.7
parent:      72416:07efe83795b0
user:        Mark Dickinson <mdickinson at enthought.com>
date:        Mon Sep 19 19:23:55 2011 +0100
summary:
  Backport issue #12973 list_repeat fix from 3.x.

files:
  Misc/NEWS            |  4 +++-
  Objects/listobject.c |  6 +++---
  2 files changed, 6 insertions(+), 4 deletions(-)


diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,7 +12,9 @@
 - Issue #12973: Fix overflow checks that invoked undefined behaviour in
   int.__pow__.  These overflow checks were causing int.__pow__ to produce
   incorrect results with recent versions of Clang, as a result of the
-  compiler optimizing the check away.
+  compiler optimizing the check away.  Also fix similar overflow check
+  in list_repeat (which caused test_list to fail with recent versions
+  of Clang).
 
 - Issue #12266: Fix str.capitalize() to correctly uppercase/lowercase
   titlecased and cased non-letter characters.
diff --git a/Objects/listobject.c b/Objects/listobject.c
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -58,7 +58,7 @@
     if (newsize == 0)
         new_allocated = 0;
     items = self->ob_item;
-    if (new_allocated <= ((~(size_t)0) / sizeof(PyObject *)))
+    if (new_allocated <= (PY_SIZE_MAX / sizeof(PyObject *)))
         PyMem_RESIZE(items, PyObject *, new_allocated);
     else
         items = NULL;
@@ -551,9 +551,9 @@
     PyObject *elem;
     if (n < 0)
         n = 0;
+    if (n > 0 && Py_SIZE(a) > PY_SSIZE_T_MAX / n)
+        return PyErr_NoMemory();
     size = Py_SIZE(a) * n;
-    if (n && size/n != Py_SIZE(a))
-        return PyErr_NoMemory();
     if (size == 0)
         return PyList_New(0);
     np = (PyListObject *) PyList_New(size);

-- 
Repository URL: http://hg.python.org/cpython