SF bug #761337: datetime.strftime fails on trivial format string
The interning of short strings violates the refcnt==1 assumption for
_PyString_Resize().
A simple fix is to boost the initial value of "totalnew" by 1.
Combined with an NULL argument to PyString_FromStringAndSize(),
this assures that resulting format string is not interned.
This will remain true even if the implementation of
PyString_FromStringAndSize() changes because only the uninitialized
strings that can be interned are those of zero length.
Added a test case.
diff --git a/Lib/test/test_datetime.py b/Lib/test/test_datetime.py
index cca0c9d..c6dbb48 100644
--- a/Lib/test/test_datetime.py
+++ b/Lib/test/test_datetime.py
@@ -831,6 +831,7 @@
def test_strftime(self):
t = self.theclass(2005, 3, 2)
self.assertEqual(t.strftime("m:%m d:%d y:%y"), "m:03 d:02 y:05")
+ self.assertEqual(t.strftime(""), "") # SF bug #761337
self.assertRaises(TypeError, t.strftime) # needs an arg
self.assertRaises(TypeError, t.strftime, "one", "two") # too many args
diff --git a/Modules/datetimemodule.c b/Modules/datetimemodule.c
index 164492e..d8aed17 100644
--- a/Modules/datetimemodule.c
+++ b/Modules/datetimemodule.c
@@ -1175,7 +1175,7 @@
* a new format. Since computing the replacements for those codes
* is expensive, don't unless they're actually used.
*/
- totalnew = PyString_Size(format); /* realistic if no %z/%Z */
+ totalnew = PyString_Size(format) + 1; /* realistic if no %z/%Z */
newfmt = PyString_FromStringAndSize(NULL, totalnew);
if (newfmt == NULL) goto Done;
pnew = PyString_AsString(newfmt);