_PyLong_AsByteArray: added assert that the input is normalized. This is

outside the function's control, but is crucial to correct operation.

diff --git a/Objects/longobject.c b/Objects/longobject.c
index 3c22470fb0d1cd041fa9298455f3603b0400739f..f8a912940a94415f4513c7adec38b407e076dfa9 100644 (file)
--- a/Objects/longobject.c
+++ b/Objects/longobject.c
@@ -358,7 +358,11 @@ _PyLong_AsByteArray(PyLongObject* v,
                pincr = -1;
        }
 
-       /* Copy over all the Python digits. */
+       /* Copy over all the Python digits.
+          It's crucial that every Python digit except for the MSD contribute
+          exactly SHIFT bits to the total, so first assert that the long is
+          normalized. */
+       assert(ndigits == 0 || v->ob_digit[ndigits - 1] != 0);
        j = 0;
        accum = 0;
        accumbits = 0;