An issue remains with the implicit conversion:

On a 64-bit platform (sizeof(long)=64):

>>> c.printf("%d\n",1<<64)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ctypes.ArgumentError: argument 2: <type 'exceptions.OverflowError'>: long int too long to convert

so it does do overflow checking, but

>>> c.printf("%d\n",(1<<64)-1)
-1
3
>>> c.printf("%d\n",(1<<32))
0
2