[Python-3000] bug in py3k buffer object?

[Travis Oliphant]

Lisandro Dalcin wrote:
> Dear Travis, in my MPI wrappers, I use MPI_Alloc_mem function to get
> 'special' MPI memory, and next I return it to Python using
> 
> return PyBuffer_FromReadWriteMemory(ptr, len);
> 
> Well, getting back this rw-buffer in python, I tried to do
> 
> mem = MPI.Alloc_mem(10)
> mem[:] = str8('\0') * 8 # sort of memzero
> 
> but then I get this error:
> 
> Traceback (most recent call last):
>   File "<stdin>", line 1, in <module>
> TypeError: buffer is read-only
> 
> 
> I noticed you use PyBuff_SIMPLE in
> buffer_ass_item/buffer_ass_subscript... Is this OK? perhaps
> PyBuf_WRITEABLE is the right flag? No much more time to go deeper.
> 

yes, I see the problem.  The problem is with get_buf not setting 
view->readonly when it the buffer object has a NULL base (i.e. its own 
memory).

I'll fix this and check it in as soon as I get on a machine with 
check-in possibilities.

-Travis