[Python-Dev] How to fix the buffer object's broken char buffer support

Guido van Rossum guido at python.org
Wed Jun 7 04:13:43 CEST 2006

On 6/6/06, Brett Cannon <brett at python.org> wrote:
> If you run ``import array; int(buffer(array.array('c')))`` the
> interpreter will segfault.  While investigating this I discovered that
> buffer objects, for their tp_as_buffer->bf_getcharbuffer, return the
> result by calling the wrapped object bf_getreadbuffer or
> bf_getwritebuffer.  This is wrong since it is essentially redirecting
> the expected call to the wrong tp_as_buffer slot for the wrapped
> object.  Plus it doesn't have Py_TPFLAGS_HAVE_GETCHARBUFFER defined.
> I see two options here.  One is to remove the bf_getcharbuffer slot
> from the buffer object.  The other option is to fix it so that it only
> returns bf_getcharbuffer and doesn't redirect improperly (this also
> brings up the issue if Py_TPFLAGS_HAVE_GETCHARBUFFER should then also
> be defined for buffer objects).
> Since I don't use buffer objects I don't know if it is better to fix
> this or just rip it out.

How ironic. the charbuffer slot was added late in the game -- now we'd
be ripping it out...

I suspect that there's a reason for it; but in Py3k it will
*definitely* be ripped out. Buffers will purely deal in byte then,
never in characters; you won't be able to get a buffer from a
(unicode) string at all.


--Guido van Rossum (home page: http://www.python.org/~guido/)

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