Old Buffer Protocol
*******************

This section describes the legacy buffer protocol, which has been
introduced in Python 1.6. It is still supported but deprecated in the
Python 2.x series. Python 3 introduces a new buffer protocol which
fixes weaknesses and shortcomings of the protocol, and has been
backported to Python 2.6.  See Buffers and Memoryview Objects for more
information.

int PyObject_AsCharBuffer(PyObject *obj, const char **buffer, Py_ssize_t *buffer_len)

   Returns a pointer to a read-only memory location usable as
   character-based input.  The *obj* argument must support the single-
   segment character buffer interface.  On success, returns "0", sets
   *buffer* to the memory location and *buffer_len* to the buffer
   length.  Returns "-1" and sets a "TypeError" on error.

   New in version 1.6.

   Changed in version 2.5: This function used an "int *" type for
   *buffer_len*. This might require changes in your code for properly
   supporting 64-bit systems.

int PyObject_AsReadBuffer(PyObject *obj, const void **buffer, Py_ssize_t *buffer_len)

   Returns a pointer to a read-only memory location containing
   arbitrary data. The *obj* argument must support the single-segment
   readable buffer interface.  On success, returns "0", sets *buffer*
   to the memory location and *buffer_len* to the buffer length.
   Returns "-1" and sets a "TypeError" on error.

   New in version 1.6.

   Changed in version 2.5: This function used an "int *" type for
   *buffer_len*. This might require changes in your code for properly
   supporting 64-bit systems.

int PyObject_CheckReadBuffer(PyObject *o)

   Returns "1" if *o* supports the single-segment readable buffer
   interface. Otherwise returns "0".

   New in version 2.2.

int PyObject_AsWriteBuffer(PyObject *obj, void **buffer, Py_ssize_t *buffer_len)

   Returns a pointer to a writeable memory location.  The *obj*
   argument must support the single-segment, character buffer
   interface.  On success, returns "0", sets *buffer* to the memory
   location and *buffer_len* to the buffer length.  Returns "-1" and
   sets a "TypeError" on error.

   New in version 1.6.

   Changed in version 2.5: This function used an "int *" type for
   *buffer_len*. This might require changes in your code for properly
   supporting 64-bit systems.