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.. highlightlang:: c

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 3.0 introduces a new buffer protocol which fixes weaknesses and shortcomings of the protocol, and has been backported to Python 2.6. See :ref:`bufferobjects` for more information.

.. cfunction:: 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
   :exc:`TypeError` on error.

   .. versionadded:: 1.6

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



.. cfunction:: 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
   :exc:`TypeError` on error.

   .. versionadded:: 1.6

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



.. cfunction:: int PyObject_CheckReadBuffer(PyObject *o)

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

   .. versionadded:: 2.2



.. cfunction:: 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 :exc:`TypeError` on error.

   .. versionadded:: 1.6

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