cpython/Doc/c-api/objbuffer.rst

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.. highlightlang:: c
.. _abstract-buffer:
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
:ref:`bufferobjects` for more information.
.. c:function:: 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 :c:type:`int *` type for *buffer_len*. This might
require changes in your code for properly supporting 64-bit systems.
.. c:function:: 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 :c:type:`int *` type for *buffer_len*. This might
require changes in your code for properly supporting 64-bit systems.
.. c:function:: int PyObject_CheckReadBuffer(PyObject *o)
Returns ``1`` if *o* supports the single-segment readable buffer interface.
Otherwise returns ``0``.
.. versionadded:: 2.2
.. c:function:: 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 :c:type:`int *` type for *buffer_len*. This might
require changes in your code for properly supporting 64-bit systems.