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# 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 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.

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