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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 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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