Old Buffer Protocol — Python 3.9.21 documentation

# Old Buffer Protocol

Deprecated since version 3.0.

These functions were part of the “old buffer protocol” API in Python 2. In Python 3, this protocol doesn’t exist anymore but the functions are still exposed to ease porting 2.x code. They act as a compatibility wrapper around the new buffer protocol, but they don’t give you control over the lifetime of the resources acquired when a buffer is exported.

Therefore, it is recommended that you call `PyObject_GetBuffer()` (or the `y*` or `w*` format codes with the `PyArg_ParseTuple()` family of functions) to get a buffer view over an object, and `PyBuffer_Release()` when the buffer view can be released.

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.

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.

int `PyObject_CheckReadBuffer`(PyObject *o)

  Returns `1` if o supports the single-segment readable buffer interface. Otherwise returns `0`. This function always succeeds.

  Note that this function tries to get and release a buffer, and exceptions which occur while calling corresponding functions will get suppressed. To get error reporting use `PyObject_GetBuffer()` instead.

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

  Returns a pointer to a writable 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.