gh-85275: Remove old buffer APIs (#105137)

They are now abi-only.

Co-authored-by: Victor Stinner <vstinner@python.org>

Doc/c-api/abstract.rst

@@ -24,4 +24,3 @@ but whose items have not been set to some non-\ ``NULL`` value yet.
    mapping.rst
    iter.rst
    buffer.rst
-   objbuffer.rst

Doc/c-api/objbuffer.rst

@@ -1,55 +0,0 @@
-.. highlight:: c
-
-Old Buffer Protocol
--------------------
-
-.. deprecated:: 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 :ref:`new buffer protocol <bufferobjects>`, 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 :c:func:`PyObject_GetBuffer`
-(or the ``y*`` or ``w*`` :ref:`format codes <arg-parsing>` with the
-:c:func:`PyArg_ParseTuple` family of functions) to get a buffer view over
-an object, and :c:func:`PyBuffer_Release` when the buffer view can be released.
-
-
-.. 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.
-
-
-.. 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.
-
-
-.. c:function:: 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 :c:func:`PyObject_GetBuffer()` instead.
-
-
-.. c:function:: 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 :exc:`TypeError` on error.
-

Doc/data/refcounts.dat

@@ -1578,21 +1578,6 @@ PyOS_FSPath:PyObject*:path:0:
 PyObject_ASCII:PyObject*::+1:
 PyObject_ASCII:PyObject*:o:0:
 
-PyObject_AsCharBuffer:int:::
-PyObject_AsCharBuffer:PyObject*:obj:0:
-PyObject_AsCharBuffer:const char**:buffer::
-PyObject_AsCharBuffer:Py_ssize_t*:buffer_len::
-
-PyObject_AsReadBuffer:int:::
-PyObject_AsReadBuffer:PyObject*:obj:0:
-PyObject_AsReadBuffer:const void**:buffer::
-PyObject_AsReadBuffer:Py_ssize_t*:buffer_len::
-
-PyObject_AsWriteBuffer:int:::
-PyObject_AsWriteBuffer:PyObject*:obj:0:
-PyObject_AsWriteBuffer:void**:buffer::
-PyObject_AsWriteBuffer:Py_ssize_t*:buffer_len::
-
 PyObject_Bytes:PyObject*::+1:
 PyObject_Bytes:PyObject*:o:0:
 

Doc/data/stable_abi.dat

@@ -476,10 +476,7 @@ type,PyObject,3.2,,members
 member,PyObject.ob_refcnt,3.2,,
 member,PyObject.ob_type,3.2,,
 function,PyObject_ASCII,3.2,,
-function,PyObject_AsCharBuffer,3.2,,
 function,PyObject_AsFileDescriptor,3.2,,
-function,PyObject_AsReadBuffer,3.2,,
-function,PyObject_AsWriteBuffer,3.2,,
 function,PyObject_Bytes,3.2,,
 function,PyObject_Call,3.2,,
 function,PyObject_CallFunction,3.2,,
@@ -490,7 +487,6 @@ function,PyObject_CallNoArgs,3.10,,
 function,PyObject_CallObject,3.2,,
 function,PyObject_Calloc,3.7,,
 function,PyObject_CheckBuffer,3.11,,
-function,PyObject_CheckReadBuffer,3.2,,
 function,PyObject_ClearWeakRefs,3.2,,
 function,PyObject_CopyData,3.11,,
 function,PyObject_DelItem,3.2,,

Doc/whatsnew/3.13.rst

@@ -395,6 +395,42 @@ Removed
 
   (Contributed by Victor Stinner in :gh:`105107`.)
 
+* Remove old buffer protocols deprecated in Python 3.0. Use :ref:`bufferobjects` instead.
+
+   * :c:func:`!PyObject_CheckReadBuffer`: Use :c:func:`PyObject_CheckBuffer` to
+     test if the object supports the buffer protocol.
+     Note that :c:func:`PyObject_CheckBuffer` doesn't guarantee that
+     :c:func:`PyObject_GetBuffer` will succeed.
+     To test if the object is actually readable, see the next example
+     of :c:func:`PyObject_GetBuffer`.
+
+   * :c:func:`!PyObject_AsCharBuffer`, :c:func:`!PyObject_AsReadBuffer`:
+     :c:func:`PyObject_GetBuffer` and :c:func:`PyBuffer_Release` instead:
+
+     .. code-block:: c
+
+        Py_buffer view;
+        if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) < 0) {
+            return NULL;
+        }
+        // Use `view.buf` and `view.len` to read from the buffer.
+        // You may need to cast buf as `(const char*)view.buf`.
+        PyBuffer_Release(&view);
+
+   * :c:func:`!PyObject_AsWriteBuffer`: Use
+     :c:func:`PyObject_GetBuffer` and :c:func:`PyBuffer_Release` instead:
+
+     .. code-block:: c
+
+        Py_buffer view;
+        if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) < 0) {
+            return NULL;
+        }
+        // Use `view.buf` and `view.len` to write to the buffer.
+        PyBuffer_Release(&view);
+
+  (Contributed by Inada Naoki in :gh:`85275`.)
+
 * Remove the following old functions to configure the Python initialization,
   deprecated in Python 3.11:
 

Include/abstract.h

@@ -320,55 +320,6 @@ PyAPI_FUNC(int) PyObject_DelItemString(PyObject *o, const char *key);
 PyAPI_FUNC(int) PyObject_DelItem(PyObject *o, PyObject *key);
 
 
-/* === Old Buffer API ============================================ */
-
-/* FIXME:  usage of these should all be replaced in Python itself
-   but for backwards compatibility we will implement them.
-   Their usage without a corresponding "unlock" mechanism
-   may create issues (but they would already be there). */
-
-/* Takes an arbitrary object which must support the (character, single segment)
-   buffer interface and returns a pointer to a read-only memory location
-   usable as character based input for subsequent processing.
-
-   Return 0 on success.  buffer and buffer_len are only set in case no error
-   occurs. Otherwise, -1 is returned and an exception set. */
-Py_DEPRECATED(3.0)
-PyAPI_FUNC(int) PyObject_AsCharBuffer(PyObject *obj,
-                                      const char **buffer,
-                                      Py_ssize_t *buffer_len);
-
-/* Checks whether an arbitrary object supports the (character, single segment)
-   buffer interface.
-
-   Returns 1 on success, 0 on failure. */
-Py_DEPRECATED(3.0) PyAPI_FUNC(int) PyObject_CheckReadBuffer(PyObject *obj);
-
-/* Same as PyObject_AsCharBuffer() except that this API expects (readable,
-   single segment) buffer interface and returns a pointer to a read-only memory
-   location which can contain arbitrary data.
-
-   0 is returned on success.  buffer and buffer_len are only set in case no
-   error occurs.  Otherwise, -1 is returned and an exception set. */
-Py_DEPRECATED(3.0)
-PyAPI_FUNC(int) PyObject_AsReadBuffer(PyObject *obj,
-                                      const void **buffer,
-                                      Py_ssize_t *buffer_len);
-
-/* Takes an arbitrary object which must support the (writable, single segment)
-   buffer interface and returns a pointer to a writable memory location in
-   buffer of size 'buffer_len'.
-
-   Return 0 on success.  buffer and buffer_len are only set in case no error
-   occurs. Otherwise, -1 is returned and an exception set. */
-Py_DEPRECATED(3.0)
-PyAPI_FUNC(int) PyObject_AsWriteBuffer(PyObject *obj,
-                                       void **buffer,
-                                       Py_ssize_t *buffer_len);
-
-
-/* === New Buffer API ============================================ */
-
 /* Takes an arbitrary object and returns the result of calling
    obj.__format__(format_spec). */
 PyAPI_FUNC(PyObject *) PyObject_Format(PyObject *obj,

Misc/NEWS.d/next/C API/2023-05-31-19-38-45.gh-issue-85275.doojgE.rst

@@ -0,0 +1,4 @@
+``PyObject_AsCharBuffer()``, ``PyObject_AsReadBuffer()``,
+``PyObject_CheckReadBuffer()``, and ``PyObject_AsWriteBuffer()`` are
+removed. Please migrate to new buffer protocol; :c:func:`PyObject_GetBuffer`
+and :c:func:`PyBuffer_Release`.

Misc/stable_abi.toml

@@ -1755,12 +1755,16 @@
 
 [function.PyObject_AsCharBuffer]
     added = '3.2'
+    abi_only = true
 [function.PyObject_AsReadBuffer]
     added = '3.2'
+    abi_only = true
 [function.PyObject_AsWriteBuffer]
     added = '3.2'
+    abi_only = true
 [function.PyObject_CheckReadBuffer]
     added = '3.2'
+    abi_only = true
 
 # Flags are implicitly part of the ABI:
 

Objects/abstract.c

@@ -294,11 +294,17 @@ PyObject_CheckBuffer(PyObject *obj)
     return (tp_as_buffer != NULL && tp_as_buffer->bf_getbuffer != NULL);
 }
 
+// Old buffer protocols (deprecated, abi only)
 
-/* We release the buffer right after use of this function which could
+/* Checks whether an arbitrary object supports the (character, single segment)
+   buffer interface.
+
+   Returns 1 on success, 0 on failure.
+
+   We release the buffer right after use of this function which could
    cause issues later on.  Don't use these functions in new code.
  */
-int
+PyAPI_FUNC(int) /* abi_only */
 PyObject_CheckReadBuffer(PyObject *obj)
 {
     PyBufferProcs *pb = Py_TYPE(obj)->tp_as_buffer;
@@ -333,7 +339,13 @@ as_read_buffer(PyObject *obj, const void **buffer, Py_ssize_t *buffer_len)
     return 0;
 }
 
-int
+/* Takes an arbitrary object which must support the (character, single segment)
+   buffer interface and returns a pointer to a read-only memory location
+   usable as character based input for subsequent processing.
+
+   Return 0 on success.  buffer and buffer_len are only set in case no error
+   occurs. Otherwise, -1 is returned and an exception set. */
+PyAPI_FUNC(int) /* abi_only */
 PyObject_AsCharBuffer(PyObject *obj,
                       const char **buffer,
                       Py_ssize_t *buffer_len)
@@ -341,14 +353,28 @@ PyObject_AsCharBuffer(PyObject *obj,
     return as_read_buffer(obj, (const void **)buffer, buffer_len);
 }
 
-int PyObject_AsReadBuffer(PyObject *obj,
+/* Same as PyObject_AsCharBuffer() except that this API expects (readable,
+   single segment) buffer interface and returns a pointer to a read-only memory
+   location which can contain arbitrary data.
+
+   0 is returned on success.  buffer and buffer_len are only set in case no
+   error occurs.  Otherwise, -1 is returned and an exception set. */
+PyAPI_FUNC(int) /* abi_only */
+PyObject_AsReadBuffer(PyObject *obj,
                       const void **buffer,
                       Py_ssize_t *buffer_len)
 {
     return as_read_buffer(obj, buffer, buffer_len);
 }
 
-int PyObject_AsWriteBuffer(PyObject *obj,
+/* Takes an arbitrary object which must support the (writable, single segment)
+   buffer interface and returns a pointer to a writable memory location in
+   buffer of size 'buffer_len'.
+
+   Return 0 on success.  buffer and buffer_len are only set in case no error
+   occurs. Otherwise, -1 is returned and an exception set. */
+PyAPI_FUNC(int) /* abi_only */
+PyObject_AsWriteBuffer(PyObject *obj,
                        void **buffer,
                        Py_ssize_t *buffer_len)
 {