From f7c4e236429606e1c982cacf24e10fc86ef4462f Mon Sep 17 00:00:00 2001
From: scoder <stefan_ml@behnel.de>
Date: Sat, 6 Jun 2020 21:35:10 +0200
Subject: bpo-40724: Support setting buffer slots from type specs (GH-20648)

This is not part of the limited API but makes the buffer slots available for type specs.
---
 Modules/_testcapimodule.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)

(limited to 'Modules/_testcapimodule.c')

diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 101d54932d..d6a90b807d 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -6298,6 +6298,47 @@ static PyType_Spec HeapCTypeSubclass_spec = {
     HeapCTypeSubclass_slots
 };
 
+PyDoc_STRVAR(heapctypewithbuffer__doc__,
+"Heap type with buffer support.\n\n"
+"The buffer is set to [b'1', b'2', b'3', b'4']");
+
+typedef struct {
+    HeapCTypeObject base;
+    char buffer[4];
+} HeapCTypeWithBufferObject;
+
+static int
+heapctypewithbuffer_getbuffer(HeapCTypeWithBufferObject *self, Py_buffer *view, int flags)
+{
+    self->buffer[0] = '1';
+    self->buffer[1] = '2';
+    self->buffer[2] = '3';
+    self->buffer[3] = '4';
+    return PyBuffer_FillInfo(
+        view, (PyObject*)self, (void *)self->buffer, 4, 1, flags);
+}
+
+static int
+heapctypewithbuffer_releasebuffer(HeapCTypeWithBufferObject *self, Py_buffer *view)
+{
+    assert(view->obj == (void*) self);
+}
+
+static PyType_Slot HeapCTypeWithBuffer_slots[] = {
+    {Py_bf_getbuffer, heapctypewithbuffer_getbuffer},
+    {Py_bf_releasebuffer, heapctypewithbuffer_releasebuffer},
+    {Py_tp_doc, (char*)heapctypewithbuffer__doc__},
+    {0, 0},
+};
+
+static PyType_Spec HeapCTypeWithBuffer_spec = {
+    "_testcapi.HeapCTypeWithBuffer",
+    sizeof(HeapCTypeWithBufferObject),
+    0,
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    HeapCTypeWithBuffer_slots
+};
+
 PyDoc_STRVAR(heapctypesubclasswithfinalizer__doc__,
 "Subclass of HeapCType with a finalizer that reassigns __class__.\n\n"
 "__class__ is set to plain HeapCTypeSubclass during finalization.\n"
@@ -6775,6 +6816,12 @@ PyInit__testcapi(void)
     }
     PyModule_AddObject(m, "HeapCTypeWithWeakref", HeapCTypeWithWeakref);
 
+    PyObject *HeapCTypeWithBuffer = PyType_FromSpec(&HeapCTypeWithBuffer_spec);
+    if (HeapCTypeWithBuffer == NULL) {
+        return NULL;
+    }
+    PyModule_AddObject(m, "HeapCTypeWithBuffer", HeapCTypeWithBuffer);
+
     PyObject *subclass_with_finalizer_bases = PyTuple_Pack(1, HeapCTypeSubclass);
     if (subclass_with_finalizer_bases == NULL) {
         return NULL;
-- 
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