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gh-114685: Check flags in PyObject_GetBuffer() #114707

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Merged
serhiy-storchaka merged 1 commit into from
Jan 31, 2024
Merged

gh-114685: Check flags in PyObject_GetBuffer() #114707

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6 changes: 6 additions & 0 deletions Lib/test/test_buffer.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4585,6 +4585,12 @@ def test_c_buffer(self):
buf.__release_buffer__(mv)
self.assertEqual(buf.references, 0)

@unittest.skipIf(_testcapi is None, "requires _testcapi")
def test_c_buffer_invalid_flags(self):
buf = _testcapi.testBuf()
self.assertRaises(SystemError, buf.__buffer__, PyBUF_READ)
self.assertRaises(SystemError, buf.__buffer__, PyBUF_WRITE)

def test_inheritance(self):
class A(bytearray):
def __buffer__(self, flags):
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/C API/2024-01-29-12-13-24.gh-issue-114685.B07RME.rst
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@@ -0,0 +1,3 @@
:c:func:`PyObject_GetBuffer` now raises a :exc:`SystemError` if called with
:c:macro:`PyBUF_READ` or :c:macro:`PyBUF_WRITE` as flags. These flags should
only be used with the ``PyMemoryView_*`` C API.
6 changes: 4 additions & 2 deletions Modules/_testcapi/buffer.c
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Expand Up @@ -54,8 +54,10 @@ static int
testbuf_getbuf(testBufObject *self, Py_buffer *view, int flags)
{
int buf = PyObject_GetBuffer(self->obj, view, flags);
Py_SETREF(view->obj, Py_NewRef(self));
self->references++;
if (buf == 0) {
Py_SETREF(view->obj, Py_NewRef(self));
self->references++;
}
return buf;
}

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6 changes: 6 additions & 0 deletions Objects/abstract.c
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Expand Up @@ -425,6 +425,12 @@ PyObject_AsWriteBuffer(PyObject *obj,
int
PyObject_GetBuffer(PyObject *obj, Py_buffer *view, int flags)
{
if (flags != PyBUF_SIMPLE) { /* fast path */
if (flags == PyBUF_READ || flags == PyBUF_WRITE) {
PyErr_BadInternalCall();
return -1;
}
}
PyBufferProcs *pb = Py_TYPE(obj)->tp_as_buffer;

if (pb == NULL || pb->bf_getbuffer == NULL) {
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