gh-104223: Fix issues with inheriting from buffer classes (#104227)

Co-authored-by: Kumar Aditya <59607654+kumaraditya303@users.noreply.github.com>

1 files changed, 44 insertions, 1 deletions

diff --git a/Objects/memoryobject.c b/Objects/memoryobject.c
index f008a8c..b016804 100644
--- a/Objects/memoryobject.c
+++ b/Objects/memoryobject.c
@@ -193,6 +193,20 @@ PyTypeObject _PyManagedBuffer_Type = {
         return -1;                                                \
     }
 
+#define CHECK_RESTRICTED(mv) \
+    if (((PyMemoryViewObject *)(mv))->flags & _Py_MEMORYVIEW_RESTRICTED) { \
+        PyErr_SetString(PyExc_ValueError,                                  \
+            "cannot create new view on restricted memoryview");            \
+        return NULL;                                                       \
+    }
+
+#define CHECK_RESTRICTED_INT(mv) \
+    if (((PyMemoryViewObject *)(mv))->flags & _Py_MEMORYVIEW_RESTRICTED) { \
+        PyErr_SetString(PyExc_ValueError,                                  \
+            "cannot create new view on restricted memoryview");            \
+        return -1;                                                       \
+    }
+
 /* See gh-92888. These macros signal that we need to check the memoryview
    again due to possible read after frees. */
 #define CHECK_RELEASED_AGAIN(mv) CHECK_RELEASED(mv)
@@ -781,7 +795,7 @@ PyMemoryView_FromBuffer(const Py_buffer *info)
    using the given flags.
    If the object is a memoryview, the new memoryview must be registered
    with the same managed buffer. Otherwise, a new managed buffer is created. */
-PyObject *
+static PyObject *
 PyMemoryView_FromObjectAndFlags(PyObject *v, int flags)
 {
     _PyManagedBufferObject *mbuf;
@@ -789,6 +803,7 @@ PyMemoryView_FromObjectAndFlags(PyObject *v, int flags)
     if (PyMemoryView_Check(v)) {
         PyMemoryViewObject *mv = (PyMemoryViewObject *)v;
         CHECK_RELEASED(mv);
+        CHECK_RESTRICTED(mv);
         return mbuf_add_view(mv->mbuf, &mv->view);
     }
     else if (PyObject_CheckBuffer(v)) {
@@ -806,6 +821,30 @@ PyMemoryView_FromObjectAndFlags(PyObject *v, int flags)
         Py_TYPE(v)->tp_name);
     return NULL;
 }
+
+/* Create a memoryview from an object that implements the buffer protocol,
+   using the given flags.
+   If the object is a memoryview, the new memoryview must be registered
+   with the same managed buffer. Otherwise, a new managed buffer is created. */
+PyObject *
+_PyMemoryView_FromBufferProc(PyObject *v, int flags, getbufferproc bufferproc)
+{
+    _PyManagedBufferObject *mbuf = mbuf_alloc();
+    if (mbuf == NULL)
+        return NULL;
+
+    int res = bufferproc(v, &mbuf->master, flags);
+    if (res < 0) {
+        mbuf->master.obj = NULL;
+        Py_DECREF(mbuf);
+        return NULL;
+    }
+
+    PyObject *ret = mbuf_add_view(mbuf, NULL);
+    Py_DECREF(mbuf);
+    return ret;
+}
+
 /* Create a memoryview from an object that implements the buffer protocol.
    If the object is a memoryview, the new memoryview must be registered
    with the same managed buffer. Otherwise, a new managed buffer is created. */
@@ -1397,6 +1436,7 @@ memoryview_cast_impl(PyMemoryViewObject *self, PyObject *format,
     Py_ssize_t ndim = 1;
 
     CHECK_RELEASED(self);
+    CHECK_RESTRICTED(self);
 
     if (!MV_C_CONTIGUOUS(self->flags)) {
         PyErr_SetString(PyExc_TypeError,
@@ -1452,6 +1492,7 @@ memoryview_toreadonly_impl(PyMemoryViewObject *self)
 /*[clinic end generated code: output=2c7e056f04c99e62 input=dc06d20f19ba236f]*/
 {
     CHECK_RELEASED(self);
+    CHECK_RESTRICTED(self);
     /* Even if self is already readonly, we still need to create a new
      * object for .release() to work correctly.
      */
@@ -1474,6 +1515,7 @@ memory_getbuf(PyMemoryViewObject *self, Py_buffer *view, int flags)
     int baseflags = self->flags;
 
     CHECK_RELEASED_INT(self);
+    CHECK_RESTRICTED_INT(self);
 
     /* start with complete information */
     *view = *base;
@@ -2535,6 +2577,7 @@ memory_subscript(PyMemoryViewObject *self, PyObject *key)
         return memory_item(self, index);
     }
     else if (PySlice_Check(key)) {
+        CHECK_RESTRICTED(self);
         PyMemoryViewObject *sliced;
 
         sliced = (PyMemoryViewObject *)mbuf_add_view(self->mbuf, view);