make a.__dlpack__() fail if a is readonly

2 files changed, 13 insertions, 1 deletions

diff --git a/numpy/core/src/multiarray/dlpack.c b/numpy/core/src/multiarray/dlpack.c
index 21930b0ef..f061a6bf9 100644
--- a/numpy/core/src/multiarray/dlpack.c
+++ b/numpy/core/src/multiarray/dlpack.c
@@ -131,6 +131,12 @@ array_dlpack(PyArrayObject *self,
         return NULL;
     }
 
+    if ( !(PyArray_FLAGS(self) & NPY_ARRAY_WRITEABLE)) {
+        PyErr_SetString(PyExc_TypeError, "NumPy currently only supports "
+                "dlpack for writeable arrays");
+        return NULL;
+    }
+
     npy_intp itemsize = PyArray_ITEMSIZE(self);
     int ndim = PyArray_NDIM(self);
     npy_intp *strides = PyArray_STRIDES(self);
diff --git a/numpy/core/tests/test_dlpack.py b/numpy/core/tests/test_dlpack.py
index 06fc042ec..f848b2008 100644
--- a/numpy/core/tests/test_dlpack.py
+++ b/numpy/core/tests/test_dlpack.py
@@ -78,7 +78,7 @@ class TestDLPack:
         y4 = x[1]
         assert_array_equal(y4, np._from_dlpack(y4))
 
-        y5 = np.diagonal(x)
+        y5 = np.diagonal(x).copy()
         assert_array_equal(y5, np._from_dlpack(y5))
 
     @pytest.mark.parametrize("ndim", range(33))
@@ -101,3 +101,9 @@ class TestDLPack:
     def test_dlpack_destructor_exception(self):
         with pytest.raises(RuntimeError):
             self.dlpack_deleter_exception()
+
+    def test_readonly(self):
+        x = np.arange(5)
+        x.flags.writeable = False
+        with pytest.raises(TypeError):
+            x.__dlpack__()