Bugfix for transferring malloc'ed data to a pyarray under windows with the capsule

lasp/c/lasp_pyarray.h

@@ -22,65 +22,81 @@
  * Function passed to Python to use for cleanup of
  * foreignly obtained data.
  **/
+#define LASP_CAPSULE_NAME "pyarray_data_destructor"
 static inline void capsule_cleanup(PyObject *capsule) {
-    void *memory = PyCapsule_GetPointer(capsule, NULL);
+  void *memory = PyCapsule_GetPointer(capsule, LASP_CAPSULE_NAME);
-    free(memory);
+  free(memory);
 }
 
 #endif
 
+
 static inline PyObject *data_to_ndarray(void *data, int n_rows, int n_cols,
-        int typenum, bool transfer_ownership,
+    int typenum, bool transfer_ownership,
-        bool F_contiguous) {
+    bool F_contiguous) {
 
-    /* fprintf(stderr, "Enter data_to_ndarray\n"); */
+  /* fprintf(stderr, "Enter data_to_ndarray\n"); */
-    assert(data);
+  assert(data);
-    import_array();
+  import_array();
+  PyArray_Descr *descr = PyArray_DescrFromType(typenum);
+  if(!descr) return NULL;
 
-    npy_intp dims[2];
+  npy_intp dims[2] = {n_rows, n_cols};
-    if(F_contiguous){
+  npy_intp strides[2];
-        dims[0] = n_cols;
-        dims[1] = n_rows;
 
-    } else {
+  int flags = 0;
-        dims[0] = n_rows;
+  if(F_contiguous){
-        dims[1] = n_cols;
+    flags |= NPY_ARRAY_FARRAY; 
+    strides[0] = descr->elsize;
+    strides[1] = descr->elsize*n_rows;
+  } else {
+    strides[0] = descr->elsize*n_rows;
+    strides[1] = descr->elsize;
+  }
+
+  /* assert(n_rows > 0); */
+  /* assert(n_cols > 0); */
+
+  PyArrayObject *arr =
+    (PyArrayObject *)PyArray_NewFromDescr(
+        &PyArray_Type,
+        descr, // Description
+        2, // nd
+        dims, // dimensions
+        strides,  // strides
+        data, // Data pointer
+        flags, // Flags
+        NULL // obj
+        );
+
+  if (!arr) {
+    fprintf(stderr, "arr = 0!");
+    return NULL;
+  }
+
+  if (transfer_ownership == true) {
+    #ifdef MS_WIN64
+    // The default destructor of Python cannot free the data, as it is allocated
+    // with malloc. Therefore, with this code, we tell Numpy/Python to use
+    // the capsule_cleanup constructor. See:
+    // https://stackoverflow.com/questions/54269956/crash-of-jupyter-due-to-the-use-of-pyarray-enableflags/54278170#54278170
+    // Note that in general it was disadvised to build all C code with MinGW on
+    // Windows. We do it anyway, see if we find any problems on the way.
+    PyObject *capsule = PyCapsule_New(data, LASP_CAPSULE_NAME, capsule_cleanup);
+    int res = PyArray_SetBaseObject(arr, capsule);
+    if(res != 0) {
+      fprintf(stderr, "Failed to set base object of array!");
+      return NULL;
     }
-    /* assert(n_rows > 0); */
+    #endif
-    /* assert(n_cols > 0); */
+    /* fprintf(stderr, "============Ownership transfer================\n"); */
+    PyArray_ENABLEFLAGS(arr, NPY_OWNDATA);
+  }
+  /* fprintf(stderr, "Exit data_to_ndarray\n"); */
 
-    PyArrayObject *arr =
+  return (PyObject *) arr;
-        (PyArrayObject *)PyArray_SimpleNewFromData(2, dims, typenum, data);
-
-    if (!arr) {
-        return NULL;
-    }
-    if (F_contiguous) {
-        arr = (PyArrayObject*) PyArray_Transpose(arr, NULL);
-    }
-
-    if (transfer_ownership == true) {
-        #ifdef MS_WIN64
-            // The default destructor of Python cannot free the data, as it is allocated
-            // with malloc. Therefore, with this code, we tell Numpy/Python to use
-            // the capsule_cleanup constructor. See:
-            // https://stackoverflow.com/questions/54269956/crash-of-jupyter-due-to-the-use-of-pyarray-enableflags/54278170#54278170
-            // Note that in general it was disadvised to build all C code with MinGW on
-            // Windows. We do it anyway, see if we find any problems on the way.
-            PyObject *capsule = PyCapsule_New(data, "data destructor", capsule_cleanup);
-            int res = PyArray_SetBaseObject(arr, capsule);
-			if(res != 0) {
-				fprintf(stderr, "Failed to set base object of array!");
-				return NULL;
-			}
-        #endif
-        /* fprintf(stderr, "============Ownership transfer================\n"); */
-        PyArray_ENABLEFLAGS(arr, NPY_OWNDATA);
-    }
-    /* fprintf(stderr, "Exit data_to_ndarray\n"); */
-
-    return (PyObject *) arr;
 }
 
+#undef LASP_CAPSULE_NAME
 #endif // LASP_PYARRAY_H
 //////////////////////////////////////////////////////////////////////

lasp/c/lasp_python.h

@@ -13,7 +13,7 @@
 /** 
  * Create a numpy array from an existing dmat.
  *
- * @param mat dmat struccture containing array data and metadata.
+ * @param mat dmat structure containing array data and metadata.
  * @param transfer_ownership If set to true, Numpy array will be responsible
  * for freeing the data.
  *