Call PyErr_NormalizeException for exceptions (pythonnet#1265)

slide · filmor · web-flow · commit a0d1a3dbd6d5 · 2020-12-21T10:08:49.000-08:00
* Call PyErr_NormalizeException for exceptions See https://docs.python.org/3/c-api/exceptions.html#c.PyErr_NormalizeException This fixes cases where some exceptions are "unnormalized" (see https://docs.python.org/3/c-api/exceptions.html#c.PyErr_NormalizeException). Calling PyErr_NormalizeException will normalize the exception so that any calls to the traceback module functions correctly. Fixes pythonnet#1190 Co-authored-by: Benedikt Reinartz <filmor@gmail.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -40,6 +40,7 @@ details about the cause of the failure
 -    Indexers can now be used with interface objects
 -    Fixed a bug where indexers could not be used if they were inherited
 -    Made it possible to use `__len__` also on `ICollection<>` interface objects
+-    Fixed issue when calling PythonException.Format where another exception would be raise for unnormalized exceptions
 -    Made it possible to call `ToString`, `GetHashCode`, and `GetType` on inteface objects
 -    Fixed objects returned by enumerating `PyObject` being disposed too soon
 -    Incorrectly using a non-generic type with type parameters now produces a helpful Python error instead of throwing NullReferenceException
diff --git a/src/embed_tests/TestPythonException.cs b/src/embed_tests/TestPythonException.cs
@@ -86,9 +86,54 @@ public void TestPythonExceptionFormatNoTraceback()
             }
             catch (PythonException ex)
             {
-                // ImportError/ModuleNotFoundError do not have a traceback when not running in a script 
+                // ImportError/ModuleNotFoundError do not have a traceback when not running in a script
                 Assert.AreEqual(ex.StackTrace, ex.Format());
             }
         }
+
+        [Test]
+        public void TestPythonExceptionFormatNormalized()
+        {
+            try
+            {
+                PythonEngine.Exec("a=b\n");
+            }
+            catch (PythonException ex)
+            {
+                Assert.AreEqual("Traceback (most recent call last):\n  File \"<string>\", line 1, in <module>\nNameError: name 'b' is not defined\n", ex.Format());
+            }
+        }
+
+        [Test]
+        public void TestPythonException_PyErr_NormalizeException()
+        {
+            using (var scope = Py.CreateScope())
+            {
+                scope.Exec(@"
+class TestException(NameError):
+    def __init__(self, val):
+        super().__init__(val)
+        x = int(val)");
+                Assert.IsTrue(scope.TryGet("TestException", out PyObject type));
+
+                PyObject str = "dummy string".ToPython();
+                IntPtr typePtr = type.Handle;
+                IntPtr strPtr = str.Handle;
+                IntPtr tbPtr = Runtime.Runtime.None.Handle;
+                Runtime.Runtime.XIncref(typePtr);
+                Runtime.Runtime.XIncref(strPtr);
+                Runtime.Runtime.XIncref(tbPtr);
+                Runtime.Runtime.PyErr_NormalizeException(ref typePtr, ref strPtr, ref tbPtr);
+
+                using (PyObject typeObj = new PyObject(typePtr), strObj = new PyObject(strPtr), tbObj = new PyObject(tbPtr))
+                {
+                    // the type returned from PyErr_NormalizeException should not be the same type since a new
+                    // exception was raised by initializing the exception
+                    Assert.AreNotEqual(type.Handle, typePtr);
+                    // the message should now be the string from the throw exception during normalization
+                    Assert.AreEqual("invalid literal for int() with base 10: 'dummy string'", strObj.ToString());
+                }
+            }
+        }
     }
 }
diff --git a/src/runtime/pythonexception.cs b/src/runtime/pythonexception.cs
@@ -160,12 +160,18 @@ public string Format()
             {
                 if (_pyTB != IntPtr.Zero && _pyType != IntPtr.Zero && _pyValue != IntPtr.Zero)
                 {
-                    Runtime.XIncref(_pyType);
-                    Runtime.XIncref(_pyValue);
-                    Runtime.XIncref(_pyTB);
-                    using (PyObject pyType = new PyObject(_pyType))
-                    using (PyObject pyValue = new PyObject(_pyValue))
-                    using (PyObject pyTB = new PyObject(_pyTB))
+                    IntPtr tb = _pyTB;
+                    IntPtr type = _pyType;
+                    IntPtr value = _pyValue;
+
+                    Runtime.XIncref(type);
+                    Runtime.XIncref(value);
+                    Runtime.XIncref(tb);
+                    Runtime.PyErr_NormalizeException(ref type, ref value, ref tb);
+
+                    using (PyObject pyType = new PyObject(type))
+                    using (PyObject pyValue = new PyObject(value))
+                    using (PyObject pyTB = new PyObject(tb))
                     using (PyObject tb_mod = PythonEngine.ImportModule("traceback"))
                     {
                         var buffer = new StringBuilder();
diff --git a/src/runtime/runtime.cs b/src/runtime/runtime.cs
@@ -2035,7 +2035,7 @@ internal static IntPtr PyMem_Realloc(IntPtr ptr, long size)
         internal static extern int PyErr_GivenExceptionMatches(IntPtr ob, IntPtr val);
 
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
-        internal static extern void PyErr_NormalizeException(IntPtr ob, IntPtr val, IntPtr tb);
+        internal static extern void PyErr_NormalizeException(ref IntPtr ob, ref IntPtr val, ref IntPtr tb);
 
         [DllImport(_PythonDll, CallingConvention = CallingConvention.Cdecl)]
         internal static extern IntPtr PyErr_Occurred();
