Issue #21715: Extracted shared complicated code in the _io module to new

_PyErr_ChainExceptions() function.

1 files changed, 24 insertions, 0 deletions

diff --git a/Python/errors.c b/Python/errors.c
index fd55142525..940aef33a2 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -384,6 +384,30 @@ PyErr_SetExcInfo(PyObject *p_type, PyObject *p_value, PyObject *p_traceback)
     Py_XDECREF(oldtraceback);
 }
 
+/* Like PyErr_Restore(), but if an exception is already set,
+   set the context associated with it.
+ */
+void
+_PyErr_ChainExceptions(PyObject *exc, PyObject *val, PyObject *tb)
+{
+    if (exc == NULL)
+        return;
+
+    if (PyErr_Occurred()) {
+        PyObject *exc2, *val2, *tb2;
+        PyErr_Fetch(&exc2, &val2, &tb2);
+        PyErr_NormalizeException(&exc, &val, &tb);
+        Py_DECREF(exc);
+        Py_XDECREF(tb);
+        PyErr_NormalizeException(&exc2, &val2, &tb2);
+        PyException_SetContext(val2, val);
+        PyErr_Restore(exc2, val2, tb2);
+    }
+    else {
+        PyErr_Restore(exc, val, tb);
+    }
+}
+
 /* Convenience functions to set a type error exception and return 0 */
 
 int