Make PyErr_Occurred return NULL if there is no current thread. Previously it

would Py_FatalError, which called PyErr_Occurred, resulting in a semi-infinite
recursion.

Fixes issue 3605.

1 files changed, 8 insertions, 3 deletions

diff --git a/Python/errors.c b/Python/errors.c
index e98d7a9..3766973 100644
--- a/Python/errors.c
+++ b/Python/errors.c
@@ -130,9 +130,14 @@ PyErr_SetString(PyObject *exception, const char *string)
 PyObject *
 PyErr_Occurred(void)
 {
-    PyThreadState *tstate = PyThreadState_GET();
-
-    return tstate->curexc_type;
+    /* If there is no thread state, PyThreadState_GET calls
+       Py_FatalError, which calls PyErr_Occurred.  To avoid the
+       resulting infinite loop, we inline PyThreadState_GET here and
+       treat no thread as no error. */
+    PyThreadState *tstate =
+        ((PyThreadState*)_Py_atomic_load_relaxed(&_PyThreadState_Current));
+
+    return tstate == NULL ? NULL : tstate->curexc_type;
 }