Issue #21497: faulthandler functions now raise a better error if sys.stderr is

vstinner · vstinner · commit e2d66903e8e3 · 2014-05-14T17:15:50.000+02:00
None: RuntimeError("sys.stderr is None") instead of AttributeError("'NoneType'
object has no attribute 'fileno'").
diff --git a/Lib/test/test_faulthandler.py b/Lib/test/test_faulthandler.py
@@ -591,6 +591,31 @@ def test_register_threads(self):
     def test_register_chain(self):
         self.check_register(chain=True)
 
+    @contextmanager
+    def check_stderr_none(self):
+        stderr = sys.stderr
+        try:
+            sys.stderr = None
+            with self.assertRaises(RuntimeError) as cm:
+                yield
+            self.assertEqual(str(cm.exception), "sys.stderr is None")
+        finally:
+            sys.stderr = stderr
+
+    def test_stderr_None(self):
+        # Issue #21497: provide an helpful error if sys.stderr is None,
+        # instead of just an attribute error: "None has no attribute fileno".
+        with self.check_stderr_none():
+            faulthandler.enable()
+        with self.check_stderr_none():
+            faulthandler.dump_traceback()
+        if hasattr(faulthandler, 'dump_traceback_later'):
+            with self.check_stderr_none():
+                faulthandler.dump_traceback_later(1e-3)
+        if hasattr(faulthandler, "register"):
+            with self.check_stderr_none():
+                faulthandler.register(signal.SIGUSR1)
+
 
 if __name__ == "__main__":
     unittest.main()
diff --git a/Modules/faulthandler.c b/Modules/faulthandler.c
@@ -144,6 +144,10 @@ faulthandler_get_fileno(PyObject *file, int *p_fd)
             PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr");
             return NULL;
         }
+        if (file == Py_None) {
+            PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");
+            return NULL;
+        }
     }
 
     result = _PyObject_CallMethodId(file, &PyId_fileno, "");

Original file line number	Diff line number	Diff line change
`@@ -144,6 +144,10 @@ faulthandler_get_fileno(PyObject file, int p_fd)`
`144`	`144`	`PyErr_SetString(PyExc_RuntimeError, "unable to get sys.stderr");`
`145`	`145`	`return NULL;`
`146`	`146`	`}`
	`147`	`+ if (file == Py_None) {`
	`148`	`+ PyErr_SetString(PyExc_RuntimeError, "sys.stderr is None");`
	`149`	`+ return NULL;`
	`150`	`+ }`
`147`	`151`	`}`
`148`	`152`
`149`	`153`	`result = _PyObject_CallMethodId(file, &PyId_fileno, "");`