Replace a some uses of PyErr_Fetch with PyErr_Fetch1.

python · markshannon · Feb 8, 2023 · Feb 6, 2023 · Feb 6, 2023 · Feb 6, 2023
commit 8b62323f4575f5147f9a8889f66764b70c52ba05
diff --git a/Include/cpython/pyerrors.h b/Include/cpython/pyerrors.h
@@ -99,6 +99,7 @@ PyAPI_FUNC(void) _PyErr_GetExcInfo(PyThreadState *, PyObject **, PyObject **, Py
 /* Context manipulation (PEP 3134) */
 
 PyAPI_FUNC(void) _PyErr_ChainExceptions(PyObject *, PyObject *, PyObject *);
+PyAPI_FUNC(void) _PyErr_ChainExceptions1(PyObject *);
 
 /* Like PyErr_Format(), but saves current exception as __context__ and
    __cause__.

@@ -2082,11 +2082,10 @@ PyGC_Collect(void)
         n = 0;
     }
     else {
-        PyObject *exc, *value, *tb;
         gcstate->collecting = 1;
-        _PyErr_Fetch(tstate, &exc, &value, &tb);
+        PyObject *exc = _PyErr_Fetch1(tstate);
         n = gc_collect_with_callback(tstate, NUM_GENERATIONS - 1);
-        _PyErr_Restore(tstate, exc, value, tb);
+        _PyErr_Restore1(tstate, exc);
         gcstate->collecting = 0;
     }
 

@@ -1663,15 +1663,15 @@ PyDict_GetItem(PyObject *op, PyObject *key)
 #endif
 
     /* Preserve the existing exception */
-    PyObject *exc_type, *exc_value, *exc_tb;
     PyObject *value;
     Py_ssize_t ix; (void)ix;
 
-    _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+
+    PyObject *exc = _PyErr_Fetch1(tstate);
     ix = _Py_dict_lookup(mp, key, hash, &value);
 
     /* Ignore any exception raised by the lookup */
-    _PyErr_Restore(tstate, exc_type, exc_value, exc_tb);
+    _PyErr_Restore1(tstate, exc);
 
 
     assert(ix >= 0 || value == NULL);

@@ -787,9 +787,7 @@ dummy_func(
                 DECREF_INPUTS();
             }
             else {
-                PyObject *exc_type = Py_NewRef(Py_TYPE(exc_value));
-                PyObject *exc_traceback = PyException_GetTraceback(exc_value);
-                _PyErr_Restore(tstate, exc_type, Py_NewRef(exc_value), exc_traceback);
+                _PyErr_Restore1(tstate, Py_NewRef(exc_value));
                 goto exception_unwind;
             }
         }

diff --git a/Python/errors.c b/Python/errors.c
@@ -626,6 +626,28 @@ _PyErr_ChainExceptions(PyObject *typ, PyObject *val, PyObject *tb)
     }
 }
 
+/* Like PyErr_Restore1(), but if an exception is already set,
+   set the context associated with it.
+
+   The caller is responsible for ensuring that this call won't create
+   any cycles in the exception context chain. */
+void
+_PyErr_ChainExceptions1(PyObject *exc)
+{
+    if (exc == NULL) {
+        return;
+    }
+    PyThreadState *tstate = _PyThreadState_GET();
+    if (_PyErr_Occurred(tstate)) {
+        PyObject *exc2 = _PyErr_Fetch1(tstate);
+        PyException_SetContext(exc2, exc);
+        _PyErr_Restore1(tstate, exc2);
+    }
+    else {
+        _PyErr_Restore1(tstate, exc);
+    }
+}
+
 /* Set the currently set exception's context to the given exception.
 
    If the provided exc_info is NULL, then the current Python thread state's

@@ -3143,8 +3143,7 @@ init_dump_ascii_wstr(const wchar_t *str)
 void
 _Py_DumpPathConfig(PyThreadState *tstate)
 {
-    PyObject *exc_type, *exc_value, *exc_tb;
-    _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+    PyObject *exc = _PyErr_Fetch1(tstate);
 
     PySys_WriteStderr("Python path configuration:\n");
 
@@ -3202,5 +3201,5 @@ _Py_DumpPathConfig(PyThreadState *tstate)
         PySys_WriteStderr("  ]\n");
     }
 
-    _PyErr_Restore(tstate, exc_type, exc_value, exc_tb);
+    _PyErr_Restore1(tstate, exc);
 }
@@ -66,12 +66,11 @@ _PySys_GetAttr(PyThreadState *tstate, PyObject *name)
     if (sd == NULL) {
         return NULL;
     }
-    PyObject *exc_type, *exc_value, *exc_tb;
-    _PyErr_Fetch(tstate, &exc_type, &exc_value, &exc_tb);
+    PyObject *exc = _PyErr_Fetch1(tstate);
     /* XXX Suppress a new exception if it was raised and restore
      * the old one. */
     PyObject *value = _PyDict_GetItemWithError(sd, name);
-    _PyErr_Restore(tstate, exc_type, exc_value, exc_tb);
+    _PyErr_Restore1(tstate, exc);
     return value;
 }
 
@@ -3704,11 +3703,10 @@ static void
 sys_format(PyObject *key, FILE *fp, const char *format, va_list va)
 {
     PyObject *file, *message;
-    PyObject *error_type, *error_value, *error_traceback;
     const char *utf8;
     PyThreadState *tstate = _PyThreadState_GET();
 
-    _PyErr_Fetch(tstate, &error_type, &error_value, &error_traceback);
+        PyObject *error = _PyErr_Fetch1(tstate);
     file = _PySys_GetAttr(tstate, key);
     message = PyUnicode_FromFormatV(format, va);
     if (message != NULL) {
@@ -3720,7 +3718,7 @@ sys_format(PyObject *key, FILE *fp, const char *format, va_list va)
         }
         Py_DECREF(message);
     }
-    _PyErr_Restore(tstate, error_type, error_value, error_traceback);
+    _PyErr_Restore1(tstate, error);
 }
 
 void

diff --git a/Python/traceback.c b/Python/traceback.c
@@ -262,13 +262,12 @@ void _PyTraceback_Add(const char *funcname, const char *filename, int lineno)
     PyObject *globals;
     PyCodeObject *code;
     PyFrameObject *frame;
-    PyObject *exc, *val, *tb;
     PyThreadState *tstate = _PyThreadState_GET();
 
     /* Save and clear the current exception. Python functions must not be
        called with an exception set. Calling Python functions happens when
        the codec of the filesystem encoding is implemented in pure Python. */
-    _PyErr_Fetch(tstate, &exc, &val, &tb);
+    PyObject *exc = _PyErr_Fetch1(tstate);
 
     globals = PyDict_New();
     if (!globals)
@@ -285,13 +284,13 @@ void _PyTraceback_Add(const char *funcname, const char *filename, int lineno)
         goto error;
     frame->f_lineno = lineno;
 
-    _PyErr_Restore(tstate, exc, val, tb);
+    _PyErr_Restore1(tstate, exc);
     PyTraceBack_Here(frame);
     Py_DECREF(frame);
     return;
 
 error:
-    _PyErr_ChainExceptions(exc, val, tb);
+    _PyErr_ChainExceptions1(exc);
 }
 
 static PyObject *