[3.10] bpo-44630: Fix assertion errors in csv module (GH-27127) (GH-27129)
Fix incorrect handling of exceptions when interpreting dialect objects in
the csv module. Not clearing exceptions between calls to
PyObject_GetAttrString() causes assertion failures in pydebug mode (or with
assertions enabled).
Add a minimal test that would've caught this (passing None as dialect, or
any object that isn't a csv.Dialect subclass, which the csv module allows
and caters to, even though it is not documented.) In pydebug mode, the test
triggers the assertion failure in the old code.
Contributed-By: T. Wouters [Google]
(cherry picked from commit 0093876328afa330224c9d887c18dee0b3117852)
Co-authored-by: T. Wouters <thomas@python.org>
Automerge-Triggered-By: GH:gpshead
diff --git a/Modules/_csv.c b/Modules/_csv.c
index 78855b8..3109fd1 100644
--- a/Modules/_csv.c
+++ b/Modules/_csv.c
@@ -421,9 +421,14 @@ dialect_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
Py_XINCREF(skipinitialspace);
Py_XINCREF(strict);
if (dialect != NULL) {
-#define DIALECT_GETATTR(v, n) \
- if (v == NULL) \
- v = PyObject_GetAttrString(dialect, n)
+#define DIALECT_GETATTR(v, n) \
+ do { \
+ if (v == NULL) { \
+ v = PyObject_GetAttrString(dialect, n); \
+ if (v == NULL) \
+ PyErr_Clear(); \
+ } \
+ } while (0)
DIALECT_GETATTR(delimiter, "delimiter");
DIALECT_GETATTR(doublequote, "doublequote");
DIALECT_GETATTR(escapechar, "escapechar");
@@ -432,7 +437,6 @@ dialect_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
DIALECT_GETATTR(quoting, "quoting");
DIALECT_GETATTR(skipinitialspace, "skipinitialspace");
DIALECT_GETATTR(strict, "strict");
- PyErr_Clear();
}
/* check types and convert to C values */