bpo-44630: Fix assertion errors in csv module (GH-27127)

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 0093876328)

Co-authored-by: T. Wouters <thomas@python.org>
This commit is contained in:
Miss Islington (bot) 2021-07-13 16:20:28 -07:00 committed by GitHub
parent a3d20bfee3
commit fe73509c5b
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2 changed files with 14 additions and 4 deletions

View file

@ -442,9 +442,15 @@ class TestDialectRegistry(unittest.TestCase):
class testUni(csv.excel):
delimiter = "\u039B"
class unspecified():
# A class to pass as dialect but with no dialect attributes.
pass
csv.register_dialect('testC', testC)
try:
self.compare_dialect_123("1,2,3\r\n")
self.compare_dialect_123("1,2,3\r\n", dialect=None)
self.compare_dialect_123("1,2,3\r\n", dialect=unspecified)
self.compare_dialect_123("1\t2\t3\r\n", testA)
self.compare_dialect_123("1:2:3\r\n", dialect=testB())
self.compare_dialect_123("1|2|3\r\n", dialect='testC')

View file

@ -400,8 +400,13 @@ dialect_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
Py_XINCREF(strict);
if (dialect != NULL) {
#define DIALECT_GETATTR(v, n) \
do { \
if (v == NULL) { \
v = PyObject_GetAttrString(dialect, n); \
if (v == NULL) \
v = PyObject_GetAttrString(dialect, n)
PyErr_Clear(); \
} \
} while (0)
DIALECT_GETATTR(delimiter, "delimiter");
DIALECT_GETATTR(doublequote, "doublequote");
DIALECT_GETATTR(escapechar, "escapechar");
@ -410,7 +415,6 @@ 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 */