gh-129409: Fix Integer overflow - SEGV while writing data more than 2GB in CSV file

Lib/test/test_csv.py

@@ -1560,6 +1560,20 @@ def test_ordered_dict_reader(self):
              OrderedDict([('fname', 'John'), ('lname', 'Cleese')]),
             ])
 
+class HugeDataTest(unittest.TestCase):
+    def test_write_huge_data(self):
+        bad_size = 2 * 1024 * 1024 * 1024 + 1  # Just over 2GB
+        val = 'x' * bad_size
+        with TemporaryFile("w", encoding="utf-8", newline='') as fileobj:
+            csv_writer = csv.writer(fileobj, delimiter=',',
+                                    quotechar='|',
+                                    quoting=csv.QUOTE_MINIMAL)
+            csv_writer.writerow([val])
+            fileobj.seek(0)
+            reader = csv.reader(fileobj)
+            row = next(reader)
+            self.assertEqual(len(row), 1)
+
 
 class MiscTestCase(unittest.TestCase):
     def test__all__(self):

Modules/_csv.c

@@ -1138,7 +1138,7 @@ join_append_data(WriterObj *self, int field_kind, const void *field_data,
                  int copy_phase)
 {
     DialectObj *dialect = self->dialect;
-    int i;
+    Py_ssize_t i;
     Py_ssize_t rec_len;
 
 #define INCLEN \