bpo-43752: Fix sqlite3 regression for zero-sized blobs with converters (GH-25228)
diff --git a/Lib/sqlite3/test/types.py b/Lib/sqlite3/test/types.py
index 2370dd1..4bb1de8 100644
--- a/Lib/sqlite3/test/types.py
+++ b/Lib/sqlite3/test/types.py
@@ -255,7 +255,9 @@ def test_number2(self):
def test_convert_zero_sized_blob(self):
self.con.execute("insert into test(cbin) values (?)", (b"",))
cur = self.con.execute("select cbin from test")
- self.assertEqual(cur.fetchone()[0], b"blobish")
+ # Zero-sized blobs with converters returns None. This differs from
+ # blobs without a converter, where b"" is returned.
+ self.assertIsNone(cur.fetchone()[0])
class ColNamesTests(unittest.TestCase):
diff --git a/Misc/NEWS.d/next/Library/2021-04-06-21-18-29.bpo-43752.K7qmAF.rst b/Misc/NEWS.d/next/Library/2021-04-06-21-18-29.bpo-43752.K7qmAF.rst
new file mode 100644
index 0000000..ef4b953
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2021-04-06-21-18-29.bpo-43752.K7qmAF.rst
@@ -0,0 +1,3 @@
+Fix :mod:`sqlite3` regression for zero-sized blobs with converters, where
+``b""`` was returned instead of ``None``. The regression was introduced by
+GH-24723. Patch by Erlend E. Aasland.
diff --git a/Modules/_sqlite/cursor.c b/Modules/_sqlite/cursor.c
index dfaa557..09c9a8c 100644
--- a/Modules/_sqlite/cursor.c
+++ b/Modules/_sqlite/cursor.c
@@ -240,7 +240,6 @@ _pysqlite_fetch_one_row(pysqlite_Cursor* self)
{
int i, numcols;
PyObject* row;
- PyObject* item = NULL;
int coltype;
PyObject* converter;
PyObject* converted;
@@ -282,18 +281,22 @@ _pysqlite_fetch_one_row(pysqlite_Cursor* self)
*/
if (converter != Py_None) {
const void *blob = sqlite3_column_blob(self->statement->st, i);
- if (blob == NULL && sqlite3_errcode(db) == SQLITE_NOMEM) {
- PyErr_NoMemory();
- goto error;
+ if (blob == NULL) {
+ if (sqlite3_errcode(db) == SQLITE_NOMEM) {
+ PyErr_NoMemory();
+ goto error;
+ }
+ converted = Py_NewRef(Py_None);
}
-
- nbytes = sqlite3_column_bytes(self->statement->st, i);
- item = PyBytes_FromStringAndSize(blob, nbytes);
- if (item == NULL) {
- goto error;
+ else {
+ nbytes = sqlite3_column_bytes(self->statement->st, i);
+ PyObject *item = PyBytes_FromStringAndSize(blob, nbytes);
+ if (item == NULL) {
+ goto error;
+ }
+ converted = PyObject_CallOneArg(converter, item);
+ Py_DECREF(item);
}
- converted = PyObject_CallOneArg(converter, item);
- Py_DECREF(item);
} else {
Py_BEGIN_ALLOW_THREADS
coltype = sqlite3_column_type(self->statement->st, i);