From 7b3ea43e920d448f9eeb450ef04b1224d62b5542 Mon Sep 17 00:00:00 2001
From: Frazer McLean <frazer@frazermclean.co.uk>
Date: Sun, 16 Apr 2017 03:16:32 +0200
Subject: [PATCH] Handle lobject mode=None correctly

---
 psycopg/lobject_type.c | 5 ++++-
 tests/test_lobject.py  | 7 +++++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/psycopg/lobject_type.c b/psycopg/lobject_type.c
index 54f3a4be..81c56757 100644
--- a/psycopg/lobject_type.c
+++ b/psycopg/lobject_type.c
@@ -398,7 +398,7 @@ static int
 lobject_init(PyObject *obj, PyObject *args, PyObject *kwds)
 {
     Oid oid = InvalidOid, new_oid = InvalidOid;
-    const char *smode = "";
+    const char *smode = NULL;
     const char *new_file = NULL;
     PyObject *conn = NULL;
 
@@ -407,6 +407,9 @@ lobject_init(PyObject *obj, PyObject *args, PyObject *kwds)
          &oid, &smode, &new_oid, &new_file))
         return -1;
 
+    if (!smode)
+        smode = "";
+
     return lobject_setup((lobjectObject *)obj,
         (connectionObject *)conn, oid, smode, new_oid, new_file);
 }
diff --git a/tests/test_lobject.py b/tests/test_lobject.py
index 3379ec0c..f79ae5ea 100755
--- a/tests/test_lobject.py
+++ b/tests/test_lobject.py
@@ -110,6 +110,13 @@ class LargeObjectTests(LargeObjectTestCase):
         self.assertEqual(lo2.oid, lo.oid)
         self.assertEqual(lo2.closed, True)
 
+    def test_mode_defaults(self):
+        lo = self.conn.lobject()
+        lo2 = self.conn.lobject(mode=None)
+        lo3 = self.conn.lobject(mode="")
+        self.assertEqual(lo.mode, lo2.mode)
+        self.assertEqual(lo.mode, lo3.mode)
+
     def test_close_connection_gone(self):
         lo = self.conn.lobject()
         self.conn.close()