Fixed refcount handling in encrypt_password

Added tests to check bad types, which discovered the above problem: on
type error we would have decref'd on exit something that was only
borrowed (because we wouldn't have performed matching increfs).

psycopg/psycopgmodule.c

@@ -418,16 +418,20 @@ psyco_encrypt_password(PyObject *self, PyObject *args, PyObject *kwargs)
     PyObject *password = NULL, *user = NULL;
     PyObject *scope = Py_None, *algorithm = Py_None;
     PyObject *res = NULL;
+    connectionObject *conn = NULL;
 
     static char *kwlist[] = {"password", "user", "scope", "algorithm", NULL};
 
-    connectionObject *conn = NULL;
-
     if (!PyArg_ParseTupleAndKeywords(args, kwargs, "OO|OO", kwlist,
             &password, &user, &scope, &algorithm)) {
         return NULL;
     }
 
+    /* for ensure_bytes */
+    Py_INCREF(user);
+    Py_INCREF(password);
+    Py_INCREF(algorithm);
+
     if (scope != Py_None) {
         if (PyObject_TypeCheck(scope, &cursorType)) {
             conn = ((cursorObject*)scope)->conn;
@@ -437,16 +441,11 @@ psyco_encrypt_password(PyObject *self, PyObject *args, PyObject *kwargs)
         }
         else {
             PyErr_SetString(PyExc_TypeError,
-                    "the scope must be a connection or a cursor");
+                "the scope must be a connection or a cursor");
             goto exit;
         }
     }
 
-    /* for ensure_bytes */
-    Py_INCREF(user);
-    Py_INCREF(password);
-    Py_INCREF(algorithm);
-
     if (!(user = psycopg_ensure_bytes(user))) { goto exit; }
     if (!(password = psycopg_ensure_bytes(password))) { goto exit; }
     if (algorithm != Py_None) {
@@ -473,7 +472,7 @@ psyco_encrypt_password(PyObject *self, PyObject *args, PyObject *kwargs)
             goto exit;
         }
 
-        /* TODO: algo = will block: forbid on async/green conn? */
+        /* TODO: algo = None will block: forbid on async/green conn? */
         encrypted = PQencryptPasswordConn(conn->pgconn,
             Bytes_AS_STRING(password), Bytes_AS_STRING(user),
             algorithm != Py_None ? Bytes_AS_STRING(algorithm) : NULL);

tests/test_connection.py

@@ -1482,6 +1482,17 @@ def test_encrypt_scram(self):
                 password='psycopg2', user='ashesh',
                 scope=self.conn, algorithm='scram-sha-256')
 
+    def test_bad_types(self):
+        self.assertRaises(TypeError, ext.encrypt_password)
+        self.assertRaises(TypeError, ext.encrypt_password,
+            'password', 42, self.conn, 'md5')
+        self.assertRaises(TypeError, ext.encrypt_password,
+            42, 'user', self.conn, 'md5')
+        self.assertRaises(TypeError, ext.encrypt_password,
+            42, 'user', 'wat', 'abc')
+        self.assertRaises(TypeError, ext.encrypt_password,
+            'password', 'user', 'wat', 42)
+
 
 class AutocommitTests(ConnectingTestCase):
     def test_closed(self):