fd.o #21831: deserialize empty ByteArray objects correctly

For some reason libdbus gives us NULL instead of a pointer to a
zero-length object (i.e. any random place in the message would do), which
Py_BuildValue doesn't interpret the way we'd want it to.

2 files changed, 13 insertions, 0 deletions

diff --git a/_dbus_bindings/message-get-args.c b/_dbus_bindings/message-get-args.c
index 7d55ffd..d6b7aba 100644
--- a/_dbus_bindings/message-get-args.c
+++ b/_dbus_bindings/message-get-args.c
@@ -387,6 +387,12 @@ _message_iter_get_pyobject(DBusMessageIter *iter,
                 dbus_message_iter_get_fixed_array(&sub,
                                                   (const unsigned char **)&u.s,
                                                   &n);
+                if (n == 0 && u.s == NULL) {
+                    /* fd.o #21831: s# turns (NULL, 0) into None, but
+                     * dbus_message_iter_get_fixed_array produces (NULL, 0)
+                     * for an empty byte-blob... */
+                    u.s = "";
+                }
                 args = Py_BuildValue("(s#)", u.s, (Py_ssize_t)n);
                 if (!args) break;
                 ret = PyObject_Call((PyObject *)&DBusPyByteArray_Type,
diff --git a/test/test-standalone.py b/test/test-standalone.py
index 929fc37..04d1e6d 100755
--- a/test/test-standalone.py
+++ b/test/test-standalone.py
@@ -82,6 +82,9 @@ class TestTypes(unittest.TestCase):
     def test_Byte(self):
         self.assertEquals(types.Byte('x', variant_level=2), types.Byte(ord('x')))
 
+    def test_ByteArray(self):
+        self.assertEquals(types.ByteArray(''), '')
+
     def test_object_path_attr(self):
         class MyObject(object):
             __dbus_object_path__ = '/foo'
@@ -175,6 +178,10 @@ class TestMessageMarshalling(unittest.TestCase):
         s = SignalMessage('/', 'foo.bar', 'baz')
         s.append(types.ByteArray('ab'), signature='av')
         aeq(s.get_args_list(), [[types.Byte('a'), types.Byte('b')]])
+        s = SignalMessage('/', 'foo.bar', 'baz')
+        s.append(types.ByteArray(''), signature='ay')
+        aeq(s.get_args_list(), [[]])
+        aeq(s.get_args_list(byte_arrays=True), [types.ByteArray('')])
 
     def test_append_Variant(self):
         a = self.assert_