Fix missing dbus_message_unref() in error reply path

The error message was leaked when blocking on a pending call after
the connection was disconnected.
Reviewed-by: Philip Withnall <withnall@endlessm.com>
[smcv: re-word commit message]
Reviewed-by: Simon McVittie <smcv@collabora.com>
Bug: https://bugs.freedesktop.org/show_bug.cgi?id=101481

dbus/dbus-connection.c

@@ -2476,6 +2476,8 @@ _dbus_connection_block_pending_call (DBusPendingCall *pending)
 
       /* on OOM error_msg is set to NULL */
       complete_pending_call_and_unlock (connection, pending, error_msg);
+      if (error_msg != NULL)
+        dbus_message_unref (error_msg);
       dbus_pending_call_unref (pending);
       return;
     }

test/name-test/Makefile.am

@@ -31,6 +31,7 @@ AM_TESTS_ENVIRONMENT = \
 TESTS += \
 	run-test.sh \
 	run-test-systemserver.sh \
+	test-pending-call-disconnected \
 	$(NULL)
 endif
 endif
@@ -41,10 +42,11 @@ if DBUS_ENABLE_EMBEDDED_TESTS
 
 ## we use noinst_PROGRAMS not check_PROGRAMS for TESTS so that we
 ## build even when not doing "make check"
-noinst_PROGRAMS=test-pending-call-dispatch test-pending-call-timeout test-threads-init test-ids test-shutdown test-privserver test-privserver-client test-autolaunch
+noinst_PROGRAMS=test-pending-call-dispatch test-pending-call-timeout test-pending-call-disconnected test-threads-init test-ids test-shutdown test-privserver test-privserver-client test-autolaunch
 
 test_pending_call_dispatch_LDADD=$(top_builddir)/dbus/libdbus-1.la
 test_pending_call_timeout_LDADD=$(top_builddir)/dbus/libdbus-1.la
+test_pending_call_disconnected_LDADD=$(top_builddir)/dbus/libdbus-1.la
 test_threads_init_LDADD=$(top_builddir)/dbus/libdbus-1.la
 test_ids_LDADD=$(top_builddir)/dbus/libdbus-1.la
 

test/name-test/test-pending-call-disconnected.c

+/*
+ * Copyright © 2006 Red Hat Inc.
+ * Copyright © 2017 Shin-ichi MORITA <shin1morita@gmail.com>
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+/**
+* Test to make sure that pending calls unref error messages
+* when blocked after disconnected.
+**/
+
+#include <config.h>
+#include <dbus/dbus.h>
+#include <dbus/dbus-sysdeps.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static size_t count = 0;
+
+static void
+free_data (void *data)
+{
+  --count;
+  printf ("# Freed: %s\n", (const char*)data);
+}
+
+/* This test outputs TAP syntax: http://testanything.org/ */
+int
+main (int argc, char *argv[])
+{
+  dbus_int32_t slot_connection = -1;
+  dbus_int32_t slot_message = -1;
+  dbus_int32_t slot_pending = -1;
+  DBusError error;
+  DBusConnection *conn;
+  DBusMessage *method;
+  DBusPendingCall *pending;
+  DBusMessage *reply;
+
+  printf ("# Testing pending call error\n");
+
+  dbus_connection_allocate_data_slot (&slot_connection);
+  dbus_message_allocate_data_slot (&slot_message);
+  dbus_pending_call_allocate_data_slot (&slot_pending);
+
+  dbus_error_init (&error);
+  conn = dbus_bus_get_private (DBUS_BUS_SESSION, &error);
+  dbus_connection_set_data (conn, slot_connection, (void*)"connection", free_data);
+  ++count;
+  dbus_connection_set_exit_on_disconnect (conn, FALSE);
+
+  method = dbus_message_new_method_call ("org.freedesktop.TestSuiteEchoService",
+                                         "/org/freedesktop/TestSuite",
+                                         "org.freedesktop.TestSuite",
+                                         "Exit");
+  dbus_message_set_data (method, slot_message, (void*)"method", free_data);
+  ++count;
+
+  dbus_connection_send_with_reply (conn, method, &pending, -1);
+  dbus_message_unref (method);
+  dbus_pending_call_set_data (pending, slot_pending, (void*)"pending", free_data);
+  ++count;
+
+  dbus_connection_close (conn);
+
+  dbus_pending_call_block (pending);
+  reply = dbus_pending_call_steal_reply (pending);
+  dbus_pending_call_unref (pending);
+  if (reply == NULL)
+    {
+      printf ("Bail out! Reply is NULL ***\n");
+      exit (1);
+    }
+  dbus_message_set_data (reply, slot_message, (void*)"reply", free_data);
+  ++count;
+  if (dbus_message_get_type (reply) != DBUS_MESSAGE_TYPE_ERROR)
+    {
+      printf ("Bail out! Reply is not error ***\n");
+      exit (1);
+    }
+  dbus_message_unref (reply);
+
+  dbus_connection_unref (conn);
+
+  dbus_connection_free_data_slot (&slot_connection);
+  dbus_message_free_data_slot (&slot_message);
+  dbus_pending_call_free_data_slot (&slot_pending);
+
+  if (count != 0)
+    {
+      printf ("not ok # Not all refs were unrefed ***\n");
+      exit (1);
+    }
+  else
+    {
+      printf ("ok\n# Testing completed\n1..1\n");
+      exit (0);
+    }
+}