Commit 1fc89735 authored by David Zeuthen's avatar David Zeuthen

g_bus_own_name: fix race when unowning a name immediately after owning it

... and also add a test to verify that the fix works.

https://bugzilla.gnome.org/show_bug.cgi?id=662808Signed-off-by: default avatarDavid Zeuthen <davidz@redhat.com>
parent 4c038429
......@@ -74,7 +74,7 @@ typedef struct
guint name_acquired_subscription_id;
guint name_lost_subscription_id;
gboolean cancelled;
volatile gboolean cancelled; /* must hold lock when reading or modifying */
gboolean needs_release;
} Client;
......@@ -219,27 +219,39 @@ do_call (Client *client, CallType call_type)
static void
call_acquired_handler (Client *client)
{
G_LOCK (lock);
if (client->previous_call != PREVIOUS_CALL_ACQUIRED)
{
client->previous_call = PREVIOUS_CALL_ACQUIRED;
if (!client->cancelled)
{
G_UNLOCK (lock);
do_call (client, CALL_TYPE_NAME_ACQUIRED);
goto out;
}
}
G_UNLOCK (lock);
out:
;
}
static void
call_lost_handler (Client *client)
{
G_LOCK (lock);
if (client->previous_call != PREVIOUS_CALL_LOST)
{
client->previous_call = PREVIOUS_CALL_LOST;
if (!client->cancelled)
{
G_UNLOCK (lock);
do_call (client, CALL_TYPE_NAME_LOST);
goto out;
}
}
G_UNLOCK (lock);
out:
;
}
/* ---------------------------------------------------------------------------------------------------- */
......@@ -296,7 +308,8 @@ request_name_cb (GObject *source_object,
request_name_reply = 0;
result = NULL;
result = g_dbus_connection_call_finish (client->connection,
/* don't use client->connection - it may be NULL already */
result = g_dbus_connection_call_finish (G_DBUS_CONNECTION (source_object),
res,
NULL);
if (result != NULL)
......@@ -332,31 +345,47 @@ request_name_cb (GObject *source_object,
break;
}
if (subscribe)
{
GDBusConnection *connection = NULL;
/* if cancelled, there is no point in subscribing to signals - if not, make sure
* we use a known good Connection object since it may be set to NULL at any point
* after being cancelled
*/
G_LOCK (lock);
if (!client->cancelled)
connection = g_object_ref (client->connection);
G_UNLOCK (lock);
/* start listening to NameLost and NameAcquired messages */
client->name_lost_subscription_id =
g_dbus_connection_signal_subscribe (client->connection,
"org.freedesktop.DBus",
"org.freedesktop.DBus",
"NameLost",
"/org/freedesktop/DBus",
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_lost_or_acquired,
client,
NULL);
client->name_acquired_subscription_id =
g_dbus_connection_signal_subscribe (client->connection,
"org.freedesktop.DBus",
"org.freedesktop.DBus",
"NameAcquired",
"/org/freedesktop/DBus",
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_lost_or_acquired,
client,
NULL);
if (connection != NULL)
{
client->name_lost_subscription_id =
g_dbus_connection_signal_subscribe (connection,
"org.freedesktop.DBus",
"org.freedesktop.DBus",
"NameLost",
"/org/freedesktop/DBus",
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_lost_or_acquired,
client,
NULL);
client->name_acquired_subscription_id =
g_dbus_connection_signal_subscribe (connection,
"org.freedesktop.DBus",
"org.freedesktop.DBus",
"NameAcquired",
"/org/freedesktop/DBus",
client->name,
G_DBUS_SIGNAL_FLAGS_NONE,
on_name_lost_or_acquired,
client,
NULL);
g_object_unref (connection);
}
}
client_unref (client);
......@@ -423,6 +452,15 @@ connection_get_cb (GObject *source_object,
{
Client *client = user_data;
/* must not do anything if already cancelled */
G_LOCK (lock);
if (client->cancelled)
{
G_UNLOCK (lock);
goto out;
}
G_UNLOCK (lock);
client->connection = g_bus_get_finish (res, NULL);
if (client->connection == NULL)
{
......
......@@ -213,6 +213,31 @@ test_bus_own_name (void)
g_assert (!name_has_owner_reply);
g_variant_unref (result);
/* Now try owning the name and then immediately decide to unown the name */
g_assert_cmpint (data.num_bus_acquired, ==, 1);
g_assert_cmpint (data.num_acquired, ==, 1);
g_assert_cmpint (data.num_lost, ==, 0);
g_assert_cmpint (data.num_free_func, ==, 2);
id = g_bus_own_name (G_BUS_TYPE_SESSION,
name,
G_BUS_NAME_OWNER_FLAGS_NONE,
bus_acquired_handler,
name_acquired_handler,
name_lost_handler,
&data,
(GDestroyNotify) own_name_data_free_func);
g_assert_cmpint (data.num_bus_acquired, ==, 1);
g_assert_cmpint (data.num_acquired, ==, 1);
g_assert_cmpint (data.num_lost, ==, 0);
g_assert_cmpint (data.num_free_func, ==, 2);
g_bus_unown_name (id);
g_assert_cmpint (data.num_bus_acquired, ==, 1);
g_assert_cmpint (data.num_acquired, ==, 1);
g_assert_cmpint (data.num_lost, ==, 0);
g_assert_cmpint (data.num_free_func, ==, 2);
g_main_loop_run (loop); /* the GDestroyNotify is called in idle because the bus is acquired in idle */
g_assert_cmpint (data.num_free_func, ==, 3);
/*
* Own the name again.
*/
......@@ -344,7 +369,7 @@ test_bus_own_name (void)
g_bus_unown_name (id);
g_assert_cmpint (data.num_bus_acquired, ==, 1);
g_assert_cmpint (data.num_acquired, ==, 1);
g_assert_cmpint (data.num_free_func, ==, 3);
g_assert_cmpint (data.num_free_func, ==, 4);
/* grab it again */
data.num_bus_acquired = 0;
data.num_acquired = 0;
......@@ -443,7 +468,7 @@ test_bus_own_name (void)
g_assert_cmpint (data.num_acquired, ==, 2);
g_assert_cmpint (data.num_lost, ==, 2);
g_bus_unown_name (id);
g_assert_cmpint (data.num_free_func, ==, 4);
g_assert_cmpint (data.num_free_func, ==, 5);
_g_object_wait_for_single_ref (c);
g_object_unref (c);
......
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