[evolution-ews/gnome-3-38] e-ews-notification: Add thread safety around get_events thread

[Milan Crha <mcrha src gnome org>]

commit 4678dd0a57d79b1f6f0a6a38b35037bcac18951d
Author: Milan Crha <mcrha redhat com>
Date:   Tue Jan 26 15:21:45 2021 +0100

    e-ews-notification: Add thread safety around get_events thread
    
    The thread can run twice for the same notification object, which can
    lead to thread safety issues causing crashes on various places.
    
    The changes contain:
    * unref an EEwsConnection early, thus it can be freed and the notification
      object with it, otherwise it could stay alive an infinity
    * add a lock to the get_events_thread() to avoid interleaving of
      the SoupSession calls - the old subscription is first unsubscribed
      and only then a new is created
    * exit early from the functions when the operation had been cancelled
    * do not use GBinding for the "proxy-resolver", because the GBinding
      code is not thread safe and it can cause other crashes.

 src/EWS/common/e-ews-notification.c | 46 +++++++++++++++++++++++++++++--------
 1 file changed, 36 insertions(+), 10 deletions(-)
---
diff --git a/src/EWS/common/e-ews-notification.c b/src/EWS/common/e-ews-notification.c
index 4c6d1553..21e552c5 100644
--- a/src/EWS/common/e-ews-notification.c
+++ b/src/EWS/common/e-ews-notification.c
@@ -20,6 +20,7 @@
 G_DEFINE_TYPE (EEwsNotification, e_ews_notification, G_TYPE_OBJECT)
 
 struct _EEwsNotificationPrivate {
+       GMutex thread_lock;
        SoupSession *soup_session;
        GWeakRef connection_wk;
        GByteArray *chunk;
@@ -168,12 +169,6 @@ ews_notification_constructed (GObject *object)
                        camel_ews_settings_get_auth_mechanism (ews_settings));
 
                g_object_unref (ews_settings);
-
-               e_binding_bind_property (
-                       cnc, "proxy-resolver",
-                       notif->priv->soup_session, "proxy-resolver",
-                       G_BINDING_SYNC_CREATE);
-
                g_object_unref (cnc);
        }
 }
@@ -213,6 +208,7 @@ ews_notification_finalize (GObject *object)
 
        g_weak_ref_clear (&notif->priv->connection_wk);
        g_free (notif->priv->last_subscription_id);
+       g_mutex_clear (&notif->priv->thread_lock);
 
        /* Chain up to parent's method. */
        G_OBJECT_CLASS (e_ews_notification_parent_class)->finalize (object);
@@ -262,8 +258,9 @@ e_ews_notification_init (EEwsNotification *notification)
        notification->priv = E_EWS_NOTIFICATION_GET_PRIVATE (notification);
 
        g_weak_ref_init (&notification->priv->connection_wk, NULL);
+       g_mutex_init (&notification->priv->thread_lock);
 
-       notification->priv->soup_session = soup_session_sync_new ();
+       notification->priv->soup_session = soup_session_new ();
 
        soup_session_add_feature_by_type (notification->priv->soup_session,
                                          SOUP_TYPE_COOKIE_JAR);
@@ -300,6 +297,9 @@ e_ews_notification_subscribe_folder_sync (EEwsNotification *notification,
        g_return_val_if_fail (notification != NULL, FALSE);
        g_return_val_if_fail (notification->priv != NULL, FALSE);
 
+       if (g_cancellable_is_cancelled (cancellable))
+               return FALSE;
+
        cnc = e_ews_notification_ref_connection (notification);
 
        /* Can happen during process shutdown */
@@ -845,6 +845,9 @@ e_ews_notification_get_events_sync (EEwsNotification *notification,
        g_return_val_if_fail (notification != NULL, FALSE);
        g_return_val_if_fail (notification->priv != NULL, FALSE);
 
+       if (g_cancellable_is_cancelled (cancellable))
+               return FALSE;
+
        cnc = e_ews_notification_ref_connection (notification);
 
        if (!cnc)
@@ -893,20 +896,25 @@ e_ews_notification_get_events_sync (EEwsNotification *notification,
                return FALSE;
        }
 
+       /* Unref it early, thus it doesn't keep the connection alive after all backends are freed */
+       g_object_unref (cnc);
+
        cancel_handler_id = g_cancellable_connect (cancellable, G_CALLBACK (ews_notification_cancelled_cb),
                notifcation_cancel_data_new (notification->priv->soup_session, SOUP_MESSAGE (msg)), 
notifcation_cancel_data_free);
 
-       status_code = soup_session_send_message (notification->priv->soup_session, SOUP_MESSAGE (msg));
+       if (g_cancellable_is_cancelled (cancellable))
+               status_code = SOUP_STATUS_CANCELLED;
+       else
+               status_code = soup_session_send_message (notification->priv->soup_session, SOUP_MESSAGE 
(msg));
 
        if (cancel_handler_id > 0)
                g_cancellable_disconnect (cancellable, cancel_handler_id);
 
        ret = SOUP_STATUS_IS_SUCCESSFUL (status_code);
-       *out_fatal_error = SOUP_STATUS_IS_CLIENT_ERROR (status_code) || SOUP_STATUS_IS_SERVER_ERROR 
(status_code);
+       *out_fatal_error = SOUP_STATUS_IS_CLIENT_ERROR (status_code) || SOUP_STATUS_IS_SERVER_ERROR 
(status_code) || status_code == SOUP_STATUS_CANCELLED;
 
        g_signal_handler_disconnect (msg, handler_id);
        g_object_unref (msg);
-       g_object_unref (cnc);
 
        return ret;
 }
@@ -915,6 +923,7 @@ static gpointer
 e_ews_notification_get_events_thread (gpointer user_data)
 {
        EEwsNotificationThreadData *td = user_data;
+       EEwsConnection *cnc;
        gchar *subscription_id = NULL;
        gboolean ret, fatal_error = FALSE;
 
@@ -922,6 +931,22 @@ e_ews_notification_get_events_thread (gpointer user_data)
        g_return_val_if_fail (td->notification != NULL, NULL);
        g_return_val_if_fail (td->folders != NULL, NULL);
 
+       g_mutex_lock (&td->notification->priv->thread_lock);
+
+       cnc = e_ews_notification_ref_connection (td->notification);
+
+       if (cnc) {
+               GProxyResolver *proxy_resolver = NULL;
+
+               /* Skip GBinding here, due to the notification object can be freed in this thread,
+                  which can cause a crash in the GBinding code. */
+               g_object_get (cnc, "proxy-resolver", &proxy_resolver, NULL);
+               g_object_set (td->notification->priv->soup_session, "proxy-resolver", proxy_resolver, NULL);
+
+               g_clear_object (&proxy_resolver);
+               g_object_unref (cnc);
+       }
+
        if (td->notification->priv->last_subscription_id) {
                e_ews_notification_unsubscribe_folder_sync (td->notification, 
td->notification->priv->last_subscription_id);
                g_clear_pointer (&td->notification->priv->last_subscription_id, g_free);
@@ -960,6 +985,7 @@ exit:
                g_free (subscription_id);
        }
 
+       g_mutex_unlock (&td->notification->priv->thread_lock);
        g_slist_free_full (td->folders, g_free);
        g_object_unref (td->cancellable);
        g_object_unref (td->notification);