[evolution-ews] Add thread safety around ECalBackendEws::priv::cancellable

[Milan Crha <mcrha src gnome org>]

commit 7d902cbf33532a0ead121d7a1a003316cdc62a7e
Author: Milan Crha <mcrha redhat com>
Date:   Wed Mar 30 14:16:54 2016 +0200

    Add thread safety around ECalBackendEws::priv::cancellable
    
    It looks like the priv::cancellable can be read/write without
    thread safety, which can lead to a crash, as reported downstream at:
    https://bugzilla.redhat.com/show_bug.cgi?id=1321119

 src/calendar/e-cal-backend-ews.c |  123 +++++++++++++++++++++++++++-----------
 1 files changed, 88 insertions(+), 35 deletions(-)
---
diff --git a/src/calendar/e-cal-backend-ews.c b/src/calendar/e-cal-backend-ews.c
index 3b8f4bf..db33ad2 100644
--- a/src/calendar/e-cal-backend-ews.c
+++ b/src/calendar/e-cal-backend-ews.c
@@ -82,6 +82,7 @@ struct _ECalBackendEwsPrivate {
        EFlag *refreshing_done;
        GHashTable *item_id_hash;
 
+       GMutex cancellable_lock;
        GCancellable *cancellable;
 
        guint subscription_key;
@@ -202,6 +203,40 @@ convert_error_to_edc_error (GError **perror)
        *perror = error;
 }
 
+static GCancellable *
+cal_backend_ews_ref_cancellable (ECalBackendEws *cbews)
+{
+       GCancellable *cancellable = NULL;
+
+       g_return_val_if_fail (E_IS_CAL_BACKEND_EWS (cbews), NULL);
+
+       g_mutex_lock (&cbews->priv->cancellable_lock);
+       if (cbews->priv->cancellable)
+               cancellable = g_object_ref (cbews->priv->cancellable);
+       g_mutex_unlock (&cbews->priv->cancellable_lock);
+
+       return cancellable;
+}
+
+static void
+cal_backend_ews_set_cancellable (ECalBackendEws *cbews,
+                                GCancellable *cancellable)
+{
+       GCancellable *old_cancellable;
+
+       g_return_if_fail (E_IS_CAL_BACKEND_EWS (cbews));
+
+       g_mutex_lock (&cbews->priv->cancellable_lock);
+       old_cancellable = cbews->priv->cancellable;
+       cbews->priv->cancellable = cancellable;
+       g_mutex_unlock (&cbews->priv->cancellable_lock);
+
+       if (old_cancellable) {
+               g_cancellable_cancel (old_cancellable);
+               g_object_unref (old_cancellable);
+       }
+}
+
 static void
 switch_offline (ECalBackendEws *cbews)
 {
@@ -215,11 +250,7 @@ switch_offline (ECalBackendEws *cbews)
                priv->refresh_timeout = 0;
        }
 
-       if (priv->cancellable) {
-               g_cancellable_cancel (priv->cancellable);
-               g_object_unref (priv->cancellable);
-               priv->cancellable = NULL;
-       }
+       cal_backend_ews_set_cancellable (cbews, NULL);
 
        if (priv->cnc) {
                g_object_unref (priv->cnc);
@@ -311,6 +342,7 @@ typedef enum {
 
 typedef struct {
        ECalBackendEws *cbews; /* Create, Remove, Modify, FreeBusy, Attachments, DiscardAlarm */
+       GCancellable *cancellable;
        ECalComponent *comp; /* Create, Remove, Modify, FreeBusy, Attachments */
        ECalComponent *extra_comp; /* Modify, Attachments: used as old_comp. Remove: used as parent_comp */
        EDataCal *cal; /* Create, Remove, Modify, FreeBusy, Attachments, DiscardAlarm */
@@ -327,14 +359,11 @@ static void
 e_cal_backend_ews_async_data_free (EwsCalendarAsyncData *async_data)
 {
        if (async_data != NULL) {
-               if (async_data->cbews != NULL)
-                       g_clear_object (&async_data->cbews);
-               if (async_data->comp != NULL)
-                       g_clear_object (&async_data->comp);
-               if (async_data->extra_comp != NULL)
-                       g_clear_object (&async_data->extra_comp);
-               if (async_data->cal != NULL)
-                       g_clear_object (&async_data->cal);
+               g_clear_object (&async_data->cbews);
+               g_clear_object (&async_data->cancellable);
+               g_clear_object (&async_data->comp);
+               g_clear_object (&async_data->extra_comp);
+               g_clear_object (&async_data->cal);
 
                g_slist_free_full (async_data->users, g_free);
                g_free (async_data->item_id);
@@ -410,6 +439,7 @@ e_cal_backend_ews_discard_alarm (ECalBackend *backend,
         * Exchange not support that? */
        edad = g_new0 (EwsCalendarAsyncData, 1);
        edad->cbews = g_object_ref (cbews);
+       edad->cancellable = cal_backend_ews_ref_cancellable (cbews);
        edad->cal = g_object_ref (cal);
        edad->context = context;
 
@@ -441,7 +471,7 @@ e_cal_backend_ews_discard_alarm (ECalBackend *backend,
                "SendToNone", NULL,
                e_cal_backend_ews_clear_reminder_is_set,
                &convert_data,
-               priv->cancellable,
+               edad->cancellable,
                ews_cal_discard_alarm_cb,
                edad);
 }
@@ -1258,6 +1288,7 @@ e_cal_backend_ews_remove_object (ECalBackend *backend,
 
        remove_data = g_new0 (EwsCalendarAsyncData, 1);
        remove_data->cbews = g_object_ref (cbews);
+       remove_data->cancellable = cal_backend_ews_ref_cancellable (cbews);
        remove_data->comp = comp != NULL ? g_object_ref (comp) : NULL;
        remove_data->extra_comp = parent != NULL ? g_object_ref (parent) : NULL;
        remove_data->cal = g_object_ref (cal);
@@ -1270,7 +1301,7 @@ e_cal_backend_ews_remove_object (ECalBackend *backend,
        e_ews_connection_delete_item (
                priv->cnc, EWS_PRIORITY_MEDIUM, &item_id, index, EWS_HARD_DELETE,
                e_cal_backend_ews_is_organizer (cbews, comp, parent) ? EWS_SEND_TO_ALL_AND_SAVE_COPY : 
EWS_SEND_TO_NONE,
-               EWS_ALL_OCCURRENCES, priv->cancellable,
+               EWS_ALL_OCCURRENCES, remove_data->cancellable,
                ews_cal_remove_object_cb,
                remove_data);
 
@@ -1411,6 +1442,7 @@ ews_create_attachments_cb (GObject *object,
 
                modify_data = g_new0 (EwsCalendarAsyncData, 1);
                modify_data->cbews = g_object_ref (create_data->cbews);
+               modify_data->cancellable = cal_backend_ews_ref_cancellable (create_data->cbews);
                modify_data->comp = g_object_ref (create_data->comp);
                modify_data->extra_comp = g_object_ref (create_data->extra_comp);
                modify_data->cal = g_object_ref (create_data->cal);
@@ -1442,7 +1474,7 @@ ews_create_attachments_cb (GObject *object,
                        priv->folder_id,
                        e_cal_backend_ews_convert_component_to_updatexml,
                        &convert_data,
-                       priv->cancellable,
+                       modify_data->cancellable,
                        ews_cal_modify_object_cb,
                        modify_data);
        } else {
@@ -1503,10 +1535,12 @@ ews_create_object_cb (GObject *object,
 
        if (e_ews_item_get_item_type (item) == E_EWS_ITEM_TYPE_EVENT) {
                EEwsAdditionalProps *add_props;
+               GCancellable *cancellable;
 
                add_props = e_ews_additional_props_new ();
                add_props->field_uri = g_strdup ("calendar:UID");
 
+               cancellable = cal_backend_ews_ref_cancellable (cbews);
                items = g_slist_append (items, item_id->id);
 
                /* get calender uid from server*/
@@ -1517,9 +1551,11 @@ ews_create_object_cb (GObject *object,
                        add_props,
                        FALSE, NULL, E_EWS_BODY_TYPE_TEXT,
                        &items_req,
-                       NULL, NULL, priv->cancellable, &error);
+                       NULL, NULL, cancellable, &error);
 
                e_ews_additional_props_free (add_props);
+               g_clear_object (&cancellable);
+
                if (!res && error != NULL) {
                        if (items_req)
                                g_slist_free_full (items_req, g_object_unref);
@@ -1551,6 +1587,7 @@ ews_create_object_cb (GObject *object,
                EwsCalendarAsyncData *attach_data = g_new0 (EwsCalendarAsyncData, 1);
 
                attach_data->cbews = g_object_ref (create_data->cbews);
+               attach_data->cancellable = cal_backend_ews_ref_cancellable (create_data->cbews);
                attach_data->comp = g_object_ref (create_data->comp);
                attach_data->cal = g_object_ref (create_data->cal);
                attach_data->context = create_data->context;
@@ -1596,7 +1633,7 @@ ews_create_object_cb (GObject *object,
                e_ews_connection_create_attachments (
                        cnc, EWS_PRIORITY_MEDIUM,
                        item_id, info_attachments,
-                       FALSE, priv->cancellable,
+                       FALSE, attach_data->cancellable,
                        ews_create_attachments_cb,
                        attach_data);
 
@@ -2862,6 +2899,7 @@ ews_get_attachments (ECalBackendEws *cbews,
        ECalComponent *comp;
        const gchar *uid;
        GSList *uris = NULL, *info_attachments = NULL;
+       GCancellable *cancellable;
 
        e_ews_item_has_attachments (item, &has_attachment);
        if (!has_attachment)
@@ -2870,10 +2908,13 @@ ews_get_attachments (ECalBackendEws *cbews,
        item_id = e_ews_item_get_id (item);
        g_return_if_fail (item_id != NULL);
 
+       cancellable = cal_backend_ews_ref_cancellable (cbews);
+
        PRIV_LOCK (cbews->priv);
        comp = g_hash_table_lookup (cbews->priv->item_id_hash, item_id->id);
        if (!comp) {
                PRIV_UNLOCK (cbews->priv);
+               g_clear_object (&cancellable);
                g_warning ("%s: Failed to get component from item_id_hash", G_STRFUNC);
                return;
        }
@@ -2890,7 +2931,7 @@ ews_get_attachments (ECalBackendEws *cbews,
                TRUE,
                &info_attachments,
                NULL, NULL,
-               cbews->priv->cancellable,
+               cancellable,
                NULL)) {
                icalcomponent *icalcomp;
                icalproperty *icalprop;
@@ -2938,6 +2979,8 @@ ews_get_attachments (ECalBackendEws *cbews,
        }
 
        PRIV_UNLOCK (cbews->priv);
+
+       g_clear_object (&cancellable);
 }
 
 static icaltimezone *
@@ -3027,6 +3070,7 @@ add_item_to_cache (ECalBackendEws *cbews,
                if (e_ews_item_get_delegator (item) != NULL) {
                        const gchar *task_owner = e_ews_item_get_delegator (item);
                        GSList *mailboxes = NULL, *l;
+                       GCancellable *cancellable;
                        GError *error = NULL;
                        gboolean includes_last_item;
                        gchar *mailtoname;
@@ -3043,11 +3087,13 @@ add_item_to_cache (ECalBackendEws *cbews,
                        icalproperty_add_parameter (icalprop, param);
                        icalcomponent_add_property (icalcomp, icalprop);
 
+                       cancellable = cal_backend_ews_ref_cancellable (cbews);
+
                        /* get delegator mail box*/
                        e_ews_connection_resolve_names_sync (
                                priv->cnc, EWS_PRIORITY_MEDIUM, task_owner,
                                EWS_SEARCH_AD, NULL, FALSE, &mailboxes, NULL,
-                               &includes_last_item, priv->cancellable, &error);
+                               &includes_last_item, cancellable, &error);
 
                        for (l = mailboxes; l != NULL; l = g_slist_next (l)) {
                                EwsMailbox *mb = l->data;
@@ -3062,6 +3108,7 @@ add_item_to_cache (ECalBackendEws *cbews,
                                e_ews_mailbox_free (mb);
                        }
                        g_slist_free (mailboxes);
+                       g_clear_object (&cancellable);
                }
 
                if (item_type == E_EWS_ITEM_TYPE_TASK) {
@@ -3472,10 +3519,13 @@ ews_cal_sync_get_items_sync (ECalBackendEws *cbews,
        ECalBackendEwsPrivate *priv;
        gboolean ret = FALSE;
        GSList *items = NULL, *l;
+       GCancellable *cancellable;
        GError *error = NULL;
 
        priv = cbews->priv;
 
+       cancellable = cal_backend_ews_ref_cancellable (cbews);
+
        e_ews_connection_get_items_sync (
                priv->cnc,
                EWS_PRIORITY_MEDIUM,
@@ -3487,9 +3537,11 @@ ews_cal_sync_get_items_sync (ECalBackendEws *cbews,
                E_EWS_BODY_TYPE_TEXT,
                &items,
                NULL, NULL,
-               priv->cancellable,
+               cancellable,
                &error);
 
+       g_clear_object (&cancellable);
+
        if (error != NULL) {
                g_debug ("%s: Unable to get items: %s", G_STRFUNC, error->message);
                g_clear_error (&error);
@@ -3701,20 +3753,26 @@ ews_start_sync_thread (gpointer data)
        gboolean ret;
        gchar *old_sync_state = NULL;
        gchar *new_sync_state = NULL;
+       GCancellable *cancellable;
        GError *error = NULL;
 
        cbews = (ECalBackendEws *) data;
        priv = cbews->priv;
 
+       cancellable = cal_backend_ews_ref_cancellable (cbews);
+
        old_sync_state = g_strdup (e_cal_backend_store_get_key_value (priv->store, SYNC_KEY));
        do {
                EEwsAdditionalProps *add_props;
+               GCancellable *cancellable;
 
                includes_last_item = TRUE;
 
                add_props = e_ews_additional_props_new ();
                add_props->field_uri = g_strdup ("item:ItemClass");
 
+               cancellable = cal_backend_ews_ref_cancellable (cbews);
+
                ret = e_ews_connection_sync_folder_items_sync (
                        priv->cnc,
                        EWS_PRIORITY_MEDIUM,
@@ -3728,10 +3786,11 @@ ews_start_sync_thread (gpointer data)
                        &items_created,
                        &items_updated,
                        &items_deleted,
-                       priv->cancellable,
+                       cancellable,
                        &error);
 
                e_ews_additional_props_free (add_props);
+               g_clear_object (&cancellable);
                g_free (old_sync_state);
                old_sync_state = NULL;
 
@@ -3754,7 +3813,7 @@ ews_start_sync_thread (gpointer data)
                                                        &items_created,
                                                        &items_updated,
                                                        &items_deleted,
-                                                       priv->cancellable,
+                                                       cancellable,
                                                        &error)) {
                                        if (!g_error_matches (
                                                        error,
@@ -3794,6 +3853,8 @@ ews_start_sync_thread (gpointer data)
 
        ews_refreshing_dec (cbews);
 
+       g_clear_object (&cancellable);
+
        g_slist_free_full (items_created, g_object_unref);
        g_slist_free_full (items_updated, g_object_unref);
        g_slist_free_full (items_deleted, g_free);
@@ -4115,13 +4176,7 @@ e_cal_backend_ews_notify_online_cb (EBackend *backend,
        PRIV_LOCK (priv);
 
        if (e_backend_get_online (backend)) {
-               if (priv->cancellable) {
-                       g_cancellable_cancel (priv->cancellable);
-                       g_object_unref (priv->cancellable);
-                       priv->cancellable = NULL;
-               }
-               priv->cancellable = g_cancellable_new ();
-
+               cal_backend_ews_set_cancellable (cbews, g_cancellable_new ());
                priv->read_only = FALSE;
        } else {
                switch_offline (cbews);
@@ -4213,11 +4268,7 @@ e_cal_backend_ews_dispose (GObject *object)
                priv->refresh_timeout = 0;
        }
 
-       if (priv->cancellable) {
-               g_cancellable_cancel (priv->cancellable);
-               g_object_unref (priv->cancellable);
-               priv->cancellable = NULL;
-       }
+       cal_backend_ews_set_cancellable (cbews, NULL);
 
        if (priv->cnc) {
                g_signal_handlers_disconnect_by_func (priv->cnc, cbews_server_notification_cb, object);
@@ -4255,6 +4306,7 @@ e_cal_backend_ews_finalize (GObject *object)
 
        /* Clean up */
        g_rec_mutex_clear (&priv->rec_mutex);
+       g_mutex_clear (&priv->cancellable_lock);
 
        if (priv->store) {
                g_object_unref (priv->store);
@@ -4402,6 +4454,7 @@ e_cal_backend_ews_init (ECalBackendEws *cbews)
 
        /* create the mutex for thread safety */
        g_rec_mutex_init (&cbews->priv->rec_mutex);
+       g_mutex_init (&cbews->priv->cancellable_lock);
        cbews->priv->refreshing_done = e_flag_new ();
        cbews->priv->item_id_hash = g_hash_table_new_full (g_str_hash, g_str_equal, g_free, g_object_unref);
        cbews->priv->default_zone = icaltimezone_get_utc_timezone ();