[gnome-software/gnome-3-30] snap: Reference GsApp from store snap cache inside mutex

[Kalev Lember <klember src gnome org>]

commit adeaa59633a81c8e0e0cc36159558773026589ae
Author: Robert Ancell <robert ancell canonical com>
Date:   Wed Aug 29 21:08:58 2018 +1200

    snap: Reference GsApp from store snap cache inside mutex
    
    Previously the reference was done outside the mutex and there is a chance
    another thread could close the last reference before we get the next one.

 plugins/snap/gs-plugin-snap.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
---
diff --git a/plugins/snap/gs-plugin-snap.c b/plugins/snap/gs-plugin-snap.c
index 4c7948fd..8658aaf8 100644
--- a/plugins/snap/gs-plugin-snap.c
+++ b/plugins/snap/gs-plugin-snap.c
@@ -224,7 +224,13 @@ store_snap_cache_lookup (GsPlugin *plugin, const gchar *name)
 {
        GsPluginData *priv = gs_plugin_get_data (plugin);
        g_autoptr(GMutexLocker) locker = g_mutex_locker_new (&priv->store_snaps_lock);
-       return g_hash_table_lookup (priv->store_snaps, name);
+       SnapdSnap *snap;
+
+       snap = g_hash_table_lookup (priv->store_snaps, name);
+       if (snap == NULL)
+               return NULL;
+
+       return g_object_ref (snap);
 }
 
 static void