From 64a28a9e7cec4e9841118772c6a61ea62bd66ad1 Mon Sep 17 00:00:00 2001
From: Alexander Larsson <alexl@redhat.com>
Date: Tue, 26 Apr 2016 15:45:44 +0200
Subject: [PATCH] XdgAppDir helper: Update system_helper threadsafely

---
 common/xdg-app-dir.c | 57 ++++++++++++++++++++++++++++----------------
 1 file changed, 36 insertions(+), 21 deletions(-)

diff --git a/common/xdg-app-dir.c b/common/xdg-app-dir.c
index d0a71ec0..7ea98f9f 100644
--- a/common/xdg-app-dir.c
+++ b/common/xdg-app-dir.c
@@ -37,6 +37,8 @@
 
 #include "errno.h"
 
+#define NO_SYSTEM_HELPER ((XdgAppSystemHelper *)(gpointer)1)
+
 struct XdgAppDir {
   GObject parent;
 
@@ -47,7 +49,6 @@ struct XdgAppDir {
   OstreeRepo *child_repo;
   GLnxLockFile child_repo_lock;
 
-  gboolean initialized_system_helper;
   XdgAppSystemHelper *system_helper;
 
   SoupSession *soup_session;
@@ -198,35 +199,46 @@ xdg_app_ensure_user_cache_dir_location (GError **error)
   return g_steal_pointer (&cache_dir);
 }
 
-static void
-xdg_app_dir_init_system_helper (XdgAppDir *self)
+static XdgAppSystemHelper *
+xdg_app_dir_get_system_helper (XdgAppDir *self)
 {
   g_autoptr(GError) error = NULL;
 
-  if (self->initialized_system_helper)
-    return;
+  if (g_once_init_enter (&self->system_helper))
+    {
+      XdgAppSystemHelper *system_helper;
+      system_helper =
+        xdg_app_system_helper_proxy_new_for_bus_sync (G_BUS_TYPE_SYSTEM,
+                                                      G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
+                                                      G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS,
+                                                      "org.freedesktop.XdgApp.SystemHelper",
+                                                      "/org/freedesktop/XdgApp/SystemHelper",
+                                                      NULL, &error);
+      if (error != NULL)
+        {
+          g_warning ("Can't find org.freedesktop.XdgApp.SystemHelper: %s\n", error->message);
+          system_helper = NO_SYSTEM_HELPER;
+        }
 
-  self->system_helper =
-    xdg_app_system_helper_proxy_new_for_bus_sync (G_BUS_TYPE_SYSTEM,
-                                                  G_DBUS_PROXY_FLAGS_DO_NOT_LOAD_PROPERTIES |
-                                                  G_DBUS_PROXY_FLAGS_DO_NOT_CONNECT_SIGNALS,
-                                                  "org.freedesktop.XdgApp.SystemHelper",
-                                                  "/org/freedesktop/XdgApp/SystemHelper",
-                                                  NULL, &error);
-  if (error != NULL)
-    g_warning ("Can't find org.freedesktop.XdgApp.SystemHelper: %s\n", error->message);
-  self->initialized_system_helper = TRUE;
+      g_once_init_leave (&self->system_helper, system_helper);
+    }
+
+  if (self->system_helper != NO_SYSTEM_HELPER)
+    return self->system_helper;
+  return NULL;
 }
 
 gboolean
 xdg_app_dir_use_child_repo (XdgAppDir *self)
 {
+  XdgAppSystemHelper *system_helper;
+
   if (self->user || getuid () == 0)
     return FALSE;
 
-  xdg_app_dir_init_system_helper (self);
+  system_helper = xdg_app_dir_get_system_helper (self);
 
-  return self->system_helper != NULL;
+  return system_helper != NULL;
 }
 
 static OstreeRepo *
@@ -2568,10 +2580,11 @@ xdg_app_dir_deploy_install (XdgAppDir      *self,
   if (self->child_repo)
     {
       char *empty_subpaths[] = {NULL};
+      XdgAppSystemHelper *system_helper = xdg_app_dir_get_system_helper (self);
 
-      g_assert (self->system_helper != NULL);
+      g_assert (system_helper != NULL);
 
-      if (!xdg_app_system_helper_call_deploy_sync (self->system_helper,
+      if (!xdg_app_system_helper_call_deploy_sync (system_helper,
                                                    gs_file_get_path_cached (ostree_repo_get_path (self->child_repo)),
                                                    XDG_APP_HELPER_DEPLOY_FLAGS_NONE,
                                                    ref,
@@ -2678,9 +2691,11 @@ xdg_app_dir_deploy_update (XdgAppDir      *self,
       active_checksum = xdg_app_dir_read_active (self, ref, NULL);
       if (active_checksum == NULL || strcmp (active_checksum, pulled_checksum) != 0)
         {
-          g_assert (self->system_helper != NULL);
+          XdgAppSystemHelper *system_helper = xdg_app_dir_get_system_helper (self);
 
-          if (!xdg_app_system_helper_call_deploy_sync (self->system_helper,
+          g_assert (system_helper != NULL);
+
+          if (!xdg_app_system_helper_call_deploy_sync (system_helper,
                                                        gs_file_get_path_cached (ostree_repo_get_path (self->child_repo)),
                                                        XDG_APP_HELPER_DEPLOY_FLAGS_UPDATE,
                                                        ref,