[gnome-boxes] Avoid deadlock during startup

[Alexander Larsson <alexl src gnome org>]

commit d1e6add7cbeb9bfab7190061db946512578dab22
Author: Alexander Larsson <alexl redhat com>
Date:   Wed May 23 20:15:16 2012 +0200

    Avoid deadlock during startup
    
    UnattendedInstaller was doing a sync dbus call in the class
    initializer. This is a no-no in GObject because the class initializer
    is called with a recursive lock held, and the dbus call will wait
    for the dbus thread to reply, but the dbus thread may create a
    GObject and thus need the class_init lock, which causes a deadlock.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=676679

 src/unattended-installer.vala |   16 +++++++++++-----
 1 files changed, 11 insertions(+), 5 deletions(-)
---
diff --git a/src/unattended-installer.vala b/src/unattended-installer.vala
index 8637ef1..d16d49d 100644
--- a/src/unattended-installer.vala
+++ b/src/unattended-installer.vala
@@ -50,7 +50,7 @@ private abstract class Boxes.UnattendedInstaller: InstallerMedia {
     private static Regex password_regex;
     private static Regex timezone_regex;
     private static Regex lang_regex;
-    private static Fdo.Accounts accounts;
+    private static Fdo.Accounts? accounts;
 
     static construct {
         try {
@@ -58,17 +58,23 @@ private abstract class Boxes.UnattendedInstaller: InstallerMedia {
             password_regex = new Regex ("BOXES_PASSWORD");
             timezone_regex = new Regex ("BOXES_TZ");
             lang_regex = new Regex ("BOXES_LANG");
+        } catch (RegexError error) {
+            // This just can't fail
+            assert_not_reached ();
+        }
+    }
+
+    construct {
+        /* We can't do this in the class constructor as the sync call can
+           cause deadlocks, see bug #676679. */
+        if (accounts == null) {
             try {
                 accounts = Bus.get_proxy_sync (BusType.SYSTEM, "org.freedesktop.Accounts", "/org/freedesktop/Accounts");
             } catch (GLib.Error error) {
                 warning ("Failed to connect to D-Bus service '%s': %s", "org.freedesktop.Accounts", error.message);
             }
-        } catch (RegexError error) {
-            // This just can't fail
-            assert_not_reached ();
         }
     }
-
     public UnattendedInstaller.copy (InstallerMedia media,
                                      string         unattended_src_path,
                                      string         unattended_dest_name) throws GLib.Error {