gnome-power-manager does not report suspend or hibernate failures when inhibited at the pm-utils level

Binary package hint: gnome-power-manager

When the pm-utils scripts pm-suspend/pm-hibernate trigger a low-level inhibit this triggers failures from hal back to gnome-power-manager which do not contain any error strings. This is not handled by gnome-power-manager and the errors are silently ignored (from the users point of view), leading to a log entry:

    Hibernate failed in a horrible way!

If we look at hal_gpower_pm_method_void() we can see that if the dbus call is successful, but the reply is a non-zero retval with no error string associated with it we will end up with:

    ret = 0
    retval != 0
    *error == NULL

This in turn results in us producing a warning to the log and nothing for the user. This result form seems to occur when the hal runs pm-suspend/pm-hibernate and those run but exit non-zero:

   hal_gpower_pm_method_void(...)
   {
   [...]
        time (&start);
        ret = dbus_g_proxy_call (proxy, method, error,
                                 G_TYPE_INVALID,
                                 G_TYPE_INT, &retval,
                                 G_TYPE_INVALID);
        /* we might have to ignore the error */
        if (error != NULL && hal_gpower_filter_error (error))
                return TRUE;
        if (retval != 0)
                g_warning ("%s failed in a horrible way!", method);
   [...]
        return ret;
   }

Losing this information seems incorrect.

ProblemType: Bug
ACAdapter: Present
Architecture: amd64
Battery: Present
CPUScaling: Present
DistroRelease: Ubuntu 9.04
LaptopPanel: Present
Package: gnome-power-manager 2.24.2-2ubuntu8
ProcEnviron:
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: gnome-power-manager
Uname: Linux 2.6.28-13-generic x86_64