[gnome-session] systemd: Check errors on all D-Bus calls

[Matthias Clasen <matthiasc src gnome org>]

commit 7648a6158c9ab2ccf1e8e9918522a8e7acb96261
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Jul 30 14:15:32 2013 -0400

    systemd: Check errors on all D-Bus calls
    
    A somewhat common crash in F19 happens when one of these calls
    fails, and we end up freeing a wild pointer. See
    https://bugzilla.redhat.com/show_bug.cgi?id=977575
    
    https://bugzilla.gnome.org/show_bug.cgi?id=705163

 gnome-session/gsm-systemd.c |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+), 0 deletions(-)
---
diff --git a/gnome-session/gsm-systemd.c b/gnome-session/gsm-systemd.c
index ae29800..c00b1d0 100644
--- a/gnome-session/gsm-systemd.c
+++ b/gnome-session/gsm-systemd.c
@@ -321,6 +321,12 @@ gsm_systemd_init (GsmSystemd *manager)
                                       G_MAXINT,
                                       NULL,
                                       NULL);
+        if (res == NULL) {
+                g_warning ("Could not get session id for session. Check that logind is "
+                           "properly installed and pam_systemd is getting used at login.");
+                return;
+        }
+
         g_variant_get (res, "(o)", &manager->priv->session_path);
         g_variant_unref (res);
 
@@ -501,6 +507,12 @@ gsm_systemd_can_restart (GsmSystem *system)
                                       G_MAXINT,
                                       NULL,
                                       NULL);
+        if (!res) {
+                g_warning ("Calling CanReboot failed. Check that logind is "
+                           "properly installed and pam_systemd is getting used at login.");
+                return FALSE;
+        }
+
         g_variant_get (res, "(s)", &rv);
         g_variant_unref (res);
 
@@ -527,6 +539,12 @@ gsm_systemd_can_stop (GsmSystem *system)
                                       G_MAXINT,
                                       NULL,
                                       NULL);
+        if (!res) {
+                g_warning ("Calling CanPowerOff failed. Check that logind is "
+                           "properly installed and pam_systemd is getting used at login.");
+                return FALSE;
+        }
+
         g_variant_get (res, "(s)", &rv);
         g_variant_unref (res);
 
@@ -578,6 +596,12 @@ gsm_systemd_can_suspend (GsmSystem *system)
                                       G_MAXINT,
                                       NULL,
                                       NULL);
+        if (!res) {
+                g_warning ("Calling CanSuspend failed. Check that logind is "
+                           "properly installed and pam_systemd is getting used at login.");
+                return FALSE;
+        }
+
         g_variant_get (res, "(s)", &rv);
         g_variant_unref (res);
 
@@ -604,6 +628,12 @@ gsm_systemd_can_hibernate (GsmSystem *system)
                                       G_MAXINT,
                                       NULL,
                                       NULL);
+        if (!res) {
+                g_warning ("Calling CanHibernate failed. Check that logind is "
+                           "properly installed and pam_systemd is getting used at login.");
+                return FALSE;
+        }
+
         g_variant_get (res, "(s)", &rv);
         g_variant_unref (res);