[gnome-settings-daemon] power: Don't pass SHELL in the backlight helper environment

[Rui Matos <rtcm src gnome org>]

commit e9edfbb3a1341b85dd5d4e60549dd3d4e15fc4c3
Author: Rui Matos <tiagomatos gmail com>
Date:   Mon May 4 18:04:38 2015 +0200

    power: Don't pass SHELL in the backlight helper environment
    
    Doing so causes pkexec to fail[0] if the current user's SHELL doesn't
    exist in /etc/shells which happens for the gdm user in some
    distributions.
    
    Since we don't need this environment variable in the helper we can
    work around that by just unsetting it.
    
    [0] http://cgit.freedesktop.org/polkit/commit/?id=5a388b6ebb095de6dc7f315b651a84fc31d268d7
    
    https://bugzilla.gnome.org/show_bug.cgi?id=748804

 plugins/power/gpm-common.c |   14 +++++++++++++-
 1 files changed, 13 insertions(+), 1 deletions(-)
---
diff --git a/plugins/power/gpm-common.c b/plugins/power/gpm-common.c
index f8a2da5..e8769ca 100644
--- a/plugins/power/gpm-common.c
+++ b/plugins/power/gpm-common.c
@@ -392,6 +392,18 @@ backlight_available (GnomeRRScreen *rr_screen)
         return TRUE;
 }
 
+static gchar **
+get_backlight_helper_environ (void)
+{
+        static gchar **environ = NULL;
+
+        if (environ)
+                return environ;
+
+        environ = g_environ_unsetenv (g_get_environ (), "SHELL");
+        return environ;
+}
+
 static gboolean
 run_backlight_helper (enum BacklightHelperCommand   command,
                       gchar                        *value,
@@ -413,7 +425,7 @@ run_backlight_helper (enum BacklightHelperCommand   command,
 
         return g_spawn_sync (NULL,
                              command == BACKLIGHT_HELPER_SET ? argv : &argv[1],
-                             NULL,
+                             get_backlight_helper_environ (),
                              G_SPAWN_SEARCH_PATH,
                              NULL,
                              NULL,