[gnome-control-center] user-accounts: prevent the only Administrator from being demoted

[Thomas Wood <thos src gnome org>]

commit 0adf7c2073face51b70da99139e30d2eef19bd33
Author: Joshua Lock <joshua lock intel com>
Date:   Wed May 29 17:16:47 2013 -0700

    user-accounts: prevent the only Administrator from being demoted
    
    If there is only one account of type Adminstrator and it is demoted to type
    Standard the user can be left unable to unlock panels and perform other
    Administrator tasks - prevent this by only allowing the Account Type to be
    changed when the account is a standard user or, in the case that the account
    is an Administrator, when there is one or more other Administrators.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=690246

 panels/user-accounts/um-user-panel.c |   48 ++++++++++++++++++++++++++++++++-
 1 files changed, 46 insertions(+), 2 deletions(-)
---
diff --git a/panels/user-accounts/um-user-panel.c b/panels/user-accounts/um-user-panel.c
index 980a99b..31f366c 100644
--- a/panels/user-accounts/um-user-panel.c
+++ b/panels/user-accounts/um-user-panel.c
@@ -1043,6 +1043,42 @@ remove_unlock_tooltip (GtkWidget *button)
                                               G_CALLBACK (show_tooltip_now), NULL);
 }
 
+static guint
+get_num_admin (ActUserManager *um)
+{
+        GSList *list;
+        GSList *l;
+        guint num_admin = 0;
+
+        list = act_user_manager_list_users (um);
+        for (l = list; l != NULL; l = l->next) {
+                ActUser *u = l->data;
+                if (act_user_get_account_type (u) == ACT_USER_ACCOUNT_TYPE_ADMINISTRATOR) {
+                        num_admin++;
+                }
+        }
+        g_slist_free (list);
+
+        return num_admin;
+}
+
+static gboolean
+would_demote_only_admin (ActUser        *user,
+                         ActUserManager *um)
+{
+        /* Prevent the user from demoting the only admin account.
+         * Returns TRUE when user is an administrator and there is only
+         * one administrator */
+
+        if (act_user_get_account_type (user) == ACT_USER_ACCOUNT_TYPE_STANDARD)
+                return FALSE;
+
+        if (get_num_admin (um) > 1)
+                return FALSE;
+
+        return TRUE;
+}
+
 static void
 on_permission_changed (GPermission *permission,
                        GParamSpec  *pspec,
@@ -1110,7 +1146,11 @@ on_permission_changed (GPermission *permission,
                 remove_unlock_tooltip (get_widget (d, "autologin-switch"));
 
         } else if (is_authorized && act_user_is_local_account (user)) {
-                um_editable_combo_set_editable (UM_EDITABLE_COMBO (get_widget (d, "account-type-combo")), 
TRUE);
+                if (would_demote_only_admin (user, d->um)) {
+                        um_editable_combo_set_editable (UM_EDITABLE_COMBO (get_widget (d, 
"account-type-combo")), FALSE);
+                } else {
+                        um_editable_combo_set_editable (UM_EDITABLE_COMBO (get_widget (d, 
"account-type-combo")), TRUE);
+                }
                 remove_unlock_tooltip (get_widget (d, "account-type-combo"));
 
                 gtk_widget_set_sensitive (GTK_WIDGET (get_widget (d, "autologin-switch")), 
get_autologin_possible (user));
@@ -1118,7 +1158,11 @@ on_permission_changed (GPermission *permission,
         }
         else {
                 um_editable_combo_set_editable (UM_EDITABLE_COMBO (get_widget (d, "account-type-combo")), 
FALSE);
-                add_unlock_tooltip (get_widget (d, "account-type-combo"));
+                if (would_demote_only_admin (user, d->um)) {
+                        remove_unlock_tooltip (get_widget (d, "account-type-combo"));
+                } else {
+                        add_unlock_tooltip (get_widget (d, "account-type-combo"));
+                }
                 gtk_widget_set_sensitive (GTK_WIDGET (get_widget (d, "autologin-switch")), FALSE);
                 add_unlock_tooltip (get_widget (d, "autologin-switch"));
         }