[gnome-shell] gdm: Handle absence of Fprint.Manager service

[Florian Müllner <fmuellner src gnome org>]

commit c0861b122725c2d0feef6b7fae0e121c3ea5be48
Author: Florian Müllner <fmuellner gnome org>
Date:   Tue Mar 14 21:02:51 2017 +0100

    gdm: Handle absence of Fprint.Manager service
    
    We rely on the service to detect whether a fingerprint reader is
    present. It is fine to not support fingerprint authentication
    when the service is missing, but currently we don't handle this
    case at all and end up with a non-functional login screen.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=780063

 js/gdm/fingerprint.js |    8 +++++++-
 js/gdm/util.js        |    5 +++--
 2 files changed, 10 insertions(+), 3 deletions(-)
---
diff --git a/js/gdm/fingerprint.js b/js/gdm/fingerprint.js
index bce0bc6..2aeb377 100644
--- a/js/gdm/fingerprint.js
+++ b/js/gdm/fingerprint.js
@@ -23,6 +23,12 @@ function FprintManager() {
                                    g_object_path: '/net/reactivated/Fprint/Manager',
                                    g_flags: (Gio.DBusProxyFlags.DO_NOT_LOAD_PROPERTIES) });
 
-    self.init(null);
+    try {
+        self.init(null);
+    } catch(e) {
+        log('Failed to connect to Fprint service: ' + e.message);
+        return null;
+    }
+
     return self;
 }
diff --git a/js/gdm/util.js b/js/gdm/util.js
index 2ff59cb..6876cbe 100644
--- a/js/gdm/util.js
+++ b/js/gdm/util.js
@@ -133,7 +133,7 @@ const ShellUserVerifier = new Lang.Class({
                                Lang.bind(this, this._updateDefaultService));
         this._updateDefaultService();
 
-        this._fprintManager = new Fprint.FprintManager();
+        this._fprintManager = Fprint.FprintManager();
         this._smartcardManager = SmartcardManager.getSmartcardManager();
 
         // We check for smartcards right away, since an inserted smartcard
@@ -293,7 +293,8 @@ const ShellUserVerifier = new Lang.Class({
     _checkForFingerprintReader: function() {
         this._haveFingerprintReader = false;
 
-        if (!this._settings.get_boolean(FINGERPRINT_AUTHENTICATION_KEY)) {
+        if (!this._settings.get_boolean(FINGERPRINT_AUTHENTICATION_KEY) ||
+            this._fprintManager == null) {
             this._updateDefaultService();
             return;
         }