[shotwell] authenticator: Fix crash if service is unavailable

[Jens Georg <jensgeorg src gnome org>]

commit ccd2bcacea31b6cdfbf70cbf9c0111214a937288
Author: Jens Georg <mail jensge org>
Date:   Wed Aug 14 10:30:58 2019 +0200

    authenticator: Fix crash if service is unavailable
    
    We did not handle the load_failed signal properly
    
    Fixes #158

 .../shotwell/FlickrPublishingAuthenticator.vala           | 14 +++++++++++++-
 plugins/authenticator/shotwell/GoogleAuthenticator.vala   | 11 +++++++++++
 plugins/common/WebAuthenticationPane.vala                 | 15 +++++++++++++++
 3 files changed, 39 insertions(+), 1 deletion(-)
---
diff --git a/plugins/authenticator/shotwell/FlickrPublishingAuthenticator.vala 
b/plugins/authenticator/shotwell/FlickrPublishingAuthenticator.vala
index 5188ed61..ea4d9ce3 100644
--- a/plugins/authenticator/shotwell/FlickrPublishingAuthenticator.vala
+++ b/plugins/authenticator/shotwell/FlickrPublishingAuthenticator.vala
@@ -54,6 +54,12 @@ namespace Publishing.Authenticator.Shotwell.Flickr {
         }
 
         public override void on_page_load() {
+            if (this.load_error != null) {
+                this.error();
+
+                return;
+            }
+
             var uri = new Soup.URI(get_view().get_uri());
             if (uri.scheme == "shotwell-auth" && this.auth_code == null) {
                 var form_data = Soup.Form.decode (uri.query);
@@ -77,6 +83,8 @@ namespace Publishing.Authenticator.Shotwell.Flickr {
     }
 
     internal class Flickr : Publishing.Authenticator.Shotwell.OAuth1.Authenticator {
+        private WebAuthenticationPane pane;
+
         public Flickr(Spit.Publishing.PluginHost host) {
             base(API_KEY, API_SECRET, host);
         }
@@ -185,13 +193,17 @@ namespace Publishing.Authenticator.Shotwell.Flickr {
         }
 
         private void do_web_authentication(string token) {
-            var pane = new WebAuthenticationPane(token);
+            pane = new WebAuthenticationPane(token);
             host.install_dialog_pane(pane);
             pane.authorized.connect(this.do_verify_pin);
             pane.error.connect(this.on_web_login_error);
         }
 
         private void on_web_login_error() {
+            if (pane.load_error != null) {
+                host.post_error(pane.load_error);
+                return;
+            }
             host.post_error(new Spit.Publishing.PublishingError.PROTOCOL_ERROR(_("Flickr authorization 
failed")));
         }
 
diff --git a/plugins/authenticator/shotwell/GoogleAuthenticator.vala 
b/plugins/authenticator/shotwell/GoogleAuthenticator.vala
index 75d8f37f..5b38ee66 100644
--- a/plugins/authenticator/shotwell/GoogleAuthenticator.vala
+++ b/plugins/authenticator/shotwell/GoogleAuthenticator.vala
@@ -21,6 +21,12 @@ namespace Publishing.Authenticator.Shotwell.Google {
         }
 
         public override void on_page_load() {
+            if (this.load_error != null) {
+                this.error ();
+
+                return;
+            }
+
             var uri = new Soup.URI(get_view().get_uri());
             if (uri.scheme == REVERSE_CLIENT_ID && this.auth_code == null) {
                 var form_data = Soup.Form.decode (uri.query);
@@ -173,6 +179,7 @@ namespace Publishing.Authenticator.Shotwell.Google {
 
             web_auth_pane = new WebAuthenticationPane(user_authorization_url);
             web_auth_pane.authorized.connect(on_web_auth_pane_authorized);
+            web_auth_pane.error.connect(on_web_auth_pane_error);
 
             host.install_dialog_pane(web_auth_pane);
         }
@@ -185,6 +192,10 @@ namespace Publishing.Authenticator.Shotwell.Google {
             do_get_access_tokens(auth_code);
         }
 
+        private void on_web_auth_pane_error() {
+            host.post_error(web_auth_pane.load_error);
+        }
+
         private void do_get_access_tokens(string auth_code) {
             debug("ACTION: exchanging authorization code for access & refresh tokens");
 
diff --git a/plugins/common/WebAuthenticationPane.vala b/plugins/common/WebAuthenticationPane.vala
index c5377483..1704780e 100644
--- a/plugins/common/WebAuthenticationPane.vala
+++ b/plugins/common/WebAuthenticationPane.vala
@@ -12,6 +12,7 @@ namespace Shotwell.Plugins.Common {
         }
 
         public string login_uri { owned get; construct; }
+        public Error load_error { get; private set; default = null; }
 
         private WebKit.WebView webview;
 
@@ -22,6 +23,7 @@ namespace Shotwell.Plugins.Common {
             this.webview.get_settings ().enable_plugins = false;
 
             this.webview.load_changed.connect (this.on_page_load_changed);
+            this.webview.load_failed.connect (this.on_page_load_failed);
             this.webview.context_menu.connect ( () => { return false; });
         }
 
@@ -29,11 +31,24 @@ namespace Shotwell.Plugins.Common {
 
         protected void set_cursor (Gdk.CursorType type) {
             var window = webview.get_window ();
+            if (window == null)
+                return;
+
             var display = window.get_display ();
+            if (display == null)
+                return;
+
             var cursor = new Gdk.Cursor.for_display (display, type);
             window.set_cursor (cursor);
         }
 
+        private bool on_page_load_failed (WebKit.LoadEvent load_event, string uri, Error error) {
+            critical ("Failed to load uri %s: %s", uri, error.message);
+            this.load_error = error;
+
+            return false;
+        }
+
         private void on_page_load_changed (WebKit.LoadEvent load_event) {
             switch (load_event) {
                 case WebKit.LoadEvent.STARTED: