From 761f5f0b8bc9c6794f5df51041bfa404abec6b4c Mon Sep 17 00:00:00 2001
From: Cosimo Cecchi <cosimoc@gnome.org>
Date: Mon, 11 Jun 2012 08:59:09 -0400
Subject: [PATCH] background: always pass a cancellable down to I/O operations

So they will be properly cancelled when the panel is disposed.
Also, check early if the operation was cancelled, since it's not safe to
assume the data of the callback is valid anymore before that point.

https://bugzilla.gnome.org/show_bug.cgi?id=672572
---
 panels/background/bg-pictures-source.c | 50 ++++++++++++++++----------
 1 file changed, 31 insertions(+), 19 deletions(-)

diff --git a/panels/background/bg-pictures-source.c b/panels/background/bg-pictures-source.c
index 2c0469548..34ac84934 100644
--- a/panels/background/bg-pictures-source.c
+++ b/panels/background/bg-pictures-source.c
@@ -171,16 +171,29 @@ picture_scaled (GObject *source_object,
                 GAsyncResult *res,
                 gpointer user_data)
 {
-  BgPicturesSource *bg_source = BG_PICTURES_SOURCE (user_data);
+  BgPicturesSource *bg_source;
   CcBackgroundItem *item;
   GError *error = NULL;
   GdkPixbuf *pixbuf;
   const char *source_url;
   const char *software;
-
   GtkTreeIter iter;
   GtkListStore *store;
 
+  pixbuf = gdk_pixbuf_new_from_stream_finish (res, &error);
+  if (pixbuf == NULL)
+    {
+      if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        g_warning ("Failed to load image: %s", error->message);
+
+      g_error_free (error);
+      return;
+    }
+
+  /* since we were not cancelled, we can now cast user_data
+   * back to BgPicturesSource.
+   */
+  bg_source = BG_PICTURES_SOURCE (user_data);
   store = bg_source_get_liststore (BG_SOURCE (bg_source));
   item = g_object_get_data (source_object, "item");
 
@@ -194,15 +207,6 @@ picture_scaled (GObject *source_object,
                                         1,
                                         GTK_SORT_ASCENDING);
 
-  pixbuf = gdk_pixbuf_new_from_stream_finish (res, &error);
-  if (pixbuf == NULL)
-    {
-      g_warning ("Failed to load image: %s", error->message);
-      g_error_free (error);
-      g_object_unref (item);
-      return;
-    }
-
   /* Ignore screenshots */
   software = gdk_pixbuf_get_option (pixbuf, "tEXt::Software");
   if (software != NULL &&
@@ -259,7 +263,7 @@ picture_opened_for_read (GObject *source_object,
                          GAsyncResult *res,
                          gpointer user_data)
 {
-  BgPicturesSource *bg_source = BG_PICTURES_SOURCE (user_data);
+  BgPicturesSource *bg_source;
   CcBackgroundItem *item;
   GFileInputStream *stream;
   GError *error = NULL;
@@ -268,22 +272,28 @@ picture_opened_for_read (GObject *source_object,
   stream = g_file_read_finish (G_FILE (source_object), res, &error);
   if (stream == NULL)
     {
-      char *filename;
+      if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        {
+          char *filename = g_file_get_path (G_FILE (source_object));
+          g_warning ("Failed to load picture '%s': %s", filename, error->message);
+          g_free (filename);
+        }
 
-      filename = g_file_get_path (G_FILE (source_object));
-      g_warning ("Failed to load picture '%s': %s", filename, error->message);
-      g_free (filename);
       g_error_free (error);
       g_object_unref (item);
       return;
     }
 
-  g_object_set_data (G_OBJECT (stream), "item", item);
+  /* since we were not cancelled, we can now cast user_data
+   * back to BgPicturesSource.
+   */
+  bg_source = BG_PICTURES_SOURCE (user_data);
 
+  g_object_set_data (G_OBJECT (stream), "item", item);
   gdk_pixbuf_new_from_stream_at_scale_async (G_INPUT_STREAM (stream),
                                              THUMBNAIL_WIDTH, THUMBNAIL_HEIGHT,
                                              TRUE,
-                                             NULL,
+                                             bg_source->priv->cancellable,
                                              picture_scaled, bg_source);
   g_object_unref (stream);
 }
@@ -329,7 +339,9 @@ add_single_file (BgPicturesSource *bg_source,
     g_object_set (G_OBJECT (item), "source-url", source_uri, NULL);
 
   g_object_set_data (G_OBJECT (file), "item", item);
-  g_file_read_async (file, 0, NULL, picture_opened_for_read, bg_source);
+  g_file_read_async (file, G_PRIORITY_DEFAULT,
+                     bg_source->priv->cancellable,
+                     picture_opened_for_read, bg_source);
   g_object_unref (file);
   return TRUE;
 }