[libshumate] network-tile-source: Fix offline usage

[Corentin Noël <corentinnoel src gnome org>]

commit e875fb2401a8dc3a0fe625b03604ea95d4de5042
Author: James Westman <james jwestman net>
Date:   Sat Jun 19 14:41:54 2021 -0500

    network-tile-source: Fix offline usage
    
    Fix a bug where the tile cache would report an error any time the
    network request failed, even if the tile was successfully filled from
    the file cache. This would cause errors during offline use, where that
    situation would be expected.

 shumate/shumate-network-tile-source.c | 33 ++++++++++++++++++++++++++++-----
 1 file changed, 28 insertions(+), 5 deletions(-)
---
diff --git a/shumate/shumate-network-tile-source.c b/shumate/shumate-network-tile-source.c
index eed6a6a..cff9d76 100644
--- a/shumate/shumate-network-tile-source.c
+++ b/shumate/shumate-network-tile-source.c
@@ -847,7 +847,19 @@ on_message_sent (GObject *source_object, GAsyncResult *res, gpointer user_data)
   input_stream = soup_session_send_finish (priv->soup_session, res, &error);
   if (error != NULL)
     {
-      g_task_return_error (task, g_steal_pointer (&error));
+      if (data->bytes)
+        {
+          /* The tile has already been filled from the cache, so the operation
+           * was overall successful even though the network request failed. */
+          g_debug ("Fetching tile failed, but there is a cached version (error: %s)", error->message);
+          shumate_tile_set_state (data->tile, SHUMATE_STATE_DONE);
+          g_task_return_boolean (task, TRUE);
+        }
+      else
+        {
+          g_task_return_error (task, g_steal_pointer (&error));
+        }
+
       return;
     }
 
@@ -868,10 +880,21 @@ on_message_sent (GObject *source_object, GAsyncResult *res, gpointer user_data)
 
   if (!SOUP_STATUS_IS_SUCCESSFUL (data->msg->status_code))
     {
-      g_task_return_new_error (task, SHUMATE_NETWORK_SOURCE_ERROR,
-                               SHUMATE_NETWORK_SOURCE_ERROR_BAD_RESPONSE,
-                               "Unable to download tile: HTTP %s",
-                               soup_status_get_phrase (data->msg->status_code));
+      if (data->bytes)
+        {
+          g_debug ("Fetching tile failed, but there is a cached version (HTTP %s)",
+                   soup_status_get_phrase (data->msg->status_code));
+          shumate_tile_set_state (data->tile, SHUMATE_STATE_DONE);
+          g_task_return_boolean (task, TRUE);
+        }
+      else
+        {
+          g_task_return_new_error (task, SHUMATE_NETWORK_SOURCE_ERROR,
+                                   SHUMATE_NETWORK_SOURCE_ERROR_BAD_RESPONSE,
+                                   "Unable to download tile: HTTP %s",
+                                   soup_status_get_phrase (data->msg->status_code));
+        }
+
       return;
     }