[gnome-online-accounts/wip/rishi/simplify-cleanup] httpclient: Ensure that the GTask is always cleaned up

[Debarshi Ray <debarshir src gnome org>]

commit 21be1fe801df1a85d0e9010e0b637f7eb34a5100
Author: Debarshi Ray <debarshir gnome org>
Date:   Mon Nov 26 16:38:19 2018 +0100

    httpclient: Ensure that the GTask is always cleaned up
    
    The synchronous variant of goa_http_client_check runs a thread-specific
    GMainContext until the asynchronous variant invokes its callback. Once
    the callback is invoked, the GMainLoop is quit. This means that there
    won't be any further iterations of the loop and no new GSources will
    be dispatched.
    
    Therefore, when the synchronous HttpClient gets aborted by the
    GCancellable or due to an SSL error, then the following
    http_client_check_response_cb might not be invoked due to the lack of
    a running GMainLoop to drive the GMainContext; as a result, the GTask
    will get leaked.
    
    Solve this by tracking the GError and returning the GTask only when
    everything is complete.
    
    This was fixed in commit 3b35bd716dfe91ee0c1ac4b375de9dcf6e897bae, but
    broke in commit 73242fa2fe5d4b18342d33b95fa449086728aa5c when porting
    to GTask.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=764157

 src/goabackend/goahttpclient.c | 53 +++++++++++++++++++++++++-----------------
 1 file changed, 32 insertions(+), 21 deletions(-)
---
diff --git a/src/goabackend/goahttpclient.c b/src/goabackend/goahttpclient.c
index 3d3a1b95..c763d3f1 100644
--- a/src/goabackend/goahttpclient.c
+++ b/src/goabackend/goahttpclient.c
@@ -56,6 +56,7 @@ goa_http_client_new (void)
 typedef struct
 {
   GCancellable *cancellable;
+  GError *error;
   SoupMessage *msg;
   SoupSession *session;
   gboolean accept_ssl_errors;
@@ -79,6 +80,8 @@ http_client_check_data_free (gpointer user_data)
       g_object_unref (data->cancellable);
     }
 
+  g_clear_error (&data->error);
+
   /* soup_session_queue_message stole the references to data->msg */
   g_object_unref (data->session);
   g_slice_free (CheckData, data);
@@ -114,18 +117,16 @@ http_client_request_started (SoupSession *session, SoupMessage *msg, SoupSocket
 {
   CheckData *data;
   GTask *task = G_TASK (user_data);
-  GError *error;
   GTlsCertificateFlags cert_flags;
 
   data = (CheckData *) g_task_get_task_data (task);
-  error = NULL;
 
   if (!data->accept_ssl_errors
       && soup_message_get_https_status (msg, NULL, &cert_flags)
-      && cert_flags != 0)
+      && cert_flags != 0
+      && data->error == NULL)
     {
-      goa_utils_set_error_ssl (&error, cert_flags);
-      g_task_return_error (task, error);
+      goa_utils_set_error_ssl (&data->error, cert_flags);
 
       /* The callback will be invoked after we have returned to the
        * main loop.
@@ -139,45 +140,55 @@ http_client_check_cancelled_cb (GCancellable *cancellable, gpointer user_data)
 {
   CheckData *data;
   GTask *task = G_TASK (user_data);
-  gboolean cancelled;
 
   data = g_task_get_task_data (task);
 
-  cancelled = g_task_return_error_if_cancelled (task);
+  if (data->error == NULL)
+    {
+      gboolean cancelled;
 
-  /* The callback will be invoked after we have returned to the main
-   * loop.
-   */
-  soup_session_abort (data->session);
+      cancelled = g_cancellable_set_error_if_cancelled (cancellable, &data->error);
+
+      /* The callback will be invoked after we have returned to the
+       * main loop.
+       */
+      soup_session_abort (data->session);
 
-  g_return_if_fail (cancelled);
+      g_return_if_fail (cancelled);
+    }
 }
 
 static void
 http_client_check_response_cb (SoupSession *session, SoupMessage *msg, gpointer user_data)
 {
-  GError *error;
+  CheckData *data;
   GTask *task = G_TASK (user_data);
 
-  error = NULL;
+  data = (CheckData *) g_task_get_task_data (task);
 
   /* status == SOUP_STATUS_CANCELLED, if we are being aborted by the
-   * GCancellable or due to an SSL error. The GTask was already
-   * 'returned' by the respective callbacks.
+   * GCancellable or due to an SSL error.
    */
   if (msg->status_code == SOUP_STATUS_CANCELLED)
-    goto out;
+    {
+      g_return_if_fail (data->error != NULL);
+      goto out;
+    }
   else if (msg->status_code != SOUP_STATUS_OK)
     {
       g_warning ("goa_http_client_check() failed: %u — %s", msg->status_code, msg->reason_phrase);
-      goa_utils_set_error_soup (&error, msg);
-      g_task_return_error (task, error);
+      if (data->error == NULL)
+        goa_utils_set_error_soup (&data->error, msg);
+
       goto out;
     }
 
-  g_task_return_boolean (task, TRUE);
-
  out:
+  if (data->error != NULL)
+    g_task_return_error (task, g_steal_pointer (&data->error));
+  else
+    g_task_return_boolean (task, TRUE);
+
   g_object_unref (task);
 }