gdesktopappinfo: Handle task completion from spawn function

This allows delaying the return of the task until all dbus calls (in
particular the ones to setup the scope) have finished.

This fixes the behaviour of the previous commit which would not
correctly move the process into the scope if the application exited
right after the task returned.

gio/gdesktopappinfo.c

@@ -2849,11 +2849,17 @@ create_systemd_scope (GDBusConnection    *session_bus,
   g_free (unit_name);
 }
 
+typedef struct {
+  GTask *task;
+  int fd;
+} ScopeCreatedData;
+
 static void
 systemd_scope_created_cb (GObject      *object,
                           GAsyncResult *result,
                           gpointer      user_data)
 {
+  ScopeCreatedData *data = user_data;
   GVariant *res = NULL;
   GError *error = NULL;
 
@@ -2865,13 +2871,47 @@ systemd_scope_created_cb (GObject      *object,
     }
 
   /* Unblock the waiting wrapper binary. */
-  close (GPOINTER_TO_INT (user_data));
+
+  close (data->fd);
+
+  if (data->task)
+    {
+      gint pending;
+      pending = GPOINTER_TO_INT (g_task_get_task_data (data->task));
+      pending -= 1;
+      g_task_set_task_data (data->task, GINT_TO_POINTER (pending), NULL);
+
+      if (pending == 0 && !g_task_get_completed (data->task))
+        g_task_return_boolean (data->task, TRUE);
+    }
 
   if (res)
     g_variant_unref (res);
+  g_clear_object (&data->task);
+  g_free (data);
 }
 #endif
 
+static void
+launch_uris_with_spawn_flush_cb (GObject      *object,
+                                 GAsyncResult *result,
+                                 gpointer      user_data)
+{
+  GTask *task = G_TASK (user_data);
+  gint pending;
+
+  g_dbus_connection_flush_finish (G_DBUS_CONNECTION (object), result, NULL);
+
+  pending = GPOINTER_TO_INT (g_task_get_task_data (task));
+  pending -= 1;
+  g_task_set_task_data (task, GINT_TO_POINTER (pending), NULL);
+
+  if (pending == 0 && !g_task_get_completed (task))
+    g_task_return_boolean (task, TRUE);
+
+  g_object_unref (task);
+}
+
 static gboolean
 g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
                                            GDBusConnection            *session_bus,
@@ -2886,9 +2926,10 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
                                            gint                        stdin_fd,
                                            gint                        stdout_fd,
                                            gint                        stderr_fd,
-                                           GError                    **error)
+                                           GTask                      *task,
+                                           GError                    **error_out)
 {
-  gboolean completed = FALSE;
+  GError *error = NULL;
   GList *old_uris;
   GList *dup_uris;
 
@@ -2898,8 +2939,15 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
   char *sn_id = NULL;
   int argc;
 
+  /* We may get a task to report back on or an error. But never both. */
+  g_assert (!(task && error_out));
   g_return_val_if_fail (info != NULL, FALSE);
 
+  /* Surrounding code must not have set any data on the task
+   * (it is cleared before calling this function). */
+  if (session_bus && task)
+    g_assert (g_task_get_task_data (task) == NULL);
+
   if (launch_context)
     envp = g_app_launch_context_get_environment (launch_context);
   else
@@ -2922,8 +2970,8 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
       gpointer             setup_data = user_setup_data;
 
       old_uris = dup_uris;
-      if (!expand_application_parameters (info, exec_line, &dup_uris, &argc, &argv, error))
+      if (!expand_application_parameters (info, exec_line, &dup_uris, &argc, &argv, &error))
-        return FALSE;
+        goto out;
 
       /* Get the subset of URIs we're launching with this process */
       for (iter = old_uris; iter != NULL && iter != dup_uris; iter = iter->next)
@@ -2932,9 +2980,9 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
 
       if (info->terminal && !prepend_terminal_to_vector (&argc, &argv))
         {
-          g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+          error = g_error_new_literal (G_IO_ERROR, G_IO_ERROR_FAILED,
                                        _("Unable to find terminal required for application"));
-          return FALSE;
+          goto out;
         }
 
       if (info->filename)
@@ -2991,9 +3039,9 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
        * otherwise our wrapper script will close both sides. */
       if (!g_unix_open_pipe (wrapper_data.pipe, 0, NULL))
         {
-          g_set_error_literal (error, G_IO_ERROR, G_IO_ERROR_FAILED,
+          error = g_error_new_literal (G_IO_ERROR, G_IO_ERROR_FAILED,
                                        _("Unable to create pipe for systemd synchronization"));
-          return FALSE;
+          goto out;
         }
 
       /* Set CLOEXEC on the write pipe, so we don't need to deal with it in the child. */
@@ -3030,7 +3078,7 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
                                    stdin_fd,
                                    stdout_fd,
                                    stderr_fd,
-                                   error))
+                                   &error))
         {
 #if defined(__linux__) && !defined(__BIONIC__)
           close (wrapper_data.pipe[0]);
@@ -3049,11 +3097,29 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
       close (wrapper_data.pipe[0]);
 
       if (session_bus)
+        {
+          ScopeCreatedData *data;
+
+          data = g_new0 (ScopeCreatedData, 1);
+
+          if (task)
+            {
+              gint pending;
+              pending = GPOINTER_TO_INT (g_task_get_task_data (task));
+              pending += 1;
+              g_task_set_task_data (task, GINT_TO_POINTER (pending), NULL);
+
+              data->task = g_object_ref (task);
+            }
+
+          data->fd = wrapper_data.pipe[1];
+
           create_systemd_scope (session_bus,
                                 info,
                                 pid,
                                 systemd_scope_created_cb,
-                              GINT_TO_POINTER (wrapper_data.pipe[1]));
+                                data);
+        }
       else
         close (wrapper_data.pipe[1]);
 #endif
@@ -3088,8 +3154,6 @@ g_desktop_app_info_launch_uris_with_spawn (GDesktopAppInfo            *info,
     }
   while (dup_uris != NULL);
 
-  completed = TRUE;
-
 out:
   g_strfreev (argv);
   g_strfreev (envp);
@@ -3097,7 +3161,52 @@ out:
   g_list_free (launched_uris);
   g_free (sn_id);
 
-  return completed;
+  if (!error)
+    {
+      if (session_bus && task)
+        {
+          GCancellable *cancellable = g_task_get_cancellable (task);
+          gint pending;
+          pending = GPOINTER_TO_INT (g_task_get_task_data (task));
+          pending += 1;
+          g_task_set_task_data (task, GINT_TO_POINTER (pending), NULL);
+
+          /* FIXME: The D-Bus message from the notify_desktop_launch() function
+           * can be still lost even if flush is called later. See:
+           * https://gitlab.freedesktop.org/dbus/dbus/issues/72
+           */
+          g_dbus_connection_flush (session_bus,
+                                   cancellable,
+                                   launch_uris_with_spawn_flush_cb,
+                                   g_steal_pointer (&task));
+        }
+      else if (session_bus)
+        {
+          /* No task available. */
+          g_dbus_connection_flush (session_bus,
+                                   NULL,
+                                   NULL,
+                                   NULL);
+        }
+      else if (task)
+        {
+          /* Return the given task. */
+          g_task_return_boolean (task, TRUE);
+          g_object_unref (task);
+        }
+    }
+  else
+    {
+      if (task)
+        {
+          g_task_return_error (task, error);
+          g_object_unref (task);
+        }
+      else
+        g_propagate_error (error_out, error);
+    }
+
+  return !error;
 }
 
 static gchar *
@@ -3246,17 +3355,9 @@ g_desktop_app_info_launch_uris_internal (GAppInfo                   *appinfo,
     success = g_desktop_app_info_launch_uris_with_spawn (info, session_bus, info->exec, uris, launch_context,
                                                          spawn_flags, user_setup, user_setup_data,
                                                          pid_callback, pid_callback_data,
-                                                         stdin_fd, stdout_fd, stderr_fd, error);
+                                                         stdin_fd, stdout_fd, stderr_fd, NULL, error);
 
-  if (session_bus != NULL)
+  g_clear_object (&session_bus);
-    {
-      /* This asynchronous flush holds a reference until it completes,
-       * which ensures that the following unref won't immediately kill
-       * the connection if we were the initial owner.
-       */
-      g_dbus_connection_flush (session_bus, NULL, NULL, NULL);
-      g_object_unref (session_bus);
-    }
 
   return success;
 }
@@ -3310,18 +3411,6 @@ launch_uris_with_dbus_cb (GObject      *object,
   g_object_unref (task);
 }
 
-static void
-launch_uris_flush_cb (GObject      *object,
-                      GAsyncResult *result,
-                      gpointer      user_data)
-{
-  GTask *task = G_TASK (user_data);
-
-  g_dbus_connection_flush_finish (G_DBUS_CONNECTION (object), result, NULL);
-  g_task_return_boolean (task, TRUE);
-  g_object_unref (task);
-}
-
 static void
 launch_uris_bus_get_cb (GObject      *object,
                         GAsyncResult *result,
@@ -3330,12 +3419,20 @@ launch_uris_bus_get_cb (GObject      *object,
   GTask *task = G_TASK (user_data);
   GDesktopAppInfo *info = G_DESKTOP_APP_INFO (g_task_get_source_object (task));
   LaunchUrisData *data = g_task_get_task_data (task);
+  LaunchUrisData *data_copy = NULL;
   GCancellable *cancellable = g_task_get_cancellable (task);
   GDBusConnection *session_bus;
-  GError *error = NULL;
 
   session_bus = g_bus_get_finish (result, NULL);
 
+  data_copy = g_new0 (LaunchUrisData, 1);
+  data_copy->appinfo = g_steal_pointer (&data->appinfo);
+  data_copy->uris = g_steal_pointer (&data->uris);
+  data_copy->context = g_steal_pointer (&data->context);
+
+  /* Allow other data to be attached to the task. */
+  g_task_set_task_data (task, NULL, NULL);
+
   if (session_bus && info->app_id)
     {
       /* FIXME: The g_document_portal_add_documents() function, which is called
@@ -3343,34 +3440,21 @@ launch_uris_bus_get_cb (GObject      *object,
        * uses blocking calls.
        */
       g_desktop_app_info_launch_uris_with_dbus (info, session_bus,
-                                                data->uris, data->context,
+                                                data_copy->uris, data_copy->context,
                                                 cancellable,
                                                 launch_uris_with_dbus_cb,
                                                 g_steal_pointer (&task));
     }
   else
     {
-      /* FIXME: The D-Bus message from the notify_desktop_launch() function
-       * can be still lost even if flush is called later. See:
-       * https://gitlab.freedesktop.org/dbus/dbus/issues/72
-       */
       g_desktop_app_info_launch_uris_with_spawn (info, session_bus, info->exec,
-                                                 data->uris, data->context,
+                                                 data_copy->uris, data_copy->context,
                                                  _SPAWN_FLAGS_DEFAULT, NULL,
                                                  NULL, NULL, NULL, -1, -1, -1,
-                                                 &error);
+                                                 g_steal_pointer (&task), NULL);
-      if (error != NULL)
-        {
-          g_task_return_error (task, g_steal_pointer (&error));
-          g_object_unref (task);
-        }
-      else
-        g_dbus_connection_flush (session_bus,
-                                 cancellable,
-                                 launch_uris_flush_cb,
-                                 g_steal_pointer (&task));
     }
 
+  launch_uris_data_free (data_copy);
   g_clear_object (&session_bus);
 }
 
@@ -5186,16 +5270,12 @@ g_desktop_app_info_launch_action (GDesktopAppInfo   *info,
       if (exec_line)
         g_desktop_app_info_launch_uris_with_spawn (info, session_bus, exec_line, NULL, launch_context,
                                                    _SPAWN_FLAGS_DEFAULT, NULL, NULL, NULL, NULL,
-                                                   -1, -1, -1, NULL);
+                                                   -1, -1, -1, NULL, NULL);
 
       g_free (exec_line);
     }
 
-  if (session_bus != NULL)
+  g_clear_object (&session_bus);
-    {
-      g_dbus_connection_flush (session_bus, NULL, NULL, NULL);
-      g_object_unref (session_bus);
-    }
 }
 /* Epilogue {{{1 */