Simple file monitor GSource, using stat() to check for the existence of a file given its URI.

What's missing is the way to plug another file monitoring system, like gnome-vfs, into it; The idea would be to add a default hook which dispatches the source callback:

/* example using gnome-vfs */
static void
monitor_cb (GnomeVFSHandle           *handle,
            const gchar              *monitor_uri,
            const gchar              *info_uri,
            GnomeVFSMonitorEventType  event_type,
            EggFileMonitorSource       *source)
{
  gboolean res;

  switch (event_type)
    {
    case GNOME_VFS_MONITOR_EVENT_CHANGED:
      source->last_event = G_FILE_CHANGED_EVENT;
      break;
    case GNOME_VFS_MONITOR_EVENT_DELETED:
      source->last_event = G_FILE_REMOVED_EVENT:
      break;
    case GNOME_VFS_MONITOR_EVENT_CREATED:
      source->last_event = G_FILE_CREATED_EVENT;
      break;
    }

  res = egg_file_monitor_source_dispatch (source);
  if (!res)
    gnome_vfs_monitor_cancel (handle);
}

The hooks are something like this:

static gboolean
fm_add_monitor (EggFileMonitorSource *source)
{
  GnomeVFSHandle *handle;
  GnomeVFSResult res;

  res = gnome_vfs_monitor_add (&handle,
                               source->uri,
                               GNOME_VFS_MONITOR_FILE,
                               monitor_cb,
                               source);

  source->user_data = handle;

  return (res == GNOME_VFS_OK);
}

static gboolean
fm_cancel_monitor (EggFileMonitorSource *source)
{
  GnomeVFSResult res;

  res = gnome_vfs_monitor_cancel (source->user_data);

  return (res == GNOME_VFS_OK);
}

...
  static const EggFileMonitorHooks fm_hooks =
  {
    fm_add_monitor,
    fm_cancel_monitor,
    NULL,
  };

  egg_set_file_monitor_hooks (fm_hooks);
...

there are two problems/stylistic issues:

 1. EggFileMonitorSource must be public, which breaks the convention;
 2. we need a public dispatcher for the source callback, egg_file_monitor_source_dispatch(), for it to be called inside the monitor callback;

I don't know how to force the dispatch of a single GSource, in any way different that this.