What is the size of this file?

public static async Task<ulong> GetFileSize(this string filename)
{
	StorageFile file = await GetFile(filename);
	if (file == null)
		return 0;
	try
	{
		BasicProperties fileSize = await file.GetBasicPropertiesAsync();
		return fileSize.Size;
	}
	catch (Exception e)
	{
		s_log.ErrorFormat("Cannot read file {0} due to {1}", filename, e.Message);
		return 0;
	}
}