def open_file(self, name, mode=u'r'):
path = self._topath(name)
uf = self.fs.open(path, mode=mode)
if mode == u'w':
uf.content_type = 'application/structfile'
uf.force_rev = 0
sf = StructFile(uf)
sf.is_real = False
sf.fileno = None
return sf
