fn check_permission(&self, obj: &'a FsObject, perm: Permissions) -> Result<&'a FsObject, ()>
{
    match((obj.can_read(&self.user), obj.can_write(&self.user), perm))
    {
        (true, _, Permissions::Read) => Ok(obj),
        (true, true, Permissions::ReadWrite) => Ok(obj),
        _ => Err(()),
    }
}

pub fn open(&self, path: path::Path) -> Result<&'a VROFile, ()>
{
    let obj = self.vfs.get_object(path)?;
    if let Ok(FsObject{obj_type: FsObjTypes::file(file), ..}) = self.check_permission(&obj, Permissions::Read)
    {
        Ok(file.as_ref().as_ro())
    }
    else if let Ok(FsObject{obj_type: FsObjTypes::ro_file(file), ..}) = self.check_permission(&obj, Permissions::Read)
    {
        Ok(file.as_ref())
    }
    else
    {
        Err(())
    }
}