(Rails) Test if user tries to get root directories -

there script directory user. how check if user tries more level public folder?

for example, tried detect empty string, if enter "?directory=/" => root directory. tried check if way public folder in path. again => "?directory=/home/user/app/public/../../../../../" => , again i'm in root.

how test , deny access?

try this:

def path_valid?(path, base = rails.public_path)   expanded_path_name = pathname.new(path).realpath.to_s   expanded_path_name.starts_with? base end 

pathname#realpath resolve path absolute path, symlink resolution. let test precisely path of file operated on is, , ensure inside given path.