function phutil_unescape_uri_path_component($string)

libphutil Technical Documentation (Core Utilities)

Unescape text that was escaped by phutil_escape_uri_path_component(). See phutil_escape_uri() for discussion.

Note that this function is NOT the inverse of phutil_escape_uri_path_component()! It undoes additional escaping which is added to survive the implied unescaping performed by the webserver when interpreting the request.