This component intercepts File_system requests and changes
the root directory attached to requests as defined by
policy or by converting session label elements to a
hierarchy of directories.

Sessions matching policies with _path_ attributes will be "chrooted" to the
configured policy path, sessions not matching policies with _path_ attributes
will be chrooted into paths formed from each session label element. Sessions
matching polices with a _path_prefix_ attribute are both rooted at the
attribute path and in sub-directories formed by the session label.
Sessions requests are downgraded to read-only requests unless matched by
polices with an affirmative _writeable_ attribute. Sessions not matching any
policy are rejected.

Please note that this server is only effective for File_system servers that
honor the "root" or "writeable" argument to session requests.
