HIJACK victim hijacker
Cause all existing references to an ACTION! to invoke another ACTION! HIJACK is an ACTION!
The hijacked action value, null if self-hijack (no-op)
victim [action! word! path!] Action value whose references are to be affected. hijacker [action! word! path!] The action to run in its place
We want to stop
read from reading outside the current directory
; disable read outside current directory old-read: copy :read hijack 'read adapt 'old-read [ if file? :source [ source: clean-path source if not find source what-dir [ fail "Not allowed to read outside the jail!" ] ] ]
Example taken from eval used for safe evaluation of a rebol word passed by CGI