A tail-recursive semantics for stack inspection

Abstract. Security folklore holds that a security mechanism based on stack inspection is incompatible with a global tail call optimization pol icy. An implementation of such a language may have to allocate memory for a source-code tail call, and a program that uses only tail calls (and no other memory-allocating construct) may nevertheless exhaust the avail able memory. In this paper, we prove this widely held belief wrong. We exhibit an abstract machine for a language with security stack inspection whose space consumption function is equivalent to that of the canonical tail call optimizing abstract machine. Our machine is surprisingly simple and suggests that tail-calls are as easy to implement in a security setting as they are in a conventional one. 1 Stacks, Security, and Tail Calls Over the last ten years, programming language implementors have spent signifi cant effort on security issues. This effort takes many forms; one is the implemen tation of a strategy known as stack inspection [17]. It starts from the premis