#lang racket/base
;; Sandbox management and use.
;;
;;; Copyright 2010, 2011, 2012, 2013 Tony Garnock-Jones <tonyg@ccs.neu.edu>
;;;
;;; This file is part of marketplace-ssh.
;;;
;;; marketplace-ssh is free software: you can redistribute it and/or
;;; modify it under the terms of the GNU General Public License as
;;; published by the Free Software Foundation, either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; marketplace-ssh is distributed in the hope that it will be useful,
;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
;;; General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with marketplace-ssh. If not, see
;;; <http://www.gnu.org/licenses/>.

(require racket/match)
(require racket/sandbox)

(provide repl-shell)

(struct user-state (name master-sandbox master-namespace) #:transparent)

(define *user-states* (make-hash))

(define (get-user-state username)
  (when (not (hash-has-key? *user-states* username))
    (let* ((sb (make-evaluator 'racket/base))
	   (ns (call-in-sandbox-context sb current-namespace)))
      (hash-set! *user-states* username
		 (user-state username
			     sb
			     ns))))
  (hash-ref *user-states* username))

(define (repl-shell username in out)
  (match-define (user-state _ master-sandbox master-namespace) (get-user-state username))
  (parameterize ((current-input-port in)
		 (current-output-port out)
		 (current-error-port out)
		 (sandbox-input in)
		 (sandbox-output out)
		 (sandbox-error-output out)
		 (sandbox-memory-limit 2) ;; megabytes
		 (sandbox-eval-limits #f)
		 (sandbox-namespace-specs (list (lambda () master-namespace))))
    (printf "Hello, ~a.\n" username)
    (define slave-sandbox (make-evaluator '(begin)))
    ;; ^^ uses master-namespace via sandbox-namespace-specs
    (parameterize ((current-namespace master-namespace)
		   (current-eval slave-sandbox))
      (read-eval-print-loop))
    (fprintf out "\nGoodbye!\n")
    (kill-evaluator slave-sandbox)
    (close-input-port in)
    (close-output-port out)))