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;;; Consfigurator -- Lisp declarative configuration management system
;;; Copyright (C) 2021 Sean Whitton <spwhitton@spwhitton.name>
;;; This file 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, or (at your option)
;;; any later version.
;;; This file 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 this program. If not, see <http://www.gnu.org/licenses/>.
(in-package :consfigurator.connection.chroot.fork)
#+sbcl (eval-when (:compile-toplevel :load-toplevel :execute)
(require "sb-posix"))
;; use only implementation-specific fork and waitpid calls to avoid thread
;; woes. chroot(2), however, should be okay.
(defun fork ()
#+sbcl (sb-posix:fork))
(defun waitpid (pid options)
;; normalise any other implementations such that we always return
;; (values PID EXIT-STATUS), as SB-POSIX:WAITPID does
#+sbcl (sb-posix:waitpid pid options))
(defun chroot (path)
#+sbcl (sb-posix:chroot path)
#-(or sbcl) (foreign-funcall "chroot" :string path :int))
(defmethod establish-connection ((type (eql :chroot.fork)) remaining &key into)
(unless (lisp-connection-p)
(error "Forking into a chroot requires a Lisp-type connection"))
#-(or sbcl) (error "Don't know how to safely fork() in this Lisp")
(format t "Forking into chroot at ~A~%" into)
;; TODO copy required prerequisite data into the chroot -- propellor uses a
;; bind mount but we might be the root Lisp, in which case we don't have a
;; cache to bind mount in. use chroot.shell connection to upload?
(mapc #'force-output
(list *standard-output* *error-output* *debug-io* *terminal-io*))
(let ((child (fork)))
(case child
;; note that SB-POSIX:FORK can only return >=0
(-1
(error "fork(2) failed"))
(0
(handler-case
(progn
;; TODO either (reset-data-sources), or bind a restart to convert
;; data source errors into failed-change (or ignore them? or
;; what?), as they may or may not be available inside the chroot,
;; depending on whether the data source code needs to read files
;; outside of the chroot or already has the data cached, a socket
;; open etc.
(mapc #'clear-input
(list *standard-input* *debug-io* *terminal-io*))
(unless (zerop (chroot into))
(error "chroot(2) failed; are you root?"))
;; chdir, else our current working directory is a pointer to
;; something outside the chroot
(uiop:chdir "/")
;; it would be nice to reenter Consfigurator's primary loop by
;; just calling (return-from establish-connection
;; (establish-connection :local)) here, but we need to kill off
;; the child afterwards, rather than returning to the child's
;; REPL or whatever else
(continue-deploy* remaining)
(uiop:quit 0))
(serious-condition (c)
(format *error-output* ":CHROOT.FORK child failed: ~A~%" c)
(uiop:quit 2))))
(t
(multiple-value-bind (_ status) (waitpid child 0)
(declare (ignore _))
(unless (zerop status)
;; TODO instead of parsing the status ourselves here, maybe we can
;; call the various C macros for parsing the status in wait(2)
(error ":CHROOT.FORK child failed, status #x~(~4,'0X~)" status)))
nil))))
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