;;; 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 <https://www.gnu.org/licenses/>.

(in-package :consfigurator.connection.as)
(named-readtables:in-readtable :consfigurator)

;; currently we only check whether we're root, but, for example, on Linux, we
;; might have a CAP_* which lets us setuid as non-root
(defun can-setuid ()
  (zerop (nix:geteuid)))

(defmethod establish-connection ((type (eql :as)) remaining &key user)
  "Establish a :SETUID or :SU connection to another user account, depending on
whether it is possible to establish a :SETUID connection.

Note that both these connection types require root."
  ;; An alternative to :SU would be :SUDO or runuser(1), but :SU is more
  ;; portable.
  (let ((setuid (and (lisp-connection-p) (can-setuid))))
    (establish-connection
     (if setuid :setuid :su) remaining (if setuid :user :to) user)))
