;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2018, 2020 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2019, 2020, 2022 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix 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.
;;;
;;; GNU Guix 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 GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu installer final)
  #:use-module (gnu installer newt page)
  #:use-module (gnu installer steps)
  #:use-module (gnu installer utils)
  #:use-module (gnu installer user)
  #:use-module (gnu services herd)
  #:use-module (guix build syscalls)
  #:use-module (guix build utils)
  #:use-module (gnu build accounts)
  #:use-module (gnu build install)
  #:use-module (gnu build linux-container)
  #:use-module ((gnu system shadow) #:prefix sys:)
  #:use-module (rnrs io ports)
  #:use-module (srfi srfi-1)
  #:use-module (ice-9 ftw)
  #:use-module (ice-9 popen)
  #:use-module (ice-9 match)
  #:use-module (ice-9 format)
  #:use-module (ice-9 rdelim)
  #:export (install-system))

(define %seed
  (seed->random-state
   (logxor (getpid) (car (gettimeofday)))))

(define (integer->alphanumeric-char n)
  "Map N, an integer in the [0..62] range, to an alphanumeric character."
  (cond ((< n 10)
         (integer->char (+ (char->integer #\0) n)))
        ((< n 36)
         (integer->char (+ (char->integer #\A) (- n 10))))
        ((< n 62)
         (integer->char (+ (char->integer #\a) (- n 36))))
        (else
         (error "integer out of bounds" n))))

(define (random-string len)
  "Compute a random string of size LEN where each character is alphanumeric."
  (let loop ((chars '())
             (len len))
    (if (zero? len)
        (list->string chars)
        (let ((n (random 62 %seed)))
          (loop (cons (integer->alphanumeric-char n) chars)
                (- len 1))))))

(define (create-user-database users root)
  "Create /etc/passwd, /etc/shadow, and /etc/group under ROOT for the given
USERS."
  (define etc
    (string-append root "/etc"))

  (define (salt)
    ;; "$6" gives us a SHA512 password hash; the random string must be taken
    ;; from the './0-9A-Za-z' alphabet (info "(libc) Passphrase Storage").
    (string-append "$6$" (random-string 10)))

  (define users*
    (map (lambda (user)
           (define root?
             (string=? "root" (user-name user)))

           (sys:user-account (name (user-name user))
                             (comment (user-real-name user))
                             (group "users")
                             (uid (if root? 0 #f))
                             (home-directory
                              (user-home-directory user))
                             (password (crypt
                                        (secret-content (user-password user))
                                        (salt)))

                             ;; We need a string here, not a file-like, hence
                             ;; this choice.
                             (shell
                              "/run/current-system/profile/bin/bash")))
         users))

  (define-values (group password shadow)
    (user+group-databases users* sys:%base-groups
                          #:current-passwd '()
                          #:current-groups '()
                          #:current-shadow '()))

  (mkdir-p etc)
  (write-group group (string-append etc "/group"))
  (write-passwd password (string-append etc "/passwd"))
  (write-shadow shadow (string-append etc "/shadow")))

(define (call-with-mnt-container thunk)
  "This is a variant of call-with-container. Run THUNK in a new container
process, within a separate MNT namespace. The container is not jailed so that
it can interact with the rest of the system."
  (let ((pid (run-container "/" '() '(mnt) 1 thunk)))
    ;; Catch SIGINT and kill the container process.
    (sigaction SIGINT
      (lambda (signum)
        ;: FIXME: Use of SIGKILL prevents the dynamic-wind exit handler of
        ;; THUNK to run.
        (false-if-exception
         (kill pid SIGKILL))))