;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015 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 system shadow)
  #:use-module (guix records)
  #:use-module (guix gexp)
  #:use-module (guix store)
  #:use-module (guix monads)
  #:use-module (guix sets)
  #:use-module (guix ui)
  #:use-module ((gnu system file-systems)
                #:select (%tty-gid))
  #:use-module ((gnu packages admin)
                #:select (shadow))
  #:use-module (gnu packages bash)
  #:use-module (gnu packages guile-wm)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-34)
  #:use-module (srfi srfi-35)
  #:export (user-account
            user-account?
            user-account-name
            user-account-password
            user-account-uid
            user-account-group
            user-account-supplementary-groups
            user-account-comment
            user-account-home-directory
            user-account-shell
            user-account-system?

            user-group
            user-group?
            user-group-name
            user-group-password
            user-group-id
            user-group-system?

            default-skeletons
            skeleton-directory
            %base-groups
            %base-user-accounts
            assert-valid-users/groups))

;;; Commentary:
;;;
;;; Utilities for configuring the Shadow tool suite ('login', 'passwd', etc.)
;;;
;;; Code:

(define-record-type* <user-account>
  user-account make-user-account
  user-account?
  (name           user-account-name)
  (password       user-account-password (default #f))
  (uid            user-account-uid (default #f))
  (group          user-account-group)             ; number | string
  (supplementary-groups user-account-supplementary-groups
                        (default '()))            ; list of strings
  (comment        user-account-comment (default ""))
  (home-directory user-account-home-directory)
  (shell          user-account-shell              ; gexp
                  (default #~(string-append #$bash "/bin/bash")))
  (system?        user-account-system?            ; Boolean
                  (default #f)))

(define-record-type* <user-group>
  user-group make-user-group
  user-group?
  (name           user-group-name)
  (password       user-group-password (default #f))
  (id             user-group-id (default #f))
  (system?        user-group-system?              ; Boolean
                  (default #f)))

(define %base-groups
  ;; Default set of groups.
  (let-syntax ((system-group (syntax-rules ()
                               ((_ args ...)
                                (user-group (system? #t) args ...)))))
    (list (system-group (name "root") (id 0))
          (system-group (name "wheel"))              ; root-like users
          (system-group (name "users"))              ; normal users
          (system-group (name "nogroup"))            ; for daemons etc.

          ;; The following groups are conventionally used by things like udev to
          ;; control access to hardware devices.
          (system-group (name "tty") (id %tty-gid))
          (system-group (name "dialout"))
          (system-group (name "kmem"))
          (system-group (name "input"))              ; input devices, from udev
          (system-group (name "video"))
          (system-group (name "audio"))
          (system-group (name "netdev"))             ; used in avahi-dbus.conf
          (system-group (name "lp"))
          (system-group (name "disk"))
          (system-group (name "floppy"))
          (system-group (name "cdrom"))
          (system-group (name "tape"))
          (system-group (name "kvm")))))             ; for /dev/kvm

(define %base-user-accounts
  ;; List of standard user accounts.  Note that "root" is a special case, so
  ;; it's not listed here.
  (list (user-account
         (name "nobody")
         (uid 65534)
         (group "nogroup")
         (home-directory "/var/empty")
         (system? #t))))

(define (default-skeletons)
  "Return the default skeleton files for /etc/skel.  These files are copied by
'useradd' in the home directory of newly created user accounts."
  (define copy-guile-wm
    #~(begin
        (use-modules (guix build utils))
        (copy-file (car (find-files #$guile-wm "wm-init-sample.scm"))
                   #$output)))

  (mlet %store-monad ((profile (text-file "bash_profile" "\
# Honor per-interactive-shell startup file
if [ -f ~/.bashrc ]; then . ~/.bashrc; fi\n"))
                      (bashrc (text-file "bashrc" "\
# Bash initialization for interactive non-login shells and
# for remote shells (info \"(bash) Bash Startup Files\").

# Export 'SHELL' to child processes.  Programs such as 'screen'
# honor it and otherwise use /bin/sh.
export SHELL

if [ -n \"$SSH_CLIENT\" -a -z \"`type -P cat`\" ]
then
    # We are being invoked from a non-interactive SSH session
    # (as in \"ssh host command\") but 'cat' cannot be found
    # in $PATH.  Source /etc/profile so we get $PATH and other
    # essential variables.
    source /etc/profile
fi

# Adjust the prompt depending on whether we're in 'guix environment'.
if [ -n \"$GUIX_ENVIRONMENT\" ]
then
    export PS1='\\u@\\h \\w [env]\\$ '
else
    export PS1='\\u@\\h \\w\\$ '
fi
alias ls='ls -p --color'
alias ll='ls -l'\n"))
                      (zlogin (text-file "zlogin" "\
# Honor system-wide environment variables
source /etc/profile\n"))
                      (guile-wm (gexp->derivation "guile-wm" copy-guile-wm
                                                  #:modules
                                                  '((guix build utils))))
                      (xdefaults (text-file "Xdefaults" "\
XTerm*utf8: always
XTerm*metaSendsEscape: true\n"))
                      (gdbinit   (text-file "gdbinit" "\
# Tell GDB where to look for separate debugging files.
set debug-file-directory ~/.guix-profile/lib/debug\n")))
    (return `((".bash_profile" ,profile)
              (".bashrc" ,bashrc)
              (".zlogin" ,zlogin)
              (".Xdefaults" ,xdefaults)
              (".guile-wm" ,guile-wm)
              (".gdbinit" ,gdbinit)))))

(define (skeleton-directory skeletons)
  "Return a directory containing SKELETONS, a list of name/derivation pairs."
  (gexp->derivation "skel"
                    #~(begin
                        (use-modules (ice-9 match))

                        (mkdir #$output)
                        (chdir #$output)

                        ;; Note: copy the skeletons instead of symlinking
                        ;; them like 'file-union' does, because 'useradd'
                        ;; would just copy the symlinks as is.
                        (for-each (match-lambda
                                   ((target source)
                                    (copy-file source target)))
                                  '#$skeletons)
                        #t)))

(define (assert-valid-users/groups users groups)
  "Raise an error if USERS refer to groups not listed in GROUPS."
  (let ((groups (list->set (map user-group-name groups))))
    (define (validate-supplementary-group user group)
      (unless (set-contains? groups group)
        (raise (condition
                (&message
                 (message
                  (format #f (_ "supplementary group '~a' \
of user '~a' is undeclared")
                          group
                          (user-account-name user))))))))

    (for-each (lambda (user)
                (unless (set-contains? groups (user-account-group user))
                  (raise (condition
                          (&message
                           (message
                            (format #f (_ "primary group '~a' \
of user '~a' is undeclared")
                                    (user-account-group user)
                                    (user-account-name user)))))))

                (for-each (cut validate-supplementary-group user <>)
                          (user-account-supplementary-groups user)))
              users)))

;;; shadow.scm ends here
