;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016 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 file-systems)
  #:use-module (ice-9 match)
  #:use-module (guix records)
  #:use-module (guix store)
  #:use-module ((gnu build file-systems)
                #:select (string->uuid uuid->string))
  #:re-export (string->uuid
               uuid->string)
  #:export (<file-system>
            file-system
            file-system?
            file-system-device
            file-system-title
            file-system-mount-point
            file-system-type
            file-system-needed-for-boot?
            file-system-flags
            file-system-options
            file-system-mount?
            file-system-check?
            file-system-create-mount-point?
            file-system-dependencies

            file-system->spec
            specification->file-system-mapping
            uuid

            %fuse-control-file-system
            %binary-format-file-system
            %shared-memory-file-system
            %pseudo-terminal-file-system
            %tty-gid
            %immutable-store
            %control-groups
            %elogind-file-systems

            %base-file-systems
            %container-file-systems

            <file-system-mapping>
            file-system-mapping
            file-system-mapping?
            file-system-mapping-source
            file-system-mapping-target
            file-system-mapping-writable?

            %store-mapping))

;;; Commentary:
;;;
;;; Declaring file systems to be mounted.
;;;
;;; Code:

;; File system declaration.
(define-record-type* <file-system> file-system
  make-file-system
  file-system?
  (device           file-system-device)           ; string
  (title            file-system-title             ; 'device | 'label | 'uuid
                    (default 'device))
  (mount-point      file-system-mount-point)      ; string
  (type             file-system-type)             ; string
  (flags            file-system-flags             ; list of symbols
                    (default '()))
  (options          file-system-options           ; string or #f
                    (default #f))
  (mount?           file-system-mount?            ; Boolean
                    (default #t))
  (needed-for-boot? %file-system-needed-for-boot? ; Boolean
                    (default #f))
  (check?           file-system-check?            ; Boolean
                    (default #t))
  (create-mount-point? file-system-create-mount-point? ; Boolean
                       (default #f))
  (dependencies     file-system-dependencies      ; list of <file-system>
                    (default '())))               ; or <mapped-device>

(define-inlinable (file-system-needed-for-boot? fs)
  "Return true if FS has the 'needed-for-boot?' flag set, or if it's the root
file system."
  (or (%file-system-needed-for-boot? fs)
      (string=? "/" (file-system-mount-point fs))))

(define (file-system->spec fs)
  "Return a list corresponding to file-system FS that can be passed to the
initrd code."
  (match fs
    (($ <file-system> device title mount-point type flags options _ _ check?)
     (list device title mount-point type flags options check?))))

(define (specification->file-system-mapping spec writable?)
  "Read the SPEC and return the corresponding <file-system-mapping>.  SPEC is
a string of the form \"SOURCE\" or \"SOURCE=TARGET\".  The former specifies
that SOURCE from the host should be mounted at SOURCE in the other system.
The latter format specifies that SOURCE from the host should be mounted at
TARGET in the other system."
  (let ((index (string-index spec #\=)))
    (if index
        (file-system-mapping
         (source (substring spec 0 index))
         (target (substring spec (+ 1 index)))
         (writable? writable?))
        (file-system-mapping
         (source spec)
         (target spec)
         (writable? writable?)))))

(define-syntax uuid
  (lambda (s)
    "Return the bytevector corresponding to the given UUID representation."
    (syntax-case s ()
      ((_ str)
       (string? (syntax->datum #'str))
       ;; A literal string: do the conversion at expansion time.
       (let ((bv (string->uuid (syntax->datum #'str))))
         (unless bv
           (syntax-violation 'uuid "invalid UUID" s))
         (datum->syntax #'str bv)))
      ((_ str)
       #'(string->uuid str)))))


;;;
;;; Common file systems.
;;;

(define %fuse-control-file-system
  ;; Control file system for Linux' file systems in user-space (FUSE).
  (file-system
    (device "fusectl")
    (mount-point