;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
;;; Copyright © 2019 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2022 Denis 'GNUtoo' Carikli <GNUtoo@cyberdimension.org>
;;; Copyright © 2022 Timothy Sample <samplet@ngyro.com>
;;;
;;; 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 build bootloader)
#:use-module (guix build utils)
#:use-module (guix utils)
#:use-module (ice-9 binary-ports)
#:use-module (ice-9 format)
#:use-module (rnrs io ports)
#:use-module (rnrs io simple)
#:export (write-file-on-device
install-efi-loader))
;;;
;;; Writing utils.
;;;
(define (write-file-on-device file size device offset)
"Write SIZE bytes from FILE to DEVICE starting at OFFSET."
(call-with-input-file file
(lambda (input)
(let ((bv (get-bytevector-n input size)))
(call-with-port
;; Do not use "call-with-output-file" that would truncate the file.
(open-file-output-port device
(file-options no-truncate no-fail)
(buffer-mode block)
;; Use the binary-friendly ISO-8859-1
;; encoding.
(make-transcoder (latin-1-codec)))
(lambda (output)
(seek output offset SEEK_SET)
(put-bytevector output bv)))))))
;;;
;;; EFI bootloader.
;;;
(define* (install-efi grub grub-config esp #:key targets)
"Write a self-contained GRUB EFI loader to the mounted ESP using
GRUB-CONFIG.
If TARGETS is set, use its car as the GRUB image format and its cdr as
the output filename. Otherwise, use defaults for the host platform."
(let* ((system %host-type)
;; Hard code the output location to a well-known path recognized by
;; compliant firmware. See "3.5.1.1 Removable Media Boot Behaviour":
;; http://www.uefi.org/sites/default/files/resources/UEFI%20Spec%202_6.pdf
(grub-mkstandalone (string-append grub "/bin/grub-mkstandalone"))
(efi-directory (string-append esp "/EFI/BOOT"))
;; Map grub target names to boot file names.
(efi-targets (or targets
(cond ((string-prefix? "x86_64" system)
'("x86_64-efi" . "BOOTX64.EFI"))
((string-prefix? "i686" system)
'("i386-efi" . "BOOTIA32.EFI"))
((string-prefix? "armhf" system)
'("arm-efi" . "BOOTARM.EFI"))
((string-prefix? "aarch64" system)
'("arm64-efi" . "BOOTAA64.EFI"))))))
;; grub-mkstandalone requires a TMPDIR to prepare the firmware image.
(setenv "TMPDIR" esp)
(mkdir-p efi-directory)
(invoke grub-mkstandalone "-O" (car efi-targets)
"-o" (string-append efi-directory "/"
(cdr efi-targets))
;; Graft the configuration file onto the image.
(string-append "boot/grub/grub.cfg=" grub-config))))
(define* (install-efi-loader grub-efi esp #:key targets)
"Install in ESP directory the given GRUB-EFI bootloader. Configure it to
load the Grub bootloader located in the 'Guix_image' root partition.
If TARGETS is set, use its car as the GRUB image format and its cdr as
the output filename. Otherwise, use defaults for the host platform."
(let ((grub-config "grub.cfg"))
(call-with-output-file grub-config
(lambda (port)
;; Create a tiny configuration file telling the embedded grub where to
;; load the real thing. XXX This is quite fragile, and can prevent
;; the image from booting when there's more than one volume with this
;; label present. Reproducible almost-UUIDs could reduce the risk
;; (not eliminate it).
(format port
"insmod part_msdos~@
insmod part_gpt~@
search --set=root --label Guix_image~@
configfile /boot/grub/grub.cfg~%")))
(install-efi grub-efi grub-config esp #:targets targets)
(delete-file grub-config)))
