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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014 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 build linux-initrd)
#:use-module (ice-9 popen)
#:use-module (ice-9 ftw)
#:export (write-cpio-archive))
;;; Commentary:
;;;
;;; Tools to create Linux initial RAM disks ("initrds"). Initrds are
;;; essentially gzipped cpio archives, with a '/init' executable that the
;;; kernel runs at boot time.
;;;
;;; Code:
(define* (write-cpio-archive output directory
#:key
(compress? #t)
(cpio "cpio") (gzip "gzip"))
"Write a cpio archive containing DIRECTORY to file OUTPUT, using CPIO. When
COMPRESS? is true, compress it using GZIP. On success, return OUTPUT."
;; Note: don't use '--no-absolute-filenames' since that strips leading
;; slashes from symlink targets.
(let ((pipe (open-pipe* OPEN_WRITE cpio "-o" "-O" output
"-H" "newc" "--null")))
(define (print0 file)
(format pipe "~a\0" file))
;; Note: as per `ramfs-rootfs-initramfs.txt', always add directory entries
;; before the files that are inside of it: "The Linux kernel cpio
;; extractor won't create files in a directory that doesn't exist, so the
;; directory entries must go before the files that go in those
;; directories."
;; XXX: Use a deterministic order.
(file-system-fold (const #t)
(lambda (file stat result) ; leaf
(print0 file))
(lambda (dir stat result) ; down
(unless (string=? dir directory)
(print0 dir)))
(const #f) ; up
(const #f) ; skip
(const #f)
#f
directory)
(and (zero? (close-pipe pipe))
(or (not compress?)
(and (zero? (system* gzip "--best" output))
(rename-file (string-append output ".gz")
output))
output))))
;;; linux-initrd.scm ends here
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