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;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2018, 2020 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 ((guix cpio) #:prefix cpio:)
#:use-module (guix build utils)
#:use-module (guix build store-copy)
#:use-module (system base compile)
#:use-module (rnrs bytevectors)
#:use-module ((system foreign) #:select (sizeof))
#:use-module (ice-9 ftw)
#:export (write-cpio-archive
build-initrd))
;;; 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)
(gzip "gzip"))
"Write a cpio archive containing DIRECTORY to file OUTPUT, with reset
timestamps in the archive. When COMPRESS? is true, compress it using GZIP.
On success, return OUTPUT."
;; 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."
(define files
;; Use 'sort' so that (1) the order of files is deterministic, and (2)
;; directories appear before the files they contain.
(sort (file-system-fold (const #t) ;enter?
(lambda (file stat result) ;leaf
(cons file result))
(lambda (dir stat result) ;down
(if (string=? dir directory)
result
(cons dir result)))
(lambda (file stat result)
result)
(const #f) ;skip
(const #f) ;error
'()
directory)
string<?))
(call-with-output-file output
(lambda (port)
(cpio:write-cpio-archive files port
#:file->header cpio:file->cpio-header*)))
(if compress?
;; Gzip insists on adding a '.gz' suffix and does nothing if the input
;; file already has that suffix. Shuffle files around to placate it.
(let* ((gz-suffix? (string-suffix? ".gz" output))
(sans-gz (if gz-suffix?
(string-drop-right output 3)
output)))
(when gz-suffix?
(rename-file output sans-gz))
;; Use '--no-name' so that gzip records neither a file name nor a time
;; stamp in its output.
(and (zero? (system* gzip "--best" "--no-name" sans-gz))
(begin
(unless gz-suffix?
(rename-file (string-append output ".gz") output))
output)))
output))
(define (cache-compiled-file-name file)
"Return the file name of the in-cache .go file for FILE, relative to the
current directory.
This is similar to what 'compiled-file-name' in (system base compile) does."
(let loop ((file file))
(let ((target (false-if-exception (readlink file))))
(if target
(loop target)
(format #f ".cache/guile/ccache/~a-~a-~a-~a/~a"
(effective-version)
(if (eq? (native-endianness) (endianness little))
"LE"
"BE")
(sizeof '*)
(effective-version)
file)))))
(define (compile-to-cache file)
"Compile FILE to the cache."
(let ((compiled-file (cache-compiled-file-name file)))
(mkdir-p (dirname compiled-file))
(compile-file file
#:opts %auto-compilation-options
#:output-file compiled-file)))
(define* (build-initrd output
#:key
guile init
(references-graphs '())
(gzip "gzip"))
"Write an initial RAM disk (initrd) to OUTPUT. The initrd starts the script
at INIT, running GUILE. It contains all the items referred to by
REFERENCES-GRAPHS."
(mkdir "contents")
;; Copy the closures of all the items referenced in REFERENCES-GRAPHS.
(populate-store references-graphs "contents")
(with-directory-excursion "contents"
;; Make '/init'.
(symlink init "init")
;; Compile it.
(compile-to-cache "init")
;; Allow Guile to find out where it is (XXX). See
;; 'guile-relocatable.patch'.
(mkdir-p "proc/self")
(symlink (string-append guile "/bin/guile") "proc/self/exe")
(readlink "proc/self/exe")
(write-cpio-archive output "." #:gzip gzip))
;; Make sure directories are writable so we can delete files.
(for-each make-file-writable
(find-files "contents"
(lambda (file stat)
(eq? 'directory (stat:type stat)))
#:directories? #t))
(delete-file-recursively "contents"))
;;; linux-initrd.scm ends here
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