73 lines
2.8 KiB
Scheme
73 lines
2.8 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
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;;;
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;;; This file is part of GNU Guix.
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;;;
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;;; GNU Guix is free software; you can redistribute it and/or modify it
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;;; under the terms of the GNU General Public License as published by
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;;; the Free Software Foundation; either version 3 of the License, or (at
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;;; your option) any later version.
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;;;
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;;; GNU Guix is distributed in the hope that it will be useful, but
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;;; WITHOUT ANY WARRANTY; without even the implied warranty of
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;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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;;; GNU General Public License for more details.
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;;;
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;;; You should have received a copy of the GNU General Public License
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;;; along with GNU Guix. If not, see <http://www.gnu.org/licenses/>.
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(define-module (gnu build linux-initrd)
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#:use-module (ice-9 popen)
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#:use-module (ice-9 ftw)
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#:export (write-cpio-archive))
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;;; Commentary:
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;;;
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;;; Tools to create Linux initial RAM disks ("initrds"). Initrds are
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;;; essentially gzipped cpio archives, with a '/init' executable that the
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;;; kernel runs at boot time.
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;;;
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;;; Code:
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(define* (write-cpio-archive output directory
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#:key
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(compress? #t)
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(cpio "cpio") (gzip "gzip"))
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"Write a cpio archive containing DIRECTORY to file OUTPUT, using CPIO. When
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COMPRESS? is true, compress it using GZIP. On success, return OUTPUT."
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;; Note: don't use '--no-absolute-filenames' since that strips leading
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;; slashes from symlink targets.
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(let ((pipe (open-pipe* OPEN_WRITE cpio "-o" "-O" output
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"-H" "newc" "--null")))
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(define (print0 file)
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(format pipe "~a\0" file))
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;; Note: as per `ramfs-rootfs-initramfs.txt', always add directory entries
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;; before the files that are inside of it: "The Linux kernel cpio
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;; extractor won't create files in a directory that doesn't exist, so the
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;; directory entries must go before the files that go in those
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;; directories."
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;; XXX: Use a deterministic order.
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(file-system-fold (const #t)
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(lambda (file stat result) ; leaf
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(print0 file))
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(lambda (dir stat result) ; down
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(unless (string=? dir directory)
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(print0 dir)))
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(const #f) ; up
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(const #f) ; skip
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(const #f)
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#f
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directory)
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(and (zero? (close-pipe pipe))
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(or (not compress?)
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(and (zero? (system* gzip "--best" output))
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(rename-file (string-append output ".gz")
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output))
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output))))
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;;; linux-initrd.scm ends here
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