692 lines
24 KiB
Scheme
692 lines
24 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 (guix build linux-initrd)
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#:use-module (rnrs io ports)
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#:use-module (rnrs bytevectors)
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#:use-module (system foreign)
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#:use-module (system repl error-handling)
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#:autoload (system repl repl) (start-repl)
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#:autoload (system base compile) (compile-file)
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#:use-module (srfi srfi-1)
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#:use-module (srfi srfi-26)
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#:use-module (ice-9 match)
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#:use-module (ice-9 rdelim)
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#:use-module (ice-9 ftw)
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#:use-module (guix build utils)
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#:export (mount-essential-file-systems
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linux-command-line
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find-long-option
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make-essential-device-nodes
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configure-qemu-networking
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disk-partitions
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partition-label-predicate
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find-partition-by-label
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canonicalize-device-spec
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check-file-system
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mount-file-system
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bind-mount
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load-linux-module*
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device-number
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boot-system))
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;;; Commentary:
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;;;
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;;; Utility procedures useful in a Linux initial RAM disk (initrd). Note that
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;;; many of these use procedures not yet available in vanilla Guile (`mount',
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;;; `load-linux-module', etc.); these are provided by a Guile patch used in
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;;; the GNU distribution.
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;;;
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;;; Code:
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(define* (mount-essential-file-systems #:key (root "/"))
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"Mount /proc and /sys under ROOT."
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(define (scope dir)
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(string-append root
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(if (string-suffix? "/" root)
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""
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"/")
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dir))
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(unless (file-exists? (scope "proc"))
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(mkdir (scope "proc")))
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(mount "none" (scope "proc") "proc")
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(unless (file-exists? (scope "sys"))
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(mkdir (scope "sys")))
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(mount "none" (scope "sys") "sysfs"))
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(define (move-essential-file-systems root)
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"Move currently mounted essential file systems to ROOT."
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(for-each (lambda (dir)
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(let ((target (string-append root dir)))
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(unless (file-exists? target)
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(mkdir target))
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(mount dir target "" MS_MOVE)))
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'("/proc" "/sys")))
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(define (linux-command-line)
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"Return the Linux kernel command line as a list of strings."
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(string-tokenize
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(call-with-input-file "/proc/cmdline"
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get-string-all)))
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(define (find-long-option option arguments)
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"Find OPTION among ARGUMENTS, where OPTION is something like \"--load\".
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Return the value associated with OPTION, or #f on failure."
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(let ((opt (string-append option "=")))
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(and=> (find (cut string-prefix? opt <>)
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arguments)
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(lambda (arg)
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(substring arg (+ 1 (string-index arg #\=)))))))
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(define-syntax %ext2-endianness
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;; Endianness of ext2 file systems.
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(identifier-syntax (endianness little)))
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;; Offset in bytes of interesting parts of an ext2 superblock. See
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;; <http://www.nongnu.org/ext2-doc/ext2.html#DEF-SUPERBLOCK>.
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;; TODO: Use "packed structs" from Guile-OpenGL or similar.
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(define-syntax %ext2-sblock-magic (identifier-syntax 56))
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(define-syntax %ext2-sblock-creator-os (identifier-syntax 72))
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(define-syntax %ext2-sblock-uuid (identifier-syntax 104))
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(define-syntax %ext2-sblock-volume-name (identifier-syntax 120))
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(define (read-ext2-superblock device)
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"Return the raw contents of DEVICE's ext2 superblock as a bytevector, or #f
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if DEVICE does not contain an ext2 file system."
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(define %ext2-magic
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;; The magic bytes that identify an ext2 file system.
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#xef53)
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(define superblock-size
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;; Size of the interesting part of an ext2 superblock.
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264)
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(define block
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;; The superblock contents.
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(make-bytevector superblock-size))
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(call-with-input-file device
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(lambda (port)
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(seek port 1024 SEEK_SET)
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;; Note: work around <http://bugs.gnu.org/17466>.
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(and (eqv? superblock-size (get-bytevector-n! port block 0
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superblock-size))
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(let ((magic (bytevector-u16-ref block %ext2-sblock-magic
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%ext2-endianness)))
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(and (= magic %ext2-magic)
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block))))))
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(define (ext2-superblock-uuid sblock)
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"Return the UUID of ext2 superblock SBLOCK as a 16-byte bytevector."
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(let ((uuid (make-bytevector 16)))
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(bytevector-copy! sblock %ext2-sblock-uuid uuid 0 16)
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uuid))
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(define (ext2-superblock-volume-name sblock)
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"Return the volume name of SBLOCK as a string of at most 16 characters, or
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#f if SBLOCK has no volume name."
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(let ((bv (make-bytevector 16)))
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(bytevector-copy! sblock %ext2-sblock-volume-name bv 0 16)
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;; This is a Latin-1, nul-terminated string.
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(let ((bytes (take-while (negate zero?) (bytevector->u8-list bv))))
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(if (null? bytes)
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#f
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(list->string (map integer->char bytes))))))
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(define (disk-partitions)
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"Return the list of device names corresponding to valid disk partitions."
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(define (partition? major minor)
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(let ((marker (format #f "/sys/dev/block/~a:~a/partition" major minor)))
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(catch 'system-error
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(lambda ()
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(not (zero? (call-with-input-file marker read))))
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(lambda args
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(if (= ENOENT (system-error-errno args))
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#f
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(apply throw args))))))
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(call-with-input-file "/proc/partitions"
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(lambda (port)
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;; Skip the two header lines.
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(read-line port)
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(read-line port)
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;; Read each subsequent line, and extract the last space-separated
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;; field.
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(let loop ((parts '()))
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(let ((line (read-line port)))
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(if (eof-object? line)
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(reverse parts)
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(match (string-tokenize line)
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(((= string->number major) (= string->number minor)
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blocks name)
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(if (partition? major minor)
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(loop (cons name parts))
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(loop parts))))))))))
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(define (partition-label-predicate label)
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"Return a procedure that, when applied to a partition name such as \"sda1\",
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return #t if that partition's volume name is LABEL."
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(lambda (part)
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(let* ((device (string-append "/dev/" part))
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(sblock (catch 'system-error
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(lambda ()
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(read-ext2-superblock device))
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(lambda args
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;; When running on the hand-made /dev,
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;; 'disk-partitions' could return partitions for which
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;; we have no /dev node. Handle that gracefully.
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(if (= ENOENT (system-error-errno args))
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(begin
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(format (current-error-port)
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"warning: device '~a' not found~%"
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device)
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#f)
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(apply throw args))))))
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(and sblock
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(let ((volume (ext2-superblock-volume-name sblock)))
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(and volume
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(string=? volume label)))))))
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(define (find-partition-by-label label)
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"Return the first partition found whose volume name is LABEL, or #f if none
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were found."
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(and=> (find (partition-label-predicate label)
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(disk-partitions))
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(cut string-append "/dev/" <>)))
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(define* (canonicalize-device-spec spec #:optional (title 'any))
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"Return the device name corresponding to SPEC. TITLE is a symbol, one of
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the following:
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• 'device', in which case SPEC is known to designate a device node--e.g.,
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\"/dev/sda1\";
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• 'label', in which case SPEC is known to designate a partition label--e.g.,
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\"my-root-part\";
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• 'any', in which case SPEC can be anything.
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"
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(define max-trials
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;; Number of times we retry partition label resolution.
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7)
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(define canonical-title
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;; The realm of canonicalization.
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(if (eq? title 'any)
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(if (string-prefix? "/" spec)
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'device
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'label)
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title))
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(case canonical-title
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((device)
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;; Nothing to do.
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spec)
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((label)
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;; Resolve the label.
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(let loop ((count 0))
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(let ((device (find-partition-by-label spec)))
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(or device
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;; Some devices take a bit of time to appear, most notably USB
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;; storage devices. Thus, wait for the device to appear.
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(if (> count max-trials)
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(error "failed to resolve partition label" spec)
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(begin
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(sleep 1)
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(loop (+ 1 count))))))))
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;; TODO: Add support for UUIDs.
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(else
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(error "unknown device title" title))))
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(define* (make-disk-device-nodes base major #:optional (minor 0))
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"Make the block device nodes around BASE (something like \"/root/dev/sda\")
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with the given MAJOR number, starting with MINOR."
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(mknod base 'block-special #o644 (device-number major minor))
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(let loop ((i 1))
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(when (< i 6)
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(mknod (string-append base (number->string i))
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'block-special #o644 (device-number major (+ minor i)))
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(loop (+ i 1)))))
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(define* (make-essential-device-nodes #:key (root "/"))
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"Make essential device nodes under ROOT/dev."
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;; The hand-made udev!
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(define (scope dir)
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(string-append root
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(if (string-suffix? "/" root)
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""
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"/")
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dir))
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(unless (file-exists? (scope "dev"))
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(mkdir (scope "dev")))
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;; Make the device nodes for SCSI disks.
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(make-disk-device-nodes (scope "dev/sda") 8)
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(make-disk-device-nodes (scope "dev/sdb") 8 16)
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(make-disk-device-nodes (scope "dev/sdc") 8 32)
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(make-disk-device-nodes (scope "dev/sdd") 8 48)
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;; SCSI CD-ROM devices (aka. "/dev/sr0" etc.).
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(mknod (scope "dev/scd0") 'block-special #o644 (device-number 11 0))
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(mknod (scope "dev/scd1") 'block-special #o644 (device-number 11 1))
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;; The virtio (para-virtualized) block devices, as supported by QEMU/KVM.
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(make-disk-device-nodes (scope "dev/vda") 252)
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;; Memory (used by Xorg's VESA driver.)
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(mknod (scope "dev/mem") 'char-special #o640 (device-number 1 1))
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(mknod (scope "dev/kmem") 'char-special #o640 (device-number 1 2))
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;; Inputs (used by Xorg.)
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(unless (file-exists? (scope "dev/input"))
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(mkdir (scope "dev/input")))
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(mknod (scope "dev/input/mice") 'char-special #o640 (device-number 13 63))
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(mknod (scope "dev/input/mouse0") 'char-special #o640 (device-number 13 32))
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(mknod (scope "dev/input/event0") 'char-special #o640 (device-number 13 64))
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;; System console. This node is magically created by the kernel on the
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;; initrd's root, so don't try to create it in that case.
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(unless (string=? root "/")
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(mknod (scope "dev/console") 'char-special #o600
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(device-number 5 1)))
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;; TTYs.
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(mknod (scope "dev/tty") 'char-special #o600
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(device-number 5 0))
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(chmod (scope "dev/tty") #o666)
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(let loop ((n 0))
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(and (< n 50)
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(let ((name (format #f "dev/tty~a" n)))
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(mknod (scope name) 'char-special #o600
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(device-number 4 n))
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(loop (+ 1 n)))))
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;; Serial line.
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(mknod (scope "dev/ttyS0") 'char-special #o660
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(device-number 4 64))
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;; Pseudo ttys.
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(mknod (scope "dev/ptmx") 'char-special #o666
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(device-number 5 2))
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(chmod (scope "dev/ptmx") #o666)
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;; Create /dev/pts; it will be mounted later, at boot time.
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(unless (file-exists? (scope "dev/pts"))
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(mkdir (scope "dev/pts")))
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;; Rendez-vous point for syslogd.
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(mknod (scope "dev/log") 'socket #o666 0)
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(mknod (scope "dev/kmsg") 'char-special #o600 (device-number 1 11))
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;; Other useful nodes, notably relied on by guix-daemon.
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(for-each (match-lambda
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((file major minor)
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(mknod (scope file) 'char-special #o666
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(device-number major minor))
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(chmod (scope file) #o666)))
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'(("dev/null" 1 3)
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("dev/zero" 1 5)
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("dev/full" 1 7)
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("dev/random" 1 8)
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("dev/urandom" 1 9)))
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(symlink "/proc/self/fd" (scope "dev/fd"))
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(symlink "/proc/self/fd/0" (scope "dev/stdin"))
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(symlink "/proc/self/fd/1" (scope "dev/stdout"))
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(symlink "/proc/self/fd/2" (scope "dev/stderr"))
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;; Loopback devices.
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(let loop ((i 0))
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(when (< i 8)
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(mknod (scope (string-append "dev/loop" (number->string i)))
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'block-special #o660
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(device-number 7 i))
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(loop (+ 1 i))))
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;; File systems in user space (FUSE).
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(mknod (scope "dev/fuse") 'char-special #o666 (device-number 10 229)))
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(define %host-qemu-ipv4-address
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(inet-pton AF_INET "10.0.2.10"))
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(define* (configure-qemu-networking #:optional (interface "eth0"))
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"Setup the INTERFACE network interface and /etc/resolv.conf according to
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QEMU's default networking settings (see net/slirp.c in QEMU for default
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networking values.) Return #t if INTERFACE is up, #f otherwise."
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(display "configuring QEMU networking...\n")
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(let* ((sock (socket AF_INET SOCK_STREAM 0))
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(address (make-socket-address AF_INET %host-qemu-ipv4-address 0))
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(flags (network-interface-flags sock interface)))
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(set-network-interface-address sock interface address)
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(set-network-interface-flags sock interface (logior flags IFF_UP))
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(unless (file-exists? "/etc")
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(mkdir "/etc"))
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(call-with-output-file "/etc/resolv.conf"
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(lambda (p)
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(display "nameserver 10.0.2.3\n" p)))
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(logand (network-interface-flags sock interface) IFF_UP)))
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;; Linux mount flags, from libc's <sys/mount.h>.
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(define MS_RDONLY 1)
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(define MS_BIND 4096)
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(define MS_MOVE 8192)
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(define (bind-mount source target)
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"Bind-mount SOURCE at TARGET."
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(mount source target "" MS_BIND))
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(define (load-linux-module* file)
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"Load Linux module from FILE, the name of a `.ko' file."
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(define (slurp module)
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(call-with-input-file file get-bytevector-all))
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(load-linux-module (slurp file)))
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(define (device-number major minor)
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"Return the device number for the device with MAJOR and MINOR, for use as
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the last argument of `mknod'."
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(+ (* major 256) minor))
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(define (pidof program)
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"Return the PID of the first presumed instance of PROGRAM."
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(let ((program (basename program)))
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(find (lambda (pid)
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(let ((exe (format #f "/proc/~a/exe" pid)))
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(and=> (false-if-exception (readlink exe))
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(compose (cut string=? program <>) basename))))
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(filter-map string->number (scandir "/proc")))))
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(define* (mount-root-file-system root type
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#:key volatile-root? (unionfs "unionfs"))
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"Mount the root file system of type TYPE at device ROOT. If VOLATILE-ROOT?
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is true, mount ROOT read-only and make it a union with a writable tmpfs using
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UNIONFS."
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(define (mark-as-not-killable pid)
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;; Tell the 'user-processes' dmd service that PID must be kept alive when
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;; shutting down.
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(mkdir-p "/root/etc/dmd")
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(let ((port (open-file "/root/etc/dmd/do-not-kill" "a")))
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(chmod port #o600)
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(write pid port)
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(newline port)
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(close-port port)))
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(catch #t
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(lambda ()
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(if volatile-root?
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(begin
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(mkdir-p "/real-root")
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(mount root "/real-root" type MS_RDONLY)
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(mkdir-p "/rw-root")
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(mount "none" "/rw-root" "tmpfs")
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;; We want read-write /dev nodes.
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(make-essential-device-nodes #:root "/rw-root")
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;; Make /root a union of the tmpfs and the actual root. Use
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;; 'max_files' to set a high RLIMIT_NOFILE for the unionfs process
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;; itself. Failing to do that, we quickly run out of file
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;; descriptors; see <http://bugs.gnu.org/17827>.
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(unless (zero? (system* unionfs "-o"
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"cow,allow_other,use_ino,suid,dev,max_files=65536"
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"/rw-root=RW:/real-root=RO"
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"/root"))
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(error "unionfs failed"))
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;; Make sure unionfs remains alive till the end. Because
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;; 'fuse_daemonize' doesn't tell the PID of the forked daemon, we
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;; have to resort to 'pidof' here.
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(mark-as-not-killable (pidof unionfs)))
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(begin
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(check-file-system root type)
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(mount root "/root" type))))
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(lambda args
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(format (current-error-port) "exception while mounting '~a': ~s~%"
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root args)
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(start-repl)))
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(copy-file "/proc/mounts" "/root/etc/mtab"))
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(define (check-file-system device type)
|
||
"Run a file system check of TYPE on DEVICE."
|
||
(define fsck
|
||
(string-append "fsck." type))
|
||
|
||
(let ((status (system* fsck "-v" "-p" device)))
|
||
(match (status:exit-val status)
|
||
(0
|
||
#t)
|
||
(1
|
||
(format (current-error-port) "'~a' corrected errors on ~a; continuing~%"
|
||
fsck device))
|
||
(2
|
||
(format (current-error-port) "'~a' corrected errors on ~a; rebooting~%"
|
||
fsck device)
|
||
(sleep 3)
|
||
(reboot))
|
||
(code
|
||
(format (current-error-port) "'~a' exited with code ~a on ~a; spawning REPL~%"
|
||
fsck code device)
|
||
(start-repl)))))
|
||
|
||
(define* (mount-file-system spec #:key (root "/root"))
|
||
"Mount the file system described by SPEC under ROOT. SPEC must have the
|
||
form:
|
||
|
||
(DEVICE TITLE MOUNT-POINT TYPE (FLAGS ...) OPTIONS CHECK?)
|
||
|
||
DEVICE, MOUNT-POINT, and TYPE must be strings; OPTIONS can be a string or #f;
|
||
FLAGS must be a list of symbols. CHECK? is a Boolean indicating whether to
|
||
run a file system check."
|
||
(define flags->bit-mask
|
||
(match-lambda
|
||
(('read-only rest ...)
|
||
(or MS_RDONLY (flags->bit-mask rest)))
|
||
(('bind-mount rest ...)
|
||
(or MS_BIND (flags->bit-mask rest)))
|
||
(()
|
||
0)))
|
||
|
||
(match spec
|
||
((source title mount-point type (flags ...) options check?)
|
||
(let ((source (canonicalize-device-spec source title))
|
||
(mount-point (string-append root "/" mount-point)))
|
||
(when check?
|
||
(check-file-system source type))
|
||
(mkdir-p mount-point)
|
||
(mount source mount-point type (flags->bit-mask flags)
|
||
(if options
|
||
(string->pointer options)
|
||
%null-pointer))
|
||
|
||
;; Update /etc/mtab.
|
||
(mkdir-p (string-append root "/etc"))
|
||
(let ((port (open-file (string-append root "/etc/mtab") "a")))
|
||
(format port "~a ~a ~a ~a 0 0~%"
|
||
source mount-point type options)
|
||
(close-port port))))))
|
||
|
||
(define (switch-root root)
|
||
"Switch to ROOT as the root file system, in a way similar to what
|
||
util-linux' switch_root(8) does."
|
||
(move-essential-file-systems root)
|
||
(chdir root)
|
||
|
||
;; Since we're about to 'rm -rf /', try to make sure we're on an initrd.
|
||
;; TODO: Use 'statfs' to check the fs type, like klibc does.
|
||
(when (or (not (file-exists? "/init")) (directory-exists? "/home"))
|
||
(format (current-error-port)
|
||
"The root file system is probably not an initrd; \
|
||
bailing out.~%root contents: ~s~%" (scandir "/"))
|
||
(force-output (current-error-port))
|
||
(exit 1))
|
||
|
||
;; Delete files from the old root, without crossing mount points (assuming
|
||
;; there are no mount points in sub-directories.) That means we're leaving
|
||
;; the empty ROOT directory behind us, but that's OK.
|
||
(let ((root-device (stat:dev (stat "/"))))
|
||
(for-each (lambda (file)
|
||
(unless (member file '("." ".."))
|
||
(let* ((file (string-append "/" file))
|
||
(device (stat:dev (lstat file))))
|
||
(when (= device root-device)
|
||
(delete-file-recursively file)))))
|
||
(scandir "/")))
|
||
|
||
;; Make ROOT the new root.
|
||
(mount root "/" "" MS_MOVE)
|
||
(chroot ".")
|
||
(chdir "/")
|
||
|
||
(when (file-exists? "/dev/console")
|
||
;; Close the standard file descriptors since they refer to the old
|
||
;; /dev/console, and reopen them.
|
||
(let ((console (open-file "/dev/console" "r+b0")))
|
||
(for-each close-fdes '(0 1 2))
|
||
|
||
(dup2 (fileno console) 0)
|
||
(dup2 (fileno console) 1)
|
||
(dup2 (fileno console) 2)
|
||
|
||
(close-port console))))
|
||
|
||
|
||
(define* (boot-system #:key
|
||
(linux-modules '())
|
||
qemu-guest-networking?
|
||
guile-modules-in-chroot?
|
||
volatile-root?
|
||
(mounts '()))
|
||
"This procedure is meant to be called from an initrd. Boot a system by
|
||
first loading LINUX-MODULES, then setting up QEMU guest networking if
|
||
QEMU-GUEST-NETWORKING? is true, mounting the file systems specified in MOUNTS,
|
||
and finally booting into the new root if any. The initrd supports kernel
|
||
command-line options '--load', '--root', and '--repl'.
|
||
|
||
Mount the root file system, specified by the '--root' command-line argument,
|
||
if any.
|
||
|
||
MOUNTS must be a list suitable for 'mount-file-system'.
|
||
|
||
When GUILE-MODULES-IN-CHROOT? is true, make core Guile modules available in
|
||
the new root.
|
||
|
||
When VOLATILE-ROOT? is true, the root file system is writable but any changes
|
||
to it are lost."
|
||
(define root-mount-point?
|
||
(match-lambda
|
||
((device _ "/" _ ...) #t)
|
||
(_ #f)))
|
||
|
||
(define root-fs-type
|
||
(or (any (match-lambda
|
||
((device _ "/" type _ ...) type)
|
||
(_ #f))
|
||
mounts)
|
||
"ext4"))
|
||
|
||
(display "Welcome, this is GNU's early boot Guile.\n")
|
||
(display "Use '--repl' for an initrd REPL.\n\n")
|
||
|
||
(call-with-error-handling
|
||
(lambda ()
|
||
(mount-essential-file-systems)
|
||
(let* ((args (linux-command-line))
|
||
(to-load (find-long-option "--load" args))
|
||
(root (find-long-option "--root" args)))
|
||
|
||
(when (member "--repl" args)
|
||
(start-repl))
|
||
|
||
(display "loading kernel modules...\n")
|
||
(for-each (compose load-linux-module*
|
||
(cut string-append "/modules/" <>))
|
||
linux-modules)
|
||
|
||
(when qemu-guest-networking?
|
||
(unless (configure-qemu-networking)
|
||
(display "network interface is DOWN\n")))
|
||
|
||
;; Make /dev nodes.
|
||
(make-essential-device-nodes)
|
||
|
||
;; Prepare the real root file system under /root.
|
||
(unless (file-exists? "/root")
|
||
(mkdir "/root"))
|
||
(if root
|
||
(mount-root-file-system (canonicalize-device-spec root)
|
||
root-fs-type
|
||
#:volatile-root? volatile-root?)
|
||
(mount "none" "/root" "tmpfs"))
|
||
|
||
(unless (file-exists? "/root/dev")
|
||
(mkdir "/root/dev")
|
||
(make-essential-device-nodes #:root "/root"))
|
||
|
||
;; Mount the specified file systems.
|
||
(for-each mount-file-system
|
||
(remove root-mount-point? mounts))
|
||
|
||
(when guile-modules-in-chroot?
|
||
;; Copy the directories that contain .scm and .go files so that the
|
||
;; child process in the chroot can load modules (we would bind-mount
|
||
;; them but for some reason that fails with EINVAL -- XXX).
|
||
(mkdir-p "/root/share")
|
||
(mkdir-p "/root/lib")
|
||
(mount "none" "/root/share" "tmpfs")
|
||
(mount "none" "/root/lib" "tmpfs")
|
||
(copy-recursively "/share" "/root/share"
|
||
#:log (%make-void-port "w"))
|
||
(copy-recursively "/lib" "/root/lib"
|
||
#:log (%make-void-port "w")))
|
||
|
||
(if to-load
|
||
(begin
|
||
(switch-root "/root")
|
||
(format #t "loading '~a'...\n" to-load)
|
||
|
||
;; Obviously this has to be done each time we boot. Do it from here
|
||
;; so that statfs(2) returns DEVPTS_SUPER_MAGIC like libc's getpt(3)
|
||
;; expects (and thus openpty(3) and its users, such as xterm.)
|
||
(mount "none" "/dev/pts" "devpts")
|
||
|
||
;; TODO: Remove /lib, /share, and /loader.go.
|
||
(primitive-load to-load)
|
||
|
||
(format (current-error-port)
|
||
"boot program '~a' terminated, rebooting~%"
|
||
to-load)
|
||
(sleep 2)
|
||
(reboot))
|
||
(begin
|
||
(display "no boot file passed via '--load'\n")
|
||
(display "entering a warm and cozy REPL\n")
|
||
(start-repl)))))))
|
||
|
||
;;; linux-initrd.scm ends here
|