185 lines
7.0 KiB
Scheme
185 lines
7.0 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
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;;; Copyright © 2016 Andreas Enge <andreas@enge.fr>
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;;; Copyright © 2017 Mark H Weaver <mhw@netris.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 system mapped-devices)
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#:use-module (guix gexp)
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#:use-module (guix records)
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#:use-module (guix modules)
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#:use-module (gnu services)
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#:use-module (gnu services shepherd)
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#:use-module (gnu system uuid)
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#:autoload (gnu packages cryptsetup) (cryptsetup-static)
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#:autoload (gnu packages linux) (mdadm-static)
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#:use-module (srfi srfi-1)
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#:use-module (ice-9 match)
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#:export (mapped-device
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mapped-device?
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mapped-device-source
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mapped-device-target
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mapped-device-type
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mapped-device-kind
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mapped-device-kind?
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mapped-device-kind-open
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mapped-device-kind-close
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device-mapping-service-type
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device-mapping-service
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luks-device-mapping
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raid-device-mapping))
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;;; Commentary:
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;;;
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;;; This module supports "device mapping", a concept implemented by Linux's
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;;; device-mapper.
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;;;
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;;; Code:
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(define-record-type* <mapped-device> mapped-device
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make-mapped-device
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mapped-device?
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(source mapped-device-source) ;string | list of strings
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(target mapped-device-target) ;string
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(type mapped-device-type)) ;<mapped-device-kind>
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(define-record-type* <mapped-device-type> mapped-device-kind
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make-mapped-device-kind
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mapped-device-kind?
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(open mapped-device-kind-open) ;source target -> gexp
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(close mapped-device-kind-close ;source target -> gexp
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(default (const #~(const #f)))))
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;;;
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;;; Device mapping as a Shepherd service.
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;;;
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(define device-mapping-service-type
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(shepherd-service-type
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'device-mapping
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(match-lambda
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(($ <mapped-device> source target
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($ <mapped-device-type> open close))
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(shepherd-service
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(provision (list (symbol-append 'device-mapping- (string->symbol target))))
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(requirement '(udev))
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(documentation "Map a device node using Linux's device mapper.")
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(start #~(lambda () #$(open source target)))
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(stop #~(lambda _ (not #$(close source target))))
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(respawn? #f))))))
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(define (device-mapping-service mapped-device)
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"Return a service that sets up @var{mapped-device}."
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(service device-mapping-service-type mapped-device))
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;;;
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;;; Common device mappings.
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;;;
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(define (open-luks-device source target)
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"Return a gexp that maps SOURCE to TARGET as a LUKS device, using
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'cryptsetup'."
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(with-imported-modules (source-module-closure
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'((gnu build file-systems)))
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#~(let ((source #$(if (uuid? source)
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(uuid-bytevector source)
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source)))
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;; XXX: 'use-modules' should be at the top level.
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(use-modules (rnrs bytevectors) ;bytevector?
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((gnu build file-systems)
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#:select (find-partition-by-luks-uuid)))
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;; Use 'cryptsetup-static', not 'cryptsetup', to avoid pulling the
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;; whole world inside the initrd (for when we're in an initrd).
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(zero? (system* #$(file-append cryptsetup-static "/sbin/cryptsetup")
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"open" "--type" "luks"
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;; Note: We cannot use the "UUID=source" syntax here
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;; because 'cryptsetup' implements it by searching the
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;; udev-populated /dev/disk/by-id directory but udev may
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;; be unavailable at the time we run this.
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(if (bytevector? source)
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(or (let loop ((tries-left 10))
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(and (positive? tries-left)
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(or (find-partition-by-luks-uuid source)
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;; If the underlying partition is
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;; not found, try again after
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;; waiting a second, up to ten
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;; times. FIXME: This should be
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;; dealt with in a more robust way.
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(begin (sleep 1)
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(loop (- tries-left 1))))))
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(error "LUKS partition not found" source))
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source)
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#$target)))))
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(define (close-luks-device source target)
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"Return a gexp that closes TARGET, a LUKS device."
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#~(zero? (system* #$(file-append cryptsetup-static "/sbin/cryptsetup")
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"close" #$target)))
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(define luks-device-mapping
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;; The type of LUKS mapped devices.
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(mapped-device-kind
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(open open-luks-device)
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(close close-luks-device)))
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(define (open-raid-device sources target)
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"Return a gexp that assembles SOURCES (a list of devices) to the RAID device
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TARGET (e.g., \"/dev/md0\"), using 'mdadm'."
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#~(let ((sources '#$sources)
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;; XXX: We're not at the top level here. We could use a
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;; non-top-level 'use-modules' form but that doesn't work when the
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;; code is eval'd, like the Shepherd does.
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(every (@ (srfi srfi-1) every))
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(format (@ (ice-9 format) format)))
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(let loop ((attempts 0))
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(unless (every file-exists? sources)
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(when (> attempts 20)
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(error "RAID devices did not show up; bailing out"
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sources))
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(format #t "waiting for RAID source devices~{ ~a~}...~%"
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sources)
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(sleep 1)
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(loop (+ 1 attempts))))
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;; Use 'mdadm-static' rather than 'mdadm' to avoid pulling its whole
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;; closure (80 MiB) in the initrd when a RAID device is needed for boot.
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(zero? (apply system* #$(file-append mdadm-static "/sbin/mdadm")
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"--assemble" #$target sources))))
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(define (close-raid-device sources target)
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"Return a gexp that stops the RAID device TARGET."
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#~(zero? (system* #$(file-append mdadm-static "/sbin/mdadm")
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"--stop" #$target)))
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(define raid-device-mapping
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;; The type of RAID mapped devices.
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(mapped-device-kind
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(open open-raid-device)
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(close close-raid-device)))
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;;; mapped-devices.scm ends here
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