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425 lines
14 KiB
Scheme
425 lines
14 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014, 2015, 2016, 2017 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 system file-systems)
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#:use-module (ice-9 match)
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#:use-module (srfi srfi-1)
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#:use-module (guix records)
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#:use-module ((gnu build file-systems)
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#:select (string->uuid uuid->string))
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#:re-export (string->uuid
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uuid->string)
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#:export (<file-system>
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file-system
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file-system?
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file-system-device
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file-system-title
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file-system-mount-point
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file-system-type
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file-system-needed-for-boot?
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file-system-flags
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file-system-options
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file-system-mount?
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file-system-check?
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file-system-create-mount-point?
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file-system-dependencies
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file-system-type-predicate
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file-system->spec
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spec->file-system
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specification->file-system-mapping
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uuid
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%fuse-control-file-system
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%binary-format-file-system
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%shared-memory-file-system
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%pseudo-terminal-file-system
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%tty-gid
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%immutable-store
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%control-groups
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%elogind-file-systems
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%base-file-systems
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%container-file-systems
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<file-system-mapping>
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file-system-mapping
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file-system-mapping?
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file-system-mapping-source
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file-system-mapping-target
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file-system-mapping-writable?
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file-system-mapping->bind-mount
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%store-mapping
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%network-configuration-files
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%network-file-mappings))
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;;; Commentary:
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;;;
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;;; Declaring file systems to be mounted.
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;;;
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;;; Note: this file system is used both in the Shepherd and on the "host
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;;; side", so it must not include (gnu packages …) modules.
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;;;
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;;; Code:
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;; File system declaration.
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(define-record-type* <file-system> file-system
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make-file-system
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file-system?
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(device file-system-device) ; string
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(title file-system-title ; 'device | 'label | 'uuid
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(default 'device))
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(mount-point file-system-mount-point) ; string
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(type file-system-type) ; string
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(flags file-system-flags ; list of symbols
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(default '()))
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(options file-system-options ; string or #f
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(default #f))
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(mount? file-system-mount? ; Boolean
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(default #t))
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(needed-for-boot? %file-system-needed-for-boot? ; Boolean
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(default #f))
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(check? file-system-check? ; Boolean
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(default #t))
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(create-mount-point? file-system-create-mount-point? ; Boolean
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(default #f))
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(dependencies file-system-dependencies ; list of <file-system>
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(default '()))) ; or <mapped-device>
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;; Note: This module is used both on the build side and on the host side.
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;; Arrange not to pull (guix store) and (guix config) because the latter
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;; differs from user to user.
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(define (%store-prefix)
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"Return the store prefix."
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(cond ((resolve-module '(guix store) #:ensure #f)
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=>
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(lambda (store)
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((module-ref store '%store-prefix))))
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((getenv "NIX_STORE")
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=> identity)
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(else
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"/gnu/store")))
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(define %not-slash
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(char-set-complement (char-set #\/)))
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(define (file-prefix? file1 file2)
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"Return #t if FILE1 denotes the name of a file that is a parent of FILE2,
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where both FILE1 and FILE2 are absolute file name. For example:
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(file-prefix? \"/gnu\" \"/gnu/store\")
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=> #t
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(file-prefix? \"/gn\" \"/gnu/store\")
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=> #f
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"
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(and (string-prefix? "/" file1)
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(string-prefix? "/" file2)
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(let loop ((file1 (string-tokenize file1 %not-slash))
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(file2 (string-tokenize file2 %not-slash)))
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(match file1
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(()
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#t)
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((head1 tail1 ...)
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(match file2
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((head2 tail2 ...)
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(and (string=? head1 head2) (loop tail1 tail2)))
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(()
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#f)))))))
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(define (file-system-needed-for-boot? fs)
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"Return true if FS has the 'needed-for-boot?' flag set, or if it holds the
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store--e.g., if FS is the root file system."
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(or (%file-system-needed-for-boot? fs)
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(and (file-prefix? (file-system-mount-point fs) (%store-prefix))
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(not (memq 'bind-mount (file-system-flags fs))))))
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(define (file-system->spec fs)
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"Return a list corresponding to file-system FS that can be passed to the
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initrd code."
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(match fs
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(($ <file-system> device title mount-point type flags options _ _ check?)
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(list device title mount-point type flags options check?))))
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(define (spec->file-system sexp)
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"Deserialize SEXP, a list, to the corresponding <file-system> object."
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(match sexp
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((device title mount-point type flags options check?)
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(file-system
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(device device) (title title)
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(mount-point mount-point) (type type)
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(flags flags) (options options)
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(check? check?)))))
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(define (specification->file-system-mapping spec writable?)
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"Read the SPEC and return the corresponding <file-system-mapping>. SPEC is
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a string of the form \"SOURCE\" or \"SOURCE=TARGET\". The former specifies
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that SOURCE from the host should be mounted at SOURCE in the other system.
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The latter format specifies that SOURCE from the host should be mounted at
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TARGET in the other system."
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(let ((index (string-index spec #\=)))
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(if index
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(file-system-mapping
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(source (substring spec 0 index))
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(target (substring spec (+ 1 index)))
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(writable? writable?))
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(file-system-mapping
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(source spec)
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(target spec)
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(writable? writable?)))))
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(define-syntax uuid
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(lambda (s)
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"Return the bytevector corresponding to the given UUID representation."
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(syntax-case s ()
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((_ str)
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(string? (syntax->datum #'str))
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;; A literal string: do the conversion at expansion time.
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(let ((bv (string->uuid (syntax->datum #'str))))
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(unless bv
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(syntax-violation 'uuid "invalid UUID" s))
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(datum->syntax #'str bv)))
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((_ str)
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#'(string->uuid str)))))
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;;;
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;;; Common file systems.
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;;;
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(define %fuse-control-file-system
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;; Control file system for Linux' file systems in user-space (FUSE).
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(file-system
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(device "fusectl")
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(mount-point "/sys/fs/fuse/connections")
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(type "fusectl")
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(check? #f)))
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(define %binary-format-file-system
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;; Support for arbitrary executable binary format.
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(file-system
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(device "binfmt_misc")
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(mount-point "/proc/sys/fs/binfmt_misc")
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(type "binfmt_misc")
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(check? #f)))
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(define %tty-gid
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;; ID of the 'tty' group. Allocate it statically to make it easy to refer
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;; to it from here and from the 'tty' group definitions.
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996)
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(define %pseudo-terminal-file-system
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;; The pseudo-terminal file system. It needs to be mounted so that
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;; statfs(2) returns DEVPTS_SUPER_MAGIC like libc's getpt(3) expects (and
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;; thus openpty(3) and its users, such as xterm.)
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(file-system
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(device "none")
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(mount-point "/dev/pts")
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(type "devpts")
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(check? #f)
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(needed-for-boot? #f)
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(create-mount-point? #t)
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(options (string-append "gid=" (number->string %tty-gid) ",mode=620"))))
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(define %shared-memory-file-system
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;; Shared memory.
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(file-system
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(device "tmpfs")
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(mount-point "/dev/shm")
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(type "tmpfs")
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(check? #f)
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(flags '(no-suid no-dev))
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(options "size=50%") ;TODO: make size configurable
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(create-mount-point? #t)))
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(define %immutable-store
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;; Read-only store to avoid users or daemons accidentally modifying it.
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;; 'guix-daemon' has provisions to remount it read-write in its own name
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;; space.
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(file-system
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(device (%store-prefix))
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(mount-point (%store-prefix))
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(type "none")
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(check? #f)
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(flags '(read-only bind-mount))))
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(define %control-groups
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(let ((parent (file-system
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(device "cgroup")
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(mount-point "/sys/fs/cgroup")
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(type "tmpfs")
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(check? #f))))
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(cons parent
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(map (lambda (subsystem)
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(file-system
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(device "cgroup")
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(mount-point (string-append "/sys/fs/cgroup/" subsystem))
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(type "cgroup")
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(check? #f)
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(options subsystem)
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(create-mount-point? #t)
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;; This must be mounted after, and unmounted before the
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;; parent directory.
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(dependencies (list parent))))
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'("cpuset" "cpu" "cpuacct" "memory" "devices" "freezer"
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"blkio" "perf_event" "hugetlb")))))
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(define %elogind-file-systems
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;; We don't use systemd, but these file systems are needed for elogind,
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;; which was extracted from systemd.
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(list (file-system
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(device "none")
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(mount-point "/run/systemd")
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(type "tmpfs")
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(check? #f)
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(flags '(no-suid no-dev no-exec))
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(options "mode=0755")
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(create-mount-point? #t))
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(file-system
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(device "none")
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(mount-point "/run/user")
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(type "tmpfs")
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(check? #f)
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(flags '(no-suid no-dev no-exec))
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(options "mode=0755")
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(create-mount-point? #t))
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;; Elogind uses cgroups to organize processes, allowing it to map PIDs
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;; to sessions. Elogind's cgroup hierarchy isn't associated with any
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;; resource controller ("subsystem").
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(file-system
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(device "cgroup")
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(mount-point "/sys/fs/cgroup/elogind")
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(type "cgroup")
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(check? #f)
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(options "none,name=elogind")
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(create-mount-point? #t)
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(dependencies (list (car %control-groups))))))
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(define %base-file-systems
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;; List of basic file systems to be mounted. Note that /proc and /sys are
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;; currently mounted by the initrd.
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(append (list %pseudo-terminal-file-system
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%shared-memory-file-system
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%immutable-store)
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%control-groups))
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;; File systems for Linux containers differ from %base-file-systems in that
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;; they impose additional restrictions such as no-exec or need different
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;; options to function properly.
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;;
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;; The file system flags and options conform to the libcontainer
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;; specification:
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;; https://github.com/docker/libcontainer/blob/master/SPEC.md#filesystem
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(define %container-file-systems
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(list
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;; Pseudo-terminal file system.
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(file-system
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(device "none")
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(mount-point "/dev/pts")
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(type "devpts")
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(flags '(no-exec no-suid))
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(needed-for-boot? #t)
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(create-mount-point? #t)
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(check? #f)
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(options "newinstance,ptmxmode=0666,mode=620"))
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;; Shared memory file system.
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(file-system
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(device "tmpfs")
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(mount-point "/dev/shm")
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(type "tmpfs")
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(flags '(no-exec no-suid no-dev))
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(options "mode=1777,size=65536k")
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(needed-for-boot? #t)
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(create-mount-point? #t)
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(check? #f))
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;; Message queue file system.
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(file-system
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(device "mqueue")
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(mount-point "/dev/mqueue")
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(type "mqueue")
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(flags '(no-exec no-suid no-dev))
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(needed-for-boot? #t)
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(create-mount-point? #t)
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(check? #f))))
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;;;
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;;; Shared file systems, for VMs/containers.
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;;;
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;; Mapping of host file system SOURCE to mount point TARGET in the guest.
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(define-record-type* <file-system-mapping> file-system-mapping
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make-file-system-mapping
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file-system-mapping?
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(source file-system-mapping-source) ;string
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(target file-system-mapping-target) ;string
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(writable? file-system-mapping-writable? ;Boolean
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(default #f)))
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(define (file-system-mapping->bind-mount mapping)
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"Return a file system that realizes MAPPING, a <file-system-mapping>, using
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a bind mount."
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(match mapping
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(($ <file-system-mapping> source target writable?)
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(file-system
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(mount-point target)
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(device source)
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(type "none")
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(flags (if writable?
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'(bind-mount)
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'(bind-mount read-only)))
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(check? #f)
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(create-mount-point? #t)))))
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(define %store-mapping
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;; Mapping of the host's store into the guest.
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(file-system-mapping
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(source (%store-prefix))
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(target (%store-prefix))
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(writable? #f)))
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(define %network-configuration-files
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;; List of essential network configuration files.
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'("/etc/resolv.conf"
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"/etc/nsswitch.conf"
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"/etc/services"
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"/etc/hosts"))
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(define %network-file-mappings
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;; List of file mappings for essential network files.
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(filter-map (lambda (file)
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(file-system-mapping
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(source file)
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(target file)
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;; XXX: On some GNU/Linux systems, /etc/resolv.conf is a
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;; symlink to a file in a tmpfs which, for an unknown reason,
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;; cannot be bind mounted read-only within the container.
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(writable? (string=? file "/etc/resolv.conf"))))
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%network-configuration-files))
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(define (file-system-type-predicate type)
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"Return a predicate that, when passed a file system, returns #t if that file
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system has the given TYPE."
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(lambda (fs)
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(string=? (file-system-type fs) type)))
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;;; file-systems.scm ends here
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