322 lines
		
	
	
	
		
			11 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
			
		
		
	
	
			322 lines
		
	
	
	
		
			11 KiB
		
	
	
	
		
			Scheme
		
	
	
	
	
	
;;; GNU Guix --- Functional package management for GNU
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;;; Copyright © 2013, 2014, 2015, 2016 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 (guix records)
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  #:use-module (guix store)
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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->spec
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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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            %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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            %store-mapping))
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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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;;; 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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(define-inlinable (file-system-needed-for-boot? fs)
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  "Return true if FS has the 'needed-for-boot?' flag set, or if it's the root
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file system."
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  (or (%file-system-needed-for-boot? fs)
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      (string=? "/" (file-system-mount-point 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 (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 %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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;;; file-systems.scm ends here
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