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#!/bin/sh
# Print a version string.
scriptversion=2017-01-09.19; # UTC

# Copyright (C) 2007-2017 Free Software Foundation, Inc.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# This script is derived from GIT-VERSION-GEN from GIT: http://git.or.cz/.
# It may be run two ways:
# - from a git repository in which the "git describe" command below
#   produces useful output (thus requiring at least one signed tag)
# - from a non-git-repo directory containing a .tarball-version file, which
#   presumes this script is invoked like "./git-version-gen .tarball-version".

# In order to use intra-version strings in your project, you will need two
# separate generated version string files:
#
# .tarball-version - present only in a distribution tarball, and not in
#   a checked-out repository.  Created with contents that were learned at
#   the last time autoconf was run, and used by git-version-gen.  Must not
#   be present in either $(srcdir) or $(builddir) for git-version-gen to
#   give accurate answers during normal development with a checked out tree,
#   but must be present in a tarball when there is no version control system.
#   Therefore, it cannot be used in any dependencies.  GNUmakefile has
#   hooks to force a reconfigure at distribution time to get the value
#   correct, without penalizing normal development with extra reconfigures.
#
# .version - present in a checked-out repository and in a distribution
#   tarball.  Usable in dependencies, particularly for files that don't
#   want to depend on config.h but do want to track version changes.
#   Delete this file prior to any autoconf run where you want to rebuild
#   files to pick up a version string change; and leave it stale to
#   minimize rebuild time after unrelated changes to configure sources.
#
# As with any generated file in a VC'd directory, you should add
# /.version to .gitignore, so that you don't accidentally commit it.
# .tarball-version is never generated in a VC'd directory, so needn't
# be listed there.
#
# Use the following line in your configure.ac, so that $(VERSION) will
# automatically be up-to-date each time configure is run (and note that
# since configure.ac no longer includes a version string, Makefile rules
# should not depend on configure.ac for version updates).
#
# AC_INIT([GNU project],
#         m4_esyscmd([build-aux/git-version-gen .tarball-version]),
#         [bug-project@example])
#
# Then use the following lines in your Makefile.am, so that .version
# will be present for dependencies, and so that .version and
# .tarball-version will exist in distribution tarballs.
#
# EXTRA_DIST = $(top_srcdir)/.version
# BUILT_SOURCES = $(top_srcdir)/.version
# $(top_srcdir)/.version:
#	echo $(VERSION) > $@-t && mv $@-t $@
# dist-hook:
#	echo $(VERSION) > $(distdir)/.tarball-version


me=$0

version="git-version-gen $scriptversion

Copyright 2011 Free Software Foundation, Inc.
There is NO warranty.  You may redistribute this software
under the terms of the GNU General Public License.
For more information about these matters, see the files named COPYING."

usage="\
Usage: $me [OPTION]... \$srcdir/.tarball-version [TAG-NORMALIZATION-SED-SCRIPT]
Print a version string.

Options:

   --prefix PREFIX    prefix of git tags (default 'v')
   --fallback VERSION
                      fallback version to use if \"git --version\" fails

   --help             display this help and exit
   --version          output version information and exit

Running without arguments will suffice in most cases."

prefix=v
fallback=

while test $# -gt 0; do
  case $1 in
    --help) echo "$usage"; exit 0;;
    --version) echo "$version"; exit 0;;
    --prefix) shift; prefix=${1?};;
    --fallback) shift; fallback=${1?};;
    -*)
      echo "$0: Unknown option '$1'." >&2
      echo "$0: Try '--help' for more information." >&2
      exit 1;;
    *)
      if test "x$tarball_version_file" = x; then
        tarball_version_file="$1"
      elif test "x$tag_sed_script" = x; then
        tag_sed_script="$1"
      else
        echo "$0: extra non-option argument '$1'." >&2
        exit 1
      fi;;
  esac
  shift
done

if test "x$tarball_version_file" = x; then
    echo "$usage"
    exit 1
fi

tag_sed_script="${tag_sed_script:-s/x/x/}"

nl='
'

# Avoid meddling by environment variable of the same name.
v=
v_from_git=

# First see if there is a tarball-only version file.
# then try "git describe", then default.
if test -f $tarball_version_file
then
    v=`cat $tarball_version_file` || v=
    case $v in
        *$nl*) v= ;; # reject multi-line output
        [0-9]*) ;;
        *) v= ;;
    esac
    test "x$v" = x \
        && echo "$0: WARNING: $tarball_version_file is missing or damaged" 1>&2
fi

if test "x$v" != x
then
    : # use $v
# Otherwise, if there is at least one git commit involving the working
# directory, and "git describe" output looks sensible, use that to
# derive a version string.
elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
          || git describe --abbrev=4 HEAD 2>/dev/null` \
    && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
    && case $v in
         $prefix[0-9]*) ;;
         *) (exit 1) ;;
       esac
then
    # Is this a new git that lists number of commits since the last
    # tag or the previous older version that did not?
    #   Newer: v6.10-77-g0f8faeb
    #   Older: v6.10-g0f8faeb
    case $v in
        *-*-*) : git describe is okay three part flavor ;;
        *-*)
            : git describe is older two part flavor
            # Recreate the number of commits and rewrite such that the
            # result is the same as if we were using the newer version
            # of git describe.
            vtag=`echo "$v" | sed 's/-.*//'`
            commit_list=`git rev-list "$vtag"..HEAD 2>/dev/null` \
                || { commit_list=failed;
                     echo "$0: WARNING: git rev-list failed" 1>&2; }
            numcommits=`echo "$commit_list" | wc -l`
            v=`echo "$v" | sed "s/\(.*\)-\(.*\)/\1-$numcommits-\2/"`;
            test "$commit_list" = failed && v=UNKNOWN
            ;;
    esac

    # Change the first '-' to a '.', so version-comparing tools work properly.
    # Remove the "g" in git describe's output string, to save a byte.
    v=`echo "$v" | sed 's/-/./;s/\(.*\)-g/\1-/'`;
    v_from_git=1
elif test "x$fallback" = x || git --version >/dev/null 2>&1; then
    v=UNKNOWN
else
    v=$fallback
fi

v=`echo "$v" |sed "s/^$prefix//"`

# Test whether to append the "-dirty" suffix only if the version
# string we're using came from git.  I.e., skip the test if it's "UNKNOWN"
# or if it came from .tarball-version.
if test "x$v_from_git" != x; then
  # Don't declare a version "dirty" merely because a timestamp has changed.
  git update-index --refresh > /dev/null 2>&1

  dirty=`exec 2>/dev/null;git diff-index --name-only HEAD` || dirty=
  case "$dirty" in
      '') ;;
      *) # Append the suffix only if there isn't one already.
          case $v in
            *-dirty) ;;
            *) v="$v-dirty" ;;
          esac ;;
  esac
fi

# Omit the trailing newline, so that m4_esyscmd can use the result directly.
printf %s "$v"

# Local variables:
# eval: (add-hook 'write-file-hooks 'time-stamp)
# time-stamp-start: "scriptversion="
# time-stamp-format: "%:y-%02m-%02d.%02H"
# time-stamp-time-zone: "UTC0"
# time-stamp-end: "; # UTC"
# End:
>253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013-2022 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2020 Google LLC
;;; Copyright © 2020 Jakub Kądziołka <kuba@kadziolka.net>
;;; Copyright © 2020, 2021 Maxim Cournoyer <maxim.cournoyer@gmail.com>
;;; Copyright © 2021 Tobias Geerinckx-Rice <me@tobias.gr>
;;; Copyright © 2022 Oleg Pykhalov <go.wigust@gmail.com>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

(define-module (gnu system file-systems)
  #:use-module (ice-9 match)
  #:use-module (rnrs bytevectors)
  #:use-module (srfi srfi-1)
  #:use-module (srfi srfi-2)
  #:use-module (srfi srfi-9)
  #:use-module (srfi srfi-26)
  #:use-module (srfi srfi-35)
  #:use-module (srfi srfi-9 gnu)
  #:use-module (guix records)
  #:use-module ((guix diagnostics)
                #:select (source-properties->location leave &fix-hint))
  #:use-module (guix i18n)
  #:use-module (gnu system uuid)
  #:re-export (uuid                               ;backward compatibility
               string->uuid
               uuid->string)
  #:export (file-system
            file-system?
            file-system-device
            file-system-device->string
            file-system-mount-point
            file-system-type
            file-system-needed-for-boot?
            file-system-flags
            file-system-options
            file-system-options->alist
            alist->file-system-options

            file-system-mount?
            file-system-mount-may-fail?
            file-system-check?
            file-system-skip-check-if-clean?
            file-system-repair
            file-system-create-mount-point?
            file-system-dependencies
            file-system-shepherd-requirements
            file-system-location

            file-system-type-predicate
            file-system-mount-point-predicate
            btrfs-subvolume?
            btrfs-store-subvolume-file-name

            file-system-label
            file-system-label?
            file-system-label->string

            file-system->spec
            spec->file-system
            specification->file-system-mapping

            %pseudo-file-system-types
            %fuse-control-file-system
            %binary-format-file-system
            %debug-file-system
            %efivars-file-system
            %shared-memory-file-system
            %pseudo-terminal-file-system
            %tty-gid
            %immutable-store
            %control-groups
            %elogind-file-systems

            %base-file-systems
            %base-live-file-systems
            %container-file-systems

            <file-system-mapping>
            file-system-mapping
            file-system-mapping?
            file-system-mapping-source
            file-system-mapping-target
            file-system-mapping-writable?

            file-system-mapping->bind-mount

            %store-mapping
            %network-configuration-files
            %network-file-mappings

            swap-space
            swap-space?
            swap-space-target
            swap-space-dependencies
            swap-space-priority
            swap-space-discard?))

;;; Commentary:
;;;
;;; Declaring file systems to be mounted.
;;;
;;; Note: this file system is used both in the Shepherd and on the "host
;;; side", so it must not include (gnu packages …) modules.
;;;
;;; Code:

(eval-when (expand load eval)
  (define invalid-file-system-flags
    ;; Note: Keep in sync with 'mount-flags->bit-mask'.
    (let ((known-flags '(read-only
                         bind-mount no-suid no-dev no-exec
                         no-atime no-diratime strict-atime lazy-time
                         shared)))
      (lambda (flags)
        "Return the subset of FLAGS that is invalid."
        (remove (cut memq <> known-flags) flags))))

  (define (%validate-file-system-flags flags location)
    "Raise an error if FLAGS contains invalid mount flags; otherwise return
FLAGS."
    (match (invalid-file-system-flags flags)
      (() flags)
      (invalid
       (leave (source-properties->location location)
              (N_ "invalid file system mount flag:~{ ~s~}~%"
                  "invalid file system mount flags:~{ ~s~}~%"
                  (length invalid))
              invalid)))))

(define-syntax validate-file-system-flags
  (lambda (s)
    "Validate the given file system mount flags, raising an error if invalid
flags are found."
    (syntax-case s (quote)
      ((_ (quote (symbols ...)))                  ;validate at expansion time
       (begin
         (%validate-file-system-flags (syntax->datum #'(symbols ...))
                                      (syntax-source s))
         #'(quote (symbols ...))))
      ((_ flags)
       #`(%validate-file-system-flags flags
                                      '#,(datum->syntax s (syntax-source s))))
      (id
       (identifier? #'id)
       #'%validate-file-system-flags))))

;; File system declaration.
(define-record-type* <file-system> file-system
  make-file-system
  file-system?
  (device                file-system-device)               ; string | <uuid> | <file-system-label>
  (mount-point           file-system-mount-point)          ; string
  (type                  file-system-type)                 ; string
  (flags                 file-system-flags                 ; list of symbols
                         (default '())
                         (sanitize validate-file-system-flags))
  (options               file-system-options               ; string or #f
                         (default #f))
  (mount?                file-system-mount?                ; Boolean
                         (default #t))
  (mount-may-fail?       file-system-mount-may-fail?       ; Boolean
                         (default #f))
  (needed-for-boot?      %file-system-needed-for-boot?     ; Boolean
                         (default #f))
  (check?                file-system-check?                ; Boolean
                         (default #t))
  (skip-check-if-clean?  file-system-skip-check-if-clean?  ; Boolean
                         (default #t))
  (repair                file-system-repair                ; symbol or #f
                         (default 'preen))
  (create-mount-point?   file-system-create-mount-point?   ; Boolean
                         (default #f))
  (dependencies          file-system-dependencies          ; list of <file-system>
                         (default '()))                    ; or <mapped-device>
  (shepherd-requirements file-system-shepherd-requirements ; list of symbols
                         (default '()))
  (location              file-system-location
                         (default (current-source-location))
                         (innate)))

;; A file system label for use in the 'device' field.
(define-record-type <file-system-label>
  (file-system-label label)
  file-system-label?
  (label file-system-label->string))

(set-record-type-printer! <file-system-label>
                          (lambda (obj port)
                            (format port "#<file-system-label ~s>"
                                    (file-system-label->string obj))))

;; Note: This module is used both on the build side and on the host side.
;; Arrange not to pull (guix store) and (guix config) because the latter
;; differs from user to user.
(define (%store-prefix)
  "Return the store prefix."
  ;; Note: If we have (guix store database) in the search path and we do *not*
  ;; have (guix store) proper, 'resolve-module' returns an empty (guix store)
  ;; with one sub-module.
  (cond ((and=> (parameterize ((current-warning-port (%make-void-port "w0")))
                  (resolve-module '(guix store) #:ensure #f))
                (lambda (store)
                  (module-variable store '%store-prefix)))
         =>
         (lambda (variable)
           ((variable-ref variable))))
        ((getenv "NIX_STORE")
         => identity)
        (else
         "/gnu/store")))

(define %not-slash
  (char-set-complement (char-set #\/)))

(define (file-prefix? file1 file2)
  "Return #t if FILE1 denotes the name of a file that is a parent of FILE2.
FILE1 and FILE2 must both be either absolute or relative file names, else #f
is returned.

For example:

  (file-prefix? \"/gnu\" \"/gnu/store\")
  => #t

  (file-prefix? \"/gn\" \"/gnu/store\")
  => #f
"
  (define (absolute? file)
    (string-prefix? "/" file))

  (if (or (every absolute? (list file1 file2))
          (every (negate absolute?) (list file1 file2)))
      (let loop ((file1 (string-tokenize file1 %not-slash))
                 (file2 (string-tokenize file2 %not-slash)))
        (match file1
          (()
           #t)
          ((head1 tail1 ...)
           (match file2
             ((head2 tail2 ...)
              (and (string=? head1 head2) (loop tail1 tail2)))
             (()
              #f)))))
      ;; FILE1 and FILE2 are a mix of absolute and relative file names.
      #f))

(define (file-name-depth file-name)
  (length (string-tokenize file-name %not-slash)))

(define* (file-system-device->string device #:key uuid-type)
  "Return the string representations of the DEVICE field of a <file-system>
record.  When the device is a UUID, its representation is chosen depending on
UUID-TYPE, a symbol such as 'dce or 'iso9660."
  (match device
    ((? file-system-label?)
     (file-system-label->string device))
    ((? uuid?)
     (if uuid-type
         (uuid->string (uuid-bytevector device) uuid-type)
         (uuid->string device)))
    ((? string?)
     device)))

(define (file-system-options->alist string)
  "Translate the option string format of a <file-system> record into an
association list of options or option/value pairs."
  (if string
      (let ((options (string-split string #\,)))
        (map (lambda (param)
               (let ((=index (string-index param #\=)))
                 (if =index
                     (cons (string-take param =index)
                           (string-drop param (1+ =index)))
                     param)))
             options))
      '()))

(define (alist->file-system-options options)
  "Return the string representation of OPTIONS, an association list.  The
string obtained can be used as the option field of a <file-system> record."
  (if (null? options)
      #f
      (string-join (map (match-lambda
                          ((key . value)
                           (string-append key "=" value))
                          (key
                           key))
                        options)
                   ",")))

(define (file-system-needed-for-boot? fs)
  "Return true if FS has the 'needed-for-boot?' flag set, or if it holds the
store--e.g., if FS is the root file system."
  (or (%file-system-needed-for-boot? fs)
      (and (file-prefix? (file-system-mount-point fs) (%store-prefix))
           (not (memq 'bind-mount (file-system-flags fs))))))

(define (file-system->spec fs)
  "Return a list corresponding to file-system FS that can be passed to the
initrd code."
  (match fs
    (($ <file-system> device mount-point type flags options mount?
                      mount-may-fail? needed-for-boot?
                      check? skip-check-if-clean? repair)
     ;; Note: Add new fields towards the end for compatibility.
     (list (cond ((uuid? device)
                  `(uuid ,(uuid-type device) ,(uuid-bytevector device)))
                 ((file-system-label? device)
                  `(file-system-label ,(file-system-label->string device)))
                 (else device))
           mount-point type flags options mount-may-fail?
           check? skip-check-if-clean? repair))))

(define (spec->file-system sexp)
  "Deserialize SEXP, a list, to the corresponding <file-system> object."
  (match sexp
    ((device mount-point type flags options mount-may-fail?
             check? skip-check-if-clean? repair
             _ ...)                               ;placeholder for new fields
     (file-system
       (device (match device
                 (('uuid (? symbol? type) (? bytevector? bv))
                  (bytevector->uuid bv type))
                 (('file-system-label (? string? label))
                  (file-system-label label))
                 (_
                  device)))
       (mount-point mount-point) (type type)
       (flags flags) (options options)
       (mount-may-fail? mount-may-fail?)
       (check? check?)
       (skip-check-if-clean? skip-check-if-clean?)
       (repair repair)))))

(define (specification->file-system-mapping spec writable?)
  "Read the SPEC and return the corresponding <file-system-mapping>.  SPEC is
a string of the form \"SOURCE\" or \"SOURCE=TARGET\".  The former specifies
that SOURCE from the host should be mounted at SOURCE in the other system.
The latter format specifies that SOURCE from the host should be mounted at
TARGET in the other system."
  (let ((index (string-index spec #\=)))
    (if index
        (file-system-mapping
         (source (substring spec 0 index))
         (target (substring spec (+ 1 index)))
         (writable? writable?))
        (file-system-mapping
         (source spec)
         (target spec)
         (writable? writable?)))))


;;;
;;; Common file systems.
;;;

(define %pseudo-file-system-types
  ;; List of know pseudo file system types.  This is used when validating file
  ;; system definitions.
  '("binfmt_misc" "cgroup" "cgroup2" "debugfs" "devpts" "devtmpfs" "efivarfs" "fusectl"
    "hugetlbfs" "overlay" "proc" "securityfs" "sysfs" "tmpfs" "tracefs" "virtiofs" "xenfs"))

(define %fuse-control-file-system
  ;; Control file system for Linux' file systems in user-space (FUSE).
  (file-system
    (device "fusectl")
    (mount-point "/sys/fs/fuse/connections")
    (type "fusectl")
    (check? #f)))

(define %binary-format-file-system
  ;; Support for arbitrary executable binary format.
  (file-system
    (device "binfmt_misc")
    (mount-point "/proc/sys/fs/binfmt_misc")
    (type "binfmt_misc")
    (check? #f)))

(define %debug-file-system
  (file-system
    (type "debugfs")
    (device "none")
    (mount-point "/sys/kernel/debug")
    (check? #f)
    (create-mount-point? #t)))

(define %efivars-file-system
  ;; Support for EFI variables file system.
  (file-system
    (device "efivarfs")
    (mount-point "/sys/firmware/efi/efivars")
    (type "efivarfs")
    (mount-may-fail? #t)
    (needed-for-boot? #f)
    (check? #f)))

(define %tty-gid
  ;; ID of the 'tty' group.  Allocate it statically to make it easy to refer
  ;; to it from here and from the 'tty' group definitions.
  996)

(define %pseudo-terminal-file-system
  ;; The pseudo-terminal file system.  It needs to be mounted so that
  ;; statfs(2) returns DEVPTS_SUPER_MAGIC like libc's getpt(3) expects (and
  ;; thus openpty(3) and its users, such as xterm.)
  (file-system
    (device "none")
    (mount-point "/dev/pts")
    (type "devpts")
    (check? #f)
    (needed-for-boot? #f)
    (create-mount-point? #t)
    (options (string-append "gid=" (number->string %tty-gid) ",mode=620"))))

(define %shared-memory-file-system
  ;; Shared memory.
  (file-system
    (device "tmpfs")
    (mount-point "/dev/shm")
    (type "tmpfs")
    (check? #f)
    (flags '(no-suid no-dev))
    (options "size=50%")                         ;TODO: make size configurable
    (create-mount-point? #t)))

(define %immutable-store
  ;; Read-only store to avoid users or daemons accidentally modifying it.
  ;; 'guix-daemon' has provisions to remount it read-write in its own name
  ;; space.
  (file-system
    (device (%store-prefix))
    (mount-point (%store-prefix))
    (type "none")
    (check? #f)
    (flags '(read-only bind-mount no-atime))))

(define %control-groups
  ;; The cgroup2 file system.
  (list (file-system
          (device "none")
	  (mount-point "/sys/fs/cgroup")
	  (type "cgroup2")
	  (check? #f)
	  (create-mount-point? #f))))

(define %elogind-file-systems
  ;; We don't use systemd, but these file systems are needed for elogind,
  ;; which was extracted from systemd.
  (append
   (list (file-system
           (device "none")
           (mount-point "/run/systemd")
           (type "tmpfs")
           (check? #f)
           (flags '(no-suid no-dev no-exec))
           (options "mode=0755")
           (create-mount-point? #t))
         (file-system
           (device "none")
           (mount-point "/run/user")
           (type "tmpfs")
           (check? #f)
           (flags '(no-suid no-dev no-exec))
           (options "mode=0755")
           (create-mount-point? #t))
         ;; Elogind uses cgroups to organize processes, allowing it to map PIDs
         ;; to sessions.  Elogind's cgroup hierarchy isn't associated with any
         ;; resource controller ("subsystem").
         (file-system
           (device "cgroup")
           (mount-point "/sys/fs/cgroup/elogind")
           (type "cgroup")
           (check? #f)
           (options "none,name=elogind")
           (create-mount-point? #t)
           (dependencies (list (car %control-groups)))))
   %control-groups))

(define %base-file-systems
  ;; List of basic file systems to be mounted.  Note that /proc and /sys are
  ;; currently mounted by the initrd.
  (list %pseudo-terminal-file-system
        %debug-file-system
        %shared-memory-file-system
        %efivars-file-system
        %immutable-store))

(define %base-live-file-systems
  ;; This is the bare minimum to use live file-systems.
  ;; Used in installation-os.
  (list (file-system
          (mount-point "/")
          (device (file-system-label "Guix_image"))
          (type "ext4"))

        ;; Make /tmp a tmpfs instead of keeping the overlayfs.  This
        ;; originally was used for unionfs because FUSE creates
        ;; '.fuse_hiddenXYZ' files for each open file, and this confuses
        ;; Guix's test suite, for instance (see
        ;; <http://bugs.gnu.org/23056>).  We keep this for overlayfs to be
        ;; on the safe side.
        (file-system
          (mount-point "/tmp")
          (device "none")
          (type "tmpfs")
          (check? #f))))

;; File systems for Linux containers differ from %base-file-systems in that
;; they impose additional restrictions such as no-exec or need different
;; options to function properly.
;;
;; The file system flags and options conform to the libcontainer
;; specification:
;; https://github.com/docker/libcontainer/blob/master/SPEC.md#filesystem
(define %container-file-systems
  (list
   ;; Pseudo-terminal file system.
   (file-system
     (device "none")
     (mount-point "/dev/pts")
     (type "devpts")
     (flags '(no-exec no-suid))
     (needed-for-boot? #t)
     (create-mount-point? #t)
     (check? #f)
     (options "newinstance,ptmxmode=0666,mode=620"))
   ;; Shared memory file system.
   (file-system
     (device "tmpfs")
     (mount-point "/dev/shm")
     (type "tmpfs")
     (flags '(no-exec no-suid no-dev))
     (options "mode=1777,size=65536k")
     (needed-for-boot? #t)
     (create-mount-point? #t)
     (check? #f))
   ;; Message queue file system.
   (file-system
     (device "mqueue")
     (mount-point "/dev/mqueue")
     (type "mqueue")
     (flags '(no-exec no-suid no-dev))
     (needed-for-boot? #t)
     (create-mount-point? #t)
     (check? #f))))


;;;
;;; Shared file systems, for VMs/containers.
;;;

;; Mapping of host file system SOURCE to mount point TARGET in the guest.
(define-record-type* <file-system-mapping> file-system-mapping
  make-file-system-mapping
  file-system-mapping?
  (source    file-system-mapping-source)          ;string
  (target    file-system-mapping-target)          ;string
  (writable? file-system-mapping-writable?        ;Boolean
             (default #f)))

(define (file-system-mapping->bind-mount mapping)
  "Return a file system that realizes MAPPING, a <file-system-mapping>, using
a bind mount."
  (match mapping
    (($ <file-system-mapping> source target writable?)
     (file-system
       (mount-point target)
       (device source)
       (type "none")
       (flags (if writable?
                  '(bind-mount)
                  '(bind-mount read-only)))
       (check? #f)
       (create-mount-point? #t)))))

(define %store-mapping
  ;; Mapping of the host's store into the guest.
  (file-system-mapping
   (source (%store-prefix))
   (target (%store-prefix))
   (writable? #f)))

(define %network-configuration-files
  ;; List of essential network configuration files.
  '("/etc/resolv.conf"
    "/etc/nsswitch.conf"
    "/etc/services"
    "/etc/hosts"))

(define %network-file-mappings
  ;; List of file mappings for essential network files.
  (filter-map (lambda (file)
                (file-system-mapping
                 (source file)
                 (target file)
                 ;; XXX: On some GNU/Linux systems, /etc/resolv.conf is a
                 ;; symlink to a file in a tmpfs which, for an unknown reason,
                 ;; cannot be bind mounted read-only within the container.
                 (writable? (string=? file "/etc/resolv.conf"))))
              %network-configuration-files))

(define (file-system-type-predicate type)
  "Return a predicate that, when passed a file system, returns #t if that file
system has the given TYPE."
  (lambda (fs)
    (string=? (file-system-type fs) type)))

(define (file-system-mount-point-predicate mount-point)
  "Return a predicate that, when passed a file system, returns #t if that file
system has the given MOUNT-POINT."
  (lambda (fs)
    (string=? (file-system-mount-point fs) mount-point)))


;;;
;;; Btrfs specific helpers.
;;;

(define (btrfs-subvolume? fs)
  "Predicate to check if FS, a file-system object, is a Btrfs subvolume."
  (and-let* ((btrfs-file-system? (string= "btrfs" (file-system-type fs)))
             (option-keys (map (match-lambda
                                 ((key . value) key)
                                 (key key))
                               (file-system-options->alist
                                (file-system-options fs)))))
    (find (cut string-prefix? "subvol" <>) option-keys)))

(define (btrfs-store-subvolume-file-name file-systems)
  "Return the subvolume file name within the Btrfs top level onto which the
store is located, else #f."

  (define (prepend-slash/maybe s)
    (if (string=? "/" (string-take s 1))
        s
        (string-append "/" s)))

  (and-let* ((btrfs-subvolume-fs (filter btrfs-subvolume? file-systems))
             (btrfs-subvolume-fs*
              (sort btrfs-subvolume-fs
                    (lambda (fs1 fs2)
                      (> (file-name-depth (file-system-mount-point fs1))
                         (file-name-depth (file-system-mount-point fs2))))))
             (store-subvolume-fs
              (find (lambda (fs) (file-prefix? (file-system-mount-point fs)
                                               (%store-prefix)))
                    btrfs-subvolume-fs*))
             (options (file-system-options->alist
                       (file-system-options store-subvolume-fs))))
    ;; XXX: Deriving the subvolume name based from a subvolume ID is not
    ;; supported, as we'd need to query the actual file system.
    (or (and=> (assoc-ref options "subvol") prepend-slash/maybe)
        (raise (condition
                (&message
                 (message "The store is on a Btrfs subvolume, but the \
subvolume name is unknown."))
                (&fix-hint
                 (hint
                  (G_ "Use the @code{subvol} Btrfs file system option."))))))))


;;;
;;; Swap space
;;;

(define-record-type* <swap-space> swap-space make-swap-space
  swap-space?
  this-swap-space
  (target swap-space-target)
  (dependencies swap-space-dependencies
                (default '()))
  (priority swap-space-priority
            (default #f))
  (discard? swap-space-discard?
           (default #f)))

;;; file-systems.scm ends here