aboutsummaryrefslogtreecommitdiff
path: root/gnu/system/file-systems.scm
blob: 0dc472e3c7b7f3124de419b84132b9caceafdeec (about) (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
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
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015, 2016 Ludovic Courtès <ludo@gnu.org>
;;;
;;; 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 (guix records)
  #:use-module (guix store)
  #:use-module ((gnu build file-systems)
                #:select (string->uuid uuid->string))
  #:re-export (string->uuid
               uuid->string)
  #:export (<file-system>
            file-system
            file-system?
            file-system-device
            file-system-title
            file-system-mount-point
            file-system-type
            file-system-needed-for-boot?
            file-system-flags
            file-system-options
            file-system-mount?
            file-system-check?
            file-system-create-mount-point?
            file-system-dependencies

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

            %fuse-control-file-system
            %binary-format-file-system
            %shared-memory-file-system
            %pseudo-terminal-file-system
            %immutable-store
            %control-groups
            %elogind-file-systems

            %base-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?

            %store-mapping))

;;; Commentary:
;;;
;;; Declaring file systems to be mounted.
;;;
;;; Code:

;; File system declaration.
(define-record-type* <file-system> file-system
  make-file-system
  file-system?
  (device           file-system-device)           ; string
  (title            file-system-title             ; 'device | 'label | 'uuid
                    (default 'device))
  (mount-point      file-system-mount-point)      ; string
  (type             file-system-type)             ; string
  (flags            file-system-flags             ; list of symbols
                    (default '()))
  (options          file-system-options           ; string or #f
                    (default #f))
  (mount?           file-system-mount?            ; Boolean
                    (default #t))
  (needed-for-boot? %file-system-needed-for-boot? ; Boolean
                    (default #f))
  (check?           file-system-check?            ; Boolean
                    (default #t))
  (create-mount-point? file-system-create-mount-point? ; Boolean
                       (default #f))
  (dependencies     file-system-dependencies      ; list of <file-system>
                    (default '())))               ; or <mapped-device>

(define-inlinable (file-system-needed-for-boot? fs)
  "Return true if FS has the 'needed-for-boot?' flag set, or if it's the root
file system."
  (or (%file-system-needed-for-boot? fs)
      (string=? "/" (file-system-mount-point 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 title mount-point type flags options _ _ check?)
     (list device title mount-point type flags options check?))))

(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?)))))

(define-syntax uuid
  (lambda (s)
    "Return the bytevector corresponding to the given UUID representation."
    (syntax-case s ()
      ((_ str)
       (string? (syntax->datum #'str))
       ;; A literal string: do the conversion at expansion time.
       (let ((bv (string->uuid (syntax->datum #'str))))
         (unless bv
           (syntax-violation 'uuid "invalid UUID" s))
         (datum->syntax #'str bv)))
      ((_ str)
       #'(string->uuid str)))))

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

(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 %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))))

(define %control-groups
  (let ((parent (file-system
                  (device "cgroup")
                  (mount-point "/sys/fs/cgroup")
                  (type "tmpfs")
                  (check? #f))))
    (cons parent
          (map (lambda (subsystem)
                 (file-system
                   (device "cgroup")
                   (mount-point (string-append "/sys/fs/cgroup/" subsystem))
                   (type "cgroup")
                   (check? #f)
                   (options subsystem)
                   (create-mount-point? #t)

                   ;; This must be mounted after, and unmounted before the
                   ;; parent directory.
                   (dependencies (list parent))))
               '("cpuset" "cpu" "cpuacct" "memory" "devices" "freezer"
                 "blkio" "perf_event" "hugetlb")))))

(define %elogind-file-systems
  ;; We don't use systemd, but these file systems are needed for elogind,
  ;; which was extracted from systemd.
  (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))))))

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

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

;;; file-systems.scm ends here