aboutsummaryrefslogtreecommitdiff
path: root/gnu/services/dbus.scm
blob: 3e5fa14a38e833b529ee391fa0d86bc39bbfcd31 (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
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2013, 2014, 2015 Ludovic Courtès <ludo@gnu.org>
;;; Copyright © 2015 Sou Bunnbu <iyzsong@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 services dbus)
  #:use-module (gnu services)
  #:use-module (gnu services shepherd)
  #:use-module (gnu system shadow)
  #:use-module ((gnu packages glib) #:select (dbus/activation))
  #:use-module (gnu packages admin)
  #:use-module (guix gexp)
  #:use-module (guix records)
  #:use-module (srfi srfi-1)
  #:use-module (ice-9 match)
  #:export (dbus-root-service-type
            dbus-service))

;;;
;;; D-Bus.
;;;

(define-record-type* <dbus-configuration>
  dbus-configuration make-dbus-configuration
  dbus-configuration?
  (dbus      dbus-configuration-dbus              ;<package>
             (default dbus/activation))
  (services  dbus-configuration-services          ;list of <package>
             (default '())))

(define (system-service-directory services)
  "Return the system service directory, containing @code{.service} files for
all the services that may be activated by the daemon."
  (computed-file "dbus-system-services"
                 #~(begin
                     (use-modules (guix build utils)
                                  (srfi srfi-1))

                     (define files
                       (append-map (lambda (service)
                                     (find-files (string-append
                                                  service
                                                  "/share/dbus-1/system-services")
                                                 "\\.service$"))
                                   (list #$@services)))

                     (mkdir #$output)
                     (for-each (lambda (file)
                                 (symlink file
                                          (string-append #$output "/"
                                                         (basename file))))
                               files)
                     #t)
                 #:modules '((guix build utils))))

(define (dbus-configuration-directory services)
  "Return a directory contains the @code{system-local.conf} file for DBUS that
includes the @code{etc/dbus-1/system.d} directories of each package listed in
@var{services}."
  (define build
    #~(begin
        (use-modules (sxml simple)
                     (srfi srfi-1))

        (define (services->sxml services)
          ;; Return the SXML 'includedir' clauses for DIRS.
          `(busconfig
            (servicehelper "/run/setuid-programs/dbus-daemon-launch-helper")

            ;; First, the '.service' files of services subject to activation.
            ;; We use a fixed location under /etc because the setuid helper
            ;; looks for them in that location and nowhere else.  See
            ;; <https://bugs.freedesktop.org/show_bug.cgi?id=92458>.
            (servicedir "/etc/dbus-1/system-services")

            ,@(append-map (lambda (dir)
                            `((includedir
                               ,(string-append dir "/etc/dbus-1/system.d"))
                              (servicedir       ;for '.service' files
                               ,(string-append dir "/share/dbus-1/services"))))
                          services)))

        (mkdir #$output)

        ;; Provide /etc/dbus-1/system-services, which is where the setuid
        ;; helper looks for system service files.
        (symlink #$(system-service-directory services)
                 (string-append #$output "/system-services"))

        ;; 'system-local.conf' is automatically included by the default
        ;; 'system.conf', so this is where we stuff our own things.
        (call-with-output-file (string-append #$output "/system-local.conf")
          (lambda (port)
            (sxml->xml (services->sxml (list #$@services))
                       port)))))

  (computed-file "dbus-configuration" build))

(define (dbus-etc-files config)
  "Return a list of FILES for @var{etc-service-type} to build the
@code{/etc/dbus-1} directory."
  (list `("dbus-1" ,(dbus-configuration-directory
                     (dbus-configuration-services config)))))

(define %dbus-accounts
  ;; Accounts used by the system bus.
  (list (user-group (name "messagebus") (system? #t))
        (user-account
         (name "messagebus")
         (group "messagebus")
         (system? #t)
         (comment "D-Bus system bus user")
         (home-directory "/var/run/dbus")
         (shell #~(string-append #$shadow "/sbin/nologin")))))

(define dbus-setuid-programs
  ;; Return the file name of the setuid program that we need.
  (match-lambda
    (($ <dbus-configuration> dbus services)
     (list #~(string-append #$dbus "/libexec/dbus-daemon-launch-helper")))))

(define (dbus-activation config)
  "Return an activation gexp for D-Bus using @var{config}."
  #~(begin
      (use-modules (guix build utils))

      (mkdir-p "/var/run/dbus")

      (let ((user (getpwnam "messagebus")))
        (chown "/var/run/dbus"
               (passwd:uid user) (passwd:gid user)))

      (unless (file-exists? "/etc/machine-id")
        (format #t "creating /etc/machine-id...~%")
        (let ((prog (string-append #$(dbus-configuration-dbus config)
                                   "/bin/dbus-uuidgen")))
          ;; XXX: We can't use 'system' because the initrd's
          ;; guile system(3) only works when 'sh' is in $PATH.
          (let ((pid (primitive-fork)))
            (if (zero? pid)
                (call-with-output-file "/etc/machine-id"
                  (lambda (port)
                    (close-fdes 1)
                    (dup2 (port->fdes port) 1)
                    (execl prog)))
                (waitpid pid)))))))

(define dbus-dmd-service
  (match-lambda
    (($ <dbus-configuration> dbus)
     (list (dmd-service
            (documentation "Run the D-Bus system daemon.")
            (provision '(dbus-system))
            (requirement '(user-processes))
            (start #~(make-forkexec-constructor
                      (list (string-append #$dbus "/bin/dbus-daemon")
                            "--nofork" "--system")))
            (stop #~(make-kill-destructor)))))))

(define dbus-root-service-type
  (service-type (name 'dbus)
                (extensions
                 (list (service-extension dmd-root-service-type
                                          dbus-dmd-service)
                       (service-extension activation-service-type
                                          dbus-activation)
                       (service-extension etc-service-type
                                          dbus-etc-files)
                       (service-extension account-service-type
                                          (const %dbus-accounts))
                       (service-extension setuid-program-service-type
                                          dbus-setuid-programs)))

                ;; Extensions consist of lists of packages (representing D-Bus
                ;; services) that we just concatenate.
                (compose concatenate)

                ;; The service's parameters field is extended by augmenting
                ;; its <dbus-configuration> 'services' field.
                (extend (lambda (config services)
                          (dbus-configuration
                           (inherit config)
                           (services
                            (append (dbus-configuration-services config)
                                    services)))))))

(define* (dbus-service #:key (dbus dbus/activation) (services '()))
  "Return a service that runs the \"system bus\", using @var{dbus}, with
support for @var{services}.

@uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
facility.  Its system bus is used to allow system services to communicate and
be notified of system-wide events.

@var{services} must be a list of packages that provide an
@file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
and policy files.  For example, to allow avahi-daemon to use the system bus,
@var{services} must be equal to @code{(list avahi)}."
  (service dbus-root-service-type
           (dbus-configuration (dbus dbus)
                               (services services))))

;;; dbus.scm ends here