gnu: services: Add pcscd service.

* gnu/services/security-token.scm: New file.
* gnu/tests/security-token.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Register new files.
* doc/guix.texi (Miscellaneous Services): Document the service.

gnu/services/security-token.scm

@@ -0,0 +1,84 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Arun Isaac <arunisaac@systemreboot.net>
+;;;
+;;; 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 security-token)
+  #:use-module (gnu services)
+  #:use-module (gnu services shepherd)
+  #:use-module (gnu packages admin)
+  #:use-module (gnu packages security-token)
+  #:use-module (gnu system shadow)
+  #:use-module (guix gexp)
+  #:use-module (guix modules)
+  #:use-module (guix records)
+  #:use-module (ice-9 match)
+  #:use-module (srfi srfi-26)
+  #:export (pcscd-configuration
+            pcscd-configuration?
+            pcscd-configuration-pcsc-lite
+            pcscd-configuration-usb-drivers
+            pcscd-service-type))
+
+;;;
+;;; PC/SC Smart Card Daemon
+;;;
+
+(define-record-type* <pcscd-configuration>
+  pcscd-configuration make-pcscd-configuration pcscd-configuration?
+  (pcsc-lite pcscd-configuration-pcsc-lite
+             (default pcsc-lite))
+  (usb-drivers pcscd-configuration-usb-drivers
+               (default (list ccid))))
+
+(define pcscd-shepherd-service
+  (match-lambda
+    (($ <pcscd-configuration> pcsc-lite)
+     (with-imported-modules (source-module-closure
+                             '((gnu build shepherd)))
+       (shepherd-service
+        (documentation "PC/SC Smart Card Daemon")
+        (provision '(pcscd))
+        (requirement '(syslogd))
+        (modules '((gnu build shepherd)))
+        (start #~(lambda _
+                   (invoke #$(file-append pcsc-lite "/sbin/pcscd"))
+                   (call-with-input-file "/var/run/pcscd/pcscd.pid" read)))
+        (stop #~(make-kill-destructor)))))))
+
+(define pcscd-activation
+  (match-lambda
+    (($ <pcscd-configuration> pcsc-lite usb-drivers)
+     #~(begin
+         (use-modules (guix build utils))
+         (mkdir-p "/var/lib")
+         (symlink #$(directory-union
+                     "pcsc"
+                     (map (cut file-append <> "/pcsc")
+                          usb-drivers))
+                  "/var/lib/pcsc")))))
+
+(define pcscd-service-type
+  (service-type
+   (name 'pcscd)
+   (description
+    "Run @command{pcscd}, the PC/SC smart card daemon.")
+   (extensions
+    (list (service-extension shepherd-root-service-type
+                             (compose list pcscd-shepherd-service))
+          (service-extension activation-service-type
+                             pcscd-activation)))
+   (default-value (pcscd-configuration))))