[bug#31297] [PATCH] gnu: Add sound service.

[Oleg Pykhalov]

* gnu/services/sound.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add this.
* doc/guix.texi (Sound Services): New chapter.
---
 doc/guix.texi          | 33 +++++++++++++++
 gnu/local.mk           |  1 +
 gnu/services/sound.scm | 95 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 129 insertions(+)
 create mode 100644 gnu/services/sound.scm

diff --git a/doc/guix.texi b/doc/guix.texi
index 75886e94b..b057f67cb 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -235,6 +235,7 @@ Services
 * X Window::                    Graphical display.
 * Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
+* Sound Services::              ALSA and Pulseaudio services.
 * Database Services::           SQL databases, key-value stores, etc.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
 * Messaging Services::          Messaging services.
@@ -9697,6 +9698,7 @@ declaration.
 * X Window::                    Graphical display.
 * Printing Services::           Local and remote printer support.
 * Desktop Services::            D-Bus and desktop services.
+* Sound Services::              ALSA and Pulseaudio services.
 * Database Services::           SQL databases, key-value stores, etc.
 * Mail Services::               IMAP, POP3, SMTP, and all that.
 * Messaging Services::          Messaging services.
@@ -12804,6 +12806,37 @@ bluetooth keyboard or mouse.
 Users need to be in the @code{lp} group to access the D-Bus service.
 @end deffn
 
address@hidden Sound Services
address@hidden Sound Services
+
+The @code{(gnu services alsa)} module provides an
address@hidden service to generate an ALSA
address@hidden/etc/asound.conf} configuration file.
+
address@hidden {Scheme Variable} alsa-service-type
+This is the type for the @uref{https://alsa-project.org/, alsa},
address@hidden record as in this example:
+
address@hidden
+(service alsa-service-type)
address@hidden example
+
+See below for details about @code{alsa-configuration}.
address@hidden deffn
+
address@hidden {Data Type} alsa-configuration
+Data type representing the configuration for @code{alsa-service}.
+
address@hidden @asis
address@hidden @code{pulseaudio?} (default: @var{#t})
+Whether to use Pulseaudio for configuring ALSA to use PulseAudio.
+
address@hidden @code{extra-options} (default: @var{#f})
+Extra options is a string which will be appended to asound.conf file.
+
address@hidden table
address@hidden deftp
+
 @node Database Services
 @subsubsection Database Services
 
diff --git a/gnu/local.mk b/gnu/local.mk
index cbf2c6f1b..b649ae008 100644
--- a/gnu/local.mk
+++ b/gnu/local.mk
@@ -480,6 +480,7 @@ GNU_SYSTEM_MODULES =                                \
   %D%/services/networking.scm                  \
   %D%/services/nfs.scm                 \
   %D%/services/shepherd.scm                    \
+  %D%/services/sound.scm                       \
   %D%/services/herd.scm                                \
   %D%/services/pm.scm                          \
   %D%/services/rsync.scm                       \
diff --git a/gnu/services/sound.scm b/gnu/services/sound.scm
new file mode 100644
index 000000000..b34e0efc1
--- /dev/null
+++ b/gnu/services/sound.scm
@@ -0,0 +1,95 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2018 Oleg Pykhalov <address@hidden>
+;;;
+;;; 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 sound)
+  #:use-module (gnu services base)
+  #:use-module (gnu services configuration)
+  #:use-module (gnu services shepherd)
+  #:use-module (gnu services web)
+  #:use-module (gnu services)
+  #:use-module (gnu system shadow)
+  #:use-module (guix gexp)
+  #:use-module (guix packages)
+  #:use-module (guix records)
+  #:use-module (guix store)
+  #:use-module (gnu packages pulseaudio)
+  #:use-module (ice-9 match)
+  #:export (alsa-configuration
+            alsa-service-type))
+
+;;; Commentary:
+;;;
+;;; Sound services.
+;;;
+;;; Code:
+
+
+;;;
+;;; ALSA
+;;;
+
+(define-record-type* <alsa-configuration>
+  alsa-configuration make-alsa-configuration alsa-configuration?
+  (pulseaudio?   alsa-configuration-pulseaudio? ;boolean
+                 (default #t))
+  (extra-options alsa-configuration-extra-options ;string
+                 (default #f)))
+
+(define (alsa-config-file config)
+  "Return the ALSA configuration file corresponding to CONFIG."
+  (computed-file
+   "asound.conf"
+   #~(call-with-output-file #$output
+       (lambda (port)
+         (display "# Generated by 'alsa-service'.\n\n" port)
+         (when #$(alsa-configuration-pulseaudio? config)
+           (display "# Use PulseAudio by default
+pcm.!default {
+  type pulse
+  fallback \"sysdefault\"
+  hint {
+    show on
+    description \"Default ALSA Output (currently PulseAudio Sound Server)\"
+  }
+}
+
+ctl.!default {
+  type pulse
+  fallback \"sysdefault\"
+}
+"
+                    port))
+         (let ((extra-options #$(alsa-configuration-extra-options config)))
+           (when extra-options (display extra-options port)))))))
+
+(define (alsa-activation config)
+  "Return the activation GEXP for CONFIG."
+  (with-imported-modules '((guix build utils))
+    #~(begin
+        (use-modules (guix build utils))
+        (copy-file #$(alsa-config-file config) "/etc/asound.conf"))))
+
+(define alsa-service-type
+  (service-type
+   (name 'alsa)
+   (extensions
+    (list (service-extension activation-service-type alsa-activation)))
+   (default-value (alsa-configuration))
+   (description "Configure the alsa.")))
+
+;;; alsa.scm ends here
-- 
2.17.0