mirror of
https://git.in.rschanz.org/ryan77627/guix.git
synced 2024-11-15 03:15:09 -05:00
e88bf64e6f
* gnu/build/dbus-service.scm (sleep*): Pass #:ensure #f to 'resolve-module'. * gnu/build/secret-service.scm (wait-for-readable-fd): Likewise.
213 lines
8.6 KiB
Scheme
213 lines
8.6 KiB
Scheme
;;; GNU Guix --- Functional package management for GNU
|
||
;;; Copyright © 2021, 2022 Maxim Cournoyer <maxim.cournoyer@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/>.
|
||
|
||
;;; Commentary:
|
||
;;;
|
||
;;; This module contains procedures to interact with D-Bus via the 'dbus-send'
|
||
;;; command line utility. Before using any public procedure
|
||
;;;
|
||
;;; Code:
|
||
|
||
(define-module (gnu build dbus-service)
|
||
#:use-module (ice-9 match)
|
||
#:use-module (srfi srfi-1)
|
||
#:use-module (srfi srfi-19)
|
||
#:use-module (srfi srfi-26)
|
||
#:autoload (d-bus protocol connections) (d-bus-conn?
|
||
d-bus-conn-flush
|
||
d-bus-connect
|
||
d-bus-disconnect
|
||
d-bus-session-bus-address
|
||
d-bus-system-bus-address)
|
||
#:autoload (d-bus protocol messages) (MESSAGE_TYPE_METHOD_CALL
|
||
d-bus-headers-ref
|
||
d-bus-message-body
|
||
d-bus-message-headers
|
||
d-bus-read-message
|
||
d-bus-write-message
|
||
header-PATH
|
||
header-DESTINATION
|
||
header-INTERFACE
|
||
header-MEMBER
|
||
header-SIGNATURE
|
||
make-d-bus-message)
|
||
#:export (%dbus-query-timeout
|
||
|
||
initialize-dbus-connection!
|
||
%current-dbus-connection
|
||
send-dbus
|
||
call-dbus-method
|
||
|
||
dbus-available-services
|
||
dbus-service-available?
|
||
|
||
with-retries))
|
||
|
||
(define %dbus-query-timeout 2) ;in seconds
|
||
|
||
;;; Use Fibers' sleep to enable cooperative scheduling in Shepherd >= 0.9.0,
|
||
;;; which is required at least for the Jami service.
|
||
(define sleep*
|
||
(lambda () ;delay execution
|
||
(if (resolve-module '(fibers) #f #:ensure #f)
|
||
(module-ref (resolve-interface '(fibers)) 'sleep)
|
||
(begin
|
||
(format #t "Fibers not available -- blocking 'sleep' in use~%")
|
||
sleep))))
|
||
|
||
;;;
|
||
;;; Utilities.
|
||
;;;
|
||
|
||
(define-syntax-rule (with-retries n delay body ...)
|
||
"Retry the code in BODY up to N times until it doesn't raise an exception nor
|
||
return #f, else raise an error. A delay of DELAY seconds is inserted before
|
||
each retry."
|
||
(let loop ((attempts 0))
|
||
(catch #t
|
||
(lambda ()
|
||
(let ((result (begin body ...)))
|
||
(if (not result)
|
||
(error "failed attempt" attempts)
|
||
result)))
|
||
(lambda args
|
||
(if (< attempts n)
|
||
(begin
|
||
((sleep*) delay) ;else wait and retry
|
||
(loop (+ 1 attempts)))
|
||
(error "maximum number of retry attempts reached"
|
||
body ... args))))))
|
||
|
||
|
||
;;;
|
||
;;; Low level wrappers above AC/D-Bus.
|
||
;;;
|
||
|
||
;; The active D-Bus connection (a parameter) used by the other procedures.
|
||
(define %current-dbus-connection (make-parameter #f))
|
||
|
||
(define* (initialize-dbus-connection!
|
||
#:key (address (or (d-bus-session-bus-address)
|
||
(d-bus-system-bus-address))))
|
||
"Initialize the D-Bus connection. ADDRESS should be the address of the D-Bus
|
||
session, e.g. \"unix:path=/var/run/dbus/system_bus_socket\", the default value
|
||
if ADDRESS is not provided and DBUS_SESSION_BUS_ADDRESS is not set. Return
|
||
the initialized D-Bus connection."
|
||
;; Clear current correction if already active.
|
||
(when (d-bus-conn? (%current-dbus-connection))
|
||
(d-bus-disconnect (%current-dbus-connection)))
|
||
|
||
(let ((connection (d-bus-connect address)))
|
||
(%current-dbus-connection connection) ;update connection parameter
|
||
(call-dbus-method "Hello")) ;initial handshake
|
||
|
||
(%current-dbus-connection))
|
||
|
||
(define* (send-dbus message #:key
|
||
(connection (%current-dbus-connection))
|
||
timeout)
|
||
"Send a D-Bus MESSAGE to CONNECTION and return the body of its reply. Up to
|
||
READ-RETRIES replies are read until a matching reply is found, else an error
|
||
is raised. MESSAGE is to be constructed with `make-d-bus-message'. When the
|
||
body contains a single element, it is returned directly, else the body
|
||
elements are returned as a list. TIMEOUT is a timeout value in seconds."
|
||
(let ((serial (d-bus-write-message connection message))
|
||
(start-time (current-time time-monotonic))
|
||
(timeout* (or timeout %dbus-query-timeout)))
|
||
(d-bus-conn-flush connection)
|
||
(let retry ()
|
||
(when (> (time-second (time-difference (current-time time-monotonic)
|
||
start-time))
|
||
timeout*)
|
||
(error 'dbus "fail to get reply in timeout" timeout*))
|
||
(let* ((reply (d-bus-read-message connection))
|
||
(reply-headers (d-bus-message-headers reply))
|
||
(reply-serial (d-bus-headers-ref reply-headers 'REPLY_SERIAL))
|
||
(error-name (d-bus-headers-ref reply-headers 'ERROR_NAME))
|
||
(body (d-bus-message-body reply)))
|
||
;; Validate the reply matches the message.
|
||
(when error-name
|
||
(error 'dbus "method failed with error" error-name body))
|
||
;; Some replies do not include a serial header, such as the for the
|
||
;; org.freedesktop.DBus NameAcquired one.
|
||
(if (and reply-serial (= serial reply-serial))
|
||
(match body
|
||
((x x* ..1) ;contains 2 ore more elements
|
||
body)
|
||
((x)
|
||
x) ;single element; return it directly
|
||
(#f #f))
|
||
(retry))))))
|
||
|
||
(define (argument->signature-type argument)
|
||
"Infer the D-Bus signature type from ARGUMENT."
|
||
;; XXX: avoid ..1 when using vectors due to a bug (?) in (ice-9 match).
|
||
(match argument
|
||
((? boolean?) "b")
|
||
((? string?) "s")
|
||
(#((? string?) (? string?) ...) "as")
|
||
(#(((? string?) . (? string?))
|
||
((? string?) . (? string?)) ...) "a{ss}")
|
||
(_ (error 'dbus "no rule to infer type from argument" argument))))
|
||
|
||
(define* (call-dbus-method method
|
||
#:key
|
||
(path "/org/freedesktop/DBus")
|
||
(destination "org.freedesktop.DBus")
|
||
(interface "org.freedesktop.DBus")
|
||
(connection (%current-dbus-connection))
|
||
arguments
|
||
timeout)
|
||
"Call the D-Bus method specified by METHOD, PATH, DESTINATION and INTERFACE.
|
||
The currently active D-Bus CONNECTION is used unless explicitly provided.
|
||
Method arguments may be provided via ARGUMENTS sent as the message body.
|
||
TIMEOUT limit the maximum time to allow for the reply. Return the body of the
|
||
reply."
|
||
(let ((message (make-d-bus-message
|
||
MESSAGE_TYPE_METHOD_CALL 0 #f '()
|
||
`#(,(header-PATH path)
|
||
,(header-DESTINATION destination)
|
||
,(header-INTERFACE interface)
|
||
,(header-MEMBER method)
|
||
,@(if arguments
|
||
(list (header-SIGNATURE
|
||
(string-join
|
||
(map argument->signature-type arguments)
|
||
"")))
|
||
'()))
|
||
arguments)))
|
||
(send-dbus message #:connection connection #:timeout timeout)))
|
||
|
||
|
||
;;;
|
||
;;; Higher-level, D-Bus procedures.
|
||
;;;
|
||
|
||
(define (dbus-available-services)
|
||
"Return the list of available (acquired) D-Bus services."
|
||
(let ((names (vector->list (call-dbus-method "ListNames"))))
|
||
;; Remove entries such as ":1.7".
|
||
(remove (cut string-prefix? ":" <>) names)))
|
||
|
||
(define (dbus-service-available? service)
|
||
"Predicate to check for the D-Bus SERVICE availability."
|
||
(member service (dbus-available-services)))
|
||
|
||
;; Local Variables:
|
||
;; eval: (put 'with-retries 'scheme-indent-function 2)
|
||
;; End:
|