[bug#61982] [PATCH 2/2] home: services: xdg-base-directories: Deprecate XDG_LOG_HOME.

[Bruno Victal <mirai@makinata.eu>]

XDG_LOG_HOME is non-standard and log files should go to XDG_STATE_HOME
according to the XDG Base Directory Specification.

Fixes <https://issues.guix.gnu.org/61809>.

* gnu/home/services/desktop.scm (home-dbus-shepherd-services): Log to XDG_STATE_HOME.
* gnu/home/services/mcron.scm (home-mcron-shepherd-services): Ditto.
* gnu/home/services/pm.scm (home-batsignal-shepherd-services): Ditto.
* gnu/home/services/shepherd.scm (launch-shepherd-gexp): Ditto.
* gnu/home/services/xdg.scm
(home-xdg-base-directories-configuration)[log-home]: Deprecate and unset default value.
(home-xdg-base-directories-environment-variables-service)
(ensure-xdg-base-dirs-on-activation): Handle field deprecation.
(home-xdg-base-directories-service-type): Update description.
---
 gnu/home/services/desktop.scm  |  4 ++--
 gnu/home/services/mcron.scm    |  4 ++--
 gnu/home/services/pm.scm       |  6 +++---
 gnu/home/services/shepherd.scm |  4 ++--
 gnu/home/services/xdg.scm      | 36 +++++++++++++++++++++++++---------
 5 files changed, 36 insertions(+), 18 deletions(-)

diff --git a/gnu/home/services/desktop.scm b/gnu/home/services/desktop.scm
index cb25b03b64..76df7b30a2 100644
--- a/gnu/home/services/desktop.scm
+++ b/gnu/home/services/desktop.scm
@@ -206,8 +206,8 @@ (define (home-dbus-shepherd-services config)
                          (default-environment-variables))
                    #:log-file
                    (format #f "~a/dbus.log"
-                           (or (getenv "XDG_LOG_HOME")
-                               (format #f "~a/.local/var/log"
+                           (or (getenv "XDG_STATE_HOME")
+                               (format #f "~a/.local/state"
                                        (getenv "HOME"))))))
          (stop #~(make-kill-destructor)))))
 
diff --git a/gnu/home/services/mcron.scm b/gnu/home/services/mcron.scm
index 5f35bfe054..69c7f9faa6 100644
--- a/gnu/home/services/mcron.scm
+++ b/gnu/home/services/mcron.scm
@@ -99,8 +99,8 @@ (define (home-mcron-shepherd-services config)
                                         #~())
                                  #$@files)
                            #:log-file (string-append
-                                       (or (getenv "XDG_LOG_HOME")
-                                           (format #f "~a/.local/var/log"
+                                       (or (getenv "XDG_STATE_HOME")
+                                           (format #f "~a/.local/state"
                                                    (getenv "HOME")))
                                        "/mcron.log")))
                  (stop #~(make-kill-destructor))
diff --git a/gnu/home/services/pm.scm b/gnu/home/services/pm.scm
index 5f09941827..274ab2303c 100644
--- a/gnu/home/services/pm.scm
+++ b/gnu/home/services/pm.scm
@@ -128,9 +128,9 @@ (define (home-batsignal-shepherd-services config)
                                  (list "-i")
                                  (list)))
                      #:log-file (string-append
-                                 (or (getenv "XDG_LOG_HOME")
-                                     (format #f "~a/.local/var/log"
-                                               (getenv "HOME")))
+                                 (or (getenv "XDG_STATE_HOME")
+                                     (format #f "~a/.local/state"
+                                             (getenv "HOME")))
                                  "/batsignal.log")))
            (stop #~(make-kill-destructor))))))
 
diff --git a/gnu/home/services/shepherd.scm b/gnu/home/services/shepherd.scm
index 1a70a220f0..825cf66f05 100644
--- a/gnu/home/services/shepherd.scm
+++ b/gnu/home/services/shepherd.scm
@@ -108,8 +108,8 @@ (define (launch-shepherd-gexp config)
                       (or (getenv "XDG_RUNTIME_DIR")
                           (format #f "/run/user/~a" (getuid)))
                       "/shepherd/socket"))
-              (let ((log-dir (or (getenv "XDG_LOG_HOME")
-                                 (format #f "~a/.local/var/log"
+              (let ((log-dir (or (getenv "XDG_STATE_HOME")
+                                 (format #f "~a/.local/state"
                                          (getenv "HOME")))))
                 ;; TODO: Remove it, 0.9.2 creates it automatically?
                 ((@ (guix build utils) mkdir-p) log-dir)
diff --git a/gnu/home/services/xdg.scm b/gnu/home/services/xdg.scm
index ac557b4c3d..958772696b 100644
--- a/gnu/home/services/xdg.scm
+++ b/gnu/home/services/xdg.scm
@@ -1,6 +1,7 @@
 ;;; GNU Guix --- Functional package management for GNU
 ;;; Copyright © 2021, 2022 Andrew Tropin <andrew@trop.in>
 ;;; Copyright © 2021 Xinglu Chen <public@yoctocell.xyz>
+;;; Copyright © 2023 Bruno Victal <mirai@makinata.eu>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -22,6 +23,7 @@ (define-module (gnu home services xdg)
   #:use-module (gnu home services)
   #:use-module (gnu packages freedesktop)
   #:use-module (gnu home services utils)
+  #:use-module (guix deprecation)
   #:use-module (guix gexp)
   #:use-module (guix modules)
   #:use-module (guix records)
@@ -39,7 +41,7 @@ (define-module (gnu home services xdg)
             home-xdg-base-directories-configuration-config-home
             home-xdg-base-directories-configuration-data-home
             home-xdg-base-directories-configuration-state-home
-            home-xdg-base-directories-configuration-log-home
+            home-xdg-base-directories-configuration-log-home  ; deprecated
             home-xdg-base-directories-configuration-runtime-dir
 
             home-xdg-user-directories-service-type
@@ -77,6 +79,7 @@ (define-module (gnu home services xdg)
 
 (define (serialize-path field-name val) "")
 (define path? string?)
+(define-maybe path)
 
 (define-configuration home-xdg-base-directories-configuration
   (cache-home
@@ -97,12 +100,17 @@ (define-configuration home-xdg-base-directories-configuration
    (path "${XDG_RUNTIME_DIR:-/run/user/$UID}")
    "Base directory for programs to store user-specific runtime files,
 like sockets.")
+  ;; TODO: deprecated field, use $XDG_STATE_HOME(/log) instead.
   (log-home
-   (path "$HOME/.local/var/log")
+   maybe-path
    "Base directory for programs to store log files, analogus to
 @file{/var/log}, but for user.  It is not a part of XDG Base Directory
 Specification, but helps to make implementation of home services more
-consistent.")
+consistent."
+   (lambda (field-name val)
+     (when (maybe-value-set? val)
+       (warn-about-deprecation field-name #f #:replacement 'state-home))
+     (serialize-path field-name val)))
   (state-home
    (path "$HOME/.local/state")
    "Base directory for programs to store state data that should persist
@@ -117,7 +125,13 @@ (define (home-xdg-base-directories-environment-variables-service config)
             #f "XDG_~a"
             (object->snake-case-string (configuration-field-name field) 'upper))
            ((configuration-field-getter field) config)))
-   home-xdg-base-directories-configuration-fields))
+   ;; XXX: deprecated field, remove later
+   (if (maybe-value-set?
+        (home-xdg-base-directories-configuration-log-home config))
+       home-xdg-base-directories-configuration-fields
+       (filter-configuration-fields
+        home-xdg-base-directories-configuration-fields
+        '(log-home) #t))))
 
 (define (ensure-xdg-base-dirs-on-activation config)
   (with-imported-modules '((guix build utils))
@@ -138,7 +152,14 @@ (define (ensure-xdg-base-dirs-on-activation config)
                      ;; and will be provided by elogind or other service.
                      (and (not (string=? "XDG_RUNTIME_DIR" variable))
                           variable)))
-                 home-xdg-base-directories-configuration-fields)))))
+                 ;; XXX: deprecated field, remove later
+                 (if (maybe-value-set?
+                      (home-xdg-base-directories-configuration-log-home
+                       config))
+                     home-xdg-base-directories-configuration-fields
+                     (filter-configuration-fields
+                      home-xdg-base-directories-configuration-fields
+                      '(log-home) #t)))))))
 
 (define (last-extension-or-cfg config extensions)
   "Picks configuration value from last provided extension.  If there
@@ -157,10 +178,7 @@ (define home-xdg-base-directories-service-type
                 (default-value (home-xdg-base-directories-configuration))
                 (compose identity)
                 (extend last-extension-or-cfg)
-                (description "Configure XDG base directories.  This
-service introduces an additional @env{XDG_LOG_HOME} variable.  It's not
-a part of XDG specification, at least yet, but are convenient to have,
-it improves the consistency between different home services.  The
+                (description "Configure XDG base directories.  The
 services of this service-type is instantiated by default, to provide
 non-default value, extend the service-type (using @code{simple-service}
 for example).")))
-- 
2.39.1