From cc9564586729a5bb90dd5d2722b543fdde9ab821 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ludovic=20Court=C3=A8s?= <ludo@gnu.org>
Date: Sun, 4 Feb 2018 21:56:36 +0100
Subject: [PATCH] herd: 'herd status' now sorts the result.

Partly fixes <https://bugs.gnu.org/30299>.
Reported by Mark H Weaver <mhw@netris.org>.

Previously 'tests/basic.sh' could occasionally fail on:

  test "`$herd status`" == "$pristine_status"

because the order of stopped services were not always the same.  Indeed,
those services come from 'service-list' on the shepherd side, which uses
'hash-fold' to traverse the service hash table, and the traversal order
of 'hash-fold' is undefined.

* modules/shepherd/scripts/herd.scm (display-status-summary)[service<?]:
New procedure.
[display-services]: Call 'sort' and use the above.
---
 modules/shepherd/scripts/herd.scm | 8 ++++++--
 modules/shepherd/service.scm      | 5 +++--
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/modules/shepherd/scripts/herd.scm b/modules/shepherd/scripts/herd.scm
index ebcd1e1..697446c 100644
--- a/modules/shepherd/scripts/herd.scm
+++ b/modules/shepherd/scripts/herd.scm
@@ -1,5 +1,5 @@
 ;; herd.scm -- The program to herd the Shepherd.
-;; Copyright (C) 2013, 2014, 2016 Ludovic Courtès <ludo@gnu.org>
+;; Copyright (C) 2013, 2014, 2016, 2018 Ludovic Courtès <ludo@gnu.org>
 ;; Copyright (C) 2002, 2003 Wolfgang Jährling <wolfgang@pro-linux.de>
 ;;
 ;; This file is part of the GNU Shepherd.
@@ -46,13 +46,17 @@ of pairs."
 
 (define (display-status-summary services)
   "Display a summary of the status of all of SERVICES."
+  (define (service<? service1 service2)
+    (string<? (symbol->string (service-canonical-name service1))
+              (symbol->string (service-canonical-name service2))))
+
   (define (display-services header bullet services)
     (unless (null? services)
       (display header)
       (for-each (lambda (service)
                   (format #t " ~a ~a~%" bullet
                           (service-canonical-name service)))
-                services)))
+                (sort services service<?))))      ;get deterministic output
   (call-with-values
       (lambda ()
         (partition (match-lambda
diff --git a/modules/shepherd/service.scm b/modules/shepherd/service.scm
index 0ad28a0..83600e4 100644
--- a/modules/shepherd/service.scm
+++ b/modules/shepherd/service.scm
@@ -1,5 +1,5 @@
 ;; service.scm -- Representation of services.
-;; Copyright (C) 2013, 2014, 2015, 2016, 2017 Ludovic Courtès <ludo@gnu.org>
+;; Copyright (C) 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
 ;; Copyright (C) 2002, 2003 Wolfgang Järling <wolfgang@pro-linux.de>
 ;; Copyright (C) 2014 Alex Sassmannshausen <alex.sassmannshausen@gmail.com>
 ;; Copyright (C) 2016 Alex Kost <alezost@gmail.com>
@@ -949,7 +949,8 @@ Return #f if service is not found."
                  %services))
 
 (define (service-list)
-  "Return the list of services currently defined."
+  "Return the list of services currently defined.  Note: The order of the list
+returned in unspecified."
   (hash-fold (lambda (name services result)
                (let ((service (lookup-canonical-service name services)))
                  (if service
-- 
2.16.1