[bug#69343] [PATCH v4 05/11] Offer a uniform decorated-boot-label and use it.

[Lilah Tascheter via Guix-patches <guix-patches@gnu.org>]

From: Felix Lechner <felix.lechner@lease-up.com>

* gnu/system/boot.scm (decorated-boot-label): New procedure.
* gnu/machine/ssh.scm (machine-boot-parameters): Use
  decorated-boot-label.
* guix/scripts/system.scm
  (profile-boot-parameters)[system->boot-parameters]: Use
  decorated-boot-label.

Change-Id: Id348c3047df2353f76b1bad0eb2a3e0fa17e474c
---
 gnu/machine/ssh.scm     |  8 ++------
 gnu/system/boot.scm     | 13 +++++++++++++
 guix/scripts/system.scm |  8 +++-----
 3 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/gnu/machine/ssh.scm b/gnu/machine/ssh.scm
index e68e64527e..3971469e33 100644
--- a/gnu/machine/ssh.scm
+++ b/gnu/machine/ssh.scm
@@ -457,15 +457,11 @@ (define (machine-boot-parameters machine)
                (let* ((params (call-with-input-string serialized-params
                                 read-boot-parameters))
                       (root (boot-parameters-root-device params))
-                      (label (boot-parameters-label params))
+                      (text (boot-parameters-label params))
                       (version (boot-parameters-version params)))
                  (boot-parameters
                   (inherit params)
-                  (label
-                   (string-append label " (#"
-                                  (number->string generation) ", "
-                                  (epoch->date-string epoch)
-                                  ")"))
+                  (label (decorated-boot-label text generation epoch))
                   (kernel-arguments
                    (append (bootable-kernel-arguments system-path root version)
                            (boot-parameters-kernel-arguments params))))))))
diff --git a/gnu/system/boot.scm b/gnu/system/boot.scm
index 01e3a965e4..82ca353cb3 100644
--- a/gnu/system/boot.scm
+++ b/gnu/system/boot.scm
@@ -72,6 +72,7 @@ (define-module (gnu system boot)
             bootable-kernel-arguments
 
             epoch->date-string
+            decorated-boot-label
             boot-parameters->menu-entry
 
             ensure-not-/dev
@@ -304,6 +305,18 @@ (define (epoch->date-string epoch)
     (date->string (time-utc->date time)
                   "~Y-~m-~d ~H:~M")))
 
+(define (decorated-boot-label text generation epoch)
+  "Return a string for a nice boot label that includes TEXT, a numbered
+GENERATION, and a timestamp derived from EPOCH seconds."
+  (let* ((numbered (lambda (num) (string-append "#" (number->string num))))
+         (count (and=> generation numbered))
+         (timestamp (and=> epoch epoch->date-string))
+         (extras (filter identity (list count timestamp)))
+         (helpful (if (null? extras)
+                      ""
+                      (string-append "(" (string-join extras ", ") ")"))))
+    (string-join (list text helpful))))
+
 (define (boot-parameters->menu-entry conf)
   "Return a <menu-entry> instance given CONF, a <boot-parameters> instance."
   (let* ((kernel (boot-parameters-kernel conf))
diff --git a/guix/scripts/system.scm b/guix/scripts/system.scm
index b197812e63..84eb99b938 100644
--- a/guix/scripts/system.scm
+++ b/guix/scripts/system.scm
@@ -337,12 +337,10 @@ (define* (profile-boot-parameters #:optional (profile %system-profile)
   (define (system->boot-parameters system number epoch)
     (unless-file-not-found
      (let* ((params           (read-boot-parameters-file system))
-            (label            (boot-parameters-label params)))
+            (text             (boot-parameters-label params)))
        (boot-parameters
-         (inherit params)
-         (label (string-append label " (#"
-                               (number->string number) ", "
-                               (epoch->date-string epoch) ")"))))))
+        (inherit params)
+        (label (decorated-boot-label text number epoch))))))
   (let* ((systems (map (cut generation-file-name profile <>)
                        numbers))
          (times   (map (lambda (system)
-- 
2.45.2