[bug#74542] [PATCH 02/11] gnu-maintenance: ‘import-html-release’ doesn’t abort upon HTTP 404.

["Ludovic Courtès" <ludo@gnu.org>]

Previously, updaters using ‘import-html-release’ would throw to 'quit
when the HTML page isn’t found, aborting the whole process:

  $ guix refresh coreutils libchop
  guix refresh: error: https://de.freedif.org/savannah//libchop/: HTTP download failed: 404 ("Not Found")

* guix/gnu-maintenance.scm (url->links): Guard against ‘http-get-error?’
and return the empty list when it is raised.

Change-Id: I419ff96ddb424aa8c74d6bab3d66a5e85355c3dc
---
 guix/gnu-maintenance.scm | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/guix/gnu-maintenance.scm b/guix/gnu-maintenance.scm
index 881e941fbf..f34dcfc13f 100644
--- a/guix/gnu-maintenance.scm
+++ b/guix/gnu-maintenance.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2010-2023 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2010-2024 Ludovic Courtès <ludo@gnu.org>
 ;;; Copyright © 2012, 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
 ;;; Copyright © 2022 Maxime Devos <maximedevos@telenet.be>
@@ -30,6 +30,7 @@ (define-module (guix gnu-maintenance)
   #:use-module (srfi srfi-2)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
+  #:use-module (srfi srfi-34)
   #:use-module (rnrs io ports)
   #:use-module ((guix http-client) #:hide (open-socket-for-uri))
   ;; not required in many cases, so autoloaded to reduce start-up costs.
@@ -496,11 +497,16 @@ (define (html-links sxml)
 
 (define (url->links url)
   "Return the unique links on the HTML page accessible at URL."
-  (let* ((uri   (string->uri url))
-         (port  (http-fetch/cached uri #:ttl 3600))
-         (sxml  (html->sxml port)))
-    (close-port port)
-    (delete-duplicates (html-links sxml))))
+  (guard (c ((http-get-error? c)
+             (warning (G_ "failed to download '~a': ~a (~a)~%")
+                      url (http-get-error-code c)
+                      (http-get-error-reason c))
+             '()))
+    (let* ((uri   (string->uri url))
+           (port  (http-fetch/cached uri #:ttl 3600))
+           (sxml  (html->sxml port)))
+      (close-port port)
+      (delete-duplicates (html-links sxml)))))
 
 (define (canonicalize-url url base-url)
   "Make relative URL absolute, by appending URL to BASE-URL as required.  If
-- 
2.46.0