gnu-maintenance: Add support to rewrite version in URL path.

Fixes <https://issues.guix.gnu.org/64015>.
Fixes <https://issues.guix.gnu.org/65304>.

Previously, the generic HTML updater would only look for the list of files
found at the parent of its current source URL, ignoring that the URL may embed
the version elsewhere in its path.  This could cause 'guix refresh' to report
no updates available, while in fact there were, such as for 'libuv'.

* guix/gnu-maintenance.scm (strip-trailing-slash): New procedure.
(%version-rx): New variable.
(rewrite-url): New procedure.
(import-html-release): New rewrite-url? argument.  When true, use the above
procedure.
(import-html-updatable-release): Call import-html-release with #:rewrite-url
set to #t.
* tests/gnu-maintenance.scm ("rewrite-url, to-version specified")
("rewrite-url, without to-version"): New tests.

1 files changed, 99 insertions, 3 deletions

diff --git a/guix/gnu-maintenance.scm b/guix/gnu-maintenance.scm
index 9eff98217e..228a84bd4b 100644
--- a/guix/gnu-maintenance.scm
+++ b/guix/gnu-maintenance.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2012, 2013 Nikita Karetnikov <nikita@karetnikov.org>
 ;;; Copyright © 2021 Simon Tournier <zimon.toutoune@gmail.com>
 ;;; Copyright © 2022 Maxime Devos <maximedevos@telenet.be>
+;;; Copyright © 2023 Maxim Cournoyer <maxim.cournoyer@gmail.com>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -26,6 +27,7 @@
   #:use-module (ice-9 regex)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-2)
   #:use-module (srfi srfi-11)
   #:use-module (srfi srfi-26)
   #:use-module (rnrs io ports)
@@ -61,6 +63,7 @@
             gnu-package?
 
             uri-mirror-rewrite
+            rewrite-url
 
             release-file?
             releases
@@ -518,9 +521,93 @@ URL is a directory instead of a file, it should be suffixed with a slash (/)."
          ;; within a directory.
          (string-append (dirname base-url) "/" url))))
 
+(define (strip-trailing-slash s)
+  "Strip any trailing slash from S, a string."
+  (if (string-suffix? "/" s)
+      (string-drop-right s 1)
+      s))
+
+;;; TODO: Extend to support the RPM and GNOME version schemes?
+(define %version-rx "[0-9.]+")
+
+(define* (rewrite-url url version #:key to-version)
+  "Rewrite URL so that the URL path components matching the current VERSION or
+VERSION-MAJOR.VERSION-MINOR are updated with that of the latest version found
+by crawling the corresponding URL directories.  Alternatively, when TO-VERSION
+is specified, rewrite version matches directly to it without crawling URL.
+
+For example, the URL
+\"https://dist.libuv.org/dist/v1.45.0/libuv-v1.45.0.tar.gz\" could be
+rewritten to something like
+\"https://dist.libuv.org/dist/v1.46.0/libuv-v1.46.0.tar.gz\"."
+  ;; XXX: major-minor may be #f if version is not a triplet but a single
+  ;; number such as "2".
+  (let* ((major-minor (false-if-exception (version-major+minor version)))
+         (to-major-minor (false-if-exception
+                          (and=> to-version version-major+minor)))
+         (uri (string->uri url))
+         (url-prefix (string-drop-right url (string-length (uri-path uri))))
+         (url-prefix-components (string-split url-prefix #\/))
+         (path (uri-path uri))
+         ;; Strip a forward slash on the path to avoid a double slash when
+         ;; string-joining later.
+         (path (if (string-prefix? "/" path)
+                   (string-drop path 1)
+                   path))
+         (path-components (string-split path #\/)))
+    (string-join
+     (reverse
+      (fold
+       (lambda (s parents)
+         (if to-version
+             ;; Direct rewrite case; the archive is assumed to exist.
+             (let ((u (string-replace-substring s version to-version)))
+               (cons (if (and major-minor to-major-minor)
+                         (string-replace-substring u major-minor to-major-minor)
+                         u)
+                     parents))
+             ;; More involved HTML crawl case.
+             (let* ((pattern (if major-minor
+                                 (format #f "(~a|~a)" version major-minor)
+                                 (format #f "(~a)" version)))
+                    (m (string-match pattern s)))
+               (if m
+                   ;; Crawl parent and rewrite current component.
+                   (let* ((parent-url (string-join (reverse parents) "/"))
+                          (links (url->links parent-url))
+                          ;; The pattern matching the version.
+                          (pattern (string-append "^" (match:prefix m)
+                                                  "(" %version-rx ")"
+                                                  (match:suffix m) "$"))
+                          (candidates (filter-map
+                                       (lambda (l)
+                                         ;; Links may be followed by a
+                                         ;; trailing '/' in the case of
+                                         ;; directories.
+                                         (and-let*
+                                             ((l (strip-trailing-slash l))
+                                              (m (string-match pattern l))
+                                              (v (match:substring m 1)))
+                                           (cons v l)))
+                                       links)))
+                     ;; Retrieve the item having the largest version.
+                     (if (null? candidates)
+                         (error "no candidates found in rewrite-url")
+                         (cons (cdr (first (sort candidates
+                                                 (lambda (x y)
+                                                   (version>? (car x)
+                                                              (car y))))))
+                               parents)))
+                   ;; No version found in path component; continue.
+                   (cons s parents)))))
+       (reverse url-prefix-components)
+       path-components))
+     "/")))
+
 (define* (import-html-release base-url package
                               #:key
-                              (version #f)
+                              rewrite-url?
+                              version
                               (directory (string-append
                                           "/" (package-upstream-name package)))
                               file->signature)
@@ -534,11 +621,19 @@ found on 'https://kernel.org/pub'.
 When FILE->SIGNATURE is omitted or #f, guess the detached signature file name,
 if any.  Otherwise, FILE->SIGNATURE must be a procedure; it is passed a source
 file URL and must return the corresponding signature URL, or #f it signatures
-are unavailable."
-  (let* ((name (package-upstream-name package))
+are unavailable.
+
+When REWRITE-URL? is #t, versioned components in BASE-URL and/or DIRECTORY are
+also updated to the latest version, as explained in the doc of the
+\"rewrite-url\" procedure used."
+  (let* ((current-version (package-version package))
+         (name (package-upstream-name package))
          (url (if (string-null? directory)
                   base-url
                   (string-append base-url directory "/")))
+         (url (if rewrite-url?
+                  (rewrite-url url current-version #:to-version version)
+                  url))
          (links (map (cut canonicalize-url <> url) (url->links url))))
 
     (define (file->signature/guess url)
@@ -877,6 +972,7 @@ string to fetch a specific version."
                         (dirname (uri-path uri)))))
     (false-if-networking-error
      (import-html-release base package
+                          #:rewrite-url? #t
                           #:version version
                           #:directory directory))))