nnmbox-read-mbox: fix Xref header parsing

* lisp/gnus/nnmbox.el (nnmbox-read-mbox): Use the 'mail-fetch-field'
function instead of a broken regexp which matched Date-like headers.

(Bug#79167)

1 files changed, 18 insertions, 13 deletions

diff --git a/lisp/gnus/nnmbox.el b/lisp/gnus/nnmbox.el
index fb024bf9ef8..f8575445b65 100644
--- a/lisp/gnus/nnmbox.el
+++ b/lisp/gnus/nnmbox.el
@@ -683,19 +683,24 @@
             ;; headers).  In this case, there is an Xref line which
             ;; provides the relevant information to construct the
             ;; missing header(s).
-            (save-excursion
-              (save-restriction
-                (narrow-to-region start end)
-                (if (re-search-forward "\nXref: [^ ]+" end-header t)
-                    ;; generate headers from Xref:
-                    (let (alist)
-                      (while (re-search-forward " \\([^:]+\\):\\([0-9]+\\)" end-header t)
-                        (push (cons (match-string 1)
-                                    (string-to-number (match-string 2))) alist))
-                      (nnmbox-insert-newsgroup-line alist))
-                  ;; this is really a new article
-                  (nnmbox-save-mail
-                   (nnmail-article-group 'nnmbox-active-number))))))
+            (save-excursion
+              (save-restriction
+                (narrow-to-region start end)
+                (let ((xref (with-restriction start end-header
+                              (mail-fetch-field "Xref")))
+                      alist)
+                  (if (null xref)
+                      ;; this is a new article
+                      (nnmbox-save-mail
+                       (nnmail-article-group 'nnmbox-active-number))
+                    ;; generate headers from Xref
+                    ;; the first element is hostname so we skip it
+                    (dolist (xref-entry (cdr (split-string xref " ")))
+                      (push (cons
+                             (car (setq xref-entry (split-string xref-entry ":")))
+                             (string-to-number (cadr xref-entry)))
+                            alist))
+                    (nnmbox-insert-newsgroup-line alist))))))
           (goto-char end))
         ;; put article lists in order
         (setq alist nnmbox-group-active-articles)