Port message-checksum to bignums

* lisp/gnus/message.el (message--rotate-fixnum-left): New function.
(message-checksum): Use it instead of assuming fixnum-only arithmetic.
This should fix Bug#33083.

diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 03f80616d9e8bce4e96f912ede7fa9f4ff2c41d9..dc15769a4fcb719cac2f5b4051cb1473c3d87d3e 100644 (file)
--- a/lisp/gnus/message.el
+++ b/lisp/gnus/message.el
@@ -5400,6 +5400,17 @@ Otherwise, generate and save a value for `canlock-password' first."
             (message "Denied posting -- only quoted text.")
             nil)))))))
 
+(defun message--rotate-fixnum-left (n)
+  "Rotate the fixnum N left by one bit in a fixnum word.
+The result is a fixnum."
+  (logior (if (natnump n) 0 1)
+         (ash (cond ((< (ash most-positive-fixnum -1) n)
+                     (logior n most-negative-fixnum))
+                    ((< n (ash most-negative-fixnum -1))
+                     (logand n most-positive-fixnum))
+                    (n))
+              1)))
+
 (defun message-checksum ()
   "Return a \"checksum\" for the current buffer."
   (let ((sum 0))
@@ -5409,7 +5420,7 @@ Otherwise, generate and save a value for `canlock-password' first."
        (concat "^" (regexp-quote mail-header-separator) "$"))
       (while (not (eobp))
        (when (not (looking-at "[ \t\n]"))
-         (setq sum (logxor (ash sum 1) (if (natnump sum) 0 1)
+         (setq sum (logxor (message--rotate-fixnum-left sum)
                            (char-after))))
        (forward-char 1)))
     sum))