master 159d8f7a0a: Fix the mm-decode-content-transfer-encoding overflow better

[Lars Ingebrigtsen]

branch: master
commit 159d8f7a0afec26382d570ad95a1a3b2559f642d
Author: Lars Ingebrigtsen <larsi@gnus.org>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Fix the mm-decode-content-transfer-encoding overflow better
    
    * lisp/gnus/mm-bodies.el (mm-decode-content-transfer-encoding):
    Use it.
    (mm-base64-line-p): New function.
---
 lisp/gnus/mm-bodies.el | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/lisp/gnus/mm-bodies.el b/lisp/gnus/mm-bodies.el
index 9f2f80b472..0d4237a64c 100644
--- a/lisp/gnus/mm-bodies.el
+++ b/lisp/gnus/mm-bodies.el
@@ -201,8 +201,11 @@ If TYPE is `text/plain' CRLF->LF translation may occur."
               ;; mailing list software by finding the final line with
               ;; base64 text.
               (goto-char (point-max))
-              (when (re-search-backward "[A-Za-z0-9+/]{3,3}=?[\t ]*$" nil t)
-                (forward-line))
+               (beginning-of-line)
+               (while (and (not (mm-base64-line-p))
+                           (not (bobp)))
+                 (forward-line -1))
+               (forward-line 1)
               (point))))
           ((memq encoding '(nil 7bit 8bit binary))
            ;; Do nothing.
@@ -235,6 +238,18 @@ If TYPE is `text/plain' CRLF->LF translation may occur."
       (while (search-forward "\r\n" nil t)
        (replace-match "\n" t t)))))
 
+(defun mm-base64-line-p ()
+  "Say whether the current line is base64."
+  ;; This is coded in this way to avoid using regexps that may
+  ;; overflow -- a base64 line may be megabytes long.
+  (save-excursion
+    (beginning-of-line)
+    (skip-chars-forward " \t")
+    (skip-chars-forward "A-Za-z0-9+")
+    (skip-chars-forward "=")
+    (skip-chars-forward " \t")
+    (eolp)))
+
 (defun mm-decode-body (charset &optional encoding type)
   "Decode the current article that has been encoded with ENCODING to CHARSET.
 ENCODING is a MIME content transfer encoding.