master 2647b7b: Fix Rmail-MIME size estimations

[Eli Zaretskii]

branch: master
commit 2647b7b78c6c40def8f40a0169a27fd265bd4de4
Author: Eli Zaretskii <eliz@gnu.org>
Commit: Eli Zaretskii <eliz@gnu.org>

    Fix Rmail-MIME size estimations
    
    The quoted-printable estimation was obviously wrong: the size becomes
    smaller when decoded, not larger...
    * lisp/mail/rmailmm.el (rmail-mime-set-bulk-data): Fix estimations
    of decoded MIME attachment.
---
 lisp/mail/rmailmm.el | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/lisp/mail/rmailmm.el b/lisp/mail/rmailmm.el
index e08500a..1295a08 100644
--- a/lisp/mail/rmailmm.el
+++ b/lisp/mail/rmailmm.el
@@ -784,9 +784,11 @@ directly."
           (let ((encoding (rmail-mime-entity-transfer-encoding entity)))
             (setq size (- (aref body 1) (aref body 0)))
             (cond ((string= encoding "base64")
-                   (setq size (/ (* size 3) 4)))
+                    ;; https://en.wikipedia.org/wiki/Base64#MIME
+                   (setq size (max (* (- size 814) 0.73) 100)))
                   ((string= encoding "quoted-printable")
-                   (setq size (/ (* size 7) 3)))))))
+                    ;; Assume most of the text is ASCII...
+                   (setq size (/ (* size 5) 7)))))))
 
     (cond
      ((string-match "text/html" content-type)