bug#51600: 29.0.50; Entries in ~/.mailcap are overruled (Win10)

bug#51600: 29.0.50; Entries in ~/.mailcap are overruled (Win10)

[Arash Esbati]

Hi all,

I slightly changed the entry for "application/pdf" in my ~/.mailcap and
while trying out the result, I see that Emacs overrules my entries when
I start Gnus and write a message.  I'm on Win10 where for example I have
these 2 entries in ~/.mailcap:

    application/ms-tnef; wmopener.exe "%s"
    application/pdf;     start AcroRd32.exe %s

When I start Emacs and eval these forms in *scratch*, I get:

    (mailcap-mime-info "application/pdf")
    "start AcroRd32.exe %s"

    (mailcap-mime-info "application/ms-tnef")
    "wmopener.exe \"%s\""

As I'm writing this message, I get:

    (mailcap-mime-info "application/pdf")
    doc-view-mode

    (mailcap-mime-info "application/ms-tnef")
    nil

It used to work for me for a long time, so I suspect something went
wrong (at least for Windows) after this commit: daea9b3b44

Can others reproduce this?

Best, Arash

bug#51600: 29.0.50; Entries in ~/.mailcap are overruled (Win10)

[Gregory Heytings]

[-- Attachment #1: Type: text/plain, Size: 381 bytes --]


>
> When I start Emacs and eval these forms in *scratch*, I get:
>
> (mailcap-mime-info "application/pdf")
> "start AcroRd32.exe %s"
>
> (mailcap-mime-info "application/ms-tnef")
> "wmopener.exe \"%s\""
>
> As I'm writing this message, I get:
>
> (mailcap-mime-info "application/pdf")
> doc-view-mode
>
> (mailcap-mime-info "application/ms-tnef")
> nil
>

Indeed.  Patch attached.

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: Type: text/x-diff; name=Reset-mailcap-entries-only-when-mailcap-files-are-re.patch, Size: 2077 bytes --]

From 6c004a0516ddc8d4323cfef6fbc2839e624ca811 Mon Sep 17 00:00:00 2001
From: Gregory Heytings <gregory@heytings.org>
Date: Thu, 4 Nov 2021 11:04:11 +0000
Subject: [PATCH] Reset mailcap entries only when mailcap files are read again.

* lisp/net/mailcap.el (mailcap-parse-mailcaps): Move the clear and
load defaults operations at their appropriate place.  Fixes bug#51600.
---
 lisp/net/mailcap.el | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/lisp/net/mailcap.el b/lisp/net/mailcap.el
index e40cf2a336..df6bdd1aba 100644
--- a/lisp/net/mailcap.el
+++ b/lisp/net/mailcap.el
@@ -423,14 +423,6 @@ mailcap-parse-mailcaps
   (interactive (list nil t))
   (when (or (not mailcap-parsed-p)
 	    force)
-    ;; Clear out all old data.
-    (setq mailcap--computed-mime-data nil)
-    ;; Add the Emacs-distributed defaults (which will be used as
-    ;; fallbacks).  Do it this way instead of just copying the list,
-    ;; since entries are destructively modified.
-    (cl-loop for (major . minors) in mailcap-mime-data
-             do (cl-loop for (minor . entry) in minors
-                         do (mailcap-add-mailcap-entry major minor entry)))
     (cond
      (path nil)
      ((getenv "MAILCAPS")
@@ -450,6 +442,14 @@ mailcap-parse-mailcaps
     (when (seq-some (lambda (f)
                       (file-has-changed-p (car f) 'mail-parse-mailcaps))
                     path)
+      ;; Clear out all old data.
+      (setq mailcap--computed-mime-data nil)
+      ;; Add the Emacs-distributed defaults (which will be used as
+      ;; fallbacks).  Do it this way instead of just copying the list,
+      ;; since entries are destructively modified.
+      (cl-loop for (major . minors) in mailcap-mime-data
+               do (cl-loop for (minor . entry) in minors
+                           do (mailcap-add-mailcap-entry major minor entry)))
       ;; The ~/.mailcap entries will end up first in the resulting data.
       (dolist (spec (reverse
 		     (if (stringp path)
-- 
2.33.0

bug#51600: 29.0.50; Entries in ~/.mailcap are overruled (Win10)

[Lars Ingebrigtsen]

Gregory Heytings <gregory@heytings.org> writes:

> Indeed.  Patch attached.

Thanks; applied to Emacs 29.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no

bug#51600: 29.0.50; Entries in ~/.mailcap are overruled (Win10)

[Arash Esbati]

Gregory Heytings <gregory@heytings.org> writes:

> Indeed.  Patch attached.

Thanks for the quick fix, works as expected.

Best, Arash