[mu4e bug] Attachments that contain a comma (,) in the name cannot be saved

[ArneBab]

Describe the bug

I received an email with an attachment whose name contains a comma (,). When trying to save the attachment, I get an error.

How to Reproduce

• create a file with comma, i.e. /tmp/foo,bar.txt
• send an email to myself with the file as attachment (not inline)
• press e somewhere in the message text (mu4e-view-save-attachments) ⇒ see error
• try again after setting M-x toggle-debug-on-error

There’s a workaround: use M-x gnus-mime-save-part

backtrace

Debugger entered--Lisp error: (wrong-type-argument char-or-string-p nil)
  mm-insert-part(nil)
  mm-save-part-to-file(nil "/(1)nil")
  #f(compiled-function (fname) #<bytecode -0x1bec29cfd65bb31e>)("foo")
  mapc(#f(compiled-function (fname) #<bytecode -0x1bec29cfd65bb31e>) ("foo" "bar.txt"))
  seq-do(#f(compiled-function (fname) #<bytecode -0x1bec29cfd65bb31e>) ("foo" "bar.txt"))
  mu4e-view-save-attachments(nil)
  funcall-interactively(mu4e-view-save-attachments nil)
  #<subr call-interactively>(mu4e-view-save-attachments nil nil)
  apply(#<subr call-interactively> mu4e-view-save-attachments (nil nil))
  (let ((ido-cr+-current-command command)) (apply orig-fun command args))
  call-interactively@ido-cr+-record-current-command(#<subr call-interactively> mu4e-view-save-attachments nil nil)
  apply(call-interactively@ido-cr+-record-current-command #<subr call-interactively> (mu4e-view-save-attachments nil nil))
  call-interactively(mu4e-view-save-attachments nil nil)
  command-execute(mu4e-view-save-attachments)

raw message:

From: a@example.com
To: a@example.com
Subject: file with comma
BCC: 
Date: Mon, 11 Nov 2024
Message-ID: <87r07idr6s.fsf@web.de>
MIME-Version: 1.0
Content-Type: multipart/signed; boundary="==-=-=";
	micalg=pgp-sha256; protocol="application/pgp-signature"

--==-=-=
Content-Type: multipart/mixed; boundary="=-=-="

--=-=-=
Content-Type: text/plain
Content-Disposition: attachment; filename="foo,bar.txt"

file with comma

--=-=-=
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable


=2D-=20
Unpolitisch sein
hei=C3=9Ft politisch sein,
ohne es zu merken.
draketo.de

--=-=-=--

--==-=-=
Content-Type: application/pgp-signature; name="signature.asc"

-----BEGIN PGP SIGNATURE-----
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=+/YS
-----END PGP SIGNATURE-----
--==-=-=--

Environment

Please describe the versions of OS, Emacs, mu/mu4e etc. you are using.

GNU Emacs 30.0.91 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.41, cairo version 1.18.0)

Checklist

• you are running an 1.12.6 release
• you can reproduce the problem without 3rd party extensions (including Doom/Evil, various extensions etc.)
• you have read all of the above

Please make sure you all items in the checklist are set/met before filing the ticket.

Thank you!

[djcb]

I think this is due to a limitation in completing-read-multiple, see #2768. If you have many such attachments, it may be worth updating crm-separator.

The error backtrace shouldn't happen though, that's fixed in 1.12.7.