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bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages f
From: |
Alexandre Duret-Lutz |
Subject: |
bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode |
Date: |
Mon, 04 Jan 2021 22:54:18 +0100 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) |
Alexandre Duret-Lutz <adl@lrde.epita.fr> writes:
> Clicking inside this message on the "Attachement: [2. text/plain]"
> button inserts "\344\344\344\344". I.e., that's
> the Latin-1 version of "ääää". (M-x describe-char on these say that they
> are "not encodable by coding system utf-8-unix")
Digging the code, I believe that the unexpected conversion occurs in this macro:
(defmacro mm-with-part (handle &rest forms)
"Run FORMS in the temp buffer containing the contents of HANDLE."
;; The handle-buffer's content is a sequence of bytes, not a sequence of
;; chars, so the buffer should be unibyte. It may happen that the
;; handle-buffer is multibyte for some reason, in which case now is a good
;; time to adjust it, since we know at this point that it should
;; be unibyte.
`(let* ((handle ,handle))
(when (and (mm-handle-buffer handle)
(buffer-name (mm-handle-buffer handle)))
(with-temp-buffer
(mm-disable-multibyte)
(insert-buffer-substring (mm-handle-buffer handle))
(mm-decode-content-transfer-encoding
(mm-handle-encoding handle)
(mm-handle-media-type handle))
,@forms))))
In my case the (mm-handle-buffer handle) is multibyte. This
multibyteness was preserved by mm-copy-to-buffer while creating the
handle buffer, but a did not check the original source of it, since the
comment above the macro suggests that having multibyte parts is OK.
However the
(mm-disable-multibyte)
(insert-buffer-substring (mm-handle-buffer handle))
seems to be doing harm. The documentation of
insert-buffer-substring/insert notes that multibyte strings will be
converted by taking the lowest 8 bits of each multibyte character, not
by spliting those characters.
Mimicking it with
(let ((utf8string "ääää")) ; typed as utf8
(with-temp-buffer
(mm-disable-multibyte)
(insert utf8string)
(print (string-bytes utf8string))
(print (string-bytes (buffer-string)))
(buffer-string)))
this prints :
8
4
"\344\344\344\344"
So it would seem that (mm-disable-multibyte) should be called *after* the
insertion and not before, in order to perserve all bytes.
Does this make sense?
--
Alexandre Duret-Lutz
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Alexandre Duret-Lutz, 2021/01/02
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode,
Alexandre Duret-Lutz <=
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Lars Ingebrigtsen, 2021/01/05
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Alexandre Duret-Lutz, 2021/01/05
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Lars Ingebrigtsen, 2021/01/07
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Alexandre Duret-Lutz, 2021/01/07
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Lars Ingebrigtsen, 2021/01/07
- bug#44307: 27.1; UTF-8 parts transferred as 8bit in multipart messages fail to decode, Alexandre Duret-Lutz, 2021/01/07