bug report: Emacs notmuch-mode fails attachments with spaces

[Nils Dagsson Moskopp]

Tomi Ollila <tomi.ollila at iki.fi> writes:

> On Mon, Feb 09 2015, Nils Dagsson Moskopp <nils at dieweltistgarnichtso.net> wrote:
>
>> Dear notmuch developers,
>>
>>
>> I use notmuch-mode for GNU Emacs for managing my email.
>>
>> I think I have found a bug in notmuch-mode: If I do “.-v” on the line “[
>> 2015 _ Richtlinien.pdf: application/pdf ]”, then notmuch will open three
>> windows of zathura (the PDF viewer I use).
>>
>> It seems to me that someone here either forgot quoting or decided to
>> split filenames on spaces. I suggest that “2015 _ Richtlinien.pdf:
>> application/pdf” should be quoted in notmuch-show-view-part.
>>
>> Note that saving attachment (“.-s”, notmuch-show-save-part) generally
>> works even if the attachment file names have spaces. In case it matters,
>> I normally use the rc(1) shell in Debian <http://tobold.org/article/rc>.
>
> This code handles the saving and displaying in question (quick look hop i
> am right :)
>
>    2282 (defun notmuch-show-save-part ()
>    2283   "Save the MIME part containing point to a file."
>    2284   (interactive)
>    2285   (notmuch-show-apply-to-current-part-handle #'mm-save-part))
>    2286 
>    2287 (defun notmuch-show-view-part ()
>    2288   "View the MIME part containing point in an external viewer."
>    2289   (interactive)
>    2290   ;; Set mm-inlined-types to nil to force an external viewer
>    2291   (let ((mm-inlined-types nil))
>    2292     (notmuch-show-apply-to-current-part-handle #'mm-display-part)))
>
> SO, there is 2 options:
>
> 1) mm executes save part correctly but not display part

It seems I cannot investigate this with my knowledge, as “M-x
find-function RET mm-display-part” gives “Can't find library
/usr/share/emacs/23.4/lisp/gnus/mm-decode.el”. Any ideas?

> 2) there is (shell) wrapper program executing zathura which cannot handle
>    arguments with spaces (there is plenty of examples of this!)
>
>
> You could try to check how th external processes are executed by executing:
>
> strace -f -e trace=process emacs -f notmuch
>
> (emacs on X is preferable in this case ;)

Thank you for that suggestion. It seems that there does happen both some
(wrong) escaping and splitting at spaces. I can see the following trace:

--- snib ---
execve("/usr/bin/zathura", ["/usr/bin/zathura", "/tmp/emm.23178ut2/2015\\", "_\\", "Richtlinien.pdf"] [/* 51 vars */]) = 0
--- snab ---

Somewhat unusually, it is preceeded by an invocation of the shell:

--- sneb ---
execve("/usr/bin/rc", ["/usr/bin/rc", "-c", "/usr/bin/zathura /tmp/emm.23178u"...], [/* 51 vars */] <unfinished ...>
--- snob ---

It seems to me that all of the following are true in this case:

1. Emacs executes the user's default shell to start zathura.

2. For this, Emacs escapes the filename.

3. Emacs applies the wrong escaping to the filename. Note that single
   quotes are interoperable between shells, while backslashes are not.

4. The rc(1) shell splits on spaces, as it knows no backslash escaping.

5. The shell executes zathura with three arguments, all bogus filenames.

I cannot pinpoint where all this is happening, but I would suggest to
just execve() zathura with a single unescaped filename as its argument.

Greetings,
-- 
Nils Dagsson Moskopp // erlehmann
<http://dieweltistgarnichtso.net>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 212 bytes
Desc: not available
URL: <http://notmuchmail.org/pipermail/notmuch/attachments/20150210/c00a321d/attachment.pgp>