bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Pratyush Yadav]

Hi,

I use Gnus to read from the NNTP server over at nntp.lore.kernel.org on
the group org.kernel.vger.git. When I opened one particular message on
the group today Emacs froze up completely. top reported 100% CPU usage
from it. This went on for a couple minutes until I hit C-g. The message
that triggered this has Message-id
<CAN05THQGqV4hP218hb3QXjJhQbbBCDRHgf=PAty=Ydd78a679A@mail.gmail.com>
and subject "Re: [Wireshark-dev] [Outreachy] Internship blog 2020"

I dug around a bit and found out the problem comes from the function
gnus-cite-parse in the following line:

      (when (and (< guess-limit (+ begin gnus-cite-max-prefix))
         (looking-at gnus-supercite-regexp))

The call to looking-at seems to be the problem. gnus-supercite-regexp
is:

"^\\(\\([     ]*\\(\\w\\|[_.]\\)+>+\\|[     ]*[>|]\\)+\\)? *>>>>>
+\"\\([^\"\n]+\\)\" +=="

This call works fine for most lines but at the end there is the line:

"> ___________________________________________________________________________"

I wrapped this in quotes because it freezes up this buffer as well.

Is this a problem with my setup only or do other people see it as well?
What can I do to fix it?

Thanks.


In GNU Emacs 27.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.24.21,
cairo version 1.17.3)
 of 2020-08-11 built on pratyush
Repository revision: 86d8d76aa36037184db0b2897c434cdaab1a9ae8
Repository branch: makepkg
Windowing system distributor 'The X.Org Foundation', version 11.0.12010000
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-- 
Regards,
Pratyush Yadav

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Lars Ingebrigtsen]

Pratyush Yadav <pratiy0100@gmail.com> writes:

> I use Gnus to read from the NNTP server over at nntp.lore.kernel.org on
> the group org.kernel.vger.git. When I opened one particular message on
> the group today Emacs froze up completely. top reported 100% CPU usage
> from it. This went on for a couple minutes until I hit C-g. The message
> that triggered this has Message-id
> <CAN05THQGqV4hP218hb3QXjJhQbbBCDRHgf=PAty=Ydd78a679A@mail.gmail.com>
> and subject "Re: [Wireshark-dev] [Outreachy] Internship blog 2020"

I'm unable to reproduce this problem, so I'm guessing it's something in
your settings that's triggering it?

Try

(setq debug-on-quit t)

and then post the resulting backtrace when you hit `C-g'.  That should
tell us what's triggering this.

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

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> I'm unable to reproduce this problem, so I'm guessing it's something in
> your settings that's triggering it?
>
> Try
>
> (setq debug-on-quit t)
>
> and then post the resulting backtrace when you hit `C-g'.  That should
> tell us what's triggering this.

More information was requested, but no response was given within a 
month, so I'm closing this bug report.  If the problem still exists,
please respond to this email and we'll reopen the bug report.

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

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Pratyush Yadav]

On 11/01/21 04:58PM, Lars Ingebrigtsen wrote:
> Lars Ingebrigtsen <larsi@gnus.org> writes:
> 
> > I'm unable to reproduce this problem, so I'm guessing it's something in
> > your settings that's triggering it?
> >
> > Try
> >
> > (setq debug-on-quit t)
> >
> > and then post the resulting backtrace when you hit `C-g'.  That should
> > tell us what's triggering this.
> 
> More information was requested, but no response was given within a 
> month, so I'm closing this bug report.  If the problem still exists,
> please respond to this email and we'll reopen the bug report.
 
Sorry, forgot to reply. The backtrace is pasted below.

  looking-at("^\\(\\([ \11]*\\(\\w\\|[_.]\\)+>+\\|[ \11]*[>|]\\)+\\)? *>>>>> ...")
  gnus-cite-parse()
  gnus-cite-parse-wrapper()
  gnus-cite-parse-maybe(nil t)
  gnus-dissect-cited-text()
  gnus-article-fill-cited-article(nil t)
  gnus-article-fill-cited-long-lines()
  gnus-treat-article(nil 1 1 "text/plain")
  gnus-display-mime()
  gnus-article-prepare-display()
  gnus-article-prepare(411320 nil)
  gnus-summary-display-article(411320 nil)
  gnus-summary-select-article(nil force)
  gnus-summary-show-article()
  gnus-summary-select-article-buffer()
  funcall-interactively(gnus-summary-select-article-buffer)
  call-interactively(gnus-summary-select-article-buffer nil nil)
  command-execute(gnus-summary-select-article-buffer)


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

-- 
Regards,
Pratyush Yadav

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Lars Ingebrigtsen]

Pratyush Yadav <me@yadavpratyush.com> writes:

>> More information was requested, but no response was given within a 
>> month, so I'm closing this bug report.  If the problem still exists,
>> please respond to this email and we'll reopen the bug report.
>
> Sorry, forgot to reply. The backtrace is pasted below.

Thanks; reopening.

>   looking-at("^\\(\\([ \11]*\\(\\w\\|[_.]\\)+>+\\|[ \11]*[>|]\\)+\\)?
> *>>>>> ...")
>   gnus-cite-parse()

This must come from:

      (when (and (< guess-limit (+ begin gnus-cite-max-prefix))
		 (looking-at gnus-supercite-regexp))

And that's the default value of `gnus-supercite-regexp', I think?

"^\\(\\([ 	]*\\(\\w\\|[_.]\\)+>+\\|[ 	]*[>|]\\)+\\)? *>>>>> +\"\\([^\"
]+\\)\" +=="

(Only printed differently.)

But I'm not able to reproduce this bug.  When I try looking at this
message, I don't get a hang, unfortunately.  I've tried in Emacs 27, and
I don't get it there, either.

Your simpler report, that

(looking-at gnus-supercite-regexp)

"> ___________________________________________________________________________"

(without the quotes) hang, I'm not able to reproduce either (on Emacs
27.1 or Emacs 28).

Anybody guess what's going on?  Our systems look pretty similar, but I'm
on Debian, and the reported is on Arch.

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

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Lars Ingebrigtsen]

Pratyush Yadav <me@yadavpratyush.com> writes:

> FWIW, I am using Doom Emacs [0]. Could it have anything to do with this? 
> I don't think they touch Gnus all that much but maybe some other plugin 
> or setting is causing a side effect.

I don't think Doom should be influencing this, because the test case
seems straight-forward -- you said that just that looking-at, in itself,
was hanging?  That is, does eval-in the following hang for you?

(with-temp-buffer
  (insert "> ___________________________________________________________________________\n")
  (goto-char (point-min))
  (looking-at "^\\(\\([ 	]*\\(\\w\\|[_.]\\)+>+\\|[ 	]*[>|]\\)+\\)? *>>>>> +\"\\([^\" ]+\\)\" +=="))

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

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Pratyush Yadav]

On 19/01/21 04:14AM, Lars Ingebrigtsen wrote:
> Pratyush Yadav <me@yadavpratyush.com> writes:
> 
> > FWIW, I am using Doom Emacs [0]. Could it have anything to do with this? 
> > I don't think they touch Gnus all that much but maybe some other plugin 
> > or setting is causing a side effect.
> 
> I don't think Doom should be influencing this, because the test case
> seems straight-forward -- you said that just that looking-at, in itself,
> was hanging?  That is, does eval-in the following hang for you?
> 
> (with-temp-buffer
>   (insert "> ___________________________________________________________________________\n")
>   (goto-char (point-min))
>   (looking-at "^\\(\\([ 	]*\\(\\w\\|[_.]\\)+>+\\|[ 	]*[>|]\\)+\\)? *>>>>> +\"\\([^\" ]+\\)\" +=="))

My "eval-in" I assume you mean pressing `M-:`.

If I open any buffer and run this snippet, it returns nil almost 
instantly. If I add (gnus-article-mode) after (goto-char (point-min)) it 
freezes up.
 
> -- 
> (domestic pets only, the antidote for overdose, milk.)
>    bloggy blog: http://lars.ingebrigtsen.no

-- 
Regards,
Pratyush Yadav

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Lars Ingebrigtsen]

Pratyush Yadav <me@yadavpratyush.com> writes:

> If I open any buffer and run this snippet, it returns nil almost 
> instantly. If I add (gnus-article-mode) after (goto-char (point-min)) it 
> freezes up.

So the following, in Emacs 27.1, with "emacs -Q" hangs?  I'm unable to
reproduce this.

(with-temp-buffer
  (require 'gnus-art)
  (insert ">
___________________________________________________________________________\n")
  (goto-char (point-min))
  (gnus-article-mode)
  (looking-at "^\\(\\([ ]*\\(\\w\\|[_.]\\)+>+\\|[ ]*[>|]\\)+\\)?
*>>>>> +\"\\([^\" ]+\\)\" +=="))


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

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Andreas Schwab]

(with-syntax-table (make-syntax-table)
  (modify-syntax-entry ?_ "w")
  (string-match
   "^\\(\\([ ]*\\(\\w\\|[_.]\\)+>+\\|[ ]*[>|]\\)+\\)? *>>>>> +\"\\([^\" ]+\\)\" +=="
   ">___________________________________________________________________________\n"))

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Pratyush Yadav]

On 19/01/21 03:55PM, Andreas Schwab wrote:
> (with-syntax-table (make-syntax-table)
>   (modify-syntax-entry ?_ "w")

Bingo! I have this in my config. Removing it makes the freeze disappear.

>   (string-match
>    "^\\(\\([ ]*\\(\\w\\|[_.]\\)+>+\\|[ ]*[>|]\\)+\\)? *>>>>> +\"\\([^\" ]+\\)\" +=="
>    ">___________________________________________________________________________\n"))
> 
> Andreas.
> 
> -- 
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
> "And now for something completely different."

-- 
Regards,
Pratyush Yadav

bug#45041: 27.1; Emacs hangs if the cited message contains some specific text

[Lars Ingebrigtsen]

Andreas Schwab <schwab@linux-m68k.org> writes:

> (with-syntax-table (make-syntax-table)
>   (modify-syntax-entry ?_ "w")
>   (string-match
>    "^\\(\\([ ]*\\(\\w\\|[_.]\\)+>+\\|[ ]*[>|]\\)+\\)? *>>>>> +\"\\([^\" ]+\\)\" +=="
>    ">___________________________________________________________________________\n"))

Thanks.  So it's basically the same bug as bug#45944?  I'm still
wondering why I can't reproduce the reported test case, though.

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