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From: "Jan Synáček" <jan.synacek@gmail.com>
To: Lars Ingebrigtsen <larsi@gnus.org>
Cc: 56336@debbugs.gnu.org
Subject: bug#56336: 28.1.90; [28.1] Emacs prompts for password when output from async command contains "password:"
Date: Sun, 3 Jul 2022 18:54:10 +0200	[thread overview]
Message-ID: <CACA+5f3qCVp8nQgz3NAmLJp8m=fQhqyrNcX0-GW+OqmDxGuMRg@mail.gmail.com> (raw)
In-Reply-To: <87tu7z1yx9.fsf@gnus.org>

On Sat, Jul 2, 2022 at 2:28 PM Lars Ingebrigtsen <larsi@gnus.org> wrote:
> The former problem is rather intractable.  That is, if you say
>
> ssh foo@host
>
> you'll get a password prompt as the final line in the buffer, and Emacs
> will ask you to enter a password.
>
> If you say
>
> echo -n "password: "; sleep 10; echo foo
>
> then there's no way for Emacs to distinguish that from the ssh
> situation: It sees a prompt as the last thing in the buffer, and Emacs
> can't possibly know that that's not a process asking for a password.
>
> Note that
>
> echo "password: "; echo foo; sleep 10
>
> won't ask for a password.
>
> So I don't know that there's any way to fix this -- Emacs uses a
> heuristic, and it will be wrong in some cases.
>
> Or does anybody have any ideas here?

Well, I know about one thing that might work well enough as an
additional heuristic just for this case.

It seems that if a command only outputs to stdout (and probably to
stderr as well) and doesn't really ask for input, lsof -p <that async
process> shows something like this:
$ lsof -p 145475
...
sleep   145475 jsynacek    0u   CHR  136,1      0t0        4 /dev/pts/1
sleep   145475 jsynacek    1u   CHR  136,1      0t0        4 /dev/pts/1
sleep   145475 jsynacek    2u   CHR  136,1      0t0        4 /dev/pts/1

Whereas if the command really wants input ('ssh jsynacek@localhost' in
this particular example), it looks like the following:
$ lsof -p 145512
...
ssh     145512 jsynacek    0u   CHR              136,1      0t0
4 /dev/pts/1
ssh     145512 jsynacek    1u   CHR              136,1      0t0
4 /dev/pts/1
ssh     145512 jsynacek    2u   CHR              136,1      0t0
4 /dev/pts/1
ssh     145512 jsynacek    3u  IPv6             203802      0t0
TCP localhost:32864->localhost:ssh (ESTABLISHED)
ssh     145512 jsynacek    4u  unix 0x000000006034f025      0t0
203803 type=STREAM (CONNECTED)
ssh     145512 jsynacek    5u   CHR                5,0      0t0
11 /dev/tty

Note the /dev/tty in the output. I'm not sure, but I think this might
be good enough.

-- 
Jan Synáček





  parent reply	other threads:[~2022-07-03 16:54 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-07-01 12:03 bug#56336: 28.1.90; [28.1] Emacs prompts for password when output from async command contains "password:" Jan Synáček
2022-07-02 12:28 ` Lars Ingebrigtsen
2022-07-03  7:53   ` miha--- via Bug reports for GNU Emacs, the Swiss army knife of text editors
2022-07-03 12:19     ` Lars Ingebrigtsen
2022-08-02 11:02       ` Lars Ingebrigtsen
2022-07-03 16:54   ` Jan Synáček [this message]
2022-07-04 10:53     ` Lars Ingebrigtsen

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