bug#43772: 27.1; (describe-variable) breaks eshell

bug#43772: 27.1; (describe-variable) breaks eshell

[daniel]

When using eshell-mode, calling `(describe-variable)` on a variable that
starts with "eshell" causes eshell-watch-for-password-prompt to no
longer function correctly.  In the attached dribble file, I first show
the correct behavior by opening eshell and entering `sudo ls`; eshell
correctly prompts me for a password three times.  I then run
`(describe-variable 'eshell-after-prompt-hook)` and then enter `sudo
ls`.  This time, eshell displays the incorrect behavior: it prints the
string "password" but does not accept input as a password or print any
output from the command.  I selected `eshell-after-prompt-hook` becuase
it is one of the first variables starting with "eshell", but the same
behavior occurs with other variables, including user-defined ones.

The information below, generated with report-emacs-bug, is for my
laptop, where I observed the above bug on Emacs 27.1.  I also observed
the same bug on my desktop on Emacs 26.3 (build 2, x86_64-pc-linux-gnu),
so the issue isn't specific to the Void musl build.

I hope this information is helpful.  Thank you all for the wonderful
work you do on Emacs, and please let me know if I can provide any other
information.

Best regards,
Daniel 

In GNU Emacs 27.1 (build 1, x86_64-unknown-linux-musl)
 of 2020-08-12 built on vm1-a-mci-us
System Description: void

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bug#43772: 27.1; (describe-variable) breaks eshell

[Lars Ingebrigtsen]

daniel@codesections.com writes:

> When using eshell-mode, calling `(describe-variable)` on a variable that
> starts with "eshell" causes eshell-watch-for-password-prompt to no
> longer function correctly.  In the attached dribble file, I first show
> the correct behavior by opening eshell and entering `sudo ls`; eshell
> correctly prompts me for a password three times.  I then run
> `(describe-variable 'eshell-after-prompt-hook)` and then enter `sudo
> ls`.  This time, eshell displays the incorrect behavior: it prints the
> string "password" but does not accept input as a password or print any
> output from the command. 

There was no dribble file attached, but I was able to reproduce the bug
in Emacs 28, too.

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

bug#43772: 27.1; (describe-variable) breaks eshell

[Lars Ingebrigtsen]

Lars Ingebrigtsen <larsi@gnus.org> writes:

> There was no dribble file attached, but I was able to reproduce the bug
> in Emacs 28, too.

A simpler way to reproduce the bug is to say

(require 'em-tramp)

This is because that file defines eshell/su, and when that's defined,
the command is passed onto the shell directly without any parsing (and
therefore no prompting).

The logic is in

(defun eshell-invoke-directly (command)
...
	 (fboundp (intern-soft (concat "eshell/" name))))))

I'm not an eshell user, so I'm not sure what's up with that?

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

bug#43772: Fix for bug#43772

[Ruthra Kumar]

[-- Attachment #1: Type: text/plain, Size: 758 bytes --]

Hello Lars,

As you've mentioned, parsing ( and prompting ) is not done, when
command is sent directly to shell. But, i think
'eshell-invoke-directly' should not have returned true for sudo and
su. Comment section in 'eshell-find-alias-function' best describes it,

(defun eshell-find-alias-function (name)
 ...
    ;; If the function exists, but is defined in an eshell module
    ;; that's not currently enabled, don't report it as found.

eshell-tramp is disabled by default. So, eshell-invoke-directly should
return nil for su and sudo ( I'm new to eshell as well. So, I might be
wrong here ). Replacing fboundp with 'eshell-find-alias-function'
should fix this. So far, I've tested locally and it is working fine.

Patch attached.

Regards
Ruthra Kumar

[-- Attachment #2: 0001-eshell-invoke-directly-use-eshell-find-alias-functio.patch --]
[-- Type: text/x-patch, Size: 802 bytes --]

From fa4b5f71f8d0f4ea43ab9cade8b6a721dc21d604 Mon Sep 17 00:00:00 2001
From: Ruthra Kumar <ruthrab@gmail.com>
Date: Sun, 15 Nov 2020 16:31:05 +0530
Subject: [PATCH] (eshell-invoke-directly) - use 'eshell-find-alias-function'
 instead of fboundp

---
 lisp/eshell/esh-cmd.el | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lisp/eshell/esh-cmd.el b/lisp/eshell/esh-cmd.el
index e0348ba501..e54caf46fc 100644
--- a/lisp/eshell/esh-cmd.el
+++ b/lisp/eshell/esh-cmd.el
@@ -920,7 +920,7 @@ eshell-invoke-directly
 		       (funcall pred name))
 		  (throw 'simple nil)))
 	    t))
-	 (fboundp (intern-soft (concat "eshell/" name))))))
+	 (eshell-find-alias-function name))))
 
 (defun eshell-eval-command (command &optional input)
   "Evaluate the given COMMAND iteratively."
-- 
2.28.0

bug#43772: Fix for bug#43772

[Lars Ingebrigtsen]

Ruthra Kumar <ruthrab@gmail.com> writes:

> eshell-tramp is disabled by default. So, eshell-invoke-directly should
> return nil for su and sudo ( I'm new to eshell as well. So, I might be
> wrong here ). Replacing fboundp with 'eshell-find-alias-function'
> should fix this. So far, I've tested locally and it is working fine.

Thanks; I tested it and it fixes the reported case, while apparently
having no other obvious negative effects, so I've applied it to Emacs
28.  (I'm not overly familiar with how eshell is supposed to work,
though...)

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