Subject: bug#68618: closed (Re: bug#68618: 29.1; Tramp remote process fails in Eshell)

From: [email-masked] (GNU bug Tracking System)
Date: Sat, 20 Jan 2024 20:10:02 +0000

Your bug report

#68618: 29.1; Tramp remote process fails in Eshell

which was filed against the emacs package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to [email-masked].

-- 
68618: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=68618
GNU Bug Tracking System
Contact [email-masked] with problems

Subject: Re: bug#68618: 29.1; Tramp remote process fails in Eshell
From: Jim Porter <[email-masked]>
To: Sean Devlin <[email-masked]>
Cc: [email-masked]
Date: Sat, 20 Jan 2024 12:09:22 -0800
List-Id: <debbugs-submit.debbugs.gnu.org>

On 1/20/2024 11:38 AM, Sean Devlin wrote:
> Thanks, I didn’t realize 29.2 was out.
> 
> It looks like you’re correct: the bug is resolved in 29.2.

Thanks for checking. Closing this bug now.

Subject: 29.1; Tramp remote process fails in Eshell
From: Sean Devlin <[email-masked]>
To: [email-masked]
Date: Sat, 20 Jan 2024 13:30:55 -0500
List-Id: <debbugs-submit.debbugs.gnu.org>

Hi folks,

I found a situation where a Tramp remote process invoked via Eshell
fails unexpectedly. I discovered this while developing a custom Tramp
method, but it could equally apply to built-in methods under certain
system configurations.

Here's a recipe to reproduce:

1. Create a symlink to the ssh program in an unusual location:

$ mkdir -p /tmp/bin
$ ln -s $(which ssh) /tmp/bin/myssh

2. Start Emacs with this directory in your path:

$ PATH=/tmp/bin:$PATH emacs -Q

3. Evaluate these forms:

(require 'tramp)
(add-to-list 'tramp-methods
             `("myssh"
               (tramp-login-program "myssh")
               ,@(cdr (assoc "ssh" tramp-methods))))

4. M-x eshell
5. In Eshell:

$ cd /myssh:someremote:
$ uname -a

6. The Eshell buffer will show some corrupt output something like:

sh: cd: /root/: No such file or directory
///61166bb64799e9d0ec9f78bc44cc9d3d#$

I did a little debugging, and I found that the "uname -a" process is
created under a let-binding of process-environment established in
eshell-gather-process-output. This binding changes the PATH environment
variable. I think maybe it's setting it to the remote path from the
Tramp session, since our local directory in Eshell is
/myssh:someremote:.

This is a problem for Tramp, since it needs to start up a new "/bin/sh
-i" process to create the connection to run "uname -a" on the remote
host. When it starts the local shell process, it is now using the wrong
executable path, and it cannot find myssh, since it is in a non-standard
location.

You can see this by tracing process-send-string and
internal-default-process-filter before running "uname -a" in
Eshell. When Tramp tries to send "myssh ..." to the /bin/sh process, it
will get back an error saying myssh cannot be found.

I think Tramp and/or Eshell need to make sure this /bin/sh subprocess is
started with the local executable path and not the path from the remote
host.

There is a simple workaround: update your Tramp method's login program
to use an absolute filename, e.g. /tmp/bin/myssh.

Thanks!

In GNU Emacs 29.1
Windowing system distributor 'Apple'
System Description:  macOS 14

Configured using:
'configure --with-ns '--enable-locallisppath=/Library/Application
Support/Emacs/${version}/site-lisp:/Library/Application
Support/Emacs/site-lisp' --with-modules 'CFLAGS=-DFD_SETSIZE=10000
-DDARWIN_UNLIMITED_SELECT' --with-x-toolkit=no'

Configured features:
ACL GLIB GMP GNUTLS JPEG JSON LIBXML2 MODULES NOTIFY KQUEUE NS PDUMPER
PNG RSVG SQLITE3 THREADS TIFF TOOLKIT_SCROLL_BARS TREE_SITTER ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Eshell

Minor modes in effect:
  eshell-prompt-mode: t
  eshell-hist-mode: t
  eshell-pred-mode: t
  eshell-cmpl-mode: t
  eshell-proc-mode: t
  eshell-arg-mode: t
  shell-dirtrack-mode: t
  tooltip-mode: t
  global-eldoc-mode: t
  show-paren-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  tool-bar-mode: t
  menu-bar-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  line-number-mode: t
  indent-tabs-mode: t
  transient-mark-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t

Load-path shadows:
None found.

Features:
(shadow sort mail-extr emacsbug message mailcap yank-media puny rfc822
mml mml-sec epa derived epg rfc6068 epg-config gnus-util
text-property-search mm-decode mm-bodies mm-encode mail-parse rfc2231
mailabbrev gmm-utils mailheader sendmail rfc2047 rfc2045 ietf-drums
mm-util mail-prsvr mail-utils em-unix em-term term disp-table ehelp
em-script em-prompt em-ls em-hist em-pred em-glob em-extpipe em-cmpl
em-dirs esh-var em-basic em-banner em-alias esh-mode eshell esh-cmd
generator esh-ext esh-opt esh-proc esh-io esh-arg esh-module esh-groups
esh-util dired-aux dired dired-loaddefs cl-extra pp cl-print tramp-adb
tramp-archive tramp-cache time-stamp tramp-cmds tramp-container
tramp-ftp tramp-gvfs url-util url-parse url-vars dbus xml tramp-sh
thingatpt help-fns radix-tree help-mode tramp tramp-loaddefs trampver
tramp-integration files-x tramp-compat rx parse-time iso8601 time-date
format-spec auth-source cl-seq eieio eieio-core cl-macs cl-loaddefs
cl-lib password-cache json map byte-opt gv bytecomp byte-compile shell
subr-x pcomplete comint ansi-osc ansi-color ring rmc iso-transl tooltip
cconv eldoc paren electric uniquify ediff-hook vc-hooks lisp-float-type
elisp-mode mwheel term/ns-win ns-win ucs-normalize mule-util
term/common-win tool-bar dnd fontset image regexp-opt fringe
tabulated-list replace newcomment text-mode lisp-mode prog-mode register
page tab-bar menu-bar rfn-eshadow isearch easymenu timer select
scroll-bar mouse jit-lock font-lock syntax font-core term/tty-colors
frame minibuffer nadvice seq simple cl-generic indonesian philippine
cham georgian utf-8-lang misc-lang vietnamese tibetan thai tai-viet lao
korean japanese eucjp-ms cp51932 hebrew greek romanian slovak czech
european ethiopic indian cyrillic chinese composite emoji-zwj charscript
charprop case-table epa-hook jka-cmpr-hook help abbrev obarray oclosure
cl-preloaded button loaddefs theme-loaddefs faces cus-face macroexp
files window text-properties overlay sha1 md5 base64 format env
code-pages mule custom widget keymap hashtable-print-readable backquote
threads kqueue cocoa ns multi-tty make-network-process emacs)

Memory information:
((conses 16 99526 10654)
(symbols 48 10616 0)
(strings 32 37029 1504)
(string-bytes 1 1188080)
(vectors 16 22340)
(vector-slots 8 297950 17878)
(floats 8 64 26)
(intervals 56 1230 0)
(buffers 984 16))