Re: INSIDE_EMACS and Tramp

[Michael Albinus <michael.albinus@gmx.de>]

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Federico Tedin <federicotedin@gmail.com> writes:

> Hi Michael,

Hi Federico,

> OK, I see that it is more useful in this case to have a list of
> functions that are called rather than a fixed list of strings. However I
> didn't understand your use of `run-hooks' - wouldn't this function call
> return nil in all cases? What would be an easy way of getting the
> results of calling all the hooks?

You're right, `run-hooks' was a stupid idea. I have adapted my proposal
and prepared a patch which works for me as expected. See appended.

Eli, would it be OK to push something like this to master?

> - Fede

Best regards, Michael.


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diff --git a/lisp/comint.el b/lisp/comint.el
index ea06f8af87..1045d02641 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -831,7 +831,7 @@ comint-exec-1
   (let ((process-environment
 	 (nconc
           (comint-term-environment)
-	  (list (format "INSIDE_EMACS=%s,comint" emacs-version))
+	  (list (inside-emacs-envvar "comint"))
 	  process-environment))
 	(default-directory
 	  (if (file-accessible-directory-p default-directory)
diff --git a/lisp/epg.el b/lisp/epg.el
index 222fd913e1..a5c06c9ae8 100644
--- a/lisp/epg.el
+++ b/lisp/epg.el
@@ -606,8 +606,7 @@ epg--start
 	    (cons (concat "GPG_TTY=" terminal-name)
 		  (cons "TERM=xterm" process-environment))))
     (setq process-environment
-	  (cons (format "INSIDE_EMACS=%s,epg" emacs-version)
-		process-environment))
+	  (cons (inside-emacs-envvar "epg") process-environment))
     ;; Record modified time of gpg-agent socket to restore the Emacs
     ;; frame on text terminal in `epg-wait-for-completion'.
     ;; See
diff --git a/lisp/eshell/em-dirs.el b/lisp/eshell/em-dirs.el
index 51df6fa1d5..7218279e08 100644
--- a/lisp/eshell/em-dirs.el
+++ b/lisp/eshell/em-dirs.el
@@ -168,9 +168,6 @@ eshell-dirstack
 (defvar eshell-last-dir-ring nil
   "The last directory that Eshell was in.")

-(defconst eshell-inside-emacs (format "%s,eshell" emacs-version)
-  "Value for the `INSIDE_EMACS' environment variable.")
-
 ;;; Functions:

 (defun eshell-dirs-initialize ()    ;Called from `eshell-mode' via intern-soft!
@@ -195,7 +192,8 @@ eshell-dirs-initialize
 			  (expand-file-name
 			   (ring-ref eshell-last-dir-ring 0))))
             t)
-           ("INSIDE_EMACS" eshell-inside-emacs
+           ("INSIDE_EMACS" ,(lambda (_indices)
+                              (inside-emacs "eshell"))
             t))))

   (when eshell-cd-on-directory
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index a39d503e22..414fca10cc 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -4166,10 +4166,10 @@ tramp-open-shell
        vec (format
 	    (eval-when-compile
 	      (concat
-	       "exec env TERM='%s' INSIDE_EMACS='%s,tramp:%s' "
+	       "exec env TERM='%s' INSIDE_EMACS='%s' "
 	       "ENV=%s %s PROMPT_COMMAND='' PS1=%s PS2='' PS3='' %s %s"))
             tramp-terminal-type
-            emacs-version tramp-version  ; INSIDE_EMACS
+            (inside-emacs)
             (or (getenv-internal "ENV" tramp-remote-process-environment) "")
 	    (if (stringp tramp-histfile-override)
 		(format "HISTFILE=%s"
diff --git a/lisp/net/trampver.el b/lisp/net/trampver.el
index 8d21133b3b..2351867129 100644
--- a/lisp/net/trampver.el
+++ b/lisp/net/trampver.el
@@ -76,6 +76,13 @@ tramp-repository-version
             (replace-regexp-in-string "\n" "" (emacs-version))))))
   (unless (string-equal "ok" x) (error "%s" x)))

+;; `inside-emacs-functions' has been introduces with Emacs 28.1.
+(when (symbolp inside-emacs-functions)
+  (add-hook
+   'inside-emacs-functions
+   (lambda ()
+     (when (file-remote-p default-directory) "tramp:2.5.0-pre"))))
+
 ;; Tramp versions integrated into Emacs.  If a user option declares a
 ;; `:package-version' which doesn't belong to an integrated Tramp
 ;; version, it must be added here as well (see `tramp-syntax', for
diff --git a/lisp/progmodes/compile.el b/lisp/progmodes/compile.el
index a76a3c44a3..65c5257d93 100644
--- a/lisp/progmodes/compile.el
+++ b/lisp/progmodes/compile.el
@@ -1823,7 +1823,7 @@ compilation-start
 	     (append
 	      compilation-environment
               (comint-term-environment)
-	      (list (format "INSIDE_EMACS=%s,compile" emacs-version))
+	      (list (inside-emacs-envvar "compile"))
 	      (copy-sequence process-environment))))
 	(set (make-local-variable 'compilation-arguments)
 	     (list command mode name-function highlight-regexp))
diff --git a/lisp/simple.el b/lisp/simple.el
index b5ba05426f..70621225ec 100644
--- a/lisp/simple.el
+++ b/lisp/simple.el
@@ -4295,6 +4295,29 @@ list-processes
     (tabulated-list-print))
   (display-buffer buffer)
   nil)
+
+(defvar inside-emacs-functions nil
+  "List of functions to compose the environment variable INSIDE_EMACS.
+Every package which needs to set a string in that envirenmont
+variable shall add a function without arguments, which returns
+the respective string, or nil.")
+
+(defun inside-emacs (&optional context)
+  "Return the string to be set in environment variable INSIDE_EMACS.
+CONTEXT could be a string which is added."
+  (mapconcat
+   #'identity
+   (delq nil (append `(,emacs-version
+ 	               ,(and (stringp context) context))
+ 	             (mapcar #'funcall inside-emacs-functions)))
+   ","))
+
+(defun inside-emacs-envvar (&optional context)
+  "Return the \"INSIDE_EMACS=...\" string.
+This can be used to modify the `process-environment'.  See
+`inside-emacs' for the CONTEXT parameter."
+  (concat "INSIDE_EMACS=" (inside-emacs context)))
+
 \f
 ;;;; Prefix commands

diff --git a/lisp/term.el b/lisp/term.el
index b990c83cfc..d6a1bdfd1f 100644
--- a/lisp/term.el
+++ b/lisp/term.el
@@ -1535,7 +1535,7 @@ term-exec-1
 	   (format term-termcap-format "TERMCAP="
 		   term-term-name term-height term-width)

-	   (format "INSIDE_EMACS=%s,term:%s" emacs-version term-protocol-version)
+	   (inside-emacs-envvar (format "term:%s" term-protocol-version))
 	   (format "LINES=%d" term-height)
 	   (format "COLUMNS=%d" term-width))
 	  process-environment))