Tramp ELPA version 2.8.1.4 releasedexternals/tramp

10 files changed, 433 insertions, 146 deletions

diff --git a/README b/README
index 31a29b3..b92dd8a 100644
--- a/README
+++ b/README
@@ -32,11 +32,11 @@ Emacs 28 or older
 
    • Remove all byte-compiled Tramp files
 
-          $ rm -f ~/.emacs.d/elpa/tramp-2.8.1.3/tramp*.elc
+          $ rm -f ~/.emacs.d/elpa/tramp-2.8.1.4/tramp*.elc
 
    • Start Emacs with Tramp's source files
 
-          $ emacs -L ~/.emacs.d/elpa/tramp-2.8.1.3 -l tramp
+          $ emacs -L ~/.emacs.d/elpa/tramp-2.8.1.4 -l tramp
 
      This should not give you the error.
 
@@ -50,7 +50,7 @@ Mitigation of a bug in Emacs 29.1
 ---------------------------------
 
 Due to a bug in Emacs 29.1, you must apply the following change prior
-installation or upgrading Tramp 2.8.1.3 from GNU ELPA:
+installation or upgrading Tramp 2.8.1.4 from GNU ELPA:
 
      (when (string-equal emacs-version "29.1")
        (with-current-buffer
diff --git a/test/tramp-tests.el b/test/tramp-tests.el
index 3972e5f..a19a17d 100644
--- a/test/tramp-tests.el
+++ b/test/tramp-tests.el
@@ -2287,6 +2287,8 @@ being the result.")
 
 (ert-deftest tramp-test03-file-error ()
   "Check that Tramp signals an error in case of connection problems."
+  (skip-unless (tramp-file-name-p tramp-test-vec))
+
   ;; Connect to a non-existing host.
   (let ((vec (copy-tramp-file-name tramp-test-vec))
 	;; Don't poison it.
@@ -4473,6 +4475,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
 	    ;; Check, that files in symlinked directories still work.
 	    (make-symbolic-link tmp-name4 tmp-name6)
 	    (should (file-symlink-p tmp-name6))
+	    (should (file-directory-p tmp-name6))
 	    (should-not (file-regular-p tmp-name6))
 	    (write-region "foo" nil (expand-file-name "foo" tmp-name6))
 	    (delete-file (expand-file-name "foo" tmp-name6))
@@ -5393,7 +5396,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   ;; boundaries are always incorrect before that.
   (skip-unless (tramp--test-emacs31-p))
 
-  (let ((remote (file-remote-p ert-remote-temporary-file-directory)))
+  (when-let* ((remote (file-remote-p ert-remote-temporary-file-directory)))
     (dolist
 	(file `(,remote ,(concat remote "/~/")
 		,(concat remote "/usr//usr/") ,(concat remote remote "//usr/")))
@@ -8858,10 +8861,19 @@ process sentinels.  They shall not disturb each other."
   "Test operation."
   "Test operation")
 
-(defun tramp--handler-for-test-operation (&optional _file)
+(defun tramp--handle-test-operation (&optional _file)
   "Test operation handler."
   "Test operation handler")
 
+(defun tramp--handle-process-id (process)
+  "Handler for `process-id'."
+  ;; Return something else.
+  (1+ (tramp-run-real-handler #'process-id (list process))))
+
+(defun tramp--test-operation-file-name-for-operation (_operation &optional _file)
+  "Helper function for `tramp--test-operation' handler."
+  default-directory)
+
 (ert-deftest tramp-test49-external-backend-function ()
   "Check that Tramp handles external functions for a given backend."
   :tags '(:expensive-test)
@@ -8878,78 +8890,167 @@ process sentinels.  They shall not disturb each other."
     ;; There is no backend specific code.
     (should-not
      (string-equal (tramp--test-operation ert-remote-temporary-file-directory)
-		   (tramp--handler-for-test-operation
+		   (tramp--handle-test-operation
 		    ert-remote-temporary-file-directory)))
     (should-not
      (string-equal (tramp--test-operation temporary-file-directory)
-		   (tramp--handler-for-test-operation
+		   (tramp--handle-test-operation
 		    temporary-file-directory)))
     (let ((default-directory ert-remote-temporary-file-directory))
       (should-not
        (string-equal (tramp--test-operation)
-		     (tramp--handler-for-test-operation))))
+		     (tramp--handle-test-operation))))
     (let ((default-directory temporary-file-directory))
       (should-not
        (string-equal (tramp--test-operation)
-		     (tramp--handler-for-test-operation))))
+		     (tramp--handle-test-operation))))
 
     (should-error
      (tramp-add-external-operation
-      #'tramp--test-operation
-      #'tramp--handler-for-test-operation 'foo)
+      #'tramp--test-operation #'tramp--handle-test-operation 'foo)
      :type 'file-missing)
+    (should-error
+     (tramp-add-external-operation
+      #'tramp--test-operation #'tramp--handle-test-operation backend 'foo)
+     :type 'remote-file-error)
+    ;; This doesn't hurt.
     (tramp-add-external-operation
-     #'tramp--test-operation
-     #'tramp--handler-for-test-operation backend)
+     #'tramp--test-operation #'tramp--handle-test-operation backend 'file)
+
     ;; The backend specific function is called.
     (should
      (string-equal (tramp--test-operation ert-remote-temporary-file-directory)
-		   (tramp--handler-for-test-operation
+		   (tramp--handle-test-operation
 		    ert-remote-temporary-file-directory)))
     (should-not
      (string-equal (tramp--test-operation temporary-file-directory)
-		   (tramp--handler-for-test-operation
+		   (tramp--handle-test-operation
 		    temporary-file-directory)))
     (let ((default-directory ert-remote-temporary-file-directory))
       (should
        (string-equal (tramp--test-operation)
-		     (tramp--handler-for-test-operation)))
+		     (tramp--handle-test-operation)))
       (should
        (string-equal (tramp--test-operation "foo")
-		     (tramp--handler-for-test-operation "foo"))))
+		     (tramp--handle-test-operation "foo"))))
     (let ((default-directory temporary-file-directory))
       (should-not
        (string-equal (tramp--test-operation)
-		     (tramp--handler-for-test-operation)))
+		     (tramp--handle-test-operation)))
       (should-not
        (string-equal (tramp--test-operation "foo")
-		     (tramp--handler-for-test-operation "foo"))))
+		     (tramp--handle-test-operation "foo"))))
 
-    (tramp-remove-external-operation
-     #'tramp--test-operation backend)
+    (tramp-remove-external-operation #'tramp--test-operation backend)
     ;; There is no backend specific code.
     (should-not
      (string-equal (tramp--test-operation ert-remote-temporary-file-directory)
-		   (tramp--handler-for-test-operation
+		   (tramp--handle-test-operation
 		    ert-remote-temporary-file-directory)))
     (should-not
      (string-equal (tramp--test-operation temporary-file-directory)
-		   (tramp--handler-for-test-operation
+		   (tramp--handle-test-operation
 		    temporary-file-directory)))
     (let ((default-directory ert-remote-temporary-file-directory))
       (should-not
        (string-equal (tramp--test-operation)
-		     (tramp--handler-for-test-operation)))
+		     (tramp--handle-test-operation)))
+      (should-not
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+    (let ((default-directory temporary-file-directory))
+      (should-not
+       (string-equal (tramp--test-operation)
+		     (tramp--handle-test-operation)))
+      (should-not
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+
+    ;; Test `default-directory' arg type.
+    (tramp-add-external-operation
+     #'tramp--test-operation #'tramp--handle-test-operation
+     backend 'default-directory)
+
+    ;; The backend specific function is called.
+    (let ((default-directory ert-remote-temporary-file-directory))
+      (should
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+    (let ((default-directory temporary-file-directory))
+      (should-not
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+
+    (tramp-remove-external-operation #'tramp--test-operation backend)
+    ;; There is no backend specific code.
+    (let ((default-directory ert-remote-temporary-file-directory))
+      (should-not
+       (string-equal (tramp--test-operation)
+		     (tramp--handle-test-operation)))
+      (should-not
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+    (let ((default-directory temporary-file-directory))
+      (should-not
+       (string-equal (tramp--test-operation)
+		     (tramp--handle-test-operation)))
+      (should-not
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+
+    ;; Test `process' arg type.
+    (when (and (tramp--test-supports-processes-p) (not (tramp--test-smb-p)))
+      (let ((default-directory ert-remote-temporary-file-directory)
+	    proc command id)
+	(unwind-protect
+	    (with-temp-buffer
+	      (setq command '("cat")
+		    proc
+		    (make-process
+		     :name "test" :buffer (current-buffer) :command command
+		     :file-handler t))
+	      (should (processp proc))
+	      (should (eq (process-status proc) 'run))
+	      (should (natnump (setq id (process-id proc))))
+	      (tramp-add-external-operation
+	       #'process-id #'tramp--handle-process-id backend 'process)
+	      (should (= (process-id proc) (1+ id))))
+
+	  ;; Cleanup.
+	  (tramp-remove-external-operation #'process-id backend)
+	  (ignore-errors (delete-process proc)))))
+
+    ;; Test function arg type.
+    (tramp-add-external-operation
+     #'tramp--test-operation #'tramp--handle-test-operation
+     backend #'tramp--test-operation-file-name-for-operation)
+
+    ;; The backend specific function is called.
+    (let ((default-directory ert-remote-temporary-file-directory))
+      (should
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+    (let ((default-directory temporary-file-directory))
+      (should-not
+       (string-equal (tramp--test-operation "foo")
+		     (tramp--handle-test-operation "foo"))))
+
+    (tramp-remove-external-operation #'tramp--test-operation backend)
+    ;; There is no backend specific code.
+    (let ((default-directory ert-remote-temporary-file-directory))
+      (should-not
+       (string-equal (tramp--test-operation)
+		     (tramp--handle-test-operation)))
       (should-not
        (string-equal (tramp--test-operation "foo")
-		     (tramp--handler-for-test-operation "foo"))))
+		     (tramp--handle-test-operation "foo"))))
     (let ((default-directory temporary-file-directory))
       (should-not
        (string-equal (tramp--test-operation)
-		     (tramp--handler-for-test-operation)))
+		     (tramp--handle-test-operation)))
       (should-not
        (string-equal (tramp--test-operation "foo")
-		     (tramp--handler-for-test-operation "foo"))))))
+		     (tramp--handle-test-operation "foo"))))))
 
 ;; This test is inspired by Bug#29163.
 (ert-deftest tramp-test50-auto-load ()
diff --git a/texi/tramp.texi b/texi/tramp.texi
index 3af4dfb..79271d2 100644
--- a/texi/tramp.texi
+++ b/texi/tramp.texi
@@ -2042,6 +2042,12 @@ Access of a hadoop/hdfs file system.  A file is accessed via
 the user that you want to use, and @samp{node} is the name of the
 hadoop server.
 
+@c @cindex method @option{rpc}
+@c @cindex @option{rpc} method
+@c @item tramp-rpc
+@c This is a @value{tramp} backend of its own.  It uses a remote server
+@c process to serve the requests, which gains better performance.
+
 @cindex method @option{vagrant}
 @cindex @option{vagrant} method
 @item vagrant-tramp
@@ -5556,6 +5562,8 @@ operations.  For example, the GNU ELPA package @file{tramp-hlo}
 implements specialized versions of @code{dir-locals--all-files},
 @code{locate-dominating-file} and @code{dir-locals-find-file} for
 @value{tramp}'s @code{tramp-sh} backend (@pxref{New operations}).
+@c The NonGNU ELPA package @file{tramp-rpc} implements an own
+@c @value{tramp} backend (@pxref{New operations}).
 @end itemize
 
 
@@ -6728,6 +6736,45 @@ See the docstring of variable @code{tramp-methods} for possible
 @code{foo-tramp-executable} in this example would be a Lisp constant,
 which is the program name of @command{foo}.
 
+If a parameter doesn't have a static value but must be computed at
+runtime, a format specifier can be used, like @t{"%h"} in the example
+above.  See the docstring of @code{tramp-methods}, which patterns are
+expanded in which parameter.  Furthermore, other format specifiers can
+be added via the variable @code{tramp-extra-expand-args}.
+
+The following parameters expand format specifiers for the
+@code{tramp-sh} backend: @code{tramp-copy-args},
+@code{tramp-copy-env}, @code{tramp-copy-file-name},
+@code{tramp-login-args}, @code{tramp-login-program},
+@code{tramp-remote-copy-args}.
+
+The example above could use
+
+@lisp
+(tramp-login-program "%b")
+@end lisp
+
+And you could set @code{tramp-extra-expand-args} as connection-local value:
+
+@lisp
+@group
+(defun foo-tramp-get-login-program (vec)
+  "Return connection-local value of `tramp-login-program'."
+  @dots{})
+@end group
+
+@group
+(connection-local-set-profile-variables
+ 'foo-tramp-connection-local-default-profile
+ '((tramp-extra-expand-args
+    ?b (foo-tramp-get-login-program (car tramp-current-connection)))))
+
+(connection-local-set-profiles
+ '(:application tramp :protocol "foo")
+ foo-tramp-connection-local-default-profile)
+@end group
+@end lisp
+
 Another initialization could tell @value{tramp} which are the default
 user and host name for method @option{foo}.  This is done by calling
 @code{tramp-set-completion-function}:
@@ -6828,15 +6875,12 @@ For example, it could implement this by using an own shell script
 which collects the information on the remote host for this very
 special purpose with one round-trip per-call.
 
-@defun tramp-add-external-operation operation function backend
+@defun tramp-add-external-operation operation function backend &optional arg-type
 This adds an implementation of @var{operation} to @value{tramp}'s
 backend @var{backend}.  @var{function} is the new implementation.
 
 Both @var{operation} and @var{function} shall be function symbols.
-They must have the same argument list.  The first argument is used to
-determine, whether @value{tramp} is invoked (check for remote file
-name syntax).  It must be a string or nil, in the latter case
-@code{default-directory} is used for the check.
+They must have the same argument list.
 
 @var{backend}, also a symbol, is the feature name of a @value{tramp}
 backend (except @code{tramp-ftp}).  The new implementation will be
@@ -6844,18 +6888,18 @@ applied only for this backend.  Example:
 
 @lisp
 @group
-(defun test-operation (file)
+(defun my-test-operation (file)
   (message "Original implementation for %s" file))
 @end group
 
 @group
-(defun handle-test-operation (file)
+(defun my-handle-test-operation (file)
   (message "Handler implementation for %s" file))
 @end group
 
 @group
 (tramp-add-external-operation
- #'test-operation #'handle-test-operation 'tramp-sh)
+ #'my-test-operation #'my-handle-test-operation 'tramp-sh)
 @end group
 @end lisp
 
@@ -6864,23 +6908,24 @@ Then we have the different use cases:
 @lisp
 @group
 ;; Local file name.
-(test-operation "/a/b")
+(my-test-operation "/a/b")
 @result{} "Original implementation for /a/b"
 @end group
 
 @group
 ;; Remote file name, handled by `tramp-sh'.
-(test-operation "/ssh::/a/b")
+(my-test-operation "/ssh::/a/b")
 @result{} "Handler implementation for /ssh::/a/b"
 @end group
 
 @group
 ;; Remote file name, handled by `tramp-gvfs'.
-(test-operation "/sftp::/a/b")
+(my-test-operation "/sftp::/a/b")
 @result{} "Original implementation for /sftp::/a/b"
 @end group
 @end lisp
 
+@findex with-parsed-tramp-file-name
 @var{function} is implemented like an ordinary @value{tramp} backend
 handler, see the examples in @code{tramp-<backend>-handle-*} and
 @code{tramp-handle-*}.  It can expect, that the first argument (or
@@ -6888,9 +6933,71 @@ handler, see the examples in @code{tramp-<backend>-handle-*} and
 syntax.  It shall use @value{tramp} internal macros and functions like
 @code{with-parsed-tramp-file-name} and the different cache functions.
 
+@findex tramp-run-real-handler
+If @var{function} must call the original function, this can be done
+via @code{tramp-run-real-handler}.  The implementation of the example
+could look like:
+
+@lisp
+@group
+(defun my-handle-test-operation (file)
+  (message "Entry handler implementation for %s" file)
+  (tramp-run-real-handler #'my-test-operation (list file))
+  (message "Exit handler implementation for %s" file))
+@end group
+
+@group
+(my-test-operation "/ssh::/a/b")
+@result{} "Entry handler implementation for /ssh::/a/b
+   Original implementation for /ssh::/a/b
+   Exit handler implementation for /ssh::/a/b"
+@end group
+@end lisp
+
 If the same @var{function} shall be used for different @value{tramp}
 backends, @code{tramp-add-external-operation} must be called for every
 backend, respectively.
+
+The optional argument @var{arg-type} specisfies, which argument of
+@var{operation} shall be used in order to determine, whether the
+handler @var{function} should be called.  It can be
+
+@itemize @minus
+@item @code{file}@*
+The first argument of @var{operation} is the remote file name to be
+checked.  This is the default, if @var{arg-type} is @code{nil}.
+
+@item @code{default-directory}@*
+@code{default-directory} is the remote file name to be checked.
+
+@item @code{process}@*
+@code{default-directory} of the process buffer of the first argument
+of @var{operation}, a process, is the remote file name to be checked.
+@end itemize
+
+If the first argument of @var{operation} is nil,
+@code{default-directory} is the remote file name to be checked in case
+of @var{arg-type} being @code{file} or @code{process}.
+
+@findex tramp-file-name-for-operation
+If @var{arg-type} is a function symbol, it will be called with the
+same arguments as @code{tramp-file-name-for-operation}.  It must
+return a string, which is the remote file name to be checked.
+
+The example above could be changed like this:
+
+@lisp
+@group
+(defun my-file-name-for-test-operation (operation &rest args)
+  (if (stringp (car args)) (car args) default-directory))
+@end group
+
+@group
+(tramp-add-external-operation
+ #'my-test-operation #'my-handle-test-operation 'tramp-sh
+ #'my-file-name-for-test-operation)
+@end group
+@end lisp
 @end defun
 
 @defun tramp-remove-external-operation operation backend
@@ -6902,7 +7009,7 @@ they are kept.  Example:
 @lisp
 @group
 (tramp-remove-external-operation
- #'test-operation 'tramp-sh)
+ #'my-test-operation 'tramp-sh)
 @end group
 @end lisp
 @end defun
@@ -6918,6 +7025,10 @@ An example implementing this mechanism is the GNU ELPA package
 @code{dir-locals-find-file} for @value{tramp}'s @code{tramp-sh}
 backend.
 
+@c Another example is the NonGNU ELPA package @file{tramp-rpc}.  It
+@c provides an own @value{tramp} backend, using a server process on the
+@c remote host.
+
 
 @node Traces and Profiles
 @chapter How to Customize Traces
diff --git a/texi/trampver.texi b/texi/trampver.texi
index cf9aef6..cf3fd7a 100644
--- a/texi/trampver.texi
+++ b/texi/trampver.texi
@@ -7,7 +7,7 @@
 
 @c In the  Tramp GIT, the version number and the bug report address
 @c are auto-frobbed from configure.ac.
-@set trampver 2.8.1.3
+@set trampver 2.8.1.4
 @set trampurl https://www.gnu.org/software/tramp/
 @set tramp-bug-report-address tramp-devel@@gnu.org
 @set emacsver 28.1
diff --git a/tramp-cache.el b/tramp-cache.el
index 1fc3fb3..b47a2aa 100644
--- a/tramp-cache.el
+++ b/tramp-cache.el
@@ -161,6 +161,20 @@ If KEY is `tramp-cache-undefined', don't create anything, and return nil."
 ;; would fail.
 (function-put #'tramp-get-hash-table 'tramp-suppress-trace t)
 
+(defsubst tramp-suppress-remote-file-name-inhibit-cache ()
+  "Weaken `remote-file-name-inhibit-cache'.
+This is meant to be let-bound for code over many cache operations, like
+in large directories."
+  ;; If `remote-file-name-inhibit-cache' is already `nil', keep it.
+  (cond
+   (;; A timestamp.  Keep it.
+    (consp remote-file-name-inhibit-cache) remote-file-name-inhibit-cache)
+   (;; A number of seconds.  Set a timestamp with the difference.
+    (numberp remote-file-name-inhibit-cache)
+    (time-subtract nil remote-file-name-inhibit-cache))
+   (;; Cache is disabled.  Set a timestamp from now on.
+    t (current-time))))
+
 ;;;###tramp-autoload
 (defun tramp-get-file-property (key file property &optional default)
   "Get the PROPERTY of FILE from the cache context of KEY.
diff --git a/tramp-container.el b/tramp-container.el
index 91d9b23..fec2e16 100644
--- a/tramp-container.el
+++ b/tramp-container.el
@@ -266,7 +266,7 @@ BODY is the backend specific code."
 		    tramp--last-hop-directory)
 	       tramp-compat-temporary-file-directory))
 	  (program (let ((tramp-verbose 0))
-		     (tramp-get-method-parameter
+		     (tramp-expand-args
 		      (make-tramp-file-name :method ,method)
 		      'tramp-login-program)))
 	  (vec (when (tramp-tramp-file-p default-directory)
@@ -656,10 +656,9 @@ see its function help for a description of the format."
    '((tramp-config-check . tramp-kubernetes--current-context-data)
      ;; This variable will be eval'ed in `tramp-expand-args'.
      (tramp-extra-expand-args
-      . (?a (tramp-kubernetes--container (car tramp-current-connection))
-	 ?h (tramp-kubernetes--pod (car tramp-current-connection))
-	 ?x (tramp-kubernetes--context-namespace
-	     (car tramp-current-connection)))))
+      ?a (tramp-kubernetes--container (car tramp-current-connection))
+      ?h (tramp-kubernetes--pod (car tramp-current-connection))
+      ?x (tramp-kubernetes--context-namespace (car tramp-current-connection))))
    "Default connection-local variables for remote kubernetes connections.")
 
  (connection-local-set-profile-variables
diff --git a/tramp-sh.el b/tramp-sh.el
index 08a44c8..8cade9c 100644
--- a/tramp-sh.el
+++ b/tramp-sh.el
@@ -4688,19 +4688,22 @@ process to set up.  VEC specifies the connection."
 	(tramp-send-command
 	 vec (format "unset %s" (string-join unset " ")) t)))
 
+    ;; FIXME: This doesn't work with `tramp-test42-utf8' and "/ssh::tmp".
     ;; Set connection-local variable `command-line-max-length'.
     ;; `command-line-max-length' exists since Emacs 31.
     ;; `connection-local-profile-name-for-criteria' exists since Emacs 29.1.
     ;; We simulate it with `make-symbol'.
-    (when (boundp 'command-line-max-length)
-      (let* ((criteria (tramp-get-connection-local-criteria vec))
-	     (profile (if (fboundp 'connection-local-profile-name-for-criteria)
-			  (connection-local-profile-name-for-criteria criteria)
-			(make-symbol "generated-profile-name"))))
-	(connection-local-set-profile-variables
-	 profile
-	 `((command-line-max-length . ,(tramp-get-remote-pipe-buf vec))))
-	(connection-local-set-profiles criteria profile)))))
+    ;; (when (boundp 'command-line-max-length)
+    ;;   (let* ((arg-max (tramp-get-remote-arg-max vec))
+    ;; 	     (criteria (tramp-get-connection-local-criteria vec))
+    ;; 	     (profile (if (fboundp 'connection-local-profile-name-for-criteria)
+    ;; 			  (connection-local-profile-name-for-criteria criteria)
+    ;; 			(make-symbol "generated-profile-name"))))
+    ;; 	(connection-local-set-profile-variables
+    ;; 	 profile
+    ;; 	 `((command-line-max-length . ,(if arg-max (floor arg-max 4) 4094))))
+    ;; 	(connection-local-set-profiles criteria profile)))))
+    ))
 
 ;; Old text from documentation of tramp-methods:
 ;; Using a uuencode/uudecode inline method is discouraged, please use one
@@ -5036,8 +5039,7 @@ Goes through the list `tramp-inline-compress-commands'."
 
    ;; Use plink options.
    ((string-match-p
-     (rx "plink" (? ".exe") eol)
-     (tramp-get-method-parameter vec 'tramp-login-program))
+     (rx "plink" (? ".exe") eol) (tramp-expand-args vec 'tramp-login-program))
     (concat
      (if (eq tramp-use-connection-share 'suppress)
 	 "-noshare" "-share")
@@ -5397,9 +5399,7 @@ connection if a previous connection has died for some reason."
 			  (tramp-get-method-parameter
 			   hop 'tramp-connection-timeout
 			   tramp-connection-timeout))
-			 (command
-			  (tramp-get-method-parameter
-			   hop 'tramp-login-program))
+			 (command (tramp-expand-args hop 'tramp-login-program))
 			 ;; We don't create the temporary file.  In
 			 ;; fact, it is just a prefix for the
 			 ;; ControlPath option of ssh; the real
@@ -5805,12 +5805,24 @@ Nonexistent directories are removed from spec."
 	       remote-path :test #'string-equal :from-end t))
 
 	;; Remove non-existing directories.
-	(let (remote-file-name-inhibit-cache)
+	(let ((remote-file-name-inhibit-cache
+	       (tramp-suppress-remote-file-name-inhibit-cache)))
 	  (tramp-bundle-read-file-names vec remote-path)
 	  (cl-remove-if
 	   (lambda (x) (not (tramp-get-file-property vec x "file-directory-p")))
 	   remote-path))))))
 
+(defun tramp-get-remote-arg-max (vec)
+  "Return ARG_MAX config from the remote side."
+  (with-tramp-connection-property vec "arg-max"
+    (when-let* ((result
+		 (tramp-send-command-and-read
+		  vec (format "getconf ARG_MAX 2>%s"
+			      (tramp-get-remote-null-device vec))
+		  'noerror))
+		((natnump result)))
+      result)))
+
 ;; The PIPE_BUF in POSIX [1] can be as low as 512 [2].  Here are the values
 ;; on various platforms:
 ;;   - 512 on macOS, FreeBSD, NetBSD, OpenBSD, MirBSD, native Windows.
diff --git a/tramp-sshfs.el b/tramp-sshfs.el
index 2cb5b5b..f407315 100644
--- a/tramp-sshfs.el
+++ b/tramp-sshfs.el
@@ -269,7 +269,7 @@ arguments to pass to the OPERATION."
       (setq ret
 	    (apply
 	     #'tramp-call-process
-	     v (tramp-get-method-parameter v 'tramp-login-program)
+	     v (tramp-expand-args v 'tramp-login-program)
 	     nil outbuf display
 	     (tramp-expand-args
 	      v 'tramp-login-args nil
diff --git a/tramp.el b/tramp.el
index b54ae51..5705a2b 100644
--- a/tramp.el
+++ b/tramp.el
@@ -7,7 +7,7 @@
 ;; Maintainer: Michael Albinus <michael.albinus@gmx.de>
 ;; Keywords: comm, processes
 ;; Package: tramp
-;; Version: 2.8.1.3
+;; Version: 2.8.1.4
 ;; Package-Requires: ((emacs "28.1"))
 ;; Package-Type: multi
 ;; URL: https://www.gnu.org/software/tramp/
@@ -2424,7 +2424,22 @@ arguments to pass to the OPERATION."
     (apply operation args)))
 
 (defvar tramp-file-name-for-operation-external nil
-  "List of operations added by external packages.")
+  "Alist of operations added by external packages.
+An entry has the form `(OPERATION . ARG-TYPE)'.  ARG-TYPE can be the
+symbol
+
+- `file': the first argument of OERATION is the remote file name to be
+  checked.
+- `default-directory': `default-directory' is the remote file name to be
+  checked.
+- `process': `default-directory' of the process buffer of the first
+  argument of OPERATION is the remote file name to be checked.
+
+If the first argument of OPERATION is nil, `default-directory' is the
+remote file name to be checked in case of `file' and `process'.
+
+If ARG-TYPE is a function symbol, it will be called with the same
+arguments as `tramp-file-name-for-operation'.  It must return a string.")
 
 ;; We handle here all file primitives.  Most of them have the file
 ;; name as first parameter; nevertheless we check for them explicitly
@@ -2434,9 +2449,7 @@ arguments to pass to the OPERATION."
 ;; ease the life if `file-name-handler-alist' would support a decision
 ;; function as well but regexp only.
 ;; Operations added by external packages are kept in
-;; `tramp-file-name-for-operation-external'.  They expect the file
-;; name to be checked as first argument or, if there isn't any
-;; argument, `default-directory'.
+;; `tramp-file-name-for-operation-external'.
 (defun tramp-file-name-for-operation (operation &rest args)
   "Return file name related to OPERATION file primitive.
 ARGS are the arguments OPERATION has been called with.
@@ -2446,30 +2459,32 @@ first argument of `expand-file-name' is absolute and not remote.
 Must be handled by the callers."
   (cond
    ;; FILE resp DIRECTORY.
-   ((memq operation
-	  '(access-file byte-compiler-base-file-name delete-directory
-	    delete-file diff-latest-backup-file directory-file-name
-	    directory-files directory-files-and-attributes dired-compress-file
-	    dired-uncache file-acl file-accessible-directory-p file-attributes
-	    file-directory-p file-executable-p file-exists-p file-local-copy
-	    file-locked-p file-modes file-name-as-directory
-	    file-name-case-insensitive-p file-name-directory
-	    file-name-nondirectory file-name-sans-versions
-	    file-notify-add-watch file-ownership-preserved-p file-readable-p
-	    file-regular-p file-remote-p file-selinux-context file-symlink-p
-	    file-system-info file-truename file-writable-p
-	    find-backup-file-name get-file-buffer
-	    insert-directory insert-file-contents load lock-file make-directory
-	    make-lock-file-name set-file-acl set-file-modes
-	    set-file-selinux-context set-file-times substitute-in-file-name
-	    unhandled-file-name-directory unlock-file vc-registered
-	    ;; Emacs 28- only.
-	    make-directory-internal
-	    ;; Emacs 29+ only.
-	    abbreviate-file-name
-	    ;; Tramp internal magic file name function.
-	    tramp-set-file-uid-gid))
-    (if (file-name-absolute-p (nth 0 args))
+   ((or
+     (memq operation
+	   '(access-file byte-compiler-base-file-name delete-directory
+	     delete-file diff-latest-backup-file directory-file-name
+	     directory-files directory-files-and-attributes dired-compress-file
+	     dired-uncache file-acl file-accessible-directory-p file-attributes
+	     file-directory-p file-executable-p file-exists-p file-local-copy
+	     file-locked-p file-modes file-name-as-directory
+	     file-name-case-insensitive-p file-name-directory
+	     file-name-nondirectory file-name-sans-versions
+	     file-notify-add-watch file-ownership-preserved-p file-readable-p
+	     file-regular-p file-remote-p file-selinux-context file-symlink-p
+	     file-system-info file-truename file-writable-p
+	     find-backup-file-name get-file-buffer
+	     insert-directory insert-file-contents load lock-file make-directory
+	     make-lock-file-name set-file-acl set-file-modes
+	     set-file-selinux-context set-file-times substitute-in-file-name
+	     unhandled-file-name-directory unlock-file vc-registered
+	     ;; Emacs 28- only.
+	     make-directory-internal
+	     ;; Emacs 29+ only.
+	     abbreviate-file-name
+	     ;; Tramp internal magic file name function.
+	     tramp-set-file-uid-gid))
+     (eq (alist-get operation tramp-file-name-for-operation-external) 'file))
+    (if (and (stringp (nth 0 args)) (file-name-absolute-p (nth 0 args)))
 	(nth 0 args)
       default-directory))
    ;; STRING FILE.
@@ -2502,31 +2517,45 @@ Must be handled by the callers."
     (buffer-file-name
      (if (bufferp (nth 0 args)) (nth 0 args) (current-buffer))))
    ;; COMMAND.
-   ((memq operation
-	  '(exec-path make-nearby-temp-file make-process process-file
-	    shell-command start-file-process temporary-file-directory
-	    ;; Emacs 29+ only.
-            list-system-processes memory-info process-attributes
-            ;; Emacs 30+ only.
-	    file-group-gid file-user-uid))
+   ((or
+     (memq operation
+	   '(exec-path make-nearby-temp-file make-process process-file
+	     shell-command start-file-process temporary-file-directory
+	     ;; Emacs 29+ only.
+             list-system-processes memory-info process-attributes
+             ;; Emacs 30+ only.
+	     file-group-gid file-user-uid))
+     (eq (alist-get operation tramp-file-name-for-operation-external)
+	 'default-directory))
     default-directory)
-   ;; PROC.
-   ((memq operation '(file-notify-rm-watch file-notify-valid-p))
-    (when (processp (nth 0 args))
-      (tramp-get-default-directory (process-buffer (nth 0 args)))))
+   ;; PROC or BUFFER.
+   ((or
+     (memq operation '(file-notify-rm-watch file-notify-valid-p))
+     (eq (alist-get operation tramp-file-name-for-operation-external) 'process))
+    (or (when-let* (((processp (nth 0 args)))
+		    (vec (process-get (nth 0 args) 'tramp-vector)))
+	  (tramp-make-tramp-file-name vec))
+	(when-let*
+	    ((buf (cond
+		   ((processp (nth 0 args)) (process-buffer (nth 0 args)))
+		   ((bufferp (nth 0 args)) (get-buffer (nth 0 args)))
+		   ((stringp (nth 0 args))
+		    ;; Process or buffer name.
+		    (or (get-process (nth 0 args)) (get-buffer (nth 0 args)))))))
+	  (tramp-get-default-directory buf))
+	""))
    ;; VEC.
    ((memq operation
 	  '(tramp-get-home-directory tramp-get-remote-gid
 	    tramp-get-remote-groups tramp-get-remote-uid))
     (tramp-make-tramp-file-name (nth 0 args)))
-   ;; FILE resp DIRECTORY.
-   ((and (memq operation tramp-file-name-for-operation-external)
-	 (or (stringp (nth 0 args)) (null (nth 0 args))))
-    (if (and (stringp (nth 0 args)) (file-name-absolute-p (nth 0 args)))
-	(nth 0 args)
-      default-directory))
+   ;; A function.
+   ((functionp (alist-get operation tramp-file-name-for-operation-external))
+    (apply
+     (alist-get operation tramp-file-name-for-operation-external)
+     operation args))
    ;; Unknown file primitive.
-   (t (unless (member 'remote-file-error debug-ignored-errors)
+   (t (unless (memq 'remote-file-error debug-ignored-errors)
 	(tramp-error
 	 nil 'remote-file-error "Unknown file I/O primitive: %s" operation)))))
 
@@ -2544,7 +2573,7 @@ Must be handled by the callers."
 		  (funcall (setq func (car elt)) vec)
 		(error
 		 (setcar elt #'ignore)
-		 (unless (member 'remote-file-error debug-ignored-errors)
+		 (unless (memq 'remote-file-error debug-ignored-errors)
 		   (tramp-error
 		    vec 'remote-file-error
 		    "Not a valid Tramp file name function `%s'" func))))
@@ -2552,22 +2581,32 @@ Must be handled by the callers."
 		res (cdr elt))))
       res)))
 
-(defun tramp-add-external-operation (operation function backend)
+(defun tramp-add-external-operation
+    (operation function backend &optional arg-type)
   "Add FUNCTION to Tramp BACKEND as handler for OPERATION.
 OPERATION must not be one of the magic operations listed in Info
 node `(elisp) Magic File Names'.  FUNCTION must have the same argument
 list as OPERATION.  BACKEND, a symbol, must be one of the Tramp backend
-packages like `tramp-sh' (except `tramp-ftp')."
+packages like `tramp-sh' (except `tramp-ftp').  ARG-TYPE is either
+`file' (the default), `default-directory', `process' or a function
+symbol.  It describes the type of the OPERATION argument to be checked.
+See the docstring of `tramp-file-name-for-operation-external' for its
+meaning."
   (require backend)
   (when-let* ((fnha
 	       (intern-soft
 		(concat (symbol-name backend) "-file-name-handler-alist")))
-	      ((boundp fnha)))
+	      ((boundp fnha))
+	      (arg-type (or arg-type 'file)))
+    (unless (or (memq arg-type '(file default-directory process))
+		(functionp arg-type))
+      (tramp-error nil 'remote-file-error "Unknown arg type: %s" arg-type))
     ;; Make BACKEND aware of the new operation.
     (add-to-list fnha (cons operation function))
-    (unless (memq operation tramp-file-name-for-operation-external)
+    (unless (assq operation tramp-file-name-for-operation-external)
       ;; Make Tramp aware of the new operation.
-      (add-to-list 'tramp-file-name-for-operation-external operation)
+      (add-to-list
+       'tramp-file-name-for-operation-external (cons operation arg-type))
       (put #'tramp-file-name-handler
 	   'operations
            (cons operation (get 'tramp-file-name-handler 'operations)))
@@ -2577,8 +2616,7 @@ packages like `tramp-sh' (except `tramp-ftp')."
        `(lambda (orig-fun &rest args)
 	  (if-let* ((handler
 		     (find-file-name-handler
-		      (if (and (car args) (file-name-absolute-p (car args)))
-			  (car args) default-directory)
+		      (apply #'tramp-file-name-for-operation #',operation args)
 		      #',operation)))
 	      (apply handler #',operation args)
 	    (apply orig-fun args)))
@@ -2605,7 +2643,7 @@ Tramp backend packages like `tramp-sh'."
 	   tramp-foreign-file-name-handler-alist)
     ;; Make Tramp unaware of OPERATION.
     (setq tramp-file-name-for-operation-external
-	  (delq operation tramp-file-name-for-operation-external))
+	  (assq-delete-all operation tramp-file-name-for-operation-external))
     (put #'tramp-file-name-handler
 	 'operations (delq operation (get 'tramp-file-name-handler 'operations)))
     ;; Remove the advice for OPERATION.
@@ -3016,6 +3054,8 @@ BODY is the backend specific code."
       (when (file-directory-p ,directory)
 	(seq-uniq (delq nil
          (let* ((case-fold-search read-file-name-completion-ignore-case)
+                (remote-file-name-inhibit-cache
+		 (tramp-suppress-remote-file-name-inhibit-cache))
 		(result
 		 (if (tramp-tramp-file-p ,directory)
 		     (with-parsed-tramp-file-name
@@ -3027,16 +3067,14 @@ BODY is the backend specific code."
 			     (format
 			      "file-name-all-completions-%s"
 			      tramp-fnac-add-trailing-slash)
-			   ;; Mark symlinked directories.  Other
-			   ;; directories are already marked.
+			   ;; Mark directories, including symlinks to
+			   ;; directories.
 			   (mapcar
 			    (lambda (x)
 			      (let ((f (file-name-concat ,directory x)))
 				(if (and tramp-fnac-add-trailing-slash
 					 (not (string-suffix-p "/" x))
-					 (file-directory-p
-					  (if (file-symlink-p f)
-					      (file-truename f) f)))
+					 (file-directory-p f))
 				    (concat x "/") x)))
 			    ;; Some storage systems do not return "." and "..".
 			    (seq-union
@@ -5189,11 +5227,17 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
 	      (delete-file local-copy)))))
       t)))
 
+(defvar tramp-multi-hop-p-hook nil
+  "Abnormal hook for `tramp-multi-hop-p'.
+This can be used by external Tramp backends to inform, that they are
+multi-hop capable.")
+
 (defun tramp-multi-hop-p (vec)
   "Whether the method of VEC is capable of multi-hops."
   (let ((tramp-verbose 0))
-    (and (tramp-sh-file-name-handler-p vec)
-	 (tramp-get-method-parameter vec 'tramp-login-args))))
+    (or (and (tramp-sh-file-name-handler-p vec)
+	     (tramp-get-method-parameter vec 'tramp-login-args))
+	(run-hook-with-args-until-success 'tramp-multi-hop-p-hook vec))))
 
 (defun tramp-add-hops (vec)
   "Add ad-hoc proxy definitions to `tramp-default-proxies-alist'."
@@ -5325,7 +5369,7 @@ Do not set it manually, it is used buffer-local in `tramp-get-lock-pid'.")
 (defvar tramp-extra-expand-args nil
   "Method specific arguments.")
 
-(defun tramp-expand-args (vec parameter default &rest spec-list)
+(defun tramp-expand-args (vec parameter &optional default &rest spec-list)
   "Expand login arguments as given by PARAMETER in `tramp-methods'.
 PARAMETER is a symbol like `tramp-login-args', denoting a list of
 list of strings from `tramp-methods', containing %-sequences for
@@ -5348,12 +5392,15 @@ a connection-local variable."
       (setq spec-list (cddr spec-list)))
     (setq spec (apply #'format-spec-make extra-spec-list))
     ;; Expand format spec.
-    (flatten-tree
-     (mapcar
-      (lambda (x)
-	(setq x (mapcar (lambda (y) (tramp-format-spec y spec)) x))
-	(unless (member "" x) x))
-      args))))
+    (cond
+     ((consp args)
+      (flatten-tree
+       (mapcar
+	(lambda (x)
+	  (setq x (mapcar (lambda (y) (tramp-format-spec y spec)) x))
+	  (unless (member "" x) x))
+	args)))
+     (args (tramp-format-spec args spec)))))
 
 (defun tramp-post-process-creation (proc vec)
   "Apply actions after creation of process PROC."
@@ -5458,6 +5505,10 @@ processes."
 		      (setenv-internal env "HISTFILESIZE" "0" 'keep))
 		     (t env))
 		  env))
+	   ;; Add TERM.
+	   (env (if sh-file-name-handler-p
+		    (setenv-internal env "TERM" tramp-terminal-type 'keep)
+		  env))
 	   ;; Add INSIDE_EMACS.
 	   (env (setenv-internal env "INSIDE_EMACS" (tramp-inside-emacs) 'keep))
 	   (env (mapcar #'tramp-shell-quote-argument (delq nil env)))
@@ -5475,8 +5526,7 @@ processes."
 		 (tramp-get-method-parameter v 'tramp-direct-async)
                  `(,(string-join command " ")))
 	      command))
-	   (login-program
-	    (tramp-get-method-parameter v 'tramp-login-program))
+	   (login-program (tramp-expand-args v 'tramp-login-program))
 	   ;; We don't create the temporary file.  In fact, it is just
 	   ;; a prefix for the ControlPath option of ssh; the real
 	   ;; temporary file has another name, and it is created and
@@ -6333,7 +6383,7 @@ Mostly useful to protect BODY from being interrupted by timers."
   (declare (indent 1) (debug t))
   `(if (tramp-get-connection-property ,proc "locked")
        ;; Be kind for old versions of Emacs.
-       (if (member 'remote-file-error debug-ignored-errors)
+       (if (memq 'remote-file-error debug-ignored-errors)
 	   (throw 'non-essential 'non-essential)
 	 ;(tramp-backtrace ,proc 'force)
 	 (tramp-error
@@ -6699,7 +6749,7 @@ If FILENAME is remote, a file name handler is called."
 ID-FORMAT valid values are `string' and `integer'."
   ;; We use key nil for local connection properties.
   (with-tramp-connection-property nil (format "uid-%s" id-format)
-    (if (equal id-format 'integer) (user-uid) (user-login-name))))
+    (if (eq id-format 'integer) (user-uid) (user-login-name))))
 
 (defun tramp-get-local-gid (id-format)
   "The gid of the local user, in ID-FORMAT.
@@ -6707,8 +6757,8 @@ ID-FORMAT valid values are `string' and `integer'."
   ;; We use key nil for local connection properties.
   (with-tramp-connection-property nil (format "gid-%s" id-format)
     (cond
-     ((equal id-format 'integer) (group-gid))
-     ((equal id-format 'string) (group-name (group-gid)))
+     ((eq id-format 'integer) (group-gid))
+     ((eq id-format 'string) (group-name (group-gid)))
      ((file-attribute-group-id (file-attributes "~/" id-format))))))
 
 (defun tramp-get-local-locale (&optional vec)
@@ -6904,8 +6954,8 @@ ID-FORMAT valid values are `string' and `integer'."
 	   (with-tramp-connection-property vec (format "uid-%s" id-format)
 	     (tramp-file-name-handler #'tramp-get-remote-uid vec id-format)))
       ;; Ensure there is a valid result.
-      (and (equal id-format 'integer) tramp-unknown-id-integer)
-      (and (equal id-format 'string) tramp-unknown-id-string)))
+      (and (eq id-format 'integer) tramp-unknown-id-integer)
+      (and (eq id-format 'string) tramp-unknown-id-string)))
 
 (defun tramp-get-remote-gid (vec id-format)
   "The gid of the remote connection VEC, in ID-FORMAT.
@@ -6914,8 +6964,8 @@ ID-FORMAT valid values are `string' and `integer'."
 	   (with-tramp-connection-property vec (format "gid-%s" id-format)
 	     (tramp-file-name-handler #'tramp-get-remote-gid vec id-format)))
       ;; Ensure there is a valid result.
-      (and (equal id-format 'integer) tramp-unknown-id-integer)
-      (and (equal id-format 'string) tramp-unknown-id-string)))
+      (and (eq id-format 'integer) tramp-unknown-id-integer)
+      (and (eq id-format 'string) tramp-unknown-id-string)))
 
 (defun tramp-get-remote-groups (vec id-format)
   "The list of groups of the remote connection VEC, in ID-FORMAT.
@@ -7229,9 +7279,9 @@ verbosity of 6."
       (let ((default-directory temporary-file-directory))
 	(dolist (pid (list-system-processes))
 	  (and-let* ((attributes (process-attributes pid))
-		     (comm (cdr (assoc 'comm attributes)))
+		     (comm (cdr (assq 'comm attributes)))
 		     ((string-equal
-		       (cdr (assoc 'user attributes)) (user-login-name)))
+		       (cdr (assq 'user attributes)) (user-login-name)))
 		     ;; The returned command name could be truncated
 		     ;; to 15 characters.  Therefore, we cannot check
 		     ;; for `string-equal'.
diff --git a/trampver.el b/trampver.el
index bf84e89..d1c2533 100644
--- a/trampver.el
+++ b/trampver.el
@@ -7,7 +7,7 @@
 ;; Maintainer: Michael Albinus <michael.albinus@gmx.de>
 ;; Keywords: comm, processes
 ;; Package: tramp
-;; Version: 2.8.1.3
+;; Version: 2.8.1.4
 ;; Package-Requires: ((emacs "28.1"))
 ;; Package-Type: multi
 ;; URL: https://www.gnu.org/software/tramp/
@@ -40,7 +40,7 @@
 ;; ./configure" to change them.
 
 ;;;###tramp-autoload
-(defconst tramp-version "2.8.1.3"
+(defconst tramp-version "2.8.1.4"
   "This version of Tramp.")
 
 ;;;###tramp-autoload
@@ -76,7 +76,7 @@
 ;; Check for Emacs version.
 (let ((x   (if (not (string-version-lessp emacs-version "28.1"))
       "ok"
-    (format "Tramp 2.8.1.3 is not fit for %s"
+    (format "Tramp 2.8.1.4 is not fit for %s"
             (replace-regexp-in-string "\n" "" (emacs-version))))))
   (unless (string-equal "ok" x) (error "%s" x)))