Add `make-nearby-temp-file' and `temporary-file-directory'

* doc/lispref/files.texi (Unique File Names):
Introduce `make-nearby-temp-file' and `temporary-file-directory'.
(Magic File Names): Mention `make-nearby-temp-file' and
`temporary-file-directory'.

* etc/NEWS (provided): Mention `make-nearby-temp-file' and
`temporary-file-directory'.

* lisp/files.el (mounted-file-systems): New defcustom.
(temporary-file-directory, make-nearby-temp-file): New defuns.
(normal-backup-enable-predicate): Fix docstring.

* lisp/net/tramp-adb.el (tramp-adb-file-name-handler-alist):
* lisp/net/tramp-gvfs.el (tramp-gvfs-file-name-handler-alist):
* lisp/net/tramp-sh.el (tramp-sh-file-name-handler-alist):
* lisp/net/tramp-smb.el (tramp-smb-file-name-handler-alist):
<make-nearby-temp-file, temporary-file-directory>: Add handler.

* lisp/net/tramp.el (tramp-file-name-for-operation):
Add `make-nearby-temp-file' and `temporary-file-directory'.
(tramp-get-remote-tmpdir): Remove compatibility code.
(tramp-handle-temporary-file-directory)
(tramp-handle-make-nearby-temp-file): New defuns.

* lisp/org/ob-core.el (org-babel-local-file-name):
* lisp/progmodes/gud.el (gud-common-init):
* lisp/vc/vc-hooks.el (vc-user-login-name): Use `file-remote-p'.

* lisp/vc/vc-git.el (vc-git-checkin): Handle remote log message.

* test/lisp/net/tramp-tests.el (tramp-test06-directory-file-name):
Check `tramp--test-enabled'.
(tramp-test18-file-attributes): Add tests for
`file-ownership-preserved-p'.
(tramp-test27-start-file-process, tramp-test28-shell-command):
Reduce timeouts in `accept-process-output'.
(tramp-test--shell-command-to-string-asynchronously): Add timeout.
(tramp-test29-environment-variables): Remove additional sleep calls.
(tramp-test32-make-nearby-temp-file): New test.
(tramp--test-special-characters, tramp--test-utf8): Adapt docstring.
(tramp-test33-special-characters)
(tramp-test33-special-characters-with-stat)
(tramp-test33-special-characters-with-perl)
(tramp-test33-special-characters-with-ls, tramp-test34-utf8)
(tramp-test34-utf8-with-stat, tramp-test34-utf8-with-perl)
(tramp-test34-utf8-with-ls)
(tramp-test35-asynchronous-requests)
(tramp-test36-recursive-load, tramp-test37-unload): Rename.
(tramp--test-ftp-p): Simplify check.
(tramp--test-sh-p): New defun.
(tramp-test20-file-modes, tramp-test22-file-times)
(tramp-test26-process-file, tramp-test27-start-file-process)
(tramp-test28-shell-command)
(tramp-test29-environment-variables)
(tramp-test30-vc-registered)
(tramp-test33-special-characters-with-stat)
(tramp-test33-special-characters-with-perl)
(tramp-test33-special-characters-with-ls)
(tramp-test34-utf8-with-stat, tramp-test34-utf8-with-perl)
(tramp-test34-utf8-with-ls)
(tramp-test35-asynchronous-requests): Use it.

13 files changed, 249 insertions, 149 deletions

diff --git a/doc/lispref/files.texi b/doc/lispref/files.texi
index ea9d53b0ea6..0aea1dfd9a3 100644
--- a/doc/lispref/files.texi
+++ b/doc/lispref/files.texi
@@ -2440,6 +2440,50 @@ condition, between the @code{make-temp-name} call and the creation of
 the file, which in some cases may cause a security hole.
 @end defun
 
+Sometimes, it is necessary to create a temporary file on a remote host
+or a mounted directory.  The following two functions support this.
+
+@defun make-nearby-temp-file prefix &optional dir-flag suffix
+This function is similar to @code{make-temp-file}, but it creates a
+temporary file as close as possible to @code{default-directory}.  If
+@var{prefix} is a relative file name, and @code{default-directory} is
+a remote file name or located on a mounted file systems, the temporary
+file is created in the directory returned by the function
+@code{temporary-file-directory}.  Otherwise, the function
+@code{make-temp-file} is used.  @var{prefix}, @var{dir-flag} and
+@var{suffix} have the same meaning as in @code{make-temp-file}.
+
+@example
+@group
+(let ((default-directory "/ssh:remotehost:"))
+  (make-nearby-temp-file "foo"))
+     @result{} "/ssh:remotehost:/tmp/foo232J6v"
+@end group
+@end example
+@end defun
+
+@defun temporary-file-directory
+The directory for writing temporary files via
+@code{make-nearby-temp-file}.  In case of a remote
+@code{default-directory}, this is a directory for temporary files on
+that remote host.  If such a directory does not exist, or
+@code{default-directory} ought to be located on a mounted file system
+(see @code{mounted-file-systems}), the function returns
+@code{default-directory}.  For a non-remote and non-mounted
+@code{default-directory}, the value of the variable
+@code{temporary-file-directory} is returned.
+@end defun
+
+In order to extract the local part of the path name from a temporary
+file, the following code could be used:
+
+@example
+@group
+(let ((tmpfile (make-nearby-temp-file "foo")))
+  (or (file-remote-p tmpfile 'localname) tmpfile))
+@end group
+@end example
+
 @node File Name Completion
 @subsection File Name Completion
 @cindex file name completion subroutines
@@ -2903,6 +2947,7 @@ first, before handlers for jobs such as remote file access.
 @code{make-auto-save-file-name},
 @code{make-directory},
 @code{make-directory-internal},
+@code{make-nearby-temp-file},
 @code{make-symbolic-link},@*
 @code{process-file},
 @code{rename-file}, @code{set-file-acl}, @code{set-file-modes},
@@ -2910,6 +2955,7 @@ first, before handlers for jobs such as remote file access.
 @code{set-visited-file-modtime}, @code{shell-command},
 @code{start-file-process},
 @code{substitute-in-file-name},@*
+@code{temporary-file-directory},
 @code{unhandled-file-name-directory},
 @code{vc-registered},
 @code{verify-visited-file-modtime},@*
diff --git a/etc/NEWS b/etc/NEWS
index 04c293dfc7c..0a202ccade2 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -563,7 +563,11 @@ ABBR is a time zone abbreviation.  The affected functions are
 The Info-quoted and tex-verbatim faces now default to inheriting from it.
 
 ** New built-in function `mapcan' which avoids unnecessary consing (and garbage
-   collection).
+collection).
+
++++
+** The new functions `make-nearby-temp-file' and `temporary-file-directory'
+can be used for creation of temporary files of remote or mounted directories.
 
 
 * Changes in Emacs 25.2 on Non-Free Operating Systems
diff --git a/lisp/files.el b/lisp/files.el
index 4d27ef16f7d..1d7870be488 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1314,6 +1314,36 @@ Optional second argument FLAVOR controls the units and the display format:
               (car post-fixes))
             (if (eq flavor 'iec) "iB" ""))))
 
+(defcustom mounted-file-systems
+  (if (memq system-type '(windows-nt cygwin))
+      "^//[^/]+/"
+    ;; regexp-opt.el is not dumped into emacs binary.
+    ;;(concat
+    ;; "^" (regexp-opt '("/afs/" "/media/" "/mnt" "/net/" "/tmp_mnt/"))))
+    "^\\(?:/\\(?:afs/\\|m\\(?:edia/\\|nt\\)\\|\\(?:ne\\|tmp_mn\\)t/\\)\\)")
+  "File systems which ought to be mounted."
+  :group 'files
+  :version "25.2"
+  :require 'regexp-opt
+  :type 'regexp)
+
+(defun temporary-file-directory ()
+  "The directory for writing temporary files.
+In case of a remote `default-directory', this is a directory for
+temporary files on that remote host.  If such a directory does
+not exist, or `default-directory' ought to be located on a
+mounted file system (see `mounted-file-systems'), the function
+returns `default-directory'.
+For a non-remote and non-mounted `default-directory', the value of
+the variable `temporary-file-directory' is returned."
+  (let ((handler (find-file-name-handler
+                  default-directory 'temporary-file-directory)))
+    (if handler
+        (funcall handler 'temporary-file-directory)
+      (if (string-match mounted-file-systems default-directory)
+          default-directory
+        temporary-file-directory))))
+
 (defun make-temp-file (prefix &optional dir-flag suffix)
   "Create a temporary file.
 The returned file name (created by appending some random characters at the end
@@ -1350,6 +1380,21 @@ If SUFFIX is non-nil, add that at the end of the file name."
         nil)
       file)))
 
+(defun make-nearby-temp-file (prefix &optional dir-flag suffix)
+  "Create a temporary file as close as possible to `default-directory'.
+If PREFIX is a relative file name, and `default-directory' is a
+remote file name or located on a mounted file systems, the
+temporary file is created in the directory returned by the
+function `temporary-file-directory'.  Otherwise, the function
+`make-temp-file' is used.  PREFIX, DIR-FLAG and SUFFIX have the
+same meaning as in `make-temp-file'."
+  (let ((handler (find-file-name-handler
+                  default-directory 'make-nearby-temp-file)))
+    (if (and handler (not (file-name-absolute-p default-directory)))
+        (funcall handler 'make-nearby-temp-file prefix dir-flag suffix)
+      (let ((temporary-file-directory (temporary-file-directory)))
+        (make-temp-file prefix dir-flag suffix)))))
+
 (defun recode-file-name (file coding new-coding &optional ok-if-already-exists)
   "Change the encoding of FILE's name from CODING to NEW-CODING.
 The value is a new name of FILE.
@@ -4404,7 +4449,7 @@ ignored."
 (defun normal-backup-enable-predicate (name)
   "Default `backup-enable-predicate' function.
 Checks for files in `temporary-file-directory',
-`small-temporary-file-directory', and /tmp."
+`small-temporary-file-directory', and \"/tmp\"."
   (let ((temporary-file-directory temporary-file-directory)
         caseless)
     ;; On MS-Windows, file-truename will convert short 8+3 aliases to
diff --git a/lisp/net/tramp-adb.el b/lisp/net/tramp-adb.el
index 002a7fe52c1..07fc3e2bf55 100644
--- a/lisp/net/tramp-adb.el
+++ b/lisp/net/tramp-adb.el
@@ -148,6 +148,7 @@ It is used for TCP/IP devices."
     (make-auto-save-file-name . tramp-handle-make-auto-save-file-name)
     (make-directory . tramp-adb-handle-make-directory)
     (make-directory-internal . ignore)
+    (make-nearby-temp-file . tramp-handle-make-nearby-temp-file)
     (make-symbolic-link . tramp-handle-make-symbolic-link)
     (process-file . tramp-adb-handle-process-file)
     (rename-file . tramp-adb-handle-rename-file)
@@ -159,6 +160,7 @@ It is used for TCP/IP devices."
     (shell-command . tramp-adb-handle-shell-command)
     (start-file-process . tramp-adb-handle-start-file-process)
     (substitute-in-file-name . tramp-handle-substitute-in-file-name)
+    (temporary-file-directory . tramp-handle-temporary-file-directory)
     (unhandled-file-name-directory . ignore)
     (vc-registered . ignore)
     (verify-visited-file-modtime . tramp-handle-verify-visited-file-modtime)
diff --git a/lisp/net/tramp-gvfs.el b/lisp/net/tramp-gvfs.el
index 62129172d99..d12bab954af 100644
--- a/lisp/net/tramp-gvfs.el
+++ b/lisp/net/tramp-gvfs.el
@@ -502,6 +502,7 @@ Every entry is a list (NAME ADDRESS).")
     (make-auto-save-file-name . tramp-handle-make-auto-save-file-name)
     (make-directory . tramp-gvfs-handle-make-directory)
     (make-directory-internal . ignore)
+    (make-nearby-temp-file . tramp-handle-make-nearby-temp-file)
     (make-symbolic-link . tramp-handle-make-symbolic-link)
     (process-file . ignore)
     (rename-file . tramp-gvfs-handle-rename-file)
@@ -513,6 +514,7 @@ Every entry is a list (NAME ADDRESS).")
     (shell-command . ignore)
     (start-file-process . ignore)
     (substitute-in-file-name . tramp-handle-substitute-in-file-name)
+    (temporary-file-directory . tramp-handle-temporary-file-directory)
     (unhandled-file-name-directory . ignore)
     (vc-registered . ignore)
     (verify-visited-file-modtime . tramp-handle-verify-visited-file-modtime)
diff --git a/lisp/net/tramp-sh.el b/lisp/net/tramp-sh.el
index b41eeac5bb9..f1044730ff0 100644
--- a/lisp/net/tramp-sh.el
+++ b/lisp/net/tramp-sh.el
@@ -1043,6 +1043,7 @@ of command line.")
     (load . tramp-handle-load)
     (make-auto-save-file-name . tramp-handle-make-auto-save-file-name)
     (make-directory . tramp-sh-handle-make-directory)
+    (make-nearby-temp-file . tramp-handle-make-nearby-temp-file)
     (make-symbolic-link . tramp-sh-handle-make-symbolic-link)
     (process-file . tramp-sh-handle-process-file)
     (rename-file . tramp-sh-handle-rename-file)
@@ -1054,6 +1055,7 @@ of command line.")
     (shell-command . tramp-handle-shell-command)
     (start-file-process . tramp-sh-handle-start-file-process)
     (substitute-in-file-name . tramp-handle-substitute-in-file-name)
+    (temporary-file-directory . tramp-handle-temporary-file-directory)
     (unhandled-file-name-directory . ignore)
     (vc-registered . tramp-sh-handle-vc-registered)
     (verify-visited-file-modtime . tramp-sh-handle-verify-visited-file-modtime)
diff --git a/lisp/net/tramp-smb.el b/lisp/net/tramp-smb.el
index 60e2aa44c26..bbf88fbf4fc 100644
--- a/lisp/net/tramp-smb.el
+++ b/lisp/net/tramp-smb.el
@@ -265,6 +265,7 @@ See `tramp-actions-before-shell' for more info.")
     (make-auto-save-file-name . tramp-handle-make-auto-save-file-name)
     (make-directory . tramp-smb-handle-make-directory)
     (make-directory-internal . tramp-smb-handle-make-directory-internal)
+    (make-nearby-temp-file . tramp-handle-make-nearby-temp-file)
     (make-symbolic-link . tramp-smb-handle-make-symbolic-link)
     (process-file . tramp-smb-handle-process-file)
     (rename-file . tramp-smb-handle-rename-file)
@@ -276,6 +277,7 @@ See `tramp-actions-before-shell' for more info.")
     (shell-command . tramp-handle-shell-command)
     (start-file-process . tramp-smb-handle-start-file-process)
     (substitute-in-file-name . tramp-smb-handle-substitute-in-file-name)
+    (temporary-file-directory . tramp-handle-temporary-file-directory)
     (unhandled-file-name-directory . ignore)
     (vc-registered . ignore)
     (verify-visited-file-modtime . tramp-handle-verify-visited-file-modtime)
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 35b049c4f6c..29dd7038c09 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -1917,7 +1917,9 @@ ARGS are the arguments OPERATION has been called with."
      (if (bufferp (nth 0 args)) (nth 0 args) (current-buffer))))
    ;; COMMAND.
    ((member operation
-            '(process-file shell-command start-file-process))
+            '(process-file shell-command start-file-process
+              ;; Emacs 25.2+ only.
+              make-nearby-temp-file temporary-file-directory))
     default-directory)
    ;; PROC.
    ((member operation
@@ -3893,9 +3895,6 @@ be granted."
 
 (defun tramp-get-remote-tmpdir (vec)
   "Return directory for temporary files on the remote host identified by VEC."
-  (when (file-remote-p (tramp-get-connection-property vec "tmpdir" ""))
-    ;; Compatibility code: Cached value shall be the local path only.
-    (tramp-set-connection-property vec "tmpdir" 'undef))
   (let ((dir (tramp-make-tramp-file-name
               (tramp-file-name-method vec)
               (tramp-file-name-user vec)
@@ -3985,6 +3984,21 @@ ALIST is of the form ((FROM . TO) ...)."
         (setq alist (cdr alist))))
     string))
 
+(defun tramp-handle-temporary-file-directory ()
+  "Like `temporary-file-directory' for Tramp files."
+  (catch 'result
+    (dolist (dir `(,(ignore-errors
+                      (tramp-get-remote-tmpdir
+                       (tramp-dissect-file-name default-directory)))
+                   ,default-directory))
+      (when (and (stringp dir) (file-directory-p dir) (file-writable-p dir))
+        (throw 'result (expand-file-name dir))))))
+
+(defun tramp-handle-make-nearby-temp-file (prefix &optional dir-flag suffix)
+  "Like `make-nearby-temp-file' for Tramp files."
+  (let ((temporary-file-directory (temporary-file-directory)))
+    (make-temp-file prefix dir-flag suffix)))
+
 ;;; Compatibility functions section:
 
 (defun tramp-call-process
diff --git a/lisp/org/ob-core.el b/lisp/org/ob-core.el
index b7e8c237256..e3d778f73b4 100644
--- a/lisp/org/ob-core.el
+++ b/lisp/org/ob-core.el
@@ -43,11 +43,6 @@
 (declare-function org-mark-ring-push "org" (&optional pos buffer))
 (declare-function tramp-compat-make-temp-file "tramp-compat"
                   (filename &optional dir-flag))
-(declare-function tramp-dissect-file-name "tramp" (name &optional nodefault))
-(declare-function tramp-file-name-user "tramp" (vec))
-(declare-function tramp-file-name-host "tramp" (vec))
-(declare-function with-parsed-tramp-file-name "tramp" (filename var &rest body)
-                  t)
 (declare-function org-icompleting-read "org" (&rest args))
 (declare-function org-edit-src-code "org-src"
                   (&optional context code edit-buffer-name))
@@ -2670,7 +2665,7 @@ of the string."
   (start end program &optional delete buffer display &rest args)
   "Use Tramp to handle `call-process-region'.
 Fixes a bug in `tramp-handle-call-process-region'."
-  (if (and (featurep 'tramp) (file-remote-p default-directory))
+  (if (file-remote-p default-directory)
       (let ((tmpfile (tramp-compat-make-temp-file "")))
         (write-region start end tmpfile)
         (when delete (delete-region start end))
@@ -2687,11 +2682,7 @@ Fixes a bug in `tramp-handle-call-process-region'."
 
 (defun org-babel-local-file-name (file)
   "Return the local name component of FILE."
-  (if (file-remote-p file)
-      (let (localname)
-        (with-parsed-tramp-file-name file nil
-                                     localname))
-    file))
+  (or (file-remote-p file 'localname) file))
 
 (defun org-babel-process-file-name (name &optional no-quote-p)
   "Prepare NAME to be used in an external process.
diff --git a/lisp/progmodes/gud.el b/lisp/progmodes/gud.el
index 504ad546cfd..9052aa40358 100644
--- a/lisp/progmodes/gud.el
+++ b/lisp/progmodes/gud.el
@@ -2567,9 +2567,6 @@ comint mode, which see."
   :group 'gud
   :type 'boolean)
 
-(declare-function tramp-file-name-localname "tramp" (vec))
-(declare-function tramp-dissect-file-name "tramp" (name &optional nodefault))
-
 ;; Perform initializations common to all debuggers.
 ;; The first arg is the specified command line,
 ;; which starts with the program to debug.
@@ -2628,8 +2625,7 @@ comint mode, which see."
           (setcar w
                   (if (file-remote-p file)
                       ;; Tramp has already been loaded if we are here.
-                      (setq file (tramp-file-name-localname
-                                  (tramp-dissect-file-name file)))
+                      (setq file (file-remote-p file 'localname))
                     file))))
     (apply 'make-comint (concat "gud" filepart) program nil
            (if massage-args (funcall massage-args file args) args))
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index e6fe0196d88..43a831f159f 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -705,7 +705,12 @@ It is based on `log-edit-mode', and has Git-specific extensions.")
           ;; arguments must be in the system codepage, and therefore
           ;; might not support the non-ASCII characters in the log
           ;; message.
-          (if (eq system-type 'windows-nt) (make-temp-file "git-msg"))))
+          (if (eq system-type 'windows-nt)
+              (if (file-remote-p file1)
+                  (let ((default-directory (file-name-directory file1)))
+                    (file-remote-p
+                     (make-nearby-temp-file "git-msg") 'localname))
+                (make-temp-file "git-msg")))))
     (cl-flet ((boolean-arg-fn
                (argument)
                (lambda (value) (when (equal value "yes") (list argument)))))
diff --git a/lisp/vc/vc-hooks.el b/lisp/vc/vc-hooks.el
index 6b4cd6acd03..f59b4632e70 100644
--- a/lisp/vc/vc-hooks.el
+++ b/lisp/vc/vc-hooks.el
@@ -394,7 +394,7 @@ For registered files, the possible values are:
 
 (defun vc-user-login-name (file)
   "Return the name under which the user accesses the given FILE."
-  (or (and (eq (string-match tramp-file-name-regexp file) 0)
+  (or (and (file-remote-p file)
            ;; tramp case: execute "whoami" via tramp
            (let ((default-directory (file-name-directory file))
                  process-file-side-effects)
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index e05786fa070..af705f6ce67 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -639,23 +639,24 @@ This checks also `file-name-as-directory', `file-name-directory',
    (unhandled-file-name-directory "/method:host:/path/to/file"))
 
   ;; Bug#10085.
-  (dolist (n-e '(nil t))
-    ;; We must clear `tramp-default-method'.  On hydra, it is "ftp",
-    ;; which ruins the tests.
-    (let ((non-essential n-e)
-          tramp-default-method)
-      (dolist (file
-               `(,(file-remote-p tramp-test-temporary-file-directory 'method)
-                 ,(file-remote-p tramp-test-temporary-file-directory 'host)))
-        (unless (zerop (length file))
-          (setq file (format "/%s:" file))
-          (should (string-equal (directory-file-name file) file))
-          (should
-           (string-equal
-            (file-name-as-directory file)
-            (if (tramp-completion-mode-p) file (concat file "./"))))
-          (should (string-equal (file-name-directory file) file))
-          (should (string-equal (file-name-nondirectory file) "")))))))
+  (when (tramp--test-enabled) ;; Packages like tramp-gvfs.el might be disabled.
+    (dolist (n-e '(nil t))
+      ;; We must clear `tramp-default-method'.  On hydra, it is "ftp",
+      ;; which ruins the tests.
+      (let ((non-essential n-e)
+            tramp-default-method)
+        (dolist (file
+                 `(,(file-remote-p tramp-test-temporary-file-directory 'method)
+                   ,(file-remote-p tramp-test-temporary-file-directory 'host)))
+          (unless (zerop (length file))
+            (setq file (format "/%s:" file))
+            (should (string-equal (directory-file-name file) file))
+            (should
+             (string-equal
+              (file-name-as-directory file)
+              (if (tramp-completion-mode-p) file (concat file "./"))))
+            (should (string-equal (file-name-directory file) file))
+            (should (string-equal (file-name-nondirectory file) ""))))))))
 
 (ert-deftest tramp-test07-file-exists-p ()
   "Check `file-exist-p', `write-region' and `delete-file'."
@@ -1091,7 +1092,8 @@ This tests also `file-directory-p' and `file-accessible-directory-p'."
 
 (ert-deftest tramp-test18-file-attributes ()
   "Check `file-attributes'.
-This tests also `file-readable-p' and `file-regular-p'."
+This tests also `file-readable-p', `file-regular-p' and
+`file-ownership-preserved-p'."
   (skip-unless (tramp--test-enabled))
 
   ;; We must use `file-truename' for the temporary directory, because
@@ -1111,10 +1113,16 @@ This tests also `file-readable-p' and `file-regular-p'."
          attr)
     (unwind-protect
         (progn
+          ;; `file-ownership-preserved-p' should return t for
+          ;; non-existing files.  It is implemented only in tramp-sh.el.
+          (when (tramp--test-sh-p)
+            (should (file-ownership-preserved-p tmp-name1 'group)))
           (write-region "foo" nil tmp-name1)
           (should (file-exists-p tmp-name1))
           (should (file-readable-p tmp-name1))
           (should (file-regular-p tmp-name1))
+          (when (tramp--test-sh-p)
+            (should (file-ownership-preserved-p tmp-name1 'group)))
 
           ;; We do not test inodes and device numbers.
           (setq attr (file-attributes tmp-name1))
@@ -1138,9 +1146,13 @@ This tests also `file-readable-p' and `file-regular-p'."
 
           (condition-case err
               (progn
+                (when (tramp--test-sh-p)
+                  (should (file-ownership-preserved-p tmp-name2 'group)))
                 (make-symbolic-link tmp-name1 tmp-name2)
                 (should (file-exists-p tmp-name2))
                 (should (file-symlink-p tmp-name2))
+                (when (tramp--test-sh-p)
+                  (should (file-ownership-preserved-p tmp-name2 'group)))
                 (setq attr (file-attributes tmp-name2))
                 (should (string-equal
                          (car attr)
@@ -1167,11 +1179,15 @@ This tests also `file-readable-p' and `file-regular-p'."
               (tramp-file-name-localname (tramp-dissect-file-name tmp-name3))))
             (delete-file tmp-name2))
 
+          (when (tramp--test-sh-p)
+            (should (file-ownership-preserved-p tmp-name1 'group)))
           (delete-file tmp-name1)
           (make-directory tmp-name1)
           (should (file-exists-p tmp-name1))
           (should (file-readable-p tmp-name1))
           (should-not (file-regular-p tmp-name1))
+          (when (tramp--test-sh-p)
+            (should (file-ownership-preserved-p tmp-name1 'group)))
           (setq attr (file-attributes tmp-name1))
           (should (eq (car attr) t)))
 
@@ -1227,13 +1243,7 @@ This tests also `file-readable-p' and `file-regular-p'."
   "Check `file-modes'.
 This tests also `file-executable-p', `file-writable-p' and `set-file-modes'."
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (not
-    (memq
-     (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-     '(tramp-adb-file-name-handler
-       tramp-gvfs-file-name-handler
-       tramp-smb-file-name-handler))))
+  (skip-unless (tramp--test-sh-p))
 
   (let ((tmp-name (tramp--test-make-temp-name)))
     (unwind-protect
@@ -1337,11 +1347,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
 (ert-deftest tramp-test22-file-times ()
   "Check `set-file-times' and `file-newer-than-file-p'."
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (not
-    (memq
-     (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-     '(tramp-gvfs-file-name-handler tramp-smb-file-name-handler))))
+  (skip-unless (or (tramp--test-adb-p) (tramp--test-sh-p)))
 
   (let ((tmp-name1 (tramp--test-make-temp-name))
         (tmp-name2 (tramp--test-make-temp-name))
@@ -1499,11 +1505,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   "Check `process-file'."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (not
-    (memq
-     (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-     '(tramp-gvfs-file-name-handler tramp-smb-file-name-handler))))
+  (skip-unless (or (tramp--test-adb-p) (tramp--test-sh-p)))
 
   (let* ((tmp-name (tramp--test-make-temp-name))
          (fnnd (file-name-nondirectory tmp-name))
@@ -1548,13 +1550,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   "Check `start-file-process'."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (not
-    (memq
-     (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-     '(tramp-adb-file-name-handler
-       tramp-gvfs-file-name-handler
-       tramp-smb-file-name-handler))))
+  (skip-unless (tramp--test-sh-p))
 
   (let ((default-directory tramp-test-temporary-file-directory)
         (tmp-name (tramp--test-make-temp-name))
@@ -1569,7 +1565,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
           ;; Read output.
           (with-timeout (10 (ert-fail "`start-file-process' timed out"))
             (while (< (- (point-max) (point-min)) (length "foo"))
-              (accept-process-output proc 1)))
+              (accept-process-output proc 0.1)))
           (should (string-equal (buffer-string) "foo")))
 
       ;; Cleanup.
@@ -1587,7 +1583,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
           ;; Read output.
           (with-timeout (10 (ert-fail "`start-file-process' timed out"))
             (while (< (- (point-max) (point-min)) (length "foo"))
-              (accept-process-output proc 1)))
+              (accept-process-output proc 0.1)))
           (should (string-equal (buffer-string) "foo")))
 
       ;; Cleanup.
@@ -1608,7 +1604,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
           ;; Read output.
           (with-timeout (10 (ert-fail "`start-file-process' timed out"))
             (while (< (- (point-max) (point-min)) (length "foo"))
-              (accept-process-output proc 1)))
+              (accept-process-output proc 0.1)))
           (should (string-equal (buffer-string) "foo")))
 
       ;; Cleanup.
@@ -1618,13 +1614,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   "Check `shell-command'."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (not
-    (memq
-     (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-     '(tramp-adb-file-name-handler
-       tramp-gvfs-file-name-handler
-       tramp-smb-file-name-handler))))
+  (skip-unless (tramp--test-sh-p))
 
   (let ((tmp-name (tramp--test-make-temp-name))
         (default-directory tramp-test-temporary-file-directory)
@@ -1657,7 +1647,8 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
           (with-timeout (10 (ert-fail "`async-shell-command' timed out"))
             (while (< (- (point-max) (point-min))
                       (1+ (length (file-name-nondirectory tmp-name))))
-              (accept-process-output (get-buffer-process (current-buffer)) 1)))
+              (accept-process-output
+               (get-buffer-process (current-buffer)) 0.1)))
           ;; `ls' could produce colorized output.
           (goto-char (point-min))
           (while (re-search-forward tramp-display-escape-sequence-regexp nil t)
@@ -1686,7 +1677,8 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
           (with-timeout (10 (ert-fail "`async-shell-command' timed out"))
             (while (< (- (point-max) (point-min))
                       (1+ (length (file-name-nondirectory tmp-name))))
-              (accept-process-output (get-buffer-process (current-buffer)) 1)))
+              (accept-process-output
+               (get-buffer-process (current-buffer)) 0.1)))
           ;; `ls' could produce colorized output.
           (goto-char (point-min))
           (while (re-search-forward tramp-display-escape-sequence-regexp nil t)
@@ -1708,9 +1700,10 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
     (async-shell-command command (current-buffer))
     ;; Suppress nasty messages.
     (set-process-sentinel (get-buffer-process (current-buffer)) nil)
-    (while (get-buffer-process (current-buffer))
-      (accept-process-output (get-buffer-process (current-buffer)) 0.1))
-    (accept-process-output)
+    (with-timeout (10)
+      (while (get-buffer-process (current-buffer))
+        (accept-process-output (get-buffer-process (current-buffer)) 0.1)))
+    (accept-process-output nil 0.1)
     (buffer-substring-no-properties (point-min) (point-max))))
 
 ;; This test is inspired by Bug#23952.
@@ -1718,10 +1711,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   "Check that remote processes set / unset environment variables properly."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (tramp--test-sh-p))
 
   (dolist (this-shell-command-to-string
            '(;; Synchronously.
@@ -1798,10 +1788,7 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
   "Check `vc-registered'."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (tramp--test-sh-p))
 
   (let* ((default-directory tramp-test-temporary-file-directory)
          (tmp-name1 (tramp--test-make-temp-name))
@@ -1947,6 +1934,36 @@ This tests also `make-symbolic-link', `file-truename' and `add-name-to-file'."
       (ignore-errors (delete-file tmp-name1))
       (ignore-errors (delete-directory tmp-name2 'recursive)))))
 
+(ert-deftest tramp-test32-make-nearby-temp-file ()
+  "Check `make-nearby-temp-file' and `temporary-file-directory'."
+  (skip-unless (tramp--test-enabled))
+
+  (let ((default-directory tramp-test-temporary-file-directory)
+        tmp-file)
+    ;; The remote host shall know a tempory file directory.
+    (should (stringp (temporary-file-directory)))
+    (should
+     (string-equal
+      (file-remote-p default-directory)
+      (file-remote-p (temporary-file-directory))))
+
+    ;; The temporary file shall be located on the remote host.
+    (setq tmp-file (make-nearby-temp-file "tramp-test"))
+    (should (file-exists-p tmp-file))
+    (should (file-regular-p tmp-file))
+    (should
+     (string-equal
+      (file-remote-p default-directory)
+      (file-remote-p tmp-file)))
+    (delete-file tmp-file)
+    (should-not (file-exists-p tmp-file))
+
+    (setq tmp-file (make-nearby-temp-file "tramp-test" 'dir))
+    (should (file-exists-p tmp-file))
+    (should (file-directory-p tmp-file))
+    (delete-directory tmp-file)
+    (should-not (file-exists-p tmp-file))))
+
 (defun tramp--test-adb-p ()
   "Check, whether the remote host runs Android.
 This requires restrictions of file name syntax."
@@ -1956,11 +1973,13 @@ This requires restrictions of file name syntax."
   "Check, whether an FTP-like method is used.
 This does not support globbing characters in file names (yet)."
   ;; Globbing characters are ??, ?* and ?\[.
-  (and (eq (tramp-find-foreign-file-name-handler
-            tramp-test-temporary-file-directory)
-           'tramp-sh-file-name-handler)
-       (string-match
-        "ftp$" (file-remote-p tramp-test-temporary-file-directory 'method))))
+  (string-match
+   "ftp$" (file-remote-p tramp-test-temporary-file-directory 'method)))
+
+(defun tramp--test-gvfs-p ()
+  "Check, whether the remote host runs a GVFS based method.
+This requires restrictions of file name syntax."
+  (tramp-gvfs-file-name-p tramp-test-temporary-file-directory))
 
 (defun tramp--test-rsync-p ()
   "Check, whether the rsync method is used.
@@ -1968,10 +1987,11 @@ This does not support special file names."
   (string-equal
    "rsync" (file-remote-p tramp-test-temporary-file-directory 'method)))
 
-(defun tramp--test-gvfs-p ()
-  "Check, whether the remote host runs a GVFS based method.
-This requires restrictions of file name syntax."
-  (tramp-gvfs-file-name-p tramp-test-temporary-file-directory))
+(defun tramp--test-sh-p ()
+  "Check, whether the remote host runs a based method from tramp-sh.el."
+  (eq
+   (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
+   'tramp-sh-file-name-handler))
 
 (defun tramp--test-smb-or-windows-nt-p ()
   "Check, whether the locale or remote host runs MS Windows.
@@ -2123,7 +2143,7 @@ Several special characters do not work properly there."
       (ignore-errors (delete-directory tmp-name2 'recursive)))))
 
 (defun tramp--test-special-characters ()
-  "Perform the test in `tramp-test32-special-characters*'."
+  "Perform the test in `tramp-test33-special-characters*'."
   ;; Newlines, slashes and backslashes in file names are not
   ;; supported.  So we don't test.  And we don't test the tab
   ;; character on Windows or Cygwin, because the backslash is
@@ -2164,23 +2184,19 @@ Several special characters do not work properly there."
    "{foo}bar{baz}"))
 
 ;; These tests are inspired by Bug#17238.
-(ert-deftest tramp-test32-special-characters ()
+(ert-deftest tramp-test33-special-characters ()
   "Check special characters in file names."
   (skip-unless (tramp--test-enabled))
   (skip-unless (not (tramp--test-rsync-p)))
 
   (tramp--test-special-characters))
 
-(ert-deftest tramp-test32-special-characters-with-stat ()
+(ert-deftest tramp-test33-special-characters-with-stat ()
   "Check special characters in file names.
 Use the `stat' command."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless (not (tramp--test-rsync-p)))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (and (tramp--test-sh-p) (not (tramp--test-rsync-p))))
   (with-parsed-tramp-file-name tramp-test-temporary-file-directory nil
     (skip-unless (tramp-get-remote-stat v)))
 
@@ -2191,16 +2207,12 @@ Use the `stat' command."
           tramp-connection-properties)))
     (tramp--test-special-characters)))
 
-(ert-deftest tramp-test32-special-characters-with-perl ()
+(ert-deftest tramp-test33-special-characters-with-perl ()
   "Check special characters in file names.
 Use the `perl' command."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless (not (tramp--test-rsync-p)))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (and (tramp--test-sh-p) (not (tramp--test-rsync-p))))
   (with-parsed-tramp-file-name tramp-test-temporary-file-directory nil
     (skip-unless (tramp-get-remote-perl v)))
 
@@ -2214,16 +2226,12 @@ Use the `perl' command."
           tramp-connection-properties)))
     (tramp--test-special-characters)))
 
-(ert-deftest tramp-test32-special-characters-with-ls ()
+(ert-deftest tramp-test33-special-characters-with-ls ()
   "Check special characters in file names.
 Use the `ls' command."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless (not (tramp--test-rsync-p)))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (and (tramp--test-sh-p) (not (tramp--test-rsync-p))))
 
   (let ((tramp-connection-properties
          (append
@@ -2238,7 +2246,7 @@ Use the `ls' command."
     (tramp--test-special-characters)))
 
 (defun tramp--test-utf8 ()
-  "Perform the test in `tramp-test33-utf8*'."
+  "Perform the test in `tramp-test34-utf8*'."
   (let* ((utf8 (if (and (eq system-type 'darwin)
                         (memq 'utf-8-hfs (coding-system-list)))
                    'utf-8-hfs 'utf-8))
@@ -2252,23 +2260,19 @@ Use the `ls' command."
      "银河系漫游指南系列"
      "Автостопом по гала́ктике")))
 
-(ert-deftest tramp-test33-utf8 ()
+(ert-deftest tramp-test34-utf8 ()
   "Check UTF8 encoding in file names and file contents."
   (skip-unless (tramp--test-enabled))
   (skip-unless (not (tramp--test-rsync-p)))
 
   (tramp--test-utf8))
 
-(ert-deftest tramp-test33-utf8-with-stat ()
+(ert-deftest tramp-test34-utf8-with-stat ()
   "Check UTF8 encoding in file names and file contents.
 Use the `stat' command."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless (not (tramp--test-rsync-p)))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (and (tramp--test-sh-p) (not (tramp--test-rsync-p))))
   (with-parsed-tramp-file-name tramp-test-temporary-file-directory nil
     (skip-unless (tramp-get-remote-stat v)))
 
@@ -2279,16 +2283,12 @@ Use the `stat' command."
           tramp-connection-properties)))
     (tramp--test-utf8)))
 
-(ert-deftest tramp-test33-utf8-with-perl ()
+(ert-deftest tramp-test34-utf8-with-perl ()
   "Check UTF8 encoding in file names and file contents.
 Use the `perl' command."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless (not (tramp--test-rsync-p)))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (and (tramp--test-sh-p) (not (tramp--test-rsync-p))))
   (with-parsed-tramp-file-name tramp-test-temporary-file-directory nil
     (skip-unless (tramp-get-remote-perl v)))
 
@@ -2302,16 +2302,12 @@ Use the `perl' command."
           tramp-connection-properties)))
     (tramp--test-utf8)))
 
-(ert-deftest tramp-test33-utf8-with-ls ()
+(ert-deftest tramp-test34-utf8-with-ls ()
   "Check UTF8 encoding in file names and file contents.
 Use the `ls' command."
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless (not (tramp--test-rsync-p)))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (and (tramp--test-sh-p) (not (tramp--test-rsync-p))))
 
   (let ((tramp-connection-properties
          (append
@@ -2326,7 +2322,7 @@ Use the `ls' command."
     (tramp--test-utf8)))
 
 ;; This test is inspired by Bug#16928.
-(ert-deftest tramp-test34-asynchronous-requests ()
+(ert-deftest tramp-test35-asynchronous-requests ()
   "Check parallel asynchronous requests.
 Such requests could arrive from timers, process filters and
 process sentinels.  They shall not disturb each other."
@@ -2334,10 +2330,7 @@ process sentinels.  They shall not disturb each other."
   :expected-result :failed
   :tags '(:expensive-test)
   (skip-unless (tramp--test-enabled))
-  (skip-unless
-   (eq
-    (tramp-find-foreign-file-name-handler tramp-test-temporary-file-directory)
-    'tramp-sh-file-name-handler))
+  (skip-unless (tramp--test-sh-p))
 
   ;; Keep instrumentation verbosity 0 until Tramp bug is fixed.  This
   ;; has the side effect, that this test fails instead to abort.  Good
@@ -2416,7 +2409,7 @@ process sentinels.  They shall not disturb each other."
       (dolist (buf buffers)
         (ignore-errors (kill-buffer buf)))))))
 
-(ert-deftest tramp-test35-recursive-load ()
+(ert-deftest tramp-test36-recursive-load ()
   "Check that Tramp does not fail due to recursive load."
   (skip-unless (tramp--test-enabled))
 
@@ -2439,7 +2432,7 @@ process sentinels.  They shall not disturb each other."
         (mapconcat 'shell-quote-argument load-path " -L ")
         (shell-quote-argument code)))))))
 
-(ert-deftest tramp-test36-unload ()
+(ert-deftest tramp-test37-unload ()
   "Check that Tramp and its subpackages unload completely.
 Since it unloads Tramp, it shall be the last test to run."
   ;; Mark as failed until all symbols are unbound.
@@ -2477,7 +2470,6 @@ Since it unloads Tramp, it shall be the last test to run."
 ;; * dired-compress-file
 ;; * dired-uncache
 ;; * file-acl
-;; * file-ownership-preserved-p
 ;; * file-selinux-context
 ;; * find-backup-file-name
 ;; * set-file-acl
@@ -2485,10 +2477,9 @@ Since it unloads Tramp, it shall be the last test to run."
 
 ;; * Work on skipped tests.  Make a comment, when it is impossible.
 ;; * Fix `tramp-test06-directory-file-name' for `ftp'.
-;; * Fix `tramp-test15-copy-directory' for `rsync'.
 ;; * Fix `tramp-test27-start-file-process' on MS Windows (`process-send-eof'?).
-;; * Fix Bug#16928.  Set expected error of `tramp-test34-asynchronous-requests'.
-;; * Fix `tramp-test36-unload' (Not all symbols are unbound).  Set
+;; * Fix Bug#16928.  Set expected error of `tramp-test35-asynchronous-requests'.
+;; * Fix `tramp-test37-unload' (Not all symbols are unbound).  Set
 ;;   expected error.
 
 (defun tramp-test-all (&optional interactive)