master d5eab4b2d4c: Improve Tramp backup handling

branch: master
commit d5eab4b2d4cb187eb39efbba21780ba754d01816
Author: Michael Albinus <[email protected]>
Commit: Michael Albinus <[email protected]>

    Improve Tramp backup handling
    
    * doc/misc/tramp.texi (Auto-save File Lock and Backup): Adapt example.
    
    * lisp/net/tramp.el (tramp-handle-find-backup-file-name):
    Use connection-local value of `make-backup-files'.
    
    * test/lisp/net/tramp-tests.el (tramp-test38-find-backup-file-name):
    Extend test.
---
 doc/misc/tramp.texi          | 32 +++++++++++++-------
 lisp/net/tramp.el            | 70 +++++++++++++++++++++++---------------------
 test/lisp/net/tramp-tests.el | 20 ++++++++++++-
 3 files changed, 76 insertions(+), 46 deletions(-)

diff --git a/doc/misc/tramp.texi b/doc/misc/tramp.texi
index 7bee92a94d5..cc51f048d28 100644
--- a/doc/misc/tramp.texi
+++ b/doc/misc/tramp.texi
@@ -3380,13 +3380,23 @@ of the secretfile is now owned by the user logged in from
 When @code{backup-directory-alist} is @code{nil} (the default), such
 problems do not occur.
 
-To ``turn off'' the backup feature for remote files and stop
-@value{tramp} from saving to the backup directory, use this:
+@vindex make-backup-files
+In case you do not want to use backup files for remote files, use
+connection-local variable @code{make-backup-files}
+@ifinfo
+(@pxref{Connection Variables, , , emacs})
+@end ifinfo
+like this:
 
 @lisp
 @group
-(add-to-list 'backup-directory-alist
-             (cons tramp-file-name-regexp nil))
+(connection-local-set-profile-variables
+ 'no-remote-backup-files '((make-backup-files . nil)))
+@end group
+
+@group
+(connection-local-set-profiles
+ '(:application tramp) 'no-remote-backup-files)
 @end group
 @end lisp
 
@@ -3396,13 +3406,13 @@ Disabling backups can be targeted to just the @option{su} and
 
 @lisp
 @group
-(setq backup-enable-predicate
-      (lambda (name)
-        (and (normal-backup-enable-predicate name)
-             (not
-              (let ((method (file-remote-p name 'method)))
-                (when (stringp method)
-                  (member method '("su" "sudo"))))))))
+(connection-local-set-profiles
+ '(:application tramp :protocol "su") 'no-remote-backup-files)
+@end group
+
+@group
+(connection-local-set-profiles
+ '(:application tramp :protocol "sudo") 'no-remote-backup-files)
 @end group
 @end lisp
 
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 5219435cbd2..477366c6848 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -4792,40 +4792,42 @@ existing) are returned."
 
 (defun tramp-handle-find-backup-file-name (filename)
   "Like `find-backup-file-name' for Tramp files."
-  (with-parsed-tramp-file-name filename nil
-    (let ((backup-directory-alist
-	   (if tramp-backup-directory-alist
-	       (mapcar
-		(lambda (x)
-		  (cons
-		   (car x)
-		   (if (and (stringp (cdr x))
-			    (file-name-absolute-p (cdr x))
-			    (not (tramp-tramp-file-p (cdr x))))
-		       (tramp-make-tramp-file-name v (cdr x))
-		     (cdr x))))
-		tramp-backup-directory-alist)
-	     backup-directory-alist))
-	  result)
-      (prog1 ;; Run plain `find-backup-file-name'.
-	  (setq result
-		(tramp-run-real-handler
-		 #'find-backup-file-name (list filename)))
-        ;; Protect against security hole.
-	(when (and (not tramp-allow-unsafe-temporary-files)
-		   (not backup-inhibited)
-		   (file-in-directory-p (car result) temporary-file-directory)
-		   (= (or (file-attribute-user-id
-			   (file-attributes filename 'integer))
-			  tramp-unknown-id-integer)
-		      tramp-root-id-integer)
-		   (not (with-tramp-connection-property
-			    (tramp-get-process v) "unsafe-temporary-file"
-			  (yes-or-no-p
-			   (concat
-			    "Backup file on local temporary directory, "
-			    "do you want to continue?")))))
-	  (tramp-error v 'file-error "Unsafe backup file name"))))))
+  (when-let* ((default-directory (file-name-directory filename))
+	      ((tramp-compat-connection-local-value make-backup-files)))
+    (with-parsed-tramp-file-name filename nil
+      (let ((backup-directory-alist
+	     (if tramp-backup-directory-alist
+		 (mapcar
+		  (lambda (x)
+		    (cons
+		     (car x)
+		     (if (and (stringp (cdr x))
+			      (file-name-absolute-p (cdr x))
+			      (not (tramp-tramp-file-p (cdr x))))
+			 (tramp-make-tramp-file-name v (cdr x))
+		       (cdr x))))
+		  tramp-backup-directory-alist)
+	       backup-directory-alist))
+	    result)
+	(prog1 ;; Run plain `find-backup-file-name'.
+	    (setq result
+		  (tramp-run-real-handler
+		   #'find-backup-file-name (list filename)))
+          ;; Protect against security hole.
+	  (when (and (not tramp-allow-unsafe-temporary-files)
+		     (not backup-inhibited)
+		     (file-in-directory-p (car result) temporary-file-directory)
+		     (= (or (file-attribute-user-id
+			     (file-attributes filename 'integer))
+			    tramp-unknown-id-integer)
+			tramp-root-id-integer)
+		     (not (with-tramp-connection-property
+			      (tramp-get-process v) "unsafe-temporary-file"
+			    (yes-or-no-p
+			     (concat
+			      "Backup file on local temporary directory, "
+			      "do you want to continue?")))))
+	    (tramp-error v 'file-error "Unsafe backup file name")))))))
 
 (defun tramp-handle-insert-directory
     (filename switches &optional wildcard full-directory-p)
diff --git a/test/lisp/net/tramp-tests.el b/test/lisp/net/tramp-tests.el
index 6badf064efe..f4f061d2efb 100644
--- a/test/lisp/net/tramp-tests.el
+++ b/test/lisp/net/tramp-tests.el
@@ -7288,7 +7288,25 @@ INPUT, if non-nil, is a string sent to the process."
 
 	;; Cleanup.
 	(ignore-errors (delete-file tmp-name1))
-	(tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password)))))
+	(tramp-cleanup-connection tramp-test-vec 'keep-debug 'keep-password))
+
+      ;; Check connection-local `make-backup-files'.
+      (let ((clpa connection-local-profile-alist)
+	    (clca connection-local-criteria-alist))
+	(connection-local-set-profile-variables
+	 'no-remote-backup-files '((make-backup-files . nil)))
+	(connection-local-set-profiles
+	 `(:application tramp
+	   :protocol ,(file-remote-p default-directory 'method)
+	   :user ,(file-remote-p default-directory 'user)
+	   :machine ,(file-remote-p default-directory 'host))
+	 'no-remote-backup-files)
+
+	(should-not (find-backup-file-name tmp-name1))
+
+	(custom-set-variables
+	 `(connection-local-profile-alist ',clpa now)
+	 `(connection-local-criteria-alist ',clca now))))))
 
 (ert-deftest tramp-test39-make-lock-file-name ()
   "Check `make-lock-file-name', `lock-file', `unlock-file' and `file-locked-p'."