Further cleanup for file locks

* doc/misc/tramp.texi (Top, Configuration): Adapt node name for
file locks.
(Auto-save File Lock and Backup): Rename node name and section
title.  Add file-lock to @cindex.  Describe file locks.

* lisp/dired.el (dired-trivial-filenames): Add lock files.
(dired-font-lock-keywords): Move files suffixed with
`completion-ignored-extensions' up.  Add lock files to these checks.

* lisp/net/tramp.el (tramp-get-lock-file, tramp-handle-unlock-file):
Use `when-let'
(tramp-lock-file-info-regexp): Rename from
`tramp-lock-file-contents-regexp'.
(tramp-handle-file-locked-p, tramp-handle-lock-file): Adapt callees.
(tramp-handle-lock-file): Set file modes of lockname.

* src/buffer.c (Frestore_buffer_modified_p):
* src/fileio.c (write_region):
* src/insdel.c (prepare_to_modify_buffer_1): Call Flock_file.

* src/filelock.c (Qmake_lock_file_name): Declare symbol.
(make_lock_file_name): Use it.  Don't check Fboundp, it doesn't
work for interned symbols.
(lock_file): Return a Lisp_Object.  Don't check create_lockfiles.
Remove MSDOS version of the function.
(Flock_file): Check create_lockfiles.
(Flock_buffer): Call Flock_file.

* src/lisp.h (lock_file): Remove.

* test/lisp/shadowfile-tests.el (shadow-test08-shadow-todo)
(shadow-test09-shadow-copy-files): Let-bind `create-lockfiles'.

* test/lisp/net/tramp-tests.el (create-lockfiles): Don't set it
globally.
(tramp-test39-lock-file): Check also for `set-visited-file-name'.

2 files changed, 57 insertions, 53 deletions

diff --git a/lisp/dired.el b/lisp/dired.el
index 9ddd2c542dc..fb353a92e45 100644
--- a/lisp/dired.el
+++ b/lisp/dired.el
@@ -163,7 +163,7 @@ always set this variable to t."
   :type 'boolean
   :group 'dired-mark)
 
-(defcustom dired-trivial-filenames (purecopy "\\`\\.\\.?\\'\\|\\`#")
+(defcustom dired-trivial-filenames (purecopy "\\`\\.\\.?\\'\\|\\`\\.?#")
   "Regexp of files to skip when finding first file of a directory.
 A value of nil means move to the subdir line.
 A value of t means move to first file."
@@ -615,6 +615,31 @@ Subexpression 2 must end right before the \\n.")
    (list dired-re-dir
 	 '(".+" (dired-move-to-filename) nil (0 dired-directory-face)))
    ;;
+   ;; Files suffixed with `completion-ignored-extensions'.
+   '(eval .
+     ;; It is quicker to first find just an extension, then go back to the
+     ;; start of that file name.  So we do this complex MATCH-ANCHORED form.
+          (list (concat
+                 "\\(" (regexp-opt completion-ignored-extensions)
+                 "\\|#\\|\\.#.+\\)$")
+	   '(".+" (dired-move-to-filename) nil (0 dired-ignored-face))))
+   ;;
+   ;; Files suffixed with `completion-ignored-extensions'
+   ;; plus a character put in by -F.
+   '(eval .
+     (list (concat "\\(" (regexp-opt completion-ignored-extensions)
+		   "\\|#\\|\\.#.+\\)[*=|]$")
+	   '(".+" (progn
+		    (end-of-line)
+		    ;; If the last character is not part of the filename,
+		    ;; move back to the start of the filename
+		    ;; so it can be fontified.
+		    ;; Otherwise, leave point at the end of the line;
+		    ;; that way, nothing is fontified.
+		    (unless (get-text-property (1- (point)) 'mouse-face)
+		      (dired-move-to-filename)))
+	     nil (0 dired-ignored-face))))
+   ;;
    ;; Broken Symbolic link.
    (list dired-re-sym
          (list (lambda (end)
@@ -659,29 +684,6 @@ Subexpression 2 must end right before the \\n.")
    (list dired-re-special
 	 '(".+" (dired-move-to-filename) nil (0 'dired-special)))
    ;;
-   ;; Files suffixed with `completion-ignored-extensions'.
-   '(eval .
-     ;; It is quicker to first find just an extension, then go back to the
-     ;; start of that file name.  So we do this complex MATCH-ANCHORED form.
-     (list (concat "\\(" (regexp-opt completion-ignored-extensions) "\\|#\\)$")
-	   '(".+" (dired-move-to-filename) nil (0 dired-ignored-face))))
-   ;;
-   ;; Files suffixed with `completion-ignored-extensions'
-   ;; plus a character put in by -F.
-   '(eval .
-     (list (concat "\\(" (regexp-opt completion-ignored-extensions)
-		   "\\|#\\)[*=|]$")
-	   '(".+" (progn
-		    (end-of-line)
-		    ;; If the last character is not part of the filename,
-		    ;; move back to the start of the filename
-		    ;; so it can be fontified.
-		    ;; Otherwise, leave point at the end of the line;
-		    ;; that way, nothing is fontified.
-		    (unless (get-text-property (1- (point)) 'mouse-face)
-		      (dired-move-to-filename)))
-	     nil (0 dired-ignored-face))))
-   ;;
    ;; Explicitly put the default face on file names ending in a colon to
    ;; avoid fontifying them as directory header.
    (list (concat dired-re-maybe-mark dired-re-inode-size dired-re-perms ".*:$")
diff --git a/lisp/net/tramp.el b/lisp/net/tramp.el
index 7578d6fe308..fc714c9339a 100644
--- a/lisp/net/tramp.el
+++ b/lisp/net/tramp.el
@@ -3819,9 +3819,9 @@ User is always nil."
       (cons (expand-file-name filename) (cdr result)))))
 
 (defun tramp-get-lock-file (file)
-  "Read lockfile of FILE.
-Return nil when there is no lockfile"
-  (let ((lockname (tramp-compat-make-lock-file-name file)))
+  "Read lockfile info of FILE.
+Return nil when there is no lockfile."
+  (when-let ((lockname (tramp-compat-make-lock-file-name file)))
     (or (file-symlink-p lockname)
 	(and (file-readable-p lockname)
 	     (with-temp-buffer
@@ -3839,51 +3839,53 @@ Return nil when there is no lockfile"
      (or (process-id p)
 	 (tramp-get-connection-property p "lock-pid" (emacs-pid))))))
 
-(defconst tramp-lock-file-contents-regexp
+(defconst tramp-lock-file-info-regexp
   ;; USER@HOST.PID[:BOOT_TIME]
   "\\`\\(.+\\)@\\(.+\\)\\.\\([[:digit:]]+\\)\\(?::\\([[:digit:]]+\\)\\)?\\'"
   "The format of a lock file.")
 
 (defun tramp-handle-file-locked-p (file)
   "Like `file-locked-p' for Tramp files."
-  (when-let ((contents (tramp-get-lock-file file))
-	     (match (string-match tramp-lock-file-contents-regexp contents)))
-    (or (and (string-equal (match-string 1 contents) (user-login-name))
-	     (string-equal (match-string 2 contents) (system-name))
-	     (string-equal (match-string 3 contents) (tramp-get-lock-pid file)))
-	(match-string 1 contents))))
+  (when-let ((info (tramp-get-lock-file file))
+	     (match (string-match tramp-lock-file-info-regexp info)))
+    (or (and (string-equal (match-string 1 info) (user-login-name))
+	     (string-equal (match-string 2 info) (system-name))
+	     (string-equal (match-string 3 info) (tramp-get-lock-pid file)))
+	(match-string 1 info))))
 
 (defun tramp-handle-lock-file (file)
   "Like `lock-file' for Tramp files."
   ;; See if this file is visited and has changed on disk since it
   ;; was visited.
   (catch 'dont-lock
-    (unless (or (null create-lockfiles)
-		(eq (file-locked-p file) t)) ;; Locked by me.
-      (when-let ((contents (tramp-get-lock-file file))
-		 (match (string-match tramp-lock-file-contents-regexp contents)))
+    (unless (eq (file-locked-p file) t) ;; Locked by me.
+      (when-let ((info (tramp-get-lock-file file))
+		 (match (string-match tramp-lock-file-info-regexp info)))
 	(unless (ask-user-about-lock
 		 file (format
-		       "%s@%s (pid %s)" (match-string 1 contents)
-		       (match-string 2 contents) (match-string 3 contents)))
+		       "%s@%s (pid %s)" (match-string 1 info)
+		       (match-string 2 info) (match-string 3 info)))
 	  (throw 'dont-lock nil)))
 
-      (let ((lockname (tramp-compat-make-lock-file-name file))
-	    ;; USER@HOST.PID[:BOOT_TIME]
-	    (contents
-	     (format
-	      "%s@%s.%s" (user-login-name) (system-name)
-	      (tramp-get-lock-pid file)))
-	    create-lockfiles signal-hook-function)
-	(condition-case nil
-	    (make-symbolic-link contents lockname 'ok-if-already-exists)
-	  (error (write-region contents nil lockname)))))))
+      (when-let ((lockname (tramp-compat-make-lock-file-name file))
+	         ;; USER@HOST.PID[:BOOT_TIME]
+	         (info
+	          (format
+	           "%s@%s.%s" (user-login-name) (system-name)
+	           (tramp-get-lock-pid file))))
+        (let (create-lockfiles signal-hook-function)
+	  (condition-case nil
+	      (make-symbolic-link info lockname 'ok-if-already-exists)
+	    (error
+             (write-region info nil lockname)
+             (set-file-modes lockname #o0644))))))))
 
 (defun tramp-handle-unlock-file (file)
   "Like `unlock-file' for Tramp files."
-  (condition-case err
-      (delete-file (tramp-compat-make-lock-file-name file))
-    (error (userlock--handle-unlock-error err))))
+  (when-let ((lockname (tramp-compat-make-lock-file-name file)))
+    (condition-case err
+        (delete-file lockname)
+      (error (userlock--handle-unlock-error err)))))
 
 (defun tramp-handle-load (file &optional noerror nomessage nosuffix must-suffix)
   "Like `load' for Tramp files."