The RCS status is now found by reading the

master file directly, instead of using rlog.  The properties
retrieved from the master file are kept separately.  The two
main properties, `vc-workfile-version' and `vc-locking-user',
are inferred from those master file properties if the
information cannot be found elsehow.  All properties are
consistently cached now.

(vc-master-info, vc-log-info, vc-fetch-properties): functions
removed.  Their job is now done by `vc-fetch-master-properties'
and `vc-insert-file'.

(vc-fetch-master-properties):  new function, replaces
vc-fetch-properties.  Retrieves all the properties that can be
found in the master file, for all three backends (calls
`cvs status' in the CVS case).

(vc-insert-file):  new function.  Inserts an arbitrary file
into the current buffer, optionally chunkwise, until a certain
regexp shows up.

(vc-parse-locks):  new function.  Translates SCCS or RCS lock
lists, as found in the master files, into lisp lists.  Sets
the new property `vc-master-locks'.

(vc-locked-version):  property removed.  Was unnecessary, and
only referenced in vc-hooks.el.
(vc-head-version, vc-default-branch, vc-master-locks):
new properties.

(vc-top-version):  new name for the old property
`vc-branch-version'.  ("top-version" is better because it
might also be the RCS "head" if there is no default branch.)

(vc-master-locking-user):  replaces `vc-true-locking-user'.
Scans the new `vc-master-locks' property, yielding the master
file's idea of who is locking the current workfile version.

(vc-locking-user):  slightly changed to use the new properties.
Changed the actual property value for an unlocked file to
'none.  This is to distinguish it from an unknown locking
state, which is represented by nil.  The function vc-locking-user
returns nil if the property is 'none, to make it compatible with
the rest of VC.

(vc-consult-rcs-headers, vc-master-locking-user):  adpated to
the new 'none-value of vc-locking-user.

(vc-consult-rcs-headers): fixed bug that prevented
(not vc-consult-headers) from working

(vc-file-not-found-hook): set the default-directory of the new
buffer before check-out. (Otherwise, setting vc-keep-workfiles
to nil doesn't work.)

(vc-occurences, vc-branch-p): functions removed (no longer needed)

Reordered some defuns so they are grouped in a logical way.

1 files changed, 296 insertions, 281 deletions

diff --git a/lisp/vc-hooks.el b/lisp/vc-hooks.el
index c875a581024..f537980fbd3 100644
--- a/lisp/vc-hooks.el
+++ b/lisp/vc-hooks.el
@@ -79,24 +79,6 @@ value of this flag.")
 (make-variable-buffer-local 'vc-mode)
 (put 'vc-mode 'permanent-local t)
 
-
-;; branch identification
-
-(defun vc-occurrences (object sequence)
-  ;; return the number of occurences of OBJECT in SEQUENCE
-  ;; (is it really true that Emacs Lisp doesn't provide such a function?)
-  (let ((len (length sequence)) (index 0) (occ 0))
-    (while (< index len)
-      (if (eq object (elt sequence index))
-          (setq occ (1+ occ)))
-      (setq index (1+ index)))
-    occ))
-
-(defun vc-branch-p (rev)
-  ;; return t if REV is the branch part of a revision, 
-  ;; i.e. a revision without a minor number
-  (eq 0 (% (vc-occurrences ?. rev) 2)))
-
 ;; We need a notion of per-file properties because the version
 ;; control state of a file is expensive to derive --- we compute
 ;; them when the file is initially found, keep them up to date 
@@ -124,28 +106,8 @@ value of this flag.")
   ;; clear all properties of a given file
   (setplist (intern file vc-file-prop-obarray) nil))
 
-;; basic properties 
-
-(defun vc-name (file)
-  "Return the master name of a file, nil if it is not registered."
-  (or (vc-file-getprop file 'vc-name)
-      (let ((name-and-type (vc-registered file)))
-        (if name-and-type
-            (progn
-              (vc-file-setprop file 'vc-backend (cdr name-and-type))
-              (vc-file-setprop file 'vc-name (car name-and-type)))))))
-
-(defun vc-backend (file)
-  "Return the version-control type of a file, nil if it is not registered."
-  (and file
-       (or (vc-file-getprop file 'vc-backend)
-           (let ((name-and-type (vc-registered file)))
-             (if name-and-type
-                 (progn
-                   (vc-file-setprop file 'vc-name (car name-and-type))
-                   (vc-file-setprop file 'vc-backend (cdr name-and-type))))))))
-
-;; Functions for querying the master and lock files.
+;;; Functions that determine property values, by examining the 
+;;; working file, the master file, or log program output
 
 (defun vc-match-substring (bn)
   (buffer-substring (match-beginning bn) (match-end bn)))
@@ -199,95 +161,154 @@ value of this flag.")
           patterns)
   )
 
-(defun vc-master-info (file fields &optional rfile properties)
-  ;; Search for information in a master file.
-  (if (and file (file-exists-p file))
-      (save-excursion
-        (let ((buf))
-          (setq buf (create-file-buffer file))
-          (set-buffer buf))
-        (erase-buffer)
-        (insert-file-contents file)
-        (set-buffer-modified-p nil)
-        (auto-save-mode nil)
-        (prog1
-            (vc-parse-buffer fields rfile properties)
-          (kill-buffer (current-buffer)))
-        )
-    (if rfile
-        (mapcar
-         (function (lambda (p) (vc-file-setprop rfile p nil)))
-         properties))
-    )
-  )
-
-(defun vc-log-info (command file flags patterns &optional properties)
-  ;; Search for information in log program output.
-  ;; If there is a string `\X' in any of the PATTERNS, replace
-  ;; it with a regexp to search for a branch revision.
-  (if (and file (file-exists-p file))
-      (save-excursion
-        ;; Run the command (not using vc-do-command, as that is
-        ;; only available within vc.el)
-        ;; Don't switch to the *vc* buffer before running the command
-        ;; because that would change its default-directory.
-        (save-excursion (set-buffer (get-buffer-create "*vc*"))
-                        (erase-buffer))
-        (let ((exec-path (append vc-path exec-path))
-              ;; Add vc-path to PATH for the execution of this command.
-              (process-environment
-               (cons (concat "PATH=" (getenv "PATH")
-                             path-separator
-                             (mapconcat 'identity vc-path path-separator))
-                     process-environment)))
-          (apply 'call-process command nil "*vc*" nil 
-                 (append flags (list (file-name-nondirectory file)))))
-        (set-buffer (get-buffer "*vc*"))
-        (set-buffer-modified-p nil)
-        ;; in the RCS case, insert branch version into
-        ;; any patterns that contain \X
-        (if (eq (vc-backend file) 'RCS)
-            (let ((branch 
-                   (car (vc-parse-buffer 
-                         '(("^branch:[ \t]+\\([0-9.]+\\)$" 1))))))
-              (setq patterns
-                (mapcar 
-                 (function 
-                  (lambda (p)
-                    (if (string-match "\\\\X" (car p))
-                        (if branch
-                            (cond ((vc-branch-p branch)
-                                   (cons 
-                                    (concat 
-                                     (substring (car p) 0 (match-beginning 0))
-                                     (regexp-quote branch)
-                                     "\\.[0-9]+"
-                                     (substring (car p) (match-end 0)))
-                                    (cdr p)))
-                                  (t
-                                   (cons
-                                    (concat 
-                                     (substring (car p) 0 (match-beginning 0))
-                                     (regexp-quote branch)
-                                     (substring (car p) (match-end 0)))
-                                    (cdr p))))
-                          ;; if there is no current branch, 
-                          ;; return a completely different regexp, 
-                          ;; which searches for the *head*
-                          '("^head:[ \t]+\\([0-9.]+\\)$" 1))
-                      p)))
-                 patterns))))
-        (prog1
-            (vc-parse-buffer patterns file properties)
-          (kill-buffer (current-buffer))
-          )
-        )
-    (if file
-        (mapcar
-         (function (lambda (p) (vc-file-setprop file p nil)))
-         properties))
-    )
-  )
+(defun vc-insert-file (file &optional limit blocksize)
+  ;; Insert the contents of FILE into the current buffer.
+  ;; Optional argument LIMIT is a regexp. If present,
+  ;; the file is inserted in chunks of size BLOCKSIZE
+  ;; (default 8 kByte), until the first occurence of
+  ;; LIMIT is found. The function returns nil if FILE 
+  ;; doesn't exist.
+  (cond ((file-exists-p file)
+         (cond (limit
+                (if (not blocksize) (setq blocksize 8192))
+                (let (found s)
+                  (while (not found)
+                    (setq s (buffer-size))
+                    (goto-char (1+ s))
+                    (setq found 
+                          (or (zerop (car (cdr 
+                              (insert-file-contents file nil s 
+                               (+ s blocksize)))))
+                              (progn (beginning-of-line)
+                                     (re-search-forward limit nil t)))))))
+               (t (insert-file-contents file)))
+         (set-buffer-modified-p nil)
+         (auto-save-mode nil)
+         t)
+        (t nil)))
+
+(defun vc-parse-locks (file locks)
+  ;; Parse RCS or SCCS locks.
+  ;; The result is a list of the form ((VERSION USER) (VERSION USER) ...),
+  ;; which is returned and stored into the property `vc-master-locks'.
+  (if (not locks) 
+      (vc-file-setprop file 'vc-master-locks 'none)
+    (let ((found t) (index 0) master-locks version user)
+      (cond ((eq (vc-backend file) 'SCCS)
+             (while (string-match "^\\([0-9.]+\\) [0-9.]+ \\([^ ]+\\) .*\n?"
+                                   locks index)
+               (setq version (substring locks 
+                                        (match-beginning 1) (match-end 1)))
+               (setq user (substring locks 
+                                     (match-beginning 2) (match-end 2)))
+               (setq master-locks (append master-locks 
+                                          (list (cons version user))))
+               (setq index (match-end 0))))
+            ((eq (vc-backend file) 'RCS)
+             (while (string-match "[ \t\n]*\\([^:]+\\):\\([0-9.]+\\)"
+                                  locks index)
+               (setq version (substring locks 
+                                        (match-beginning 2) (match-end 2)))
+               (setq user (substring locks 
+                                     (match-beginning 1) (match-end 1)))
+               (setq master-locks (append master-locks 
+                                          (list (cons version user))))
+               (setq index (match-end 0)))))
+      (vc-file-setprop file 'vc-master-locks (or master-locks 'none)))))
+
+(defun vc-fetch-master-properties (file)
+  ;; Fetch those properties of FILE that are stored in the master file.
+  (save-excursion
+    (cond
+     ((eq (vc-backend file) 'SCCS)
+      (set-buffer (get-buffer-create "*vc-info*"))
+      (if (vc-insert-file (vc-lock-file file))
+          (progn (vc-parse-locks file (buffer-string))
+                 (erase-buffer))
+        (vc-file-setprop file 'vc-master-locks 'none))
+      (vc-insert-file (vc-name file) "^\001e")
+      (vc-parse-buffer 
+       (list '("^\001d D \\([^ ]+\\)" 1)
+             (list (concat "^\001d D \\([^ ]+\\) .* " 
+                           (regexp-quote (user-login-name)) " ") 1))
+       file
+       '(vc-latest-version vc-your-latest-version)))
+
+     ((eq (vc-backend file) 'RCS)
+      (set-buffer (get-buffer-create "*vc-info*"))
+      (vc-insert-file (vc-name file) "^desc")
+      (vc-parse-buffer 
+       (list '("^head[ \t\n]+\\([^;]+\\);" 1)
+             '("^branch[ \t\n]+\\([^;]+\\);" 1)
+             '("^locks\\([^;]+\\);" 1)
+             '("^\\([0-9]+\\.[0-9.]+\\)\ndate[ \t]+\\([0-9.]+\\);" 1 2)
+             (list (concat "^\\([0-9]+\\.[0-9.]+\\)\n"
+                           "date[ \t]+\\([0-9.]+\\);[ \t]+"
+                           "author[ \t]+"
+                           (regexp-quote (user-login-name)) ";") 1 2))
+       file
+       '(vc-head-version
+         vc-default-branch
+         vc-master-locks
+         vc-latest-version
+         vc-your-latest-version))
+      ;; determine vc-top-version: it is either the head version, 
+      ;; or the tip of the default branch
+      (let ((default-branch (vc-file-getprop file 'vc-default-branch)))
+        (cond 
+         ;; no default branch
+         ((or (not default-branch) (string= "" default-branch))
+          (vc-file-setprop file 'vc-top-version 
+                           (vc-file-getprop file 'vc-head-version)))
+         ;; default branch is actually a revision
+         ((string-match "^[0-9]+\\.[0-9]+\\(\\.[0-9]+\\.[0-9]+\\)*$" 
+                        default-branch)
+          (vc-file-setprop file 'vc-top-version default-branch))
+         ;; else, search for the tip of the default branch
+         (t (vc-parse-buffer (list (list 
+               (concat "^\\(" 
+                       (regexp-quote default-branch)
+                       "\\.[0-9]+\\)\ndate[ \t]+\\([0-9.]+\\);") 1 2))
+                         file '(vc-top-version)))))
+      ;; translate the locks
+      (vc-parse-locks file (vc-file-getprop file 'vc-master-locks)))
+
+     ((eq (vc-backend file) 'CVS)
+      ;; don't switch to the *vc-info* buffer before running the
+      ;; command, because that would change its default directory
+      (save-excursion (set-buffer (get-buffer-create "*vc-info*"))
+                      (erase-buffer))
+      (let ((exec-path (append vc-path exec-path))
+            ;; Add vc-path to PATH for the execution of this command.
+            (process-environment
+             (cons (concat "PATH=" (getenv "PATH")
+                           ":" (mapconcat 'identity vc-path ":"))
+                   process-environment)))
+        (apply 'call-process "cvs" nil "*vc-info*" nil 
+               (list "status" (file-name-nondirectory file))))
+      (set-buffer (get-buffer "*vc-info*"))
+      (set-buffer-modified-p nil)
+      (auto-save-mode nil)
+      (vc-parse-buffer     
+       ;; CVS 1.3 says "RCS Version:", other releases "RCS Revision:",
+       ;; and CVS 1.4a1 says "Repository revision:".
+       '(("\\(RCS Version\\|RCS Revision\\|Repository revision\\):[\t ]+\\([0-9.]+\\)" 2)
+      ("^File: [^ \t]+[ \t]+Status: \\(.*\\)" 1))
+       file
+       '(vc-latest-version vc-cvs-status))
+      ;; Translate those status values that are needed into symbols.
+      ;; Any other value is converted to nil.
+      (let ((status (vc-file-getprop file 'vc-cvs-status)))
+        (cond ((string-match "Up-to-date" status)
+               (vc-file-setprop file 'vc-cvs-status 'up-to-date)
+               (vc-file-setprop file 'vc-checkout-time 
+                                (nth 5 (file-attributes file))))
+              ((string-match "Locally Modified" status)
+               (vc-file-setprop file 'vc-cvs-status 'locally-modified))
+              ((string-match "Needs Merge" status)
+               (vc-file-setprop file 'vc-cvs-status 'needs-merge))
+              (t (vc-file-setprop file 'vc-cvs-status nil))))))
+    (kill-buffer (current-buffer))))
 
 ;;; Functions that determine property values, by examining the 
 ;;; working file, the master file, or log program output
@@ -304,7 +325,7 @@ value of this flag.")
   ;;          'rev-and-lock  if revision and lock info was found 
   (cond 
    ((or (not vc-consult-headers) 
-        (not (get-file-buffer file)) nil))
+        (not (get-file-buffer file))) nil)
    ((save-excursion
       (set-buffer (get-file-buffer file))
       (goto-char (point-min))
@@ -326,8 +347,7 @@ value of this flag.")
                ;; unlocked revision
                ((looking-at "\\$")
                 (vc-file-setprop file 'vc-workfile-version rev)
-                (vc-file-setprop file 'vc-locking-user nil)
-                (vc-file-setprop file 'vc-locked-version nil)
+                (vc-file-setprop file 'vc-locking-user 'none)
                 'rev-and-lock)
                ;; revision is locked by some user
                ((looking-at "\\([^ ]+\\) \\$")
@@ -335,7 +355,6 @@ value of this flag.")
                 (vc-file-setprop file 'vc-locking-user 
                                  (buffer-substring (match-beginning 1)
                                                    (match-end 1)))
-                (vc-file-setprop file 'vc-locked-version rev) 
                 'rev-and-lock)
                ;; everything else: false
                (nil))
@@ -358,15 +377,14 @@ value of this flag.")
                      (vc-file-setprop file 'vc-locking-user
                                       (buffer-substring (match-beginning 1)
                                                         (match-end 1)))
-                     (vc-file-setprop file 'vc-locked-version rev)
                      'rev-and-lock)
                     ((looking-at " *\\$") 
                      (vc-file-setprop file 'vc-workfile-version rev)
-                     (vc-file-setprop file 'vc-locking-user nil)
-                     (vc-file-setprop file 'vc-locked-version nil)
+                     (vc-file-setprop file 'vc-locking-user 'none)
                      'rev-and-lock)
                     (t 
                      (vc-file-setprop file 'vc-workfile-version rev)
+                     (vc-file-setprop file 'vc-locking-user 'none)
                      'rev-and-lock))
             (vc-file-setprop file 'vc-workfile-version rev)
             'rev)))
@@ -374,67 +392,15 @@ value of this flag.")
        ;; -------------------
        (t nil))))))
 
-(defun vc-fetch-properties (file)
-  ;; Re-fetch some properties associated with the given file.
-  (cond 
-   ((eq (vc-backend file) 'SCCS)
-    (progn
-      (vc-master-info (vc-lock-file file)
-                      (list
-                       '("^[^ ]+ [^ ]+ \\([^ ]+\\)" 1)
-                       '("^\\([^ ]+\\)" 1))
-                      file
-                      '(vc-locking-user vc-locked-version))
-      (vc-master-info (vc-name file)
-                      (list
-                       '("^\001d D \\([^ ]+\\)" 1)
-                       (list (concat "^\001d D \\([^ ]+\\) .* " 
-                                     (regexp-quote (user-login-name)) " ")
-                             1)
-                       )
-                      file
-                      '(vc-latest-version vc-your-latest-version))
-      ))
-   ((eq (vc-backend file) 'RCS)
-    (vc-log-info "rlog" file nil
-                 (list
-                  '("^locks: strict\n\t\\([^:]+\\)" 1)
-                  '("^locks: strict\n\t[^:]+: \\(.+\\)" 1)
-                  '("^revision[\t ]+\\([0-9.]+\\)\\(\n\\|[ \t].*\n\\)date: \\([ /0-9:]+\\);" 1 3)
-                  (list 
-                   (concat
-                    "^revision[\t ]+\\([0-9.]+\\)\\(\n\\|[ \t].*\n\\)date: \\([ /0-9:]+\\); *author: "
-                    (regexp-quote (user-login-name))
-                    ";") 1 3)
-                  ;; special regexp to search for branch revision:
-                  ;; \X will be replaced by vc-log-info (see there)
-                  '("^revision[\t ]+\\(\\X\\)\\(\n\\|[ \t].*\n\\)date: \\([ /0-9:]+\\);" 1 3))
-
-                 '(vc-locking-user 
-                   vc-locked-version
-                   vc-latest-version 
-                   vc-your-latest-version
-                   vc-branch-version)))
-   ((eq (vc-backend file) 'CVS)
-    (vc-log-info "cvs" file '("status")
-    ;; CVS 1.3 says "RCS Version:", other releases "RCS Revision:",
-    ;; and CVS 1.4a1 says "Repository revision:".
-    '(("\\(RCS Version\\|RCS Revision\\|Repository revision\\):[\t ]+\\([0-9.]+\\)" 2)
-      ("^File: [^ \t]+[ \t]+Status: \\(.*\\)" 1))
-    '(vc-latest-version vc-cvs-status))
-    ;; Translate those status values that are needed into symbols.
-    ;; Any other value is converted to nil.
-    (let ((status (vc-file-getprop file 'vc-cvs-status)))
-      (cond ((string-match "Up-to-date" status)
-             (vc-file-setprop file 'vc-cvs-status 'up-to-date)
-             (vc-file-setprop file 'vc-checkout-time 
-                              (nth 5 (file-attributes file))))
-            ((string-match "Locally Modified" status)
-             (vc-file-setprop file 'vc-cvs-status 'locally-modified))
-            ((string-match "Needs Merge" status)
-             (vc-file-setprop file 'vc-cvs-status 'needs-merge))
-            (t (vc-file-setprop file 'vc-cvs-status nil))))
-   )))
+;;; Access functions to file properties
+;;; (Properties should be _set_ using vc-file-setprop, but
+;;; _retrieved_ only through these functions, which decide
+;;; if the property is already known or not. A property should
+;;; only be retrieved by vc-file-getprop if there is no 
+;;; access function.)
+
+;;; properties indicating the backend 
+;;; being used for FILE
 
 (defun vc-backend-subdirectory-name (&optional file)
   ;; Where the master and lock files for the current directory are kept
@@ -444,115 +410,163 @@ value of this flag.")
     vc-default-back-end
     (setq vc-default-back-end (if (vc-find-binary "rcs") 'RCS 'SCCS)))))
 
+(defun vc-name (file)
+  "Return the master name of a file, nil if it is not registered."
+  (or (vc-file-getprop file 'vc-name)
+      (let ((name-and-type (vc-registered file)))
+        (if name-and-type
+            (progn
+              (vc-file-setprop file 'vc-backend (cdr name-and-type))
+              (vc-file-setprop file 'vc-name (car name-and-type)))))))
 
-;;; Access functions to file properties
-;;; (Properties should be _set_ using vc-file-setprop, but
-;;; _retrieved_ only through these functions, which decide
-;;; if the property is already known or not. A property should
-;;; only be retrieved by vc-file-getprop if there is no 
-;;; access function.)
+(defun vc-backend (file)
+  "Return the version-control type of a file, nil if it is not registered."
+  (and file
+       (or (vc-file-getprop file 'vc-backend)
+           (let ((name-and-type (vc-registered file)))
+             (if name-and-type
+                 (progn
+                   (vc-file-setprop file 'vc-name (car name-and-type))
+                   (vc-file-setprop file 'vc-backend (cdr name-and-type))))))))
 
-;; functions vc-name and vc-backend come earlier above, 
-;; because they are needed by vc-log-info etc.
+;;; properties indicating the locking state
 
 (defun vc-cvs-status (file)
   ;; Return the cvs status of FILE
   ;; (Status field in output of "cvs status")
   (cond ((vc-file-getprop file 'vc-cvs-status))
-        (t (vc-fetch-properties file)
+        (t (vc-fetch-master-properties file)
            (vc-file-getprop file 'vc-cvs-status))))
 
+(defun vc-master-locks (file)
+  ;; Return the lock entries in the master of FILE.
+  ;; Return 'none if there are no such entries, and a list
+  ;; of the form ((VERSION USER) (VERSION USER) ...) otherwise.
+  (cond ((vc-file-getprop file 'vc-master-locks))
+        (t (vc-fetch-master-properties file)
+           (vc-file-getprop file 'vc-master-locks))))
+
+(defun vc-master-locking-user (file)
+  ;; Return the master file's idea of who is locking 
+  ;; the current workfile version of FILE.  
+  ;; Return 'none if it is not locked.
+  (let ((master-locks (vc-master-locks file)) lock)
+    (if (eq master-locks 'none) 'none
+      ;; search for a lock on the current workfile version
+      (setq lock (assoc (vc-workfile-version file) master-locks))
+      (cond (lock (cdr lock))
+            ('none)))))
+
 (defun vc-locking-user (file)
-  "Return the name of the person currently holding a lock on FILE.
-Return nil if there is no such person.
-Under CVS, a file is considered locked if it has been modified since it
-was checked out.  Under CVS, this will sometimes return the uid of
-the owner of the file (as a number) instead of a string."
-  ;; The property is cached. If it is non-nil, it is simply returned.
-  ;; The other routines clear it when the locking state changes.
-  (setq file (expand-file-name file));; ??? Work around bug in 19.0.4
-  (cond
-   ((vc-file-getprop file 'vc-locking-user))
-   ((eq (vc-backend file) 'CVS)
-    (if (eq (vc-cvs-status file) 'up-to-date)
-        nil
-      ;; The expression below should return the username of the owner
-      ;; of the file.  It doesn't.  It returns the username if it is
-      ;; you, or otherwise the UID of the owner of the file.  The
-      ;; return value from this function is only used by
-      ;; vc-dired-reformat-line, and it does the proper thing if a UID
-      ;; is returned.
-      ;; 
-      ;; The *proper* way to fix this would be to implement a built-in
-      ;; function in Emacs, say, (username UID), that returns the
-      ;; username of a given UID.
-      ;;
-      ;; The result of this hack is that vc-directory will print the
-      ;; name of the owner of the file for any files that are
-      ;; modified.
-      (let ((uid (nth 2 (file-attributes file))))
-        (if (= uid (user-uid))
-            (vc-file-setprop file 'vc-locking-user (user-login-name))
-          (vc-file-setprop file 'vc-locking-user uid)))))
-   (t
-    (if (and (eq (vc-backend file) 'RCS)
-             (eq (vc-consult-rcs-headers file) 'rev-and-lock))
-        (vc-file-getprop file 'vc-locking-user)
-      (if (or (not vc-keep-workfiles)
-              (eq vc-mistrust-permissions 't)
-              (and vc-mistrust-permissions
-                   (funcall vc-mistrust-permissions 
-                            (vc-backend-subdirectory-name file))))
-          (vc-file-setprop file 'vc-locking-user (vc-true-locking-user file))
-        ;; This implementation assumes that any file which is under version
-        ;; control and has -rw-r--r-- is locked by its owner.  This is true
-        ;; for both RCS and SCCS, which keep unlocked files at -r--r--r--.
-        ;; We have to be careful not to exclude files with execute bits on;
-        ;; scripts can be under version control too.  Also, we must ignore
-        ;; the group-read and other-read bits, since paranoid users turn them off.
-        ;; This hack wins because calls to the very expensive vc-fetch-properties
-        ;; function only have to be made if (a) the file is locked by someone
-        ;; other than the current user, or (b) some untoward manipulation
-        ;; behind vc's back has changed the owner or the `group' or `other'
-        ;; write bits.
-        (let ((attributes (file-attributes file)))
-          (cond ((string-match ".r-..-..-." (nth 8 attributes))
-                 nil)
-                ((and (= (nth 2 attributes) (user-uid))
-                      (string-match ".rw..-..-." (nth 8 attributes)))
-                 (vc-file-setprop file 'vc-locking-user (user-login-name)))
-                (t
-                 (vc-file-setprop file 'vc-locking-user 
-                                  (vc-true-locking-user file))))))))))
-
-(defun vc-true-locking-user (file)
-  ;; The slow but reliable version
-  (vc-fetch-properties file)
-  (vc-file-getprop file 'vc-locking-user))
+  ;; Return the name of the person currently holding a lock on FILE.
+  ;; Return nil if there is no such person.
+  ;;   Under CVS, a file is considered locked if it has been modified since
+  ;; it was checked out.  Under CVS, this will sometimes return the uid of
+  ;; the owner of the file (as a number) instead of a string.
+  ;;   The property is cached.  It is only looked up if it is currently nil.
+  ;; Note that, for a file that is not locked, the actual property value
+  ;; is 'none, to distinguish it from an unknown locking state.  That value
+  ;; is converted to nil by this function, and returned to the caller.
+  (let ((locking-user (vc-file-getprop file 'vc-locking-user)))
+    (if locking-user
+        ;; if we already know the property, return it
+        (if (eq locking-user 'none) nil locking-user)
+
+      ;; otherwise, infer the property...
+      (cond
+       ;; in the CVS case, check the status
+       ((eq (vc-backend file) 'CVS)
+        (if (eq (vc-cvs-status file) 'up-to-date)
+            (vc-file-setprop file 'vc-locking-user 'none)
+          ;; The expression below should return the username of the owner
+          ;; of the file.  It doesn't.  It returns the username if it is
+          ;; you, or otherwise the UID of the owner of the file.  The
+          ;; return value from this function is only used by
+          ;; vc-dired-reformat-line, and it does the proper thing if a UID
+          ;; is returned.
+          ;; 
+          ;; The *proper* way to fix this would be to implement a built-in
+          ;; function in Emacs, say, (username UID), that returns the
+          ;; username of a given UID.
+          ;;
+          ;; The result of this hack is that vc-directory will print the
+          ;; name of the owner of the file for any files that are
+          ;; modified.
+          (let ((uid (nth 2 (file-attributes file))))
+            (if (= uid (user-uid))
+                (vc-file-setprop file 'vc-locking-user (user-login-name))
+              (vc-file-setprop file 'vc-locking-user uid)))))
+
+       ;; RCS case: attempt a header search. If this feature is
+       ;; disabled, vc-consult-rcs-headers always returns nil.
+       ((and (eq (vc-backend file) 'RCS)
+             (eq (vc-consult-rcs-headers file) 'rev-and-lock)))
+
+       ;; if the file permissions are not trusted,
+       ;; use the information from the master file
+       ((or (not vc-keep-workfiles)
+            (eq vc-mistrust-permissions 't)
+            (and vc-mistrust-permissions
+                 (funcall vc-mistrust-permissions 
+                          (vc-backend-subdirectory-name file))))
+        (vc-file-setprop file 'vc-locking-user (vc-master-locking-user file)))
+
+     ;; Otherwise: Use the file permissions. (But if it turns out that the
+     ;; file is not owned by the user, use the master file.)
+     ;;   This implementation assumes that any file which is under version
+     ;; control and has -rw-r--r-- is locked by its owner.  This is true
+     ;; for both RCS and SCCS, which keep unlocked files at -r--r--r--.
+     ;; We have to be careful not to exclude files with execute bits on;
+     ;; scripts can be under version control too.  Also, we must ignore the
+     ;; group-read and other-read bits, since paranoid users turn them off.
+     ;;   This hack wins because calls to the somewhat expensive 
+     ;; `vc-fetch-master-properties' function only have to be made if 
+     ;; (a) the file is locked by someone other than the current user, 
+     ;; or (b) some untoward manipulation behind vc's back has changed 
+     ;; the owner or the `group' or `other' write bits.
+     (t
+      (let ((attributes (file-attributes file)))
+        (cond ((string-match ".r-..-..-." (nth 8 attributes))
+               (vc-file-setprop file 'vc-locking-user 'none))
+              ((and (= (nth 2 attributes) (user-uid))
+                    (string-match ".rw..-..-." (nth 8 attributes)))
+               (vc-file-setprop file 'vc-locking-user (user-login-name)))
+              (t
+               (vc-file-setprop file 'vc-locking-user 
+                                (vc-master-locking-user file))))
+        )))
+      ;; recursively call the function again,
+      ;; to convert a possible 'none value
+      (vc-locking-user file))))
+
+;;; properties to store current and recent version numbers
 
 (defun vc-latest-version (file)
   ;; Return version level of the latest version of FILE
-  (vc-fetch-properties file)
-  (vc-file-getprop file 'vc-latest-version))
+  (cond ((vc-file-getprop file 'vc-latest-version))
+        (t (vc-fetch-master-properties file)
+           (vc-file-getprop file 'vc-latest-version))))
 
 (defun vc-your-latest-version (file)
   ;; Return version level of the latest version of FILE checked in by you
-  (vc-fetch-properties file)
-  (vc-file-getprop file 'vc-your-latest-version))
+  (cond ((vc-file-getprop file 'vc-your-latest-version))
+        (t (vc-fetch-master-properties file)
+           (vc-file-getprop file 'vc-your-latest-version))))
 
-(defun vc-branch-version (file)
+(defun vc-top-version (file)
   ;; Return version level of the highest revision on the default branch
   ;; If there is no default branch, return the highest version number
   ;; on the trunk.
   ;; This property is defined for RCS only.
-  (vc-fetch-properties file)
-  (vc-file-getprop file 'vc-branch-version))
+  (cond ((vc-file-getprop file 'vc-top-version))
+        (t (vc-fetch-master-properties file)
+           (vc-file-getprop file 'vc-top-version))))
 
 (defun vc-workfile-version (file)
   ;; Return version level of the current workfile FILE
   ;; This is attempted by first looking at the RCS keywords.
   ;; If there are no keywords in the working file, 
-  ;; vc-branch-version is taken.
+  ;; vc-top-version is taken.
   ;; Note that this property is cached, that is, it is only 
   ;; looked up if it is nil.
   ;; For SCCS, this property is equivalent to vc-latest-version.
@@ -561,7 +575,7 @@ the owner of the file (as a number) instead of a string."
         ((eq (vc-backend file) 'RCS)
          (if (vc-consult-rcs-headers file)
              (vc-file-getprop file 'vc-workfile-version)
-           (let ((rev (cond ((vc-branch-version file))
+           (let ((rev (cond ((vc-top-version file))
                             ((vc-latest-version file)))))
              (vc-file-setprop file 'vc-workfile-version rev)
              rev)))
@@ -759,6 +773,7 @@ Returns t if checkout was successful, nil otherwise."
   (if (vc-backend buffer-file-name)
       (save-excursion
         (require 'vc)
+        (setq default-directory (file-name-directory (buffer-file-name)))
         (not (vc-error-occurred (vc-checkout buffer-file-name))))))
 
 (add-hook 'find-file-not-found-hooks 'vc-file-not-found-hook)