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[emacs.git] / lisp / vc-cvs.el

;;; vc-cvs.el --- non-resident support for CVS version-control

;; Copyright (C) 1995,98,99,2000  Free Software Foundation, Inc.

;; Author:      FSF (see vc.el for full credits)
;; Maintainer:  Andre Spiegel <spiegel@gnu.org>

;; $Id: vc-cvs.el,v 1.4 2000/09/09 00:48:39 monnier Exp $

;; This file is part of GNU Emacs.

;; GNU Emacs is free software; you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation; either version 2, or (at your option)
;; any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs; see the file COPYING.  If not, write to the
;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
;; Boston, MA 02111-1307, USA.

;;; Commentary:

;;; Code:

(defcustom vc-cvs-register-switches nil
  "*Extra switches for registering a file into CVS.
A string or list of strings passed to the checkin program by
\\[vc-register]."
  :type '(choice (const :tag "None" nil)
                 (string :tag "Argument String")
                 (repeat :tag "Argument List"
                         :value ("")
                         string))
  :version "21.1"
  :group 'vc)

(defcustom vc-cvs-header (or (cdr (assoc 'CVS vc-header-alist)) '("\$Id\$"))
  "*Header keywords to be inserted by `vc-insert-headers'."
  :version "21.1"
  :type 'string
  :group 'vc)

(defcustom vc-cvs-use-edit t
  "*Non-nil means to use `cvs edit' to \"check out\" a file.
This is only meaningful if you don't use the implicit checkout model
\(i.e. if you have $CVSREAD set)."
  :type 'boolean
  :version "21.1"
  :group 'vc)

(defcustom vc-cvs-stay-local t
  "*Non-nil means use local operations when possible for remote repositories.
This avoids slow queries over the network.  Turning this option on
will instruct VC to use only heuristics and past information to
determine the current status of a file.  The value can also be a
regular expression to match against the host name of a repository;
then VC only stays local for hosts that match it."
  :type '(choice (const :tag "Always stay local" t)
                 (string :tag "Host regexp")
                 (const :tag "Don't stay local" nil))
  :version "21.1"
  :group 'vc)

;;;###autoload (defun vc-cvs-registered (f)
;;;###autoload   (when (file-readable-p (expand-file-name
;;;###autoload                    "CVS/Entries" (file-name-directory f)))
;;;###autoload       (require 'vc-cvs)
;;;###autoload       (vc-cvs-registered f)))

(defun vc-cvs-registered (file)
  "Check if FILE is CVS registered."
  (let ((dirname (or (file-name-directory file) ""))
        (basename (file-name-nondirectory file))
        ;; make sure that the file name is searched case-sensitively
        (case-fold-search nil))
    (if (file-readable-p (expand-file-name "CVS/Entries" dirname))
        (with-temp-buffer
          (vc-insert-file (expand-file-name "CVS/Entries" dirname))
          (goto-char (point-min))
          (cond
           ((re-search-forward
             (concat "^/" (regexp-quote basename) "/") nil t)
            (beginning-of-line)
            (vc-cvs-parse-entry file)
            t)
           (t nil)))
      nil)))

(defun vc-cvs-stay-local-p (file)
  "Return non-nil if VC should stay local when handling FILE."
  (if vc-cvs-stay-local
      (let* ((dirname (if (file-directory-p file)
                          (directory-file-name file)
                        (file-name-directory file)))
             (prop
              (or (vc-file-getprop dirname 'vc-cvs-stay-local-p)
                  (let ((rootname (expand-file-name "CVS/Root" dirname)))
                    (vc-file-setprop
                     dirname 'vc-cvs-stay-local-p
                     (when (file-readable-p rootname)
                       (with-temp-buffer
                         (vc-insert-file rootname)
                         (goto-char (point-min))
                         (if (looking-at "\\([^:]*\\):")
                             (if (not (stringp vc-cvs-stay-local))
                                 'yes
                               (let ((hostname (match-string 1)))
                                 (if (string-match vc-cvs-stay-local hostname)
                                     'yes
                                   'no)))
                           'no))))))))
        (if (eq prop 'yes) t nil))))
           
(defun vc-cvs-workfile-version (file)
  "CVS-specific version of `vc-workfile-version'."
  ;; There is no need to consult RCS headers under CVS, because we
  ;; get the workfile version for free when we recognize that a file
  ;; is registered in CVS.
  (vc-cvs-registered file)
  (vc-file-getprop file 'vc-workfile-version))

(defun vc-cvs-checkout-model (file)
  "CVS-specific version of `vc-checkout-model'."
  (if (or (getenv "CVSREAD")
          ;; If the file is not writable (despite CVSREAD being
          ;; undefined), this is probably because the file is being
          ;; "watched" by other developers.
          ;; (If vc-mistrust-permissions was t, we actually shouldn't
          ;; trust this, but there is no other way to learn this from CVS
          ;; at the moment (version 1.9).)
          (string-match "r-..-..-." (nth 8 (file-attributes file))))
      'announce
    'implicit))
\f
;; VC Dired functions

(defun vc-cvs-dired-state-info (file)
  "CVS-specific version of `vc-dired-state-info'."
  (let* ((cvs-state (vc-state file))
         (state (cond ((eq cvs-state 'edited)    "modified")
                      ((eq cvs-state 'needs-patch)      "patch")
                      ((eq cvs-state 'needs-merge)         "merge")
                      ;; FIXME: those two states cannot occur right now
                      ((eq cvs-state 'unlocked-changes) "conflict")
                      ((eq cvs-state 'locally-added)       "added")
                      )))
    (if state (concat "(" state ")"))))

(defun vc-cvs-parse-status (&optional full)
  "Parse output of \"cvs status\" command in the current buffer.
Set file properties accordingly.  Unless FULL is t, parse only
essential information."
  (let (file status)
    (goto-char (point-min))
    (if (re-search-forward "^File: " nil t)
        (cond
         ((looking-at "no file") nil)
         ((re-search-forward "\\=\\([^ \t]+\\)" nil t)
          (setq file (expand-file-name (match-string 1)))
          (vc-file-setprop file 'vc-backend 'CVS)
          (if (not (re-search-forward "\\=[ \t]+Status: \\(.*\\)" nil t))
              (setq status "Unknown")
            (setq status (match-string 1)))
          (if (and full
                   (re-search-forward
                    "\\(RCS Version\\|RCS Revision\\|Repository revision\\):\
\[\t ]+\\([0-9.]+\\)"
                    nil t))
              (vc-file-setprop file 'vc-latest-version (match-string 2)))
          (cond
           ((string-match "Up-to-date" status)
            (vc-file-setprop file 'vc-checkout-time
                             (nth 5 (file-attributes file)))
            'up-to-date)
           ((string-match "Locally Modified"    status) 'edited)
           ((string-match "Needs Merge"         status) 'needs-merge)
           ((string-match "Needs \\(Checkout\\|Patch\\)" status) 'needs-patch)
           (t 'edited)))))))

(defun vc-cvs-state (file)
  "CVS-specific version of `vc-state'."
  (if (vc-cvs-stay-local-p file)
      (let ((state (vc-file-getprop file 'vc-state)))
        ;; If we should stay local, use the heuristic but only if
        ;; we don't have a more precise state already available.
        (if (memq state '(up-to-date edited))
            (vc-cvs-state-heuristic file)
          state))
    (with-temp-buffer
      (cd (file-name-directory file))
      (vc-do-command t 0 "cvs" file "status")
      (vc-cvs-parse-status t))))

(defun vc-cvs-state-heuristic (file)
  "CVS-specific state heuristic."
  ;; If the file has not changed since checkout, consider it `up-to-date'.
  ;; Otherwise consider it `edited'.
  (let ((checkout-time (vc-file-getprop file 'vc-checkout-time))
        (lastmod (nth 5 (file-attributes file))))
    (if (equal checkout-time lastmod)
        'up-to-date
      'edited)))

(defun vc-cvs-mode-line-string (file)
  "Return string for placement into the modeline for FILE.
Compared to the default implementation, this function handles the
special case of a CVS file that is added but not yet comitted."
  (let ((state   (vc-state file))
        (rev     (vc-workfile-version file)))
    (cond ((string= rev "0")
           ;; A file that is added but not yet comitted.
           "CVS @@")
          ((or (eq state 'up-to-date)
               (eq state 'needs-patch))
           (concat "CVS-" rev))
          ((stringp state)
           (concat "CVS:" state ":" rev))
          (t
           ;; Not just for the 'edited state, but also a fallback
           ;; for all other states.  Think about different symbols
           ;; for 'needs-patch and 'needs-merge.
           (concat "CVS:" rev)))))

(defun vc-cvs-dir-state (dir)
  "Find the CVS state of all files in DIR."
  (if (vc-cvs-stay-local-p dir)
      (vc-cvs-dir-state-heuristic dir)
    (let ((default-directory dir))
      ;; Don't specify DIR in this command, the default-directory is
      ;; enough.  Otherwise it might fail with remote repositories.
      (with-temp-buffer
        (vc-do-command t 0 "cvs" nil "status" "-l")
        (goto-char (point-min))
        (while (re-search-forward "^=+\n\\([^=\n].*\n\\|\n\\)+" nil t)
          (narrow-to-region (match-beginning 0) (match-end 0))
          (vc-cvs-parse-status)
          (goto-char (point-max))
          (widen))))))

(defun vc-cvs-dir-state-heuristic (dir)
  "Find the CVS state of all files in DIR, using only local information."
  (with-temp-buffer
    (vc-insert-file (expand-file-name "CVS/Entries" dir))
    (goto-char (point-min))
    (while (not (eobp))
      (when (looking-at "/\\([^/]*\\)/")
        (let ((file (expand-file-name (match-string 1) dir)))
          (unless (vc-file-getprop file 'vc-state)
            (vc-cvs-parse-entry file t))))
      (forward-line 1))))

(defun vc-cvs-parse-entry (file &optional set-state)
  "Parse a line from CVS/Entries.
Compare modification time to that of the FILE, set file properties
accordingly.  However, `vc-state' is set only if optional arg SET-STATE
is non-nil."
  (cond
   ;; entry for a "locally added" file (not yet committed)
   ((looking-at "/[^/]+/0/")
    (vc-file-setprop file 'vc-checkout-time 0)
    (vc-file-setprop file 'vc-workfile-version "0")
    (if set-state (vc-file-setprop file 'vc-state 'edited)))
   ;; normal entry
   ((looking-at
     (concat "/[^/]+"
             ;; revision
             "/\\([^/]*\\)"
             ;; timestamp
             "/[A-Z][a-z][a-z]"       ;; week day (irrelevant)
             " \\([A-Z][a-z][a-z]\\)" ;; month name
             " *\\([0-9]*\\)"         ;; day of month
             " \\([0-9]*\\):\\([0-9]*\\):\\([0-9]*\\)"  ;; hms
             " \\([0-9]*\\)"          ;; year
             ;; optional conflict field
             "\\(+[^/]*\\)?/"))
    (vc-file-setprop file 'vc-workfile-version (match-string 1))
    ;; compare checkout time and modification time
    (let ((second (string-to-number (match-string 6)))
          (minute (string-to-number (match-string 5)))
          (hour (string-to-number (match-string 4)))
          (day (string-to-number (match-string 3)))
          (year (string-to-number (match-string 7)))
          (month (/ (string-match
                     (match-string 2)
                     "xxxJanFebMarAprMayJunJulAugSepOctNovDec")
                    3))
          (mtime (nth 5 (file-attributes file))))
      (cond ((equal mtime
                    (encode-time second minute hour day month year 0))
             (vc-file-setprop file 'vc-checkout-time mtime)
             (if set-state (vc-file-setprop file 'vc-state 'up-to-date)))
            (t
             (vc-file-setprop file 'vc-checkout-time 0)
             (if set-state (vc-file-setprop file 'vc-state 'edited))))))
   ;; entry with arbitrary text as timestamp
   ;; (this means we should consider it modified)
   ((looking-at
     (concat "/[^/]+"
             ;; revision
             "/\\([^/]*\\)"
             ;; timestamp (arbitrary text)
             "/[^/]*"
             ;; optional conflict field
             "\\(+[^/]*\\)?/"))
    (vc-file-setprop file 'vc-workfile-version (match-string 1))
    (vc-file-setprop file 'vc-checkout-time 0)
    (if set-state (vc-file-setprop file 'vc-state 'edited)))))
\f
(defun vc-cvs-print-log (file)
  "Get change log associated with FILE."
  (vc-do-command t 'async "cvs" file "log"))

(defun vc-cvs-show-log-entry (version)
  (when (re-search-forward
         ;; also match some context, for safety
         (concat "----\nrevision " version
                 "\\(\tlocked by:.*\n\\|\n\\)date: ") nil t)
    ;; set the display window so that
    ;; the whole log entry is displayed
    (let (start end lines)
      (beginning-of-line) (forward-line -1) (setq start (point))
      (if (not (re-search-forward "^----*\nrevision" nil t))
          (setq end (point-max))
        (beginning-of-line) (forward-line -1) (setq end (point)))
      (setq lines (count-lines start end))
      (cond
       ;; if the global information and this log entry fit
       ;; into the window, display from the beginning
       ((< (count-lines (point-min) end) (window-height))
        (goto-char (point-min))
        (recenter 0)
        (goto-char start))
       ;; if the whole entry fits into the window,
       ;; display it centered
       ((< (1+ lines) (window-height))
        (goto-char start)
        (recenter (1- (- (/ (window-height) 2) (/ lines 2)))))
       ;; otherwise (the entry is too large for the window),
       ;; display from the start
       (t
        (goto-char start)
        (recenter 0))))))

(defun vc-cvs-create-snapshot (dir name branchp)
  "Assign to DIR's current version a given NAME.
If BRANCHP is non-nil, the name is created as a branch (and the current
workspace is immediately moved to that new branch)."
  (vc-do-command nil 0 "cvs" dir "tag" "-c" (if branchp "-b") name)
  (when branchp (vc-do-command nil 0 "cvs" dir "update" "-r" name)))

(defun vc-cvs-retrieve-snapshot (dir name update)
  "Retrieve a snapshot at and below DIR.
NAME is the name of the snapshot; if it is empty, do a `cvs update'.
If UPDATE is non-nil, then update (resynch) any affected buffers."
  (with-current-buffer (get-buffer-create "*vc*")
    (let ((default-directory dir))
      (erase-buffer)
      (if (or (not name) (string= name ""))
          (vc-do-command t 0 "cvs" nil "update")
        (vc-do-command t 0 "cvs" nil "update" "-r" name))
      (when update
        (goto-char (point-min))
        (while (not (eobp))
          (if (looking-at "\\([CMUP]\\) \\(.*\\)")
              (let* ((file (expand-file-name (match-string 2) dir))
                     (state (match-string 1))
                     (buffer (find-buffer-visiting file)))
                (when buffer
                  (cond
                   ((or (string= state "U")
                        (string= state "P"))
                    (vc-file-setprop file 'vc-state 'up-to-date)
                    (vc-file-setprop file 'vc-workfile-version nil)
                    (vc-file-setprop file 'vc-checkout-time
                                     (nth 5 (file-attributes file))))
                   ((or (string= state "M")
                        (string= state "C"))
                    (vc-file-setprop file 'vc-state 'edited)
                    (vc-file-setprop file 'vc-workfile-version nil)
                    (vc-file-setprop file 'vc-checkout-time 0)))
                  (vc-resynch-buffer file t t))))
          (forward-line 1))))))

(defun vc-cvs-merge (file first-version &optional second-version)
  "Merge changes into current working copy of FILE.
The changes are between FIRST-VERSION and SECOND-VERSION."
  (vc-do-command nil 0 "cvs" file
                 "update" "-kk"
                 (concat "-j" first-version)
                 (concat "-j" second-version))
  (vc-file-setprop file 'vc-state 'edited)
  (save-excursion
    (set-buffer (get-buffer "*vc*"))
    (goto-char (point-min))
    (if (re-search-forward "conflicts during merge" nil t)
        1                               ; signal error
      0)))                              ; signal success

(defun vc-cvs-merge-news (file)
  "Merge in any new changes made to FILE."
  (message "Merging changes into %s..." file)
  (save-excursion
    ;; (vc-file-setprop file 'vc-workfile-version nil)
    (vc-file-setprop file 'vc-checkout-time 0)
    (vc-do-command nil 0 "cvs" file "update")
    ;; Analyze the merge result reported by CVS, and set
    ;; file properties accordingly.
    (set-buffer (get-buffer "*vc*"))
    (goto-char (point-min))
    ;; get new workfile version
    (if (re-search-forward (concat "^Merging differences between "
                                   "[01234567890.]* and "
                                   "\\([01234567890.]*\\) into")
                           nil t)
        (vc-file-setprop file 'vc-workfile-version (match-string 1))
      (vc-file-setprop file 'vc-workfile-version nil))
    ;; get file status
    (prog1
        (if (re-search-forward
             (concat "^\\([CMUP] \\)?"
                     (regexp-quote (file-name-nondirectory file))
                     "\\( already contains the differences between \\)?")
             nil t)
            (cond
             ;; Merge successful, we are in sync with repository now
             ((or (match-string 2)
                  (string= (match-string 1) "U ")
                  (string= (match-string 1) "P "))
              (vc-file-setprop file 'vc-state 'up-to-date)
              (vc-file-setprop file 'vc-checkout-time
                               (nth 5 (file-attributes file)))
              0);; indicate success to the caller
             ;; Merge successful, but our own changes are still in the file
             ((string= (match-string 1) "M ")
              (vc-file-setprop file 'vc-state 'edited)
              0);; indicate success to the caller
             ;; Conflicts detected!
             (t
              (vc-file-setprop file 'vc-state 'edited)
              1);; signal the error to the caller
             )
          (pop-to-buffer "*vc*")
          (error "Couldn't analyze cvs update result"))
      (message "Merging changes into %s...done" file))))

(defun vc-cvs-check-headers ()
  "Check if the current file has any headers in it."
  (save-excursion
    (goto-char (point-min))
    (re-search-forward "\\$[A-Za-z\300-\326\330-\366\370-\377]+\
\\(: [\t -#%-\176\240-\377]*\\)?\\$" nil t)))

(defun vc-cvs-steal (file &optional rev)
  "Steal the lock on the current workfile for FILE and revision REV.
Inappropriate for CVS"
  (error "You cannot steal a CVS lock; there are no CVS locks to steal"))

;; vc-check `not reached' for CVS.

(defun vc-cvs-revert (file)
  "Revert FILE to the version it was based on."
  ;; Check out via standard output (caused by the final argument
  ;; FILE below), so that no sticky tag is set.
  (vc-cvs-checkout file nil (vc-workfile-version file) file)
  ;; If "cvs edit" was used to make the file writable,
  ;; call "cvs unedit" now to undo that.
  (if (not (eq (vc-cvs-checkout-model file) 'implicit))
      (vc-do-command nil 0 "cvs" file "unedit")))

(defun vc-cvs-diff (file &optional oldvers newvers)
  "Get a difference report using CVS between two versions of FILE."
  (let (options status
        (diff-switches-list (if (listp diff-switches)
                                diff-switches
                              (list diff-switches))))
    (if (string= (vc-workfile-version file) "0")
        ;; This file is added but not yet committed; there is no master file.
        (if (or oldvers newvers)
            (error "No revisions of %s exist" file)
          ;; we regard this as "changed".
          ;; diff it against /dev/null.
          (apply 'vc-do-command t
                 'async "diff" file
                 (append diff-switches-list '("/dev/null"))))
      (apply 'vc-do-command t
             'async "cvs" file "diff"
             (and oldvers (concat "-r" oldvers))
             (and newvers (concat "-r" newvers))
             diff-switches-list))
    ;; We can't know yet, so we assume there'll be a difference
    1))

(defun vc-cvs-latest-on-branch-p (file)
  "Return t iff current workfile version of FILE is the latest on its branch."
  ;; Since this is only used as a sanity check for vc-cancel-version,
  ;; and that is not supported under CVS at all, we can safely return t here.
  ;; TODO: Think of getting rid of this altogether.
  t)

(defun vc-cvs-checkin (file rev comment)
  "CVS-specific version of `vc-backend-checkin'."
  (let ((switches (if (stringp vc-checkin-switches)
                      (list vc-checkin-switches)
                    vc-checkin-switches))
        status)
    ;; explicit check-in to the trunk requires a double check-in (first
    ;; unexplicit) (CVS-1.3)
    (if (and rev (vc-trunk-p rev))
        (apply 'vc-do-command nil 1 "cvs" file
               "ci" "-m" "intermediate"
               switches))
    (setq status (apply 'vc-do-command nil 1 "cvs" file
                        "ci" (if rev (concat "-r" rev))
                        (concat "-m" comment)
                        switches))
    ;; determine and store the new workfile version
    (set-buffer "*vc*")
    (goto-char (point-min))
    ;; Check checkin problem.  We could check `status' as well.
    (when (re-search-forward "Up-to-date check failed" nil t)
      (vc-file-setprop file 'vc-state 'needs-merge)
      (error (substitute-command-keys
              "Up-to-date check failed: type \\[vc-next-action] to merge in changes")))
    ;; Update file properties
    (vc-file-setprop
     file 'vc-workfile-version
     (vc-parse-buffer "^\\(new\\|initial\\) revision: \\([0-9.]+\\)" 2))
    ;; Forget the checkout model of the file, because we might have
    ;; guessed wrong when we found the file.  After commit, we can
    ;; tell it from the permissions of the file (see
    ;; vc-cvs-checkout-model).
    (vc-file-setprop file 'vc-checkout-model nil)
    ;; if this was an explicit check-in, remove the sticky tag
    (if rev (vc-do-command t 0 "cvs" file "update" "-A"))))

(defun vc-cvs-responsible-p (file)
  "Return non-nil if CVS thinks it is responsible for FILE."
  (file-directory-p (expand-file-name "CVS"
                                      (if (file-directory-p file)
                                          file
                                        (file-name-directory file)))))

(defun vc-cvs-could-register (file)
  "Return non-nil if FILE could be registered in CVS.
This is only possible if CVS is responsible for FILE's directory."
  (vc-cvs-responsible-p file))

(defun vc-cvs-make-version-backups (file)
  "Return non-nil if version backups should be made for FILE."
  (vc-cvs-stay-local-p file))

(defun vc-cvs-register (file &optional rev comment)
  "Register FILE into the CVS version-control system.
COMMENT can be used to provide an initial description of FILE.

`vc-register-switches' and `vc-cvs-register-switches' are passed to
the CVS command (in that order)."
    (let ((switches (list
                     (if (stringp vc-register-switches)
                         (list vc-register-switches)
                       vc-register-switches)
                     (if (stringp vc-cvs-register-switches)
                         (list vc-cvs-register-switches)
                       vc-cvs-register-switches))))
    
      (apply 'vc-do-command nil 0 "cvs" file
             "add"
             (and comment (string-match "[^\t\n ]" comment)
                  (concat "-m" comment))
             switches)))

(defun vc-cvs-checkout (file &optional writable rev workfile)
  "Retrieve a revision of FILE into a WORKFILE.
WRITABLE non-nil means that the file should be writable.
REV is the revision to check out into WORKFILE."
  (let ((filename (or workfile file))
        (file-buffer (get-file-buffer file))
        switches)
    (message "Checking out %s..." filename)
    (save-excursion
      ;; Change buffers to get local value of vc-checkout-switches.
      (if file-buffer (set-buffer file-buffer))
      (setq switches (if (stringp vc-checkout-switches)
                         (list vc-checkout-switches)
                       vc-checkout-switches))
      ;; Save this buffer's default-directory
      ;; and use save-excursion to make sure it is restored
      ;; in the same buffer it was saved in.
      (let ((default-directory default-directory))
        (save-excursion
          ;; Adjust the default-directory so that the check-out creates
          ;; the file in the right place.
          (setq default-directory (file-name-directory filename))
          (if workfile
              (let ((failed t))
                (unwind-protect
                    (progn
                      (let ((coding-system-for-read 'no-conversion)
                            (coding-system-for-write 'no-conversion))
                        (with-temp-file filename
                          (apply 'vc-do-command
                                 (current-buffer) 0 "cvs" file
                                 "-Q"   ; suppress diagnostic output
                                 "update"
                                 (and rev (not (string= rev ""))
                                      (concat "-r" rev))
                                 "-p"
                                 switches)))
                      (setq failed nil))
                  (and failed (file-exists-p filename) (delete-file filename))))
            (if (and (file-exists-p file) (not rev))
                ;; If no revision was specified, just make the file writable
                ;; if necessary (using `cvs-edit' if requested).
                (and writable (not (eq (vc-cvs-checkout-model file) 'implicit))
                     (if vc-cvs-use-edit
                         (vc-do-command nil 0 "cvs" file "edit")
                       (set-file-modes file (logior (file-modes file) 128))
                       (if file-buffer (toggle-read-only -1))))
              ;; Check out a particular version (or recreate the file).
              (vc-file-setprop file 'vc-workfile-version nil)
              (apply 'vc-do-command nil 0 "cvs" file
                     (and writable
                          (or (not (file-exists-p file))
                              (not (eq (vc-cvs-checkout-model file)
                                       'implicit)))
                          "-w")
                     "update"
                     ;; default for verbose checkout: clear the sticky tag so
                     ;; that the actual update will get the head of the trunk
                     (if (or (not rev) (string= rev ""))
                         "-A"
                       (concat "-r" rev))
                     switches))))
        (vc-mode-line file)
        (message "Checking out %s...done" filename)))))

(defun vc-cvs-annotate-command (file buffer)
  "Execute \"cvs annotate\" on FILE.
Use `call-process' and insert the contents in BUFFER."
  (call-process "cvs" nil buffer nil "annotate" file))

(defvar vc-cvs-local-month-numbers
  '(("Jan" . 1) ("Feb" .  2) ("Mar" .  3) ("Apr" .  4)
    ("May" . 5) ("Jun" .  6) ("Jul" .  7) ("Aug" .  8)
    ("Sep" . 9) ("Oct" . 10) ("Nov" . 11) ("Dec" . 12))
  "Local association list of month numbers.")

(defun vc-cvs-annotate-difference (point)
  "Return the difference between the time of the line and the current time.
Return values are as defined for `current-time'."
  ;; We need a list of months and their corresponding numbers.
  (if (looking-at "^\\S-+\\s-+\\S-+\\s-+\\([0-9]+\\)-\\(\\sw+\\)-\\([0-9]+\\)): ")
      (progn
        (let* ((day (string-to-number (match-string 1)))
               (month (cdr (assoc (match-string 2) vc-cvs-local-month-numbers)))
               (year-tmp (string-to-number (match-string 3)))
               ;; Years 0..68 are 2000..2068.
               ;; Years 69..99 are 1969..1999.
               (year (+ (cond ((> 69 year-tmp) 2000)
                              ((> 100 year-tmp) 1900)
                              (t 0))
                        year-tmp)))
          (goto-char (match-end 0)) ; Position at end makes for nicer overlay result
          (- (car (current-time))
             (car (encode-time 0 0 0 day month year)))))
    ;; If we did not look directly at an annotation, there might be
    ;; some further down.  This is the case if we are positioned at
    ;; the very top of the buffer, for instance.
    (if (re-search-forward
         "^\\S-+\\s-+\\S-+\\s-+\\([0-9]+\\)-\\(\\sw+\\)-\\([0-9]+\\)): " nil t)
        (progn
          (beginning-of-line nil)
          (vc-cvs-annotate-difference (point))))))

(provide 'vc-cvs)

;;; vc-cvs.el ends here