lisp/vc.el

   1 ;;; vc.el --- drive a version-control system from within Emacs
   2
   3 ;; Copyright (C) 1992, 1993 Free Software Foundation, Inc.
   4
   5 ;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
   6 ;; Version: 5.4
   7
   8 ;; This file is part of GNU Emacs.
   9
  10 ;; GNU Emacs is free software; you can redistribute it and/or modify
  11 ;; it under the terms of the GNU General Public License as published by
  12 ;; the Free Software Foundation; either version 2, or (at your option)
  13 ;; any later version.
  14
  15 ;; GNU Emacs is distributed in the hope that it will be useful,
  16 ;; but WITHOUT ANY WARRANTY; without even the implied warranty of
  17 ;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18 ;; GNU General Public License for more details.
  19
  20 ;; You should have received a copy of the GNU General Public License
  21 ;; along with GNU Emacs; see the file COPYING.  If not, write to
  22 ;; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
  23
  24 ;;; Commentary:
  25
  26 ;; This mode is fully documented in the Emacs user's manual.
  27 ;;
  28 ;; This was designed and implemented by Eric Raymond <esr@snark.thyrsus.com>.
  29 ;; Paul Eggert <eggert@twinsun.com>, Sebastian Kremer <sk@thp.uni-koeln.de>,
  30 ;; and Richard Stallman contributed valuable criticism, support, and testing.
  31 ;;
  32 ;; Supported version-control systems presently include SCCS and RCS;
  33 ;; your RCS version should be 5.6.2 or later for proper operation of
  34 ;; the lock-breaking code.
  35 ;;
  36 ;; The RCS code assumes strict locking.  You can support the RCS -x option
  37 ;; by adding pairs to the vc-master-templates list.
  38 ;;
  39 ;; Proper function of the SCCS diff commands requires the shellscript vcdiff
  40 ;; to be installed somewhere on Emacs's path for executables.
  41 ;;
  42 ;; If your site uses the ChangeLog convention supported by Emacs, the
  43 ;; function vc-comment-to-change-log should prove a useful checkin hook.
  44 ;;
  45 ;; This code depends on call-process passing back the subprocess exit
  46 ;; status.  Thus, you need Emacs 18.58 or later to run it.  For the
  47 ;; vc-directory command to work properly as documented, you need 19.
  48 ;; You also need Emacs 19's ring.el.
  49 ;;
  50 ;; The vc code maintains some internal state in order to reduce expensive
  51 ;; version-control operations to a minimum.  Some names are only computed
  52 ;; once.  If you perform version control operations with RCS/SCCS/CVS while
  53 ;; vc's back is turned, or move/rename master files while vc is running,
  54 ;; vc may get seriously confused.  Don't do these things!
  55 ;;
  56 ;; Developer's notes on some concurrency issues are included at the end of
  57 ;; the file.
  58
  59 ;;; Code:
  60
  61 (require 'vc-hooks)
  62 (require 'ring)
  63
  64 (if (not (assoc 'vc-parent-buffer minor-mode-alist))
  65     (setq minor-mode-alist
  66           (cons '(vc-parent-buffer vc-parent-buffer-name)
  67                 minor-mode-alist)))
  68
  69 ;; General customization
  70
  71 (defvar vc-default-back-end nil
  72   "*Back-end actually used by this interface; may be SCCS or RCS.
  73 The value is only computed when needed to avoid an expensive search.")
  74 (defvar vc-suppress-confirm nil
  75   "*If non-nil, treat user as expert; suppress yes-no prompts on some things.")
  76 (defvar vc-keep-workfiles t
  77   "*If non-nil, don't delete working files after registering changes.")
  78 (defvar vc-initial-comment nil
  79   "*Prompt for initial comment when a file is registered.")
  80 (defvar vc-command-messages nil
  81   "*Display run messages from back-end commands.")
  82 (defvar vc-mistrust-permissions 'file-symlink-p
  83   "*Don't assume that permissions and ownership track version-control status.")
  84 (defvar vc-checkin-switches nil
  85   "*Extra switches passed to the checkin program by \\[vc-checkin].")
  86
  87 (defconst vc-maximum-comment-ring-size 32
  88   "Maximum number of saved comments in the comment ring.")
  89
  90 ;;; This is duplicated in diff.el.
  91 (defvar diff-switches "-c"
  92   "*A string or list of strings specifying switches to be be passed to diff.")
  93
  94 ;;;###autoload
  95 (defvar vc-checkin-hook nil
  96   "*List of functions called after a checkin is done.  See `run-hooks'.")
  97
  98 ;; Header-insertion hair
  99
 100 (defvar vc-header-alist
 101   '((SCCS "\%W\%") (RCS "\$Id\$"))
 102   "*Header keywords to be inserted when `vc-insert-header' is executed.")
 103 (defconst vc-static-header-alist
 104   '(("\\.c$" .
 105      "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n#endif /* lint */\n"))
 106   "*Associate static header string templates with file types.  A \%s in the
 107 template is replaced with the first string associated with the file's
 108 version-control type in `vc-header-alist'.")
 109
 110 (defvar vc-comment-alist
 111   '((nroff-mode ".\\\"" ""))
 112   "*Special comment delimiters to be used in generating vc headers only.
 113 Add an entry in this list if you need to override the normal comment-start
 114 and comment-end variables.  This will only be necessary if the mode language
 115 is sensitive to blank lines.")
 116
 117 ;; Variables the user doesn't need to know about.
 118 (defvar vc-log-entry-mode nil)
 119 (defvar vc-log-operation nil)
 120 (defvar vc-log-after-operation-hook nil)
 121 (defvar vc-checkout-writable-buffer-hook 'vc-checkout-writable-buffer)
 122 (defvar vc-parent-buffer nil)
 123 (defvar vc-parent-buffer-name nil)
 124
 125 (defvar vc-log-file)
 126 (defvar vc-log-version)
 127
 128 (defconst vc-name-assoc-file "VC-names")
 129
 130 (defvar vc-dired-mode nil)
 131 (make-variable-buffer-local 'vc-dired-mode)
 132
 133 (defvar vc-comment-ring nil)
 134 (defvar vc-comment-ring-index nil)
 135 (defvar vc-last-comment-match nil)
 136
 137 ;; File property caching
 138
 139 (defun vc-file-clearprops (file)
 140   ;; clear all properties of a given file
 141   (setplist (intern file vc-file-prop-obarray) nil))
 142
 143 (defun vc-clear-context ()
 144   "Clear all cached file properties and the comment ring."
 145   (interactive)
 146   (fillarray vc-file-prop-obarray nil)
 147   ;; Note: there is potential for minor lossage here if there is an open
 148   ;; log buffer with a nonzero local value of vc-comment-ring-index.
 149   (setq vc-comment-ring nil))
 150
 151 ;; Random helper functions
 152
 153 (defun vc-name (file)
 154   "Return the master name of a file, nil if it is not registered."
 155   (or (vc-file-getprop file 'vc-name)
 156       (vc-file-setprop file 'vc-name
 157                        (let ((name-and-type (vc-registered file)))
 158                          (and name-and-type (car name-and-type))))))
 159
 160 (defun vc-registration-error (file)
 161   (if file
 162       (error "File %s is not under version control." file)
 163     (error "Buffer %s is not associated with a file." (buffer-name))))
 164
 165 (defvar vc-binary-assoc nil)
 166
 167 (defun vc-find-binary (name)
 168   "Look for a command anywhere on the subprocess-command search path."
 169   (or (cdr (assoc name vc-binary-assoc))
 170       (let ((full nil))
 171         (catch 'found
 172           (mapcar
 173            (function (lambda (s)
 174               (if (and s (file-exists-p (setq full (concat s "/" name))))
 175                   (throw 'found nil))))
 176           exec-path))
 177         (if full
 178             (setq vc-binary-assoc (cons (cons name full) vc-binary-assoc)))
 179         full)))
 180
 181 (defun vc-do-command (okstatus command file &rest flags)
 182   "Execute a version-control command, notifying user and checking for errors.
 183 The command is successful if its exit status does not exceed OKSTATUS.
 184 Output from COMMAND goes to buffer *vc*.  The last argument of the command is
 185 the master name of FILE; this is appended to an optional list of FLAGS."
 186   (setq file (expand-file-name file))
 187   (if vc-command-messages
 188       (message "Running %s on %s..." command file))
 189   (let ((obuf (current-buffer)) (camefrom (current-buffer))
 190         (squeezed nil)
 191         (vc-file (and file (vc-name file)))
 192         status)
 193     (set-buffer (get-buffer-create "*vc*"))
 194     (set (make-local-variable 'vc-parent-buffer) camefrom)
 195     (set (make-local-variable 'vc-parent-buffer-name)
 196          (concat " from " (buffer-name camefrom)))
 197
 198     (erase-buffer)
 199
 200     ;; This is so that command arguments typed in the *vc* buffer will
 201     ;; have reasonable defaults.
 202     (setq default-directory (file-name-directory file))
 203
 204     (mapcar
 205      (function (lambda (s) (and s (setq squeezed (append squeezed (list s))))))
 206      flags)
 207     (if vc-file
 208         (setq squeezed (append squeezed (list vc-file))))
 209     (let ((default-directory (file-name-directory (or file "./"))))
 210       (setq status (apply 'call-process command nil t nil squeezed)))
 211     (goto-char (point-max))
 212     (previous-line 1)
 213     (if (or (not (integerp status)) (< okstatus status))
 214         (progn
 215           (previous-line 1)
 216           (print (cons command squeezed))
 217           (next-line 1)
 218           (pop-to-buffer "*vc*")
 219           (vc-shrink-to-fit)
 220           (goto-char (point-min))
 221           (error "Running %s...FAILED (%s)" command
 222                  (if (integerp status)
 223                      (format "status %d" status)
 224                    status))
 225           )
 226       (if vc-command-messages
 227           (message "Running %s...OK" command))
 228       )
 229     (set-buffer obuf)
 230     status)
 231   )
 232
 233 ;;; Save a bit of the text around POSN in the current buffer, to help
 234 ;;; us find the corresponding position again later.  This works even
 235 ;;; if all markers are destroyed or corrupted.
 236 (defun vc-position-context (posn)
 237   (list posn
 238         (buffer-size)
 239         (buffer-substring posn
 240                           (min (point-max) (+ posn 100)))))
 241
 242 ;;; Return the position of CONTEXT in the current buffer, or nil if we
 243 ;;; couldn't find it.
 244 (defun vc-find-position-by-context (context)
 245   (let ((context-string (nth 2 context)))
 246     (if (equal "" context-string)
 247         (point-max)
 248       (save-excursion
 249         (let ((diff (- (nth 1 context) (buffer-size))))
 250           (if (< diff 0) (setq diff (- diff)))
 251           (goto-char (nth 0 context))
 252           (if (or (search-forward context-string nil t)
 253                   ;; Can't use search-backward since the match may continue
 254                   ;; after point.
 255                   (progn (goto-char (- (point) diff (length context-string)))
 256                          ;; goto-char doesn't signal an error at
 257                          ;; beginning of buffer like backward-char would
 258                          (search-forward context-string nil t)))
 259               ;; to beginning of OSTRING
 260               (- (point) (length context-string))))))))
 261
 262 (defun vc-revert-buffer1 (&optional arg no-confirm)
 263   ;; Most of this was shamelessly lifted from Sebastian Kremer's rcs.el mode.
 264   ;; Revert buffer, try to keep point and mark where user expects them in spite
 265   ;; of changes because of expanded version-control key words.
 266   ;; This is quite important since otherwise typeahead won't work as expected.
 267   (interactive "P")
 268   (widen)
 269   (let ((point-context (vc-position-context (point)))
 270         ;; Use mark-marker to avoid confusion in transient-mark-mode.
 271         (mark-context  (if (eq (marker-buffer (mark-marker)) (current-buffer))
 272                            (vc-position-context (mark-marker))))
 273         ;; Make the right thing happen in transient-mark-mode.
 274         (mark-active nil)
 275         ;; We may want to reparse the compilation buffer after revert
 276         (reparse (and (boundp 'compilation-error-list) ;compile loaded
 277                       (let ((curbuf (current-buffer)))
 278                         ;; Construct a list; each elt is nil or a buffer
 279                         ;; iff that buffer is a compilation output buffer
 280                         ;; that contains markers into the current buffer.
 281                         (save-excursion
 282                           (mapcar (function
 283                                    (lambda (buffer)
 284                                     (set-buffer buffer)
 285                                     (let ((errors (or
 286                                                    compilation-old-error-list
 287                                                    compilation-error-list))
 288                                           (buffer-error-marked-p nil))
 289                                       (while (and (consp errors)
 290                                                   (not buffer-error-marked-p))
 291                                         (and (markerp (cdr (car errors)))
 292                                              (eq buffer
 293                                                  (marker-buffer
 294                                                   (cdr (car errors))))
 295                                              (setq buffer-error-marked-p t))
 296                                         (setq errors (cdr errors)))
 297                                       (if buffer-error-marked-p buffer))))
 298                                   (buffer-list)))))))
 299
 300     ;; the actual revisit
 301     (revert-buffer arg no-confirm)
 302
 303     ;; Reparse affected compilation buffers.
 304     (while reparse
 305       (if (car reparse)
 306           (save-excursion
 307             (set-buffer (car reparse))
 308             (let ((compilation-last-buffer (current-buffer)) ;select buffer
 309                   ;; Record the position in the compilation buffer of
 310                   ;; the last error next-error went to.
 311                   (error-pos (marker-position
 312                               (car (car-safe compilation-error-list)))))
 313               ;; Reparse the error messages as far as they were parsed before.
 314               (compile-reinitialize-errors '(4) compilation-parsing-end)
 315               ;; Move the pointer up to find the error we were at before
 316               ;; reparsing.  Now next-error should properly go to the next one.
 317               (while (and compilation-error-list
 318                           (/= error-pos (car (car compilation-error-list))))
 319                 (setq compilation-error-list (cdr compilation-error-list))))))
 320       (setq reparse (cdr reparse)))
 321
 322     ;; Restore point and mark
 323     (let ((new-point (vc-find-position-by-context point-context)))
 324       (if new-point (goto-char new-point)))
 325     (if mark-context
 326         (let ((new-mark (vc-find-position-by-context mark-context)))
 327           (if new-mark (set-mark new-mark))))))
 328
 329
 330 (defun vc-buffer-sync ()
 331   ;; Make sure the current buffer and its working file are in sync
 332   (if (and (buffer-modified-p)
 333            (or
 334             vc-suppress-confirm
 335             (y-or-n-p (format "%s has been modified.  Write it out? "
 336                               (buffer-name)))))
 337       (save-buffer)))
 338
 339 (defun vc-workfile-unchanged-p (file)
 340   ;; Has the given workfile changed since last checkout?
 341   (let ((checkout-time (vc-file-getprop file 'vc-checkout-time))
 342         (lastmod (nth 5 (file-attributes file))))
 343     (if checkout-time
 344      (equal lastmod checkout-time)
 345      (if (zerop (vc-backend-diff file nil))
 346          (progn
 347            (vc-file-setprop file 'vc-checkout-time lastmod)
 348            t)
 349        (progn
 350            (vc-file-setprop file 'vc-checkout-time '(0 . 0))
 351            nil
 352          ))
 353      )))
 354
 355 (defun vc-next-action-on-file (file verbose &optional comment)
 356   ;;; If comment is specified, it will be used as an admin or checkin comment.
 357   (let (owner version (vc-file (vc-name file)))
 358     (cond
 359
 360      ;; if there is no master file corresponding, create one
 361      ((not vc-file)
 362       (vc-register verbose comment)
 363       (if vc-initial-comment
 364           (setq vc-log-after-operation-hook
 365                 'vc-checkout-writable-buffer-hook)
 366         (vc-checkout-writable-buffer file)))
 367
 368      ;; if there is no lock on the file, assert one and get it
 369      ((not (setq owner (vc-locking-user file)))
 370       (vc-checkout-writable-buffer file))
 371
 372      ;; a checked-out version exists, but the user may not own the lock
 373      ((not (string-equal owner (user-login-name)))
 374       (if comment
 375           (error "Sorry, you can't steal the lock on %s this way." file))
 376       (vc-steal-lock
 377        file
 378        (and verbose (read-string "Version to steal: "))
 379        owner))
 380
 381      ;; OK, user owns the lock on the file
 382      (t
 383           (find-file file)
 384
 385           ;; give luser a chance to save before checking in.
 386           (vc-buffer-sync)
 387
 388           ;; Revert if file is unchanged and buffer is too.
 389           ;; If buffer is modified, that means the user just said no
 390           ;; to saving it; in that case, don't revert,
 391           ;; because the user might intend to save
 392           ;; after finishing the log entry.
 393           (if (and (vc-workfile-unchanged-p file)
 394                    (not (buffer-modified-p)))
 395               (progn
 396                 (vc-backend-revert file)
 397                 ;; DO NOT revert the file without asking the user!
 398                 (vc-resynch-window file t nil))
 399
 400             ;; user may want to set nonstandard parameters
 401             (if verbose
 402                 (setq version (read-string "New version level: ")))
 403
 404             ;; OK, let's do the checkin
 405             (vc-checkin file version comment)
 406             )))))
 407
 408 (defun vc-next-action-dired (file rev comment)
 409   ;; We've accepted a log comment, now do a vc-next-action using it on all
 410   ;; marked files.
 411   (set-buffer vc-parent-buffer)
 412   (dired-map-over-marks
 413    (save-window-excursion
 414      (let ((file (dired-get-filename)))
 415        (message "Processing %s..." file)
 416        (vc-next-action-on-file file nil comment)
 417        (message "Processing %s...done" file)))
 418    nil t)
 419   )
 420
 421 ;; Here's the major entry point.
 422
 423 ;;;###autoload
 424 (defun vc-next-action (verbose)
 425   "Do the next logical checkin or checkout operation on the current file.
 426    If the file is not already registered, this registers it for version
 427 control and then retrieves a writable, locked copy for editing.
 428    If the file is registered and not locked by anyone, this checks out
 429 a writable and locked file ready for editing.
 430    If the file is checked out and locked by the calling user, this
 431 first checks to see if the file has changed since checkout.  If not,
 432 it performs a revert.
 433    If the file has been changed, this pops up a buffer for entry
 434 of a log message; when the message has been entered, it checks in the
 435 resulting changes along with the log message as change commentary.  If
 436 the variable `vc-keep-workfiles' is non-nil (which is its default), a
 437 read-only copy of the changed file is left in place afterwards.
 438    If the file is registered and locked by someone else, you are given
 439 the option to steal the lock.
 440    If you call this from within a VC dired buffer with no files marked,
 441 it will operate on the file in the current line.
 442    If you call this from within a VC dired buffer, and one or more
 443 files are marked, it will accept a log message and then operate on
 444 each one.  The log message will be used as a comment for any register
 445 or checkin operations, but ignored when doing checkouts.  Attempted
 446 lock steals will raise an error."
 447   (interactive "P")
 448   (catch 'nogo
 449     (if vc-dired-mode
 450         (let ((files (dired-get-marked-files)))
 451           (if (= (length files) 1)
 452               (find-file-other-window (dired-get-filename))
 453             (vc-start-entry nil nil nil
 454                             "Enter a change comment for the marked files."
 455                             'vc-next-action-dired)
 456             (throw 'nogo))))
 457     (while vc-parent-buffer
 458       (pop-to-buffer vc-parent-buffer))
 459     (if buffer-file-name
 460         (vc-next-action-on-file buffer-file-name verbose)
 461       (vc-registration-error nil))))
 462
 463 ;;; These functions help the vc-next-action entry point
 464
 465 (defun vc-checkout-writable-buffer (&optional file)
 466   "Retrieve a writable copy of the latest version of the current buffer's file."
 467   (vc-checkout (or file (buffer-file-name)) t)
 468   )
 469
 470 ;;;###autoload
 471 (defun vc-register (&optional override comment)
 472   "Register the current file into your version-control system."
 473   (interactive "P")
 474   (if (vc-name buffer-file-name)
 475       (error "This file is already registered."))
 476   ;; Watch out for new buffers of size 0: the corresponding file
 477   ;; does not exist yet, even though buffer-modified-p is nil.
 478   (if (and (not (buffer-modified-p))
 479            (zerop (buffer-size))
 480            (not (file-exists-p buffer-file-name)))
 481       (set-buffer-modified-p t))
 482   (vc-buffer-sync)
 483   (vc-admin
 484    buffer-file-name
 485    (and override
 486         (read-string
 487          (format "Initial version level for %s: " buffer-file-name))))
 488   )
 489
 490 (defun vc-resynch-window (file &optional keep noquery)
 491   ;; If the given file is in the current buffer,
 492   ;; either revert on it so we see expanded keyworks,
 493   ;; or unvisit it (depending on vc-keep-workfiles)
 494   ;; NOQUERY if non-nil inhibits confirmation for reverting.
 495   ;; NOQUERY should be t *only* if it is known the only difference
 496   ;; between the buffer and the file is due to RCS rather than user editing!
 497   (and (string= buffer-file-name file)
 498        (if keep
 499            (progn
 500              (vc-revert-buffer1 t noquery)
 501              (vc-mode-line buffer-file-name))
 502          (progn
 503            (delete-window)
 504            (kill-buffer (current-buffer))))))
 505
 506 (defun vc-start-entry (file rev comment msg action)
 507   ;; Accept a comment for an operation on FILE revision REV.  If COMMENT
 508   ;; is nil, pop up a VC-log buffer, emit MSG, and set the
 509   ;; action on close to ACTION; otherwise, do action immediately.
 510   ;; Remember the file's buffer in parent-buffer (current one if no file).
 511   (let ((parent (if file (find-file-noselect file) (current-buffer))))
 512     (if comment
 513         (set-buffer (get-buffer-create "*VC-log*"))
 514       (pop-to-buffer (get-buffer-create "*VC-log*")))
 515     (set (make-local-variable 'vc-parent-buffer) parent)
 516     (set (make-local-variable 'vc-parent-buffer-name)
 517          (concat " from " (buffer-name vc-parent-buffer)))
 518     (vc-mode-line (if file (file-name-nondirectory file) " (no file)"))
 519     (vc-log-mode)
 520     (setq vc-log-operation action)
 521     (setq vc-log-file file)
 522     (setq vc-log-version rev)
 523     (if comment
 524         (progn
 525           (erase-buffer)
 526           (if (eq comment t)
 527               (vc-finish-logentry t)
 528             (insert comment)
 529             (vc-finish-logentry nil)))
 530       (message "%s  Type C-c C-c when done." msg))))
 531
 532 (defun vc-admin (file rev &optional comment)
 533   "Check a file into your version-control system.
 534 FILE is the unmodified name of the file.  REV should be the base version
 535 level to check it in under.  COMMENT, if specified, is the checkin comment."
 536       (vc-start-entry file rev
 537                       (or comment (not vc-initial-comment))
 538                       "Enter initial comment." 'vc-backend-admin))
 539
 540 (defun vc-checkout (file &optional writable)
 541   "Retrieve a copy of the latest version of the given file."
 542   ;; If ftp is on this system and the name matches the ange-ftp format
 543   ;; for a remote file, the user is trying something that won't work.
 544   (if (and (string-match "^/[^/:]+:" file) (vc-find-binary "ftp"))
 545       (error "Sorry, you can't check out files over FTP"))
 546   (vc-backend-checkout file writable)
 547   (if (string-equal file buffer-file-name)
 548       (vc-resynch-window file t t))
 549   )
 550
 551 (defun vc-steal-lock (file rev &optional owner)
 552   "Steal the lock on the current workfile."
 553   (interactive)
 554   (if (not owner)
 555       (setq owner (vc-locking-user file)))
 556   (if (not (y-or-n-p (format "Take the lock on %s:%s from %s?" file rev owner)))
 557       (error "Steal cancelled."))
 558   (pop-to-buffer (get-buffer-create "*VC-mail*"))
 559   (setq default-directory (expand-file-name "~/"))
 560   (auto-save-mode auto-save-default)
 561   (mail-mode)
 562   (erase-buffer)
 563   (mail-setup owner (format "%s:%s" file rev) nil nil nil
 564               (list (list 'vc-finish-steal file rev)))
 565   (goto-char (point-max))
 566   (insert
 567    (format "I stole the lock on %s:%s, " file rev)
 568    (current-time-string)
 569    ".\n")
 570   (message "Please explain why you stole the lock.  Type C-c C-c when done."))
 571
 572 ;; This is called when the notification has been sent.
 573 (defun vc-finish-steal (file version)
 574   (vc-backend-steal file version)
 575   (vc-resynch-window file t t))
 576
 577 (defun vc-checkin (file &optional rev comment)
 578   "Check in the file specified by FILE.
 579 The optional argument REV may be a string specifying the new version level
 580 \(if nil increment the current level).  The file is either retained with write
 581 permissions zeroed, or deleted (according to the value of `vc-keep-workfiles').
 582 COMMENT is a comment string; if omitted, a buffer is
 583 popped up to accept a comment."
 584   (setq vc-log-after-operation-hook 'vc-checkin-hook)
 585   (vc-start-entry file rev comment "Enter a change comment." 'vc-backend-checkin))
 586
 587 ;;; Here is a checkin hook that may prove useful to sites using the
 588 ;;; ChangeLog facility supported by Emacs.
 589 (defun vc-comment-to-change-log ()
 590   "Update change log from VC change comments entered for the current file.
 591 See `vc-update-change-log'."
 592   (interactive)
 593   (let ((log (find-change-log)))
 594     (if log
 595         (vc-update-change-log
 596          (file-relative-name buffer-file-name
 597                              (file-name-directory (expand-file-name log)))))))
 598
 599 (defun vc-finish-logentry (&optional nocomment)
 600   "Complete the operation implied by the current log entry."
 601   (interactive)
 602   ;; Check and record the comment, if any.
 603   (if (not nocomment)
 604       (progn
 605         (goto-char (point-max))
 606         (if (not (bolp))
 607             (newline))
 608         ;; Comment too long?
 609         (vc-backend-logentry-check vc-log-file)
 610         ;; Record the comment in the comment ring
 611         (if (null vc-comment-ring)
 612             (setq vc-comment-ring (make-ring vc-maximum-comment-ring-size)))
 613         (ring-insert vc-comment-ring (buffer-string))
 614         ))
 615   ;; OK, do it to it
 616   (if vc-log-operation
 617       (save-excursion
 618         (funcall vc-log-operation
 619                  vc-log-file
 620                  vc-log-version
 621                  (buffer-string)))
 622     (error "No log operation is pending."))
 623   ;; Return to "parent" buffer of this checkin and remove checkin window
 624   (pop-to-buffer vc-parent-buffer)
 625   (vc-error-occurred
 626    (delete-window (get-buffer-window "*VC-log*")))
 627   (kill-buffer "*VC-log*")
 628   ;; Now make sure we see the expanded headers
 629   (if buffer-file-name
 630         (vc-resynch-window buffer-file-name vc-keep-workfiles t))
 631   (run-hooks vc-log-after-operation-hook))
 632
 633 ;; Code for access to the comment ring
 634
 635 (defun vc-previous-comment (arg)
 636   "Cycle backwards through comment history."
 637   (interactive "*p")
 638   (let ((len (ring-length vc-comment-ring)))
 639     (cond ((<= len 0)
 640            (message "Empty comment ring")
 641            (ding))
 642           (t
 643            (erase-buffer)
 644            ;; Initialize the index on the first use of this command
 645            ;; so that the first M-p gets index 0, and the first M-n gets
 646            ;; index -1.
 647            (if (null vc-comment-ring-index)
 648                (setq vc-comment-ring-index
 649                      (if (> arg 0) -1
 650                          (if (< arg 0) 1 0))))
 651            (setq vc-comment-ring-index
 652                  (ring-mod (+ vc-comment-ring-index arg) len))
 653            (message "%d" (1+ vc-comment-ring-index))
 654            (insert (ring-ref vc-comment-ring vc-comment-ring-index))))))
 655
 656 (defun vc-next-comment (arg)
 657   "Cycle forwards through comment history."
 658   (interactive "*p")
 659   (vc-previous-comment (- arg)))
 660
 661 (defun vc-comment-search-reverse (str)
 662   "Searches backwards through comment history for substring match."
 663   (interactive "sComment substring: ")
 664   (if (string= str "")
 665       (setq str vc-last-comment-match)
 666     (setq vc-last-comment-match str))
 667   (if (null vc-comment-ring-index)
 668       (setq vc-comment-ring-index -1))
 669   (let ((str (regexp-quote str))
 670         (len (ring-length vc-comment-ring))
 671         (n (1+ vc-comment-ring-index)))
 672     (while (and (< n len) (not (string-match str (ring-ref vc-comment-ring n))))
 673       (setq n (+ n 1)))
 674     (cond ((< n len)
 675            (vc-previous-comment (- n vc-comment-ring-index)))
 676           (t (error "Not found")))))
 677
 678 (defun vc-comment-search-forward (str)
 679   "Searches forwards through comment history for substring match."
 680   (interactive "sComment substring: ")
 681   (if (string= str "")
 682       (setq str vc-last-comment-match)
 683     (setq vc-last-comment-match str))
 684   (if (null vc-comment-ring-index)
 685       (setq vc-comment-ring-index 0))
 686   (let ((str (regexp-quote str))
 687         (len (ring-length vc-comment-ring))
 688         (n vc-comment-ring-index))
 689     (while (and (>= n 0) (not (string-match str (ring-ref vc-comment-ring n))))
 690       (setq n (- n 1)))
 691     (cond ((>= n 0)
 692            (vc-next-comment (- n vc-comment-ring-index)))
 693           (t (error "Not found")))))
 694
 695 ;; Additional entry points for examining version histories
 696
 697 ;;;###autoload
 698 (defun vc-diff (historic)
 699   "Display diffs between file versions.
 700 Normally this compares the current file and buffer with the most recent
 701 checked in version of that file.  This uses no arguments.
 702 With a prefix argument, it reads the file name to use
 703 and two version designators specifying which versions to compare."
 704   (interactive "P")
 705   (if vc-dired-mode
 706       (set-buffer (find-file-noselect (dired-get-filename))))
 707   (while vc-parent-buffer
 708       (pop-to-buffer vc-parent-buffer))
 709   (if historic
 710       (call-interactively 'vc-version-diff)
 711     (if (or (null buffer-file-name) (null (vc-name buffer-file-name)))
 712         (error "There is no version-control master associated with this buffer."))
 713     (let ((file buffer-file-name)
 714           unchanged)
 715       (or (and file (vc-name file))
 716           (vc-registration-error file))
 717       (vc-buffer-sync)
 718       (setq unchanged (vc-workfile-unchanged-p buffer-file-name))
 719       (if unchanged
 720           (message "No changes to %s since latest version." file)
 721         (vc-backend-diff file nil)
 722         ;; Ideally, we'd like at this point to parse the diff so that
 723         ;; the buffer effectively goes into compilation mode and we
 724         ;; can visit the old and new change locations via next-error.
 725         ;; Unfortunately, this is just too painful to do.  The basic
 726         ;; problem is that the `old' file doesn't exist to be
 727         ;; visited.  This plays hell with numerous assumptions in
 728         ;; the diff.el and compile.el machinery.
 729         (pop-to-buffer "*vc*")
 730         (vc-shrink-to-fit)
 731         (goto-char (point-min))
 732         )
 733       (not unchanged)
 734       )
 735     )
 736   )
 737
 738 (defun vc-version-diff (file rel1 rel2)
 739   "For FILE, report diffs between two stored versions REL1 and REL2 of it.
 740 If FILE is a directory, generate diffs between versions for all registered
 741 files in or below it."
 742   (interactive "FFile or directory to diff: \nsOlder version: \nsNewer version: ")
 743   (if (string-equal rel1 "") (setq rel1 nil))
 744   (if (string-equal rel2 "") (setq rel2 nil))
 745   (if (file-directory-p file)
 746       (let ((camefrom (current-buffer)))
 747         (set-buffer (get-buffer-create "*vc-status*"))
 748         (set (make-local-variable 'vc-parent-buffer) camefrom)
 749         (set (make-local-variable 'vc-parent-buffer-name)
 750              (concat " from " (buffer-name camefrom)))
 751         (erase-buffer)
 752         (insert "Diffs between "
 753                 (or rel1 "last version checked in")
 754                 " and "
 755                 (or rel2 "current workfile(s)")
 756                 ":\n\n")
 757         (set-buffer (get-buffer-create "*vc*"))
 758         (cd file)
 759         (vc-file-tree-walk
 760          (function (lambda (f)
 761                      (message "Looking at %s" f)
 762                      (and
 763                       (not (file-directory-p f))
 764                       (vc-registered f)
 765                       (vc-backend-diff f rel1 rel2)
 766                       (append-to-buffer "*vc-status*" (point-min) (point-max)))
 767                      )))
 768         (pop-to-buffer "*vc-status*")
 769         (insert "\nEnd of diffs.\n")
 770         (goto-char (point-min))
 771         (set-buffer-modified-p nil)
 772         )
 773     (if (zerop (vc-backend-diff file rel1 rel2))
 774         (message "No changes to %s between %s and %s." file rel1 rel2)
 775       (pop-to-buffer "*vc*"))))
 776
 777 ;; Header-insertion code
 778
 779 ;;;###autoload
 780 (defun vc-insert-headers ()
 781   "Insert headers in a file for use with your version-control system.
 782 Headers desired are inserted at the start of the buffer, and are pulled from
 783 the variable `vc-header-alist'."
 784   (interactive)
 785   (if vc-dired-mode
 786       (find-file-other-window (dired-get-filename)))
 787   (while vc-parent-buffer
 788       (pop-to-buffer vc-parent-buffer))
 789   (save-excursion
 790     (save-restriction
 791       (widen)
 792       (if (or (not (vc-check-headers))
 793               (y-or-n-p "Version headers already exist.  Insert another set?"))
 794           (progn
 795             (let* ((delims (cdr (assq major-mode vc-comment-alist)))
 796                    (comment-start-vc (or (car delims) comment-start "#"))
 797                    (comment-end-vc (or (car (cdr delims)) comment-end ""))
 798                    (hdstrings (cdr (assoc (vc-backend-deduce (buffer-file-name)) vc-header-alist))))
 799               (mapcar (function (lambda (s)
 800                                   (insert comment-start-vc "\t" s "\t"
 801                                           comment-end-vc "\n")))
 802                       hdstrings)
 803               (if vc-static-header-alist
 804                   (mapcar (function (lambda (f)
 805                                       (if (string-match (car f) buffer-file-name)
 806                                           (insert (format (cdr f) (car hdstrings))))))
 807                           vc-static-header-alist))
 808               )
 809             )))))
 810
 811 ;; The VC directory submode.  Coopt Dired for this.
 812 ;; All VC commands get mapped into logical equivalents.
 813
 814 (defvar vc-dired-prefix-map (make-sparse-keymap))
 815 (define-key vc-dired-prefix-map "\C-xv" vc-prefix-map)
 816
 817 (or (not (boundp 'minor-mode-map-alist))
 818     (assq 'vc-dired-mode minor-mode-map-alist)
 819     (setq minor-mode-map-alist
 820            (cons (cons 'vc-dired-mode vc-dired-prefix-map)
 821                  minor-mode-map-alist)))
 822
 823 (defun vc-dired-mode ()
 824   "The augmented Dired minor mode used in VC directory buffers.
 825 All Dired commands operate normally.  Users currently locking listed files
 826 are listed in place of the file's owner and group.
 827 Keystrokes bound to VC commands will execute as though they had been called
 828 on a buffer attached to the file named in the current Dired buffer line."
 829   (setq vc-dired-mode t)
 830   (setq vc-mode " under VC"))
 831
 832 (defun vc-dired-reformat-line (x)
 833   ;; Hack a directory-listing line, plugging in locking-user info in
 834   ;; place of the user and group info.  Should have the beneficial
 835   ;; side-effect of shortening the listing line.  Each call starts with
 836   ;; point immediately following the dired mark area on the line to be
 837   ;; hacked.
 838   ;;
 839   ;; Simplest possible one:
 840   ;; (insert (concat x "\t")))
 841   ;;
 842   ;; This code, like dired, assumes UNIX -l format.
 843   (forward-word 1)      ;; skip over any extra field due to -ibs options
 844   (if x (setq x (concat "(" x ")")))
 845   (if (re-search-forward "\\([0-9]+ \\).................\\( .*\\)" nil 0)
 846       (let ((rep (substring (concat x "                 ") 0 9)))
 847         (replace-match (concat "\\1" rep "\\2") t)))
 848   )
 849
 850 ;;; Note in Emacs 18 the following defun gets overridden
 851 ;;; with the symbol 'vc-directory-18.  See below.
 852 ;;;###autoload
 853 (defun vc-directory (verbose)
 854   "Show version-control status of all files under the current directory."
 855   (interactive "P")
 856   (let (nonempty
 857         (dl (length default-directory))
 858         (filelist nil) (userlist nil)
 859         dired-buf
 860         dired-buf-mod-count)
 861     (vc-file-tree-walk
 862      (function (lambda (f)
 863                  (if (vc-registered f)
 864                      (let ((user (vc-locking-user f)))
 865                        (and (or verbose user)
 866                             (setq filelist (cons (substring f dl) filelist))
 867                             (setq userlist (cons user userlist))))))))
 868     (save-excursion
 869       ;; This uses a semi-documented feature of dired; giving a switch
 870       ;; argument forces the buffer to refresh each time.
 871       (dired
 872        (cons default-directory (nreverse filelist))
 873        dired-listing-switches)
 874       (setq dired-buf (current-buffer))
 875       (setq nonempty (not (zerop (buffer-size)))))
 876     (if nonempty
 877         (progn
 878           (pop-to-buffer dired-buf)
 879           (vc-dired-mode)
 880           (goto-char (point-min))
 881           (setq buffer-read-only nil)
 882           (forward-line 1)      ;; Skip header line
 883           (mapcar
 884            (function
 885             (lambda (x)
 886              (forward-char 2)   ;; skip dired's mark area
 887              (vc-dired-reformat-line x)
 888              (forward-line 1))) ;; go to next line
 889            (nreverse userlist))
 890           (setq buffer-read-only t)
 891           (goto-char (point-min))
 892           )
 893       (message "No files are currently %s under %s"
 894                (if verbose "registered" "locked") default-directory))
 895     ))
 896
 897 ;; Emacs 18 version
 898 (defun vc-directory-18 (verbose)
 899   "Show version-control status of all files under the current directory."
 900   (interactive "P")
 901   (let (nonempty (dir default-directory))
 902     (save-excursion
 903       (set-buffer (get-buffer-create "*vc-status*"))
 904       (erase-buffer)
 905       (cd dir)
 906       (vc-file-tree-walk
 907        (function (lambda (f)
 908                    (if (vc-registered f)
 909                        (let ((user (vc-locking-user f)))
 910                          (if (or user verbose)
 911                              (insert (format
 912                                       "%s       %s\n"
 913                                       (concat user) f))))))))
 914       (setq nonempty (not (zerop (buffer-size)))))
 915     (if nonempty
 916         (progn
 917           (pop-to-buffer "*vc-status*" t)
 918           (vc-shrink-to-fit)
 919           (goto-char (point-min)))
 920       (message "No files are currently %s under %s"
 921                (if verbose "registered" "locked") default-directory))
 922     ))
 923
 924 (or (boundp 'minor-mode-map-alist)
 925     (fset 'vc-directory 'vc-directory-18))
 926
 927 ; Emacs 18 also lacks these.
 928 (or (boundp 'compilation-old-error-list)
 929     (setq compilation-old-error-list nil))
 930
 931 ;; Named-configuration support for SCCS
 932
 933 (defun vc-add-triple (name file rev)
 934   (save-excursion
 935     (find-file (concat (vc-backend-subdirectory-name file) "/" vc-name-assoc-file))
 936     (goto-char (point-max))
 937     (insert name "\t:\t" file "\t" rev "\n")
 938     (basic-save-buffer)
 939     (kill-buffer (current-buffer))
 940     ))
 941
 942 (defun vc-record-rename (file newname)
 943   (save-excursion
 944     (find-file (concat (vc-backend-subdirectory-name file) "/" vc-name-assoc-file))
 945     (goto-char (point-min))
 946     (replace-regexp (concat ":" (regexp-quote file) "$") (concat ":" newname))
 947     (basic-save-buffer)
 948     (kill-buffer (current-buffer))
 949     ))
 950
 951 (defun vc-lookup-triple (file name)
 952   ;; Return the numeric version corresponding to a named snapshot of file
 953   ;; If name is nil or a version number string it's just passed through
 954   (cond ((null name) "")
 955         ((let ((firstchar (aref name 0)))
 956            (and (>= firstchar ?0) (<= firstchar ?9)))
 957          name)
 958         (t
 959          (car (vc-master-info
 960                (concat (vc-backend-subdirectory-name file) "/" vc-name-assoc-file)
 961                (list (concat name "\t:\t" file "\t\\(.+\\)"))))
 962          )))
 963
 964 ;; Named-configuration entry points
 965
 966 (defun vc-quiescent-p ()
 967   ;; Is the current directory ready to be snapshot?
 968   (catch 'quiet
 969     (vc-file-tree-walk
 970      (function (lambda (f)
 971                  (if (and (vc-registered f) (vc-locking-user f))
 972                      (throw 'quiet nil)))))
 973     t))
 974
 975 ;;;###autoload
 976 (defun vc-create-snapshot (name)
 977   "Make a snapshot called NAME.
 978 The snapshot is made from all registered files at or below the current
 979 directory.  For each file, the version level of its latest
 980 version becomes part of the named configuration."
 981   (interactive "sNew snapshot name: ")
 982   (if (not (vc-quiescent-p))
 983       (error "Can't make a snapshot, locked files are in the way.")
 984     (vc-file-tree-walk
 985      (function (lambda (f) (and
 986                    (vc-name f)
 987                    (vc-backend-assign-name f name)))))
 988     ))
 989
 990 ;;;###autoload
 991 (defun vc-retrieve-snapshot (name)
 992   "Retrieve the snapshot called NAME.
 993 This function fails if any files are locked at or below the current directory
 994 Otherwise, all registered files are checked out (unlocked) at their version
 995 levels in the snapshot."
 996   (interactive "sSnapshot name to retrieve: ")
 997   (if (not (vc-quiescent-p))
 998       (error "Can't retrieve a snapshot, locked files are in the way.")
 999     (vc-file-tree-walk
1000      (function (lambda (f) (and
1001                    (vc-name f)
1002                    (vc-error-occurred (vc-backend-checkout f nil name))))))
1003     ))
1004
1005 ;; Miscellaneous other entry points
1006
1007 ;;;###autoload
1008 (defun vc-print-log ()
1009   "List the change log of the current buffer in a window."
1010   (interactive)
1011   (if vc-dired-mode
1012       (set-buffer (find-file-noselect (dired-get-filename))))
1013   (while vc-parent-buffer
1014       (pop-to-buffer vc-parent-buffer))
1015   (if (and buffer-file-name (vc-name buffer-file-name))
1016       (progn
1017         (vc-backend-print-log buffer-file-name)
1018         (pop-to-buffer (get-buffer-create "*vc*"))
1019         (vc-shrink-to-fit)
1020         (goto-char (point-min))
1021         )
1022     (vc-registration-error buffer-file-name)
1023     )
1024   )
1025
1026 ;;;###autoload
1027 (defun vc-revert-buffer ()
1028   "Revert the current buffer's file back to the latest checked-in version.
1029 This asks for confirmation if the buffer contents are not identical
1030 to that version."
1031   (interactive)
1032   (if vc-dired-mode
1033       (find-file-other-window (dired-get-filename)))
1034   (while vc-parent-buffer
1035       (pop-to-buffer vc-parent-buffer))
1036   (let ((file buffer-file-name)
1037         (obuf (current-buffer)) (changed (vc-diff nil)))
1038     (if (and changed (or vc-suppress-confirm
1039                          (not (yes-or-no-p "Discard changes? "))))
1040         (progn
1041           (delete-window)
1042           (error "Revert cancelled."))
1043       (set-buffer obuf))
1044     (if changed
1045         (delete-window))
1046     (vc-backend-revert file)
1047     (vc-resynch-window file t t)
1048     )
1049   )
1050
1051 ;;;###autoload
1052 (defun vc-cancel-version (norevert)
1053   "Get rid of most recently checked in version of this file.
1054 A prefix argument means do not revert the buffer afterwards."
1055   (interactive "P")
1056   (if vc-dired-mode
1057       (find-file-other-window (dired-get-filename)))
1058   (while vc-parent-buffer
1059     (pop-to-buffer vc-parent-buffer))
1060   (let* ((target (concat (vc-latest-version (buffer-file-name))))
1061         (yours (concat (vc-your-latest-version (buffer-file-name))))
1062         (prompt (if (string-equal yours target)
1063                     "Remove your version %s from master?"
1064                   "Version %s was not your change.  Remove it anyway?")))
1065     (if (null (yes-or-no-p (format prompt target)))
1066         nil
1067       (vc-backend-uncheck (buffer-file-name) target)
1068       (if (or norevert
1069               (not (yes-or-no-p "Revert buffer to most recent remaining version? ")))
1070           (vc-mode-line (buffer-file-name))
1071         (vc-checkout (buffer-file-name) nil)))
1072     ))
1073
1074 (defun vc-rename-file (old new)
1075   "Rename file OLD to NEW, and rename its master file likewise."
1076   (interactive "fVC rename file: \nFRename to: ")
1077   (let ((oldbuf (get-file-buffer old)))
1078     (if (buffer-modified-p oldbuf)
1079         (error "Please save files before moving them."))
1080     (if (get-file-buffer new)
1081         (error "Already editing new file name."))
1082     (let ((oldmaster (vc-name old)))
1083       (if oldmaster
1084         (if (vc-locking-user old)
1085             (error "Please check in files before moving them."))
1086         (if (or (file-symlink-p oldmaster)
1087                 ;; This had FILE, I changed it to OLD. -- rms.
1088                 (file-symlink-p (vc-backend-subdirectory-name old)))
1089             (error "This is not a safe thing to do in the presence of symbolic links."))
1090         (rename-file oldmaster (vc-name new)))
1091       (if (or (not oldmaster) (file-exists-p old))
1092           (rename-file old new)))
1093 ; ?? Renaming a file might change its contents due to keyword expansion.
1094 ; We should really check out a new copy if the old copy was precisely equal
1095 ; to some checked in version.  However, testing for this is tricky....
1096     (if oldbuf
1097         (save-excursion
1098           (set-buffer oldbuf)
1099           (set-visited-file-name new)
1100           (set-buffer-modified-p nil))))
1101   ;; This had FILE, I changed it to OLD. -- rms.
1102   (vc-backend-dispatch old
1103                        (vc-record-rename old new)
1104                        nil)
1105   )
1106
1107 ;;;###autoload
1108 (defun vc-update-change-log (&rest args)
1109   "Find change log file and add entries from recent RCS logs.
1110 The mark is left at the end of the text prepended to the change log.
1111 With prefix arg of C-u, only find log entries for the current buffer's file.
1112 With any numeric prefix arg, find log entries for all files currently visited.
1113 From a program, any arguments are passed to the `rcs2log' script."
1114   (interactive
1115    (cond ((consp current-prefix-arg)    ;C-u
1116           (list buffer-file-name))
1117          (current-prefix-arg            ;Numeric argument.
1118           (let ((files nil)
1119                 (buffers (buffer-list))
1120                 file)
1121             (while buffers
1122               (setq file (buffer-file-name (car buffers)))
1123               (and file (vc-backend-deduce file)
1124                    (setq files (cons (file-relative-name file) files)))
1125               (setq buffers (cdr buffers)))
1126             files))))
1127   (find-file-other-window (find-change-log))
1128   (barf-if-buffer-read-only)
1129   (vc-buffer-sync)
1130   (undo-boundary)
1131   (goto-char (point-min))
1132   (push-mark)
1133   (message "Computing change log entries...")
1134   (message "Computing change log entries... %s"
1135            (if (eq 0 (apply 'call-process "rcs2log" nil t nil args))
1136                "done" "failed")))
1137
1138 ;; Functions for querying the master and lock files.
1139
1140 (defun vc-match-substring (bn)
1141   (buffer-substring (match-beginning bn) (match-end bn)))
1142
1143 (defun vc-parse-buffer (patterns &optional file properties)
1144   ;; Use PATTERNS to parse information out of the current buffer
1145   ;; by matching each regular expression in the list and returning \\1.
1146   ;; If a regexp has two tag brackets, assume the second is a date
1147   ;; field and we want the most recent entry matching the template.
1148   ;; If FILE and PROPERTIES are given, the latter must be a list of
1149   ;; properties of the same length as PATTERNS; each property is assigned
1150   ;; the corresponding value.
1151   (mapcar (function (lambda (p)
1152              (goto-char (point-min))
1153              (if (string-match "\\\\(.*\\\\(" p)
1154                  (let ((latest-date "") (latest-val))
1155                    (while (re-search-forward p nil t)
1156                      (let ((date (vc-match-substring 2)))
1157                        (if (string< latest-date date)
1158                            (progn
1159                              (setq latest-date date)
1160                              (setq latest-val
1161                                    (vc-match-substring 1))))))
1162                    latest-val))
1163              (prog1
1164                  (and (re-search-forward p nil t)
1165                       (let ((value (vc-match-substring 1)))
1166                         (if file
1167                             (vc-file-setprop file (car properties) value))
1168                         value))
1169                (setq properties (cdr properties)))))
1170           patterns)
1171   )
1172
1173 (defun vc-master-info (file fields &optional rfile properties)
1174   ;; Search for information in a master file.
1175   (if (and file (file-exists-p file))
1176       (save-excursion
1177         (let ((buf))
1178           (setq buf (create-file-buffer file))
1179           (set-buffer buf))
1180         (erase-buffer)
1181         (insert-file-contents file nil)
1182         (set-buffer-modified-p nil)
1183         (auto-save-mode nil)
1184         (prog1
1185             (vc-parse-buffer fields rfile properties)
1186           (kill-buffer (current-buffer)))
1187         )
1188     (if rfile
1189         (mapcar
1190          (function (lambda (p) (vc-file-setprop rfile p nil)))
1191          properties))
1192     )
1193   )
1194
1195 (defun vc-log-info (command file patterns &optional properties)
1196   ;; Search for information in log program output
1197   (if (and file (file-exists-p file))
1198       (save-excursion
1199         (let ((buf))
1200           (setq buf (get-buffer-create "*vc*"))
1201           (set-buffer buf))
1202         (apply 'vc-do-command 0 command file nil)
1203         (set-buffer-modified-p nil)
1204         (prog1
1205             (vc-parse-buffer patterns file properties)
1206           (kill-buffer (current-buffer))
1207           )
1208         )
1209     (if file
1210         (mapcar
1211          (function (lambda (p) (vc-file-setprop file p nil)))
1212          properties))
1213     )
1214   )
1215
1216 (defun vc-locking-user (file)
1217   "Return the name of the person currently holding a lock on FILE.
1218 Return nil if there is no such person."
1219   (setq file (expand-file-name file))   ;; ??? Work around bug in 19.0.4
1220   (if (or (not vc-keep-workfiles)
1221           (eq vc-mistrust-permissions 't)
1222           (and vc-mistrust-permissions
1223                (funcall vc-mistrust-permissions (vc-backend-subdirectory-name file))))
1224       (vc-true-locking-user file)
1225     ;; This implementation assumes that any file which is under version
1226     ;; control and has -rw-r--r-- is locked by its owner.  This is true
1227     ;; for both RCS and SCCS, which keep unlocked files at -r--r--r--.
1228     ;; We have to be careful not to exclude files with execute bits on;
1229     ;; scripts can be under version control too.  The advantage of this
1230     ;; hack is that calls to the very expensive vc-fetch-properties
1231     ;; function only have to be made if (a) the file is locked by someone
1232     ;; other than the current user, or (b) some untoward manipulation
1233     ;; behind vc's back has changed the owner or the `group' or `other'
1234     ;; write bits.
1235     (let ((attributes (file-attributes file)))
1236       (cond ((string-match ".r-.r-.r-." (nth 8 attributes))
1237              nil)
1238             ((and (= (nth 2 attributes) (user-uid))
1239                   (string-match ".rw.r-.r-." (nth 8 attributes)))
1240              (user-login-name))
1241             (t
1242              (vc-true-locking-user file))))))
1243
1244 (defun vc-true-locking-user (file)
1245   ;; The slow but reliable version
1246   (vc-fetch-properties file)
1247   (vc-file-getprop file 'vc-locking-user))
1248
1249 (defun vc-latest-version (file)
1250   ;; Return version level of the latest version of FILE
1251   (vc-fetch-properties file)
1252   (vc-file-getprop file 'vc-latest-version))
1253
1254 (defun vc-your-latest-version (file)
1255   ;; Return version level of the latest version of FILE checked in by you
1256   (vc-fetch-properties file)
1257   (vc-file-getprop file 'vc-your-latest-version))
1258
1259 ;; Collect back-end-dependent stuff here
1260 ;;
1261 ;; Everything eventually funnels through these functions.  To implement
1262 ;; support for a new version-control system, add another branch to the
1263 ;; vc-backend-dispatch macro and fill it in in each call.  The variable
1264 ;; vc-master-templates in vc-hooks.el will also have to change.
1265
1266 (defmacro vc-backend-dispatch (f s r)
1267   "Execute FORM1 or FORM2 depending on whether we're using SCCS or RCS."
1268   (list 'let (list (list 'type (list 'vc-backend-deduce f)))
1269         (list 'cond
1270               (list (list 'eq 'type (quote 'SCCS)) s)   ;; SCCS
1271               (list (list 'eq 'type (quote 'RCS)) r)    ;; RCS
1272               )))
1273
1274 (defun vc-lock-file (file)
1275   ;; Generate lock file name corresponding to FILE
1276   (let ((master (vc-name file)))
1277     (and
1278      master
1279      (string-match "\\(.*/\\)s\\.\\(.*\\)" master)
1280      (concat
1281       (substring master (match-beginning 1) (match-end 1))
1282       "p."
1283       (substring master (match-beginning 2) (match-end 2))))))
1284
1285
1286 (defun vc-fetch-properties (file)
1287   ;; Re-fetch all properties associated with the given file.
1288   ;; Currently these properties are:
1289   ;;    vc-locking-user
1290   ;;    vc-locked-version
1291   ;;    vc-latest-version
1292   ;;    vc-your-latest-version
1293   (vc-backend-dispatch
1294    file
1295    ;; SCCS
1296    (progn
1297      (vc-master-info (vc-lock-file file)
1298                      (list
1299                       "^[^ ]+ [^ ]+ \\([^ ]+\\)"
1300                       "^\\([^ ]+\\)")
1301                      file
1302                      '(vc-locking-user vc-locked-version))
1303      (vc-master-info (vc-name file)
1304                   (list
1305                    "^\001d D \\([^ ]+\\)"
1306                    (concat "^\001d D \\([^ ]+\\) .* "
1307                            (regexp-quote (user-login-name)) " ")
1308                    )
1309                   file
1310                   '(vc-latest-version vc-your-latest-version))
1311      )
1312    ;; RCS
1313    (vc-log-info "rlog" file
1314                 (list
1315                  "^locks: strict\n\t\\([^:]+\\)"
1316                  "^locks: strict\n\t[^:]+: \\(.+\\)"
1317                  "^revision[\t ]+\\([0-9.]+\\).*\ndate: \\([ /0-9:]+\\);"
1318                  (concat
1319                   "^revision[\t ]+\\([0-9.]+\\)\n.*author: "
1320                   (regexp-quote (user-login-name))
1321                   ";"))
1322                 '(vc-locking-user vc-locked-version
1323                                   vc-latest-version vc-your-latest-version))
1324    ))
1325
1326 (defun vc-backend-subdirectory-name (&optional file)
1327   ;; Where the master and lock files for the current directory are kept
1328   (symbol-name
1329    (or
1330     (and file (vc-backend-deduce file))
1331     vc-default-back-end
1332     (setq vc-default-back-end (if (vc-find-binary "rcs") 'RCS 'SCCS)))))
1333
1334 (defun vc-backend-admin (file &optional rev comment)
1335   ;; Register a file into the version-control system
1336   ;; Automatically retrieves a read-only version of the file with
1337   ;; keywords expanded if vc-keep-workfiles is non-nil, otherwise
1338   ;; it deletes the workfile.
1339   (vc-file-clearprops file)
1340   (or vc-default-back-end
1341       (setq vc-default-back-end (if (vc-find-binary "rcs") 'RCS 'SCCS)))
1342   (message "Registering %s..." file)
1343   (let ((backend
1344          (cond
1345           ((file-exists-p (vc-backend-subdirectory-name)) vc-default-back-end)
1346           ((file-exists-p "RCS") 'RCS)
1347           ((file-exists-p "SCCS") 'SCCS)
1348           (t vc-default-back-end))))
1349     (cond ((eq backend 'SCCS)
1350            (vc-do-command 0 "admin" file        ;; SCCS
1351                           (and rev (concat "-r" rev))
1352                           "-fb"
1353                           (concat "-i" file)
1354                           (and comment (concat "-y" comment))
1355                           (format
1356                            (car (rassq 'SCCS vc-master-templates))
1357                            (or (file-name-directory file) "")
1358                            (file-name-nondirectory file)))
1359            (delete-file file)
1360            (if vc-keep-workfiles
1361                (vc-do-command 0 "get" file)))
1362           ((eq backend 'RCS)
1363            (vc-do-command 0 "ci" file   ;; RCS
1364                           (concat (if vc-keep-workfiles "-u" "-r") rev)
1365                           (and comment (concat "-t-" comment))
1366                           file)
1367            )))
1368   (message "Registering %s...done" file)
1369   )
1370
1371 (defun vc-backend-checkout (file &optional writable rev)
1372   ;; Retrieve a copy of a saved version into a workfile
1373   (message "Checking out %s..." file)
1374   (vc-backend-dispatch file
1375    (progn
1376      (vc-do-command 0 "get" file        ;; SCCS
1377                     (if writable "-e")
1378                     (and rev (concat "-r" (vc-lookup-triple file rev))))
1379      )
1380    (vc-do-command 0 "co" file   ;; RCS
1381                   (if writable "-l")
1382                   (and rev (concat "-r" rev)))
1383    )
1384   (vc-file-setprop file 'vc-checkout-time (nth 5 (file-attributes file)))
1385   (message "Checking out %s...done" file)
1386   )
1387
1388 (defun vc-backend-logentry-check (file)
1389   (vc-backend-dispatch file
1390    (if (>= (buffer-size) 512)   ;; SCCS
1391        (progn
1392          (goto-char 512)
1393          (error
1394           "Log must be less than 512 characters.  Point is now at char 512.")))
1395    nil)
1396   )
1397
1398 (defun vc-backend-checkin (file &optional rev comment)
1399   ;; Register changes to FILE as level REV with explanatory COMMENT.
1400   ;; Automatically retrieves a read-only version of the file with
1401   ;; keywords expanded if vc-keep-workfiles is non-nil, otherwise
1402   ;; it deletes the workfile.
1403   (message "Checking in %s..." file)
1404   (save-excursion
1405     ;; Change buffers to get local value of vc-checkin-switches.
1406     (set-buffer (or (get-file-buffer file) (current-buffer)))
1407     (vc-backend-dispatch file
1408       (progn
1409         (apply 'vc-do-command 0 "delta" file
1410                (if rev (concat "-r" rev))
1411                (concat "-y" comment)
1412                vc-checkin-switches)
1413         (if vc-keep-workfiles
1414             (vc-do-command 0 "get" file))
1415         )
1416       (apply 'vc-do-command 0 "ci" file
1417              (concat (if vc-keep-workfiles "-u" "-r") rev)
1418              (concat "-m" comment)
1419              vc-checkin-switches)
1420       ))
1421   (vc-file-setprop file 'vc-locking-user nil)
1422   (message "Checking in %s...done" file)
1423   )
1424
1425 (defun vc-backend-revert (file)
1426   ;; Revert file to latest checked-in version.
1427   (message "Reverting %s..." file)
1428   (vc-backend-dispatch
1429    file
1430    (progn                       ;; SCCS
1431      (vc-do-command 0 "unget" file nil)
1432      (vc-do-command 0 "get" file nil))
1433    (progn
1434      (delete-file file)         ;; RCS
1435      (vc-do-command 0 "co" file "-u")))
1436   (vc-file-setprop file 'vc-locking-user nil)
1437   (message "Reverting %s...done" file)
1438   )
1439
1440 (defun vc-backend-steal (file &optional rev)
1441   ;; Steal the lock on the current workfile.  Needs RCS 5.6.2 or later for -M.
1442   (message "Stealing lock on %s..." file)
1443   (progn
1444     (vc-do-command 0 "unget" file "-n" (if rev (concat "-r" rev)))
1445     (vc-do-command 0 "get" file "-g" (if rev (concat "-r" rev)))
1446     )
1447   (progn
1448     (vc-do-command 0 "rcs" "-M" (concat "-u" rev) file)
1449     (delete-file file)
1450     (vc-do-command 0 "rcs" (concat "-l" rev) file)
1451     )
1452   (vc-file-setprop file 'vc-locking-user (user-login-name))
1453   (message "Stealing lock on %s...done" file)
1454   )
1455
1456 (defun vc-backend-uncheck (file target)
1457   ;; Undo the latest checkin.  Note: this code will have to get a lot
1458   ;; smarter when we support multiple branches.
1459   (message "Removing last change from %s..." file)
1460   (vc-backend-dispatch file
1461    (vc-do-command 0 "rmdel" file (concat "-r" target))
1462    (vc-do-command 0 "rcs" file (concat "-o" target))
1463    )
1464   (message "Removing last change from %s...done" file)
1465   )
1466
1467 (defun vc-backend-print-log (file)
1468   ;; Print change log associated with FILE to buffer *vc*.
1469   (vc-do-command 0
1470                  (vc-backend-dispatch file "prs" "rlog")
1471                  file)
1472   )
1473
1474 (defun vc-backend-assign-name (file name)
1475   ;; Assign to a FILE's latest version a given NAME.
1476   (vc-backend-dispatch file
1477    (vc-add-triple name file (vc-latest-version file))   ;; SCCS
1478    (vc-do-command 0 "rcs" file (concat "-n" name ":"))  ;; RCS
1479    )
1480   )
1481
1482 (defun vc-backend-diff (file oldvers &optional newvers)
1483   ;; Get a difference report between two versions
1484   (if (eq (vc-backend-deduce file) 'SCCS)
1485       (setq oldvers (vc-lookup-triple file oldvers))
1486       (setq newvers (vc-lookup-triple file newvers)))
1487   (apply 'vc-do-command 1
1488          (or (vc-backend-dispatch file "vcdiff" "rcsdiff")
1489              (vc-registration-error file))
1490          file
1491          (and oldvers (concat "-r" oldvers))
1492          (and newvers (concat "-r" newvers))
1493          (if (listp diff-switches)
1494              diff-switches
1495            (list diff-switches))
1496   ))
1497
1498 (defun vc-check-headers ()
1499   "Check if the current file has any headers in it."
1500   (interactive)
1501   (save-excursion
1502     (goto-char (point-min))
1503     (vc-backend-dispatch buffer-file-name
1504      (re-search-forward  "%[MIRLBSDHTEGUYFPQCZWA]%" nil t)      ;; SCCS
1505      (re-search-forward "\\$[A-Za-z\300-\326\330-\366\370-\377]+\\(: [\t -#%-\176\240-\377]*\\)?\\$" nil t)             ;; RCS
1506      )
1507     ))
1508
1509 ;; Back-end-dependent stuff ends here.
1510
1511 ;; Set up key bindings for use while editing log messages
1512
1513 (defun vc-log-mode ()
1514   "Minor mode for driving version-control tools.
1515 These bindings are added to the global keymap when you enter this mode:
1516 \\[vc-next-action]              perform next logical version-control operation on current file
1517 \\[vc-register]                 register current file
1518 \\[vc-toggle-read-only]         like next-action, but won't register files
1519 \\[vc-insert-headers]           insert version-control headers in current file
1520 \\[vc-print-log]                display change history of current file
1521 \\[vc-revert-buffer]            revert buffer to latest version
1522 \\[vc-cancel-version]           undo latest checkin
1523 \\[vc-diff]             show diffs between file versions
1524 \\[vc-directory]                show all files locked by any user in or below .
1525 \\[vc-update-change-log]                add change log entry from recent checkins
1526
1527 While you are entering a change log message for a version, the following
1528 additional bindings will be in effect.
1529
1530 \\[vc-finish-logentry]  proceed with check in, ending log message entry
1531
1532 Whenever you do a checkin, your log comment is added to a ring of
1533 saved comments.  These can be recalled as follows:
1534
1535 \\[vc-next-comment]     replace region with next message in comment ring
1536 \\[vc-previous-comment] replace region with previous message in comment ring
1537 \\[vc-comment-search-reverse]   search backward for regexp in the comment ring
1538 \\[vc-comment-search-forward]   search backward for regexp in the comment ring
1539
1540 Entry to the change-log submode calls the value of text-mode-hook, then
1541 the value of vc-log-mode-hook.
1542
1543 Global user options:
1544         vc-initial-comment      If non-nil, require user to enter a change
1545                                 comment upon first checkin of the file.
1546
1547         vc-keep-workfiles       Non-nil value prevents workfiles from being
1548                                 deleted when changes are checked in
1549
1550         vc-suppress-confirm     Suppresses some confirmation prompts,
1551                                 notably for reversions.
1552
1553         vc-header-alist         Which keywords to insert when adding headers
1554                                 with \\[vc-insert-headers].  Defaults to
1555                                 '(\"\%\W\%\") under SCCS, '(\"\$Id\$\") under RCS.
1556
1557         vc-static-header-alist  By default, version headers inserted in C files
1558                                 get stuffed in a static string area so that
1559                                 ident(RCS) or what(SCCS) can see them in the
1560                                 compiled object code.  You can override this
1561                                 by setting this variable to nil, or change
1562                                 the header template by changing it.
1563
1564         vc-command-messages     if non-nil, display run messages from the
1565                                 actual version-control utilities (this is
1566                                 intended primarily for people hacking vc
1567                                 itself).
1568 "
1569   (interactive)
1570   (set-syntax-table text-mode-syntax-table)
1571   (use-local-map vc-log-entry-mode)
1572   (setq local-abbrev-table text-mode-abbrev-table)
1573   (setq major-mode 'vc-log-mode)
1574   (setq mode-name "VC-Log")
1575   (make-local-variable 'vc-log-file)
1576   (make-local-variable 'vc-log-version)
1577   (make-local-variable 'vc-comment-ring-index)
1578   (set-buffer-modified-p nil)
1579   (setq buffer-file-name nil)
1580   (run-hooks 'text-mode-hook 'vc-log-mode-hook)
1581 )
1582
1583 ;; Initialization code, to be done just once at load-time
1584 (if vc-log-entry-mode
1585     nil
1586   (setq vc-log-entry-mode (make-sparse-keymap))
1587   (define-key vc-log-entry-mode "\M-n" 'vc-next-comment)
1588   (define-key vc-log-entry-mode "\M-p" 'vc-previous-comment)
1589   (define-key vc-log-entry-mode "\M-r" 'vc-comment-search-reverse)
1590   (define-key vc-log-entry-mode "\M-s" 'vc-comment-search-forward)
1591   (define-key vc-log-entry-mode "\C-c\C-c" 'vc-finish-logentry)
1592   )
1593
1594 ;;; These things should probably be generally available
1595
1596 (defun vc-shrink-to-fit ()
1597   "Shrink window vertically until it's just large enough to contain its text."
1598   (let ((minsize (1+ (count-lines (point-min) (point-max)))))
1599     (if (< minsize (window-height))
1600         (let ((window-min-height 2))
1601           (shrink-window (- (window-height) minsize))))))
1602
1603 (defun vc-file-tree-walk (func &rest args)
1604   "Walk recursively through default directory.
1605 Invoke FUNC f ARGS on each non-directory file f underneath it."
1606   (vc-file-tree-walk-internal default-directory func args)
1607   (message "Traversing directory %s...done" default-directory))
1608
1609 (defun vc-file-tree-walk-internal (file func args)
1610   (if (not (file-directory-p file))
1611       (apply func file args)
1612     (message "Traversing directory %s..." file)
1613     (let ((dir (file-name-as-directory file)))
1614       (mapcar
1615        (function
1616         (lambda (f) (or
1617                      (string-equal f ".")
1618                      (string-equal f "..")
1619                      (let ((dirf (concat dir f)))
1620                         (or
1621                          (file-symlink-p dirf) ;; Avoid possible loops
1622                          (vc-file-tree-walk-internal dirf func args))))))
1623        (directory-files dir)))))
1624
1625 (provide 'vc)
1626
1627 ;;; DEVELOPER'S NOTES ON CONCURRENCY PROBLEMS IN THIS CODE
1628 ;;;
1629 ;;; These may be useful to anyone who has to debug or extend the package.
1630 ;;;
1631 ;;; A fundamental problem in VC is that there are time windows between
1632 ;;; vc-next-action's computations of the file's version-control state and
1633 ;;; the actions that change it.  This is a window open to lossage in a
1634 ;;; multi-user environment; someone else could nip in and change the state
1635 ;;; of the master during it.
1636 ;;;
1637 ;;; The performance problem is that rlog/prs calls are very expensive; we want
1638 ;;; to avoid them as much as possible.
1639 ;;;
1640 ;;; ANALYSIS:
1641 ;;;
1642 ;;; The performance problem, it turns out, simplifies in practice to the
1643 ;;; problem of making vc-locking-user fast.  The two other functions that call
1644 ;;; prs/rlog will not be so commonly used that the slowdown is a problem; one
1645 ;;; makes snapshots, the other deletes the calling user's last change in the
1646 ;;; master.
1647 ;;;
1648 ;;; The race condition implies that we have to either (a) lock the master
1649 ;;; during the entire execution of vc-next-action, or (b) detect and
1650 ;;; recover from errors resulting from dispatch on an out-of-date state.
1651 ;;;
1652 ;;; Alternative (a) appears to be unfeasible.  The problem is that we can't
1653 ;;; guarantee that the lock will ever be removed.  Suppose a user starts a
1654 ;;; checkin, the change message buffer pops up, and the user, having wandered
1655 ;;; off to do something else, simply forgets about it?
1656 ;;;
1657 ;;; Alternative (b), on the other hand, works well with a cheap way to speed up
1658 ;;; vc-locking-user.  Usually, if a file is registered, we can read its locked/
1659 ;;; unlocked state and its current owner from its permissions.
1660 ;;;
1661 ;;; This shortcut will fail if someone has manually changed the workfile's
1662 ;;; permissions; also if developers are munging the workfile in several
1663 ;;; directories, with symlinks to a master (in this latter case, the
1664 ;;; permissions shortcut will fail to detect a lock asserted from another
1665 ;;; directory).
1666 ;;;
1667 ;;; Note that these cases correspond exactly to the errors which could happen
1668 ;;; because of a competing checkin/checkout race in between two instances of
1669 ;;; vc-next-action.
1670 ;;;
1671 ;;; For VC's purposes, a workfile/master pair may have the following states:
1672 ;;;
1673 ;;; A. Unregistered.  There is a workfile, there is no master.
1674 ;;;
1675 ;;; B. Registered and not locked by anyone.
1676 ;;;
1677 ;;; C. Locked by calling user and unchanged.
1678 ;;;
1679 ;;; D. Locked by the calling user and changed.
1680 ;;;
1681 ;;; E. Locked by someone other than the calling user.
1682 ;;;
1683 ;;; This makes for 25 states and 20 error conditions.  Here's the matrix:
1684 ;;;
1685 ;;; VC's idea of state
1686 ;;;  |
1687 ;;;  V  Actual state   RCS action              SCCS action          Effect
1688 ;;;    A  B  C  D  E
1689 ;;;  A .  1  2  3  4   ci -u -t-          admin -fb -i<file>      initial admin
1690 ;;;  B 5  .  6  7  8   co -l              get -e                  checkout
1691 ;;;  C 9  10 .  11 12  co -u              unget; get              revert
1692 ;;;  D 13 14 15 .  16  ci -u -m<comment>  delta -y<comment>; get  checkin
1693 ;;;  E 17 18 19 20 .   rcs -u -M ; rcs -l unget -n ; get -g       steal lock
1694 ;;;
1695 ;;; All commands take the master file name as a last argument (not shown).
1696 ;;;
1697 ;;; In the discussion below, a "self-race" is a pathological situation in
1698 ;;; which VC operations are being attempted simultaneously by two or more
1699 ;;; Emacsen running under the same username.
1700 ;;;
1701 ;;; The vc-next-action code has the following windows:
1702 ;;;
1703 ;;; Window P:
1704 ;;;    Between the check for existence of a master file and the call to
1705 ;;; admin/checkin in vc-buffer-admin (apparent state A).  This window may
1706 ;;; never close if the initial-comment feature is on.
1707 ;;;
1708 ;;; Window Q:
1709 ;;;    Between the call to vc-workfile-unchanged-p in and the immediately
1710 ;;; following revert (apparent state C).
1711 ;;;
1712 ;;; Window R:
1713 ;;;    Between the call to vc-workfile-unchanged-p in and the following
1714 ;;; checkin (apparent state D).  This window may never close.
1715 ;;;
1716 ;;; Window S:
1717 ;;;    Between the unlock and the immediately following checkout during a
1718 ;;; revert operation (apparent state C).  Included in window Q.
1719 ;;;
1720 ;;; Window T:
1721 ;;;    Between vc-locking-user and the following checkout (apparent state B).
1722 ;;;
1723 ;;; Window U:
1724 ;;;    Between vc-locking-user and the following revert (apparent state C).
1725 ;;; Includes windows Q and S.
1726 ;;;
1727 ;;; Window V:
1728 ;;;    Between vc-locking-user and the following checkin (apparent state
1729 ;;; D).  This window may never be closed if the user fails to complete the
1730 ;;; checkin message.  Includes window R.
1731 ;;;
1732 ;;; Window W:
1733 ;;;    Between vc-locking-user and the following steal-lock (apparent
1734 ;;; state E).  This window may never close if the user fails to complete
1735 ;;; the steal-lock message.  Includes window X.
1736 ;;;
1737 ;;; Window X:
1738 ;;;    Between the unlock and the immediately following re-lock during a
1739 ;;; steal-lock operation (apparent state E).  This window may never cloce
1740 ;;; if the user fails to complete the steal-lock message.
1741 ;;;
1742 ;;; Errors:
1743 ;;;
1744 ;;; Apparent state A ---
1745 ;;;
1746 ;;; 1. File looked unregistered but is actually registered and not locked.
1747 ;;;
1748 ;;;    Potential cause: someone else's admin during window P, with
1749 ;;; caller's admin happening before their checkout.
1750 ;;;
1751 ;;;    RCS: ci will fail with a "no lock set by <user>" message.
1752 ;;;    SCCS: admin will fail with error (ad19).
1753 ;;;
1754 ;;;    We can let these errors be passed up to the user.
1755 ;;;
1756 ;;; 2. File looked unregistered but is actually locked by caller, unchanged.
1757 ;;;
1758 ;;;    Potential cause: self-race during window P.
1759 ;;;
1760 ;;;    RCS: will revert the file to the last saved version and unlock it.
1761 ;;;    SCCS: will fail with error (ad19).
1762 ;;;
1763 ;;;    Either of these consequences is acceptable.
1764 ;;;
1765 ;;; 3. File looked unregistered but is actually locked by caller, changed.
1766 ;;;
1767 ;;;    Potential cause: self-race during window P.
1768 ;;;
1769 ;;;    RCS: will register the caller's workfile as a delta with a
1770 ;;; null change comment (the -t- switch will be ignored).
1771 ;;;    SCCS: will fail with error (ad19).
1772 ;;;
1773 ;;; 4. File looked unregistered but is locked by someone else.
1774 ;;;
1775 ;;;    Potential cause: someone else's admin during window P, with
1776 ;;; caller's admin happening *after* their checkout.
1777 ;;;
1778 ;;;    RCS: will fail with a "no lock set by <user>" message.
1779 ;;;    SCCS: will fail with error (ad19).
1780 ;;;
1781 ;;;    We can let these errors be passed up to the user.
1782 ;;;
1783 ;;; Apparent state B ---
1784 ;;;
1785 ;;; 5. File looked registered and not locked, but is actually unregistered.
1786 ;;;
1787 ;;;    Potential cause: master file got nuked during window P.
1788 ;;;
1789 ;;;    RCS: will fail with "RCS/<file>: No such file or directory"
1790 ;;;    SCCS: will fail with error ut4.
1791 ;;;
1792 ;;;    We can let these errors be passed up to the user.
1793 ;;;
1794 ;;; 6. File looked registered and not locked, but is actually locked by the
1795 ;;; calling user and unchanged.
1796 ;;;
1797 ;;;    Potential cause: self-race during window T.
1798 ;;;
1799 ;;;    RCS: in the same directory as the previous workfile, co -l will fail
1800 ;;; with "co error: writable foo exists; checkout aborted".  In any other
1801 ;;; directory, checkout will succeed.
1802 ;;;    SCCS: will fail with ge17.
1803 ;;;
1804 ;;;    Either of these consequences is acceptable.
1805 ;;;
1806 ;;; 7. File looked registered and not locked, but is actually locked by the
1807 ;;; calling user and changed.
1808 ;;;
1809 ;;;    As case 6.
1810 ;;;
1811 ;;; 8. File looked registered and not locked, but is actually locked by another
1812 ;;; user.
1813 ;;;
1814 ;;;    Potential cause: someone else checks it out during window T.
1815 ;;;
1816 ;;;    RCS: co error: revision 1.3 already locked by <user>
1817 ;;;    SCCS: fails with ge4 (in directory) or ut7 (outside it).
1818 ;;;
1819 ;;;    We can let these errors be passed up to the user.
1820 ;;;
1821 ;;; Apparent state C ---
1822 ;;;
1823 ;;; 9. File looks locked by calling user and unchanged, but is unregistered.
1824 ;;;
1825 ;;;    As case 5.
1826 ;;;
1827 ;;; 10. File looks locked by calling user and unchanged, but is actually not
1828 ;;; locked.
1829 ;;;
1830 ;;;    Potential cause: a self-race in window U, or by the revert's
1831 ;;; landing during window X of some other user's steal-lock or window S
1832 ;;; of another user's revert.
1833 ;;;
1834 ;;;    RCS: succeeds, refreshing the file from the identical version in
1835 ;;; the master.
1836 ;;;    SCCS: fails with error ut4 (p file nonexistent).
1837 ;;;
1838 ;;;    Either of these consequences is acceptable.
1839 ;;;
1840 ;;; 11. File is locked by calling user.  It looks unchanged, but is actually
1841 ;;; changed.
1842 ;;;
1843 ;;;    Potential cause: the file would have to be touched by a self-race
1844 ;;; during window Q.
1845 ;;;
1846 ;;;    The revert will succeed, removing whatever changes came with
1847 ;;; the touch.  It is theoretically possible that work could be lost.
1848 ;;;
1849 ;;; 12. File looks like it's locked by the calling user and unchanged, but
1850 ;;; it's actually locked by someone else.
1851 ;;;
1852 ;;;    Potential cause: a steal-lock in window V.
1853 ;;;
1854 ;;;    RCS: co error: revision <rev> locked by <user>; use co -r or rcs -u
1855 ;;;    SCCS: fails with error un2
1856 ;;;
1857 ;;;    We can pass these errors up to the user.
1858 ;;;
1859 ;;; Apparent state D ---
1860 ;;;
1861 ;;; 13. File looks like it's locked by the calling user and changed, but it's
1862 ;;; actually unregistered.
1863 ;;;
1864 ;;;    Potential cause: master file got nuked during window P.
1865 ;;;
1866 ;;;    RCS: Checks in the user's version as an initial delta.
1867 ;;;    SCCS: will fail with error ut4.
1868 ;;;
1869 ;;;    This case is kind of nasty.  It means VC may fail to detect the
1870 ;;; loss of previous version information.
1871 ;;;
1872 ;;; 14. File looks like it's locked by the calling user and changed, but it's
1873 ;;; actually unlocked.
1874 ;;;
1875 ;;;    Potential cause: self-race in window V, or the checkin happening
1876 ;;; during the window X of someone else's steal-lock or window S of
1877 ;;; someone else's revert.
1878 ;;;
1879 ;;;    RCS: ci will fail with "no lock set by <user>".
1880 ;;;    SCCS: delta will fail with error ut4.
1881 ;;;
1882 ;;; 15. File looks like it's locked by the calling user and changed, but it's
1883 ;;; actually locked by the calling user and unchanged.
1884 ;;;
1885 ;;;    Potential cause: another self-race --- a whole checkin/checkout
1886 ;;; sequence by the calling user would have to land in window R.
1887 ;;;
1888 ;;;    SCCS: checks in a redundant delta and leaves the file unlocked as usual.
1889 ;;;    RCS: reverts to the file state as of the second user's checkin, leaving
1890 ;;; the file unlocked.
1891 ;;;
1892 ;;;    It is theoretically possible that work could be lost under RCS.
1893 ;;;
1894 ;;; 16. File looks like it's locked by the calling user and changed, but it's
1895 ;;; actually locked by a different user.
1896 ;;;
1897 ;;;    RCS: ci error: no lock set by <user>
1898 ;;;    SCCS: unget will fail with error un2
1899 ;;;
1900 ;;;    We can pass these errors up to the user.
1901 ;;;
1902 ;;; Apparent state E ---
1903 ;;;
1904 ;;; 17. File looks like it's locked by some other user, but it's actually
1905 ;;; unregistered.
1906 ;;;
1907 ;;;    As case 13.
1908 ;;;
1909 ;;; 18. File looks like it's locked by some other user, but it's actually
1910 ;;; unlocked.
1911 ;;;
1912 ;;;    Potential cause: someone released a lock during window W.
1913 ;;;
1914 ;;;    RCS: The calling user will get the lock on the file.
1915 ;;;    SCCS: unget -n will fail with cm4.
1916 ;;;
1917 ;;;    Either of these consequences will be OK.
1918 ;;;
1919 ;;; 19. File looks like it's locked by some other user, but it's actually
1920 ;;; locked by the calling user and unchanged.
1921 ;;;
1922 ;;;    Potential cause: the other user relinquishing a lock followed by
1923 ;;; a self-race, both in window W.
1924 ;;;
1925 ;;;     Under both RCS and SCCS, both unlock and lock will succeed, making
1926 ;;; the sequence a no-op.
1927 ;;;
1928 ;;; 20. File looks like it's locked by some other user, but it's actually
1929 ;;; locked by the calling user and changed.
1930 ;;;
1931 ;;;     As case 19.
1932 ;;;
1933 ;;; PROBLEM CASES:
1934 ;;;
1935 ;;;    In order of decreasing severity:
1936 ;;;
1937 ;;;    Cases 11 and 15 under RCS are the only one that potentially lose work.
1938 ;;; They would require a self-race for this to happen.
1939 ;;;
1940 ;;;    Case 13 in RCS loses information about previous deltas, retaining
1941 ;;; only the information in the current workfile.  This can only happen
1942 ;;; if the master file gets nuked in window P.
1943 ;;;
1944 ;;;    Case 3 in RCS and case 15 under SCCS insert a redundant delta with
1945 ;;; no change comment in the master.  This would require a self-race in
1946 ;;; window P or R respectively.
1947 ;;;
1948 ;;;    Cases 2, 10, 19 and 20 do extra work, but make no changes.
1949 ;;;
1950 ;;;    Unfortunately, it appears to me that no recovery is possible in these
1951 ;;; cases.  They don't yield error messages, so there's no way to tell that
1952 ;;; a race condition has occurred.
1953 ;;;
1954 ;;;    All other cases don't change either the workfile or the master, and
1955 ;;; trigger command errors which the user will see.
1956 ;;;
1957 ;;;    Thus, there is no explicit recovery code.
1958
1959 ;;; vc.el ends here