(vc-next-action-on-file): Do not visit the file if it's

not necessary.  If verbose in state `needs-patch', do the same as
under `up-to-date'.  When NOT verbose and `needs-patch', check out
latest version instead of `merge-news'.
(vc-next-action-dired): Don't mess with default-directory here; it
breaks other parts of dired.  It is the job of the
backend-specific functions to adjust it temporarily if they need
it.
(vc-next-action): Remove a special CVS case.
(vc-clear-headers): New optional arg FILE.
(vc-checkin, vc-checkout): Set properties vc-state and
vc-checkout-time properly.
(vc-finish-steal): Call steal-lock, not steal, which doesn't
exist.
(vc-print-log): Use new backend function `show-log-entry'.
(vc-cancel-version): Do the checks in a different order.  Added a
FIXME concerning RCS-only code.
(vc-responsible-backend): New optional arg `register'.
(vc-default-could-register): New function.
(vc-dired-buffers-for-dir, vc-dired-resynch-file): New functions.
(vc-resynch-buffer): Call vc-dired-resynch-file.
(vc-start-entry, vc-finish-logentry, vc-revert-buffer): Use
vc-resynch-buffer instead of vc-resynch-window.
(vc-next-action-dired): Don't redisplay here, that gets done as a
result of the individual file operations.
(vc-retrieve-snapshot): Corrected prompt order.
(vc-version-diff): Use `require' to check for existence of
diff-mode.
(vc-do-command): Doc fix.
(vc-finish-logentry): When checking in from vc-dired, choose the
right backend for logentry check.
(vc-dired-mode-map): Inherit from dired-mode-map.
(vc-dired-mode): Local value of dired-move-to-filename-regexp
simplified.
(vc-dired-state-info): Removed, updated caller.
(vc-default-dired-state-info): Use parentheses instead of hyphens.
(vc-dired-hook): Use vc-BACKEND-dir-state, if available.
(vc-dired-listing-switches): New variable.
(vc-directory): Use it, instead of dired-listing-switches.
(vc-revert-buffer): Hide the frame for dedicated windows
(vc-update-changelog): Split into generic part and default
implementation.  Doc string adapted.
(vc-default-update-changelog): New function.  Call the `rcs2log'
script in exec-directory, to fix a long-standing nuisance.
(vc-next-action-on-file): Doc fix.
(vc-maybe-resolve-conflicts): Don't just toggle smerge-mode.
(vc-print-log): Eval `file' before constructing the continuation.
(vc-next-action-on-file): Corrected several messages.
(vc-merge): Add prefix arg `merge-news'; handle it.
(vc-finish-logentry): Thinko in the "same comment"
detection.
(vc-parent-buffer, vc-parent-buffer-name): Protect them
against kill-all-local-variables.
(vc-log-edit): Don't save vc-parent-buffer any more.
(vc-last-comment-match): Initialize to an empty string.
(vc-post-command-functions): New hook.
(vc-do-command): Run it.
(vc-next-action-on-file): Remove unnecessary pop-to-buffer.
(vc-finish-logentry): Only add the comment to the ring if it's
different from the last comment entered.
(vc-new-comment-index): New function.
(vc-previous-comment): Use it.  Make the minibuffer message
slightly less terse.
(vc-comment-search-reverse): Make it work forward as well.  Don't
set vc-comment-ring-index if no match is found.  Use
vc-new-comment-index.
(vc-comment-search-forward): Use vc-comment-search-reverse.
(vc-dired-mode-map): Don't inherit from dired-mode-map since
define-derived-mode will do it for us.  Bind `v' to a keymap that
inherits from vc-prefix-map so that we can bind `vt' without
binding C-x v t.
(vc-retrieve-snapshot): Parenthesis typo.
(vc-create-snapshot, vc-default-create-snapshot): Swap DIR
and NAME.
(vc-retrieve-snapshot): Split into two parts.
(vc-default-retrieve-snapshot): New function.
(vc-do-command): Remove unused commands.
(vc-version-diff): Make sure default-directory ends with a slash.
Move the window commands into a vc-exec-after.
(vc-print-log): Move more of the code into the `vc-exec-after'.
(vc-exec-after): Fix disassembly of previous sentinel.
(vc-print-log): Search current revision from beginning of buffer.
(vc-revert-buffer): Clear echo area after the diff is finished.
(vc-prefix-map): Removed definition of "t" for terse display in vc
dired.
(vc-dired-mode-map): Inherit from dired-mode-map.  Added
definition of "vt" for terse display.
(vc-dired-mode): Fix dired-move-to-filename-regexp.
(vc-exec-after): Avoid caddr.
(vc-exec-after): New function.
(vc-do-command): Use it to add a termination message for async
procs.
(vc-checkout): Try to handle a missing-backend situation.
(vc-version-diff): Use vc-exec-after to fix the behavior for diffs
of a directory with a backend using async diffs.
(vc-print-log): Use vc-exec-after and use log-view-goto-rev if
present.
(vc-next-action-on-file): Use vc-revert-buffer to revert
when there are no changes.
(vc-prefix-map): Move the autoload to vc-hooks.el and move
the `fset' outside of the defvar so that it works even if
vc-prefix-map was already defined.
(vc-setup-buffer): New function, split out of vc-do-command.
(vc-do-command): Allow BUFFER to be t to mean `just use the
current buffer without any fuss'.
(vc-version-diff): Change the `diff' backend operation to just put
the diff in the current buffer without erasing it.  Always use
(vc-workfile-unchanged-p): If checkout-time comparison is
not possible, use vc-BACKEND-workfile-unchanged-p.
(vc-default-workfile-unchanged-p): New function.  Delegates to a
full vc-BACKEND-diff.
(vc-editable-p): Renamed from vc-writable-p.
(with-vc-file, vc-merge): Use vc-editable-p.
(vc-do-command): Remove unused var vc-file and fix the
doubly-defined `status' var.  Add a user message when starting an
async command.
(vc-restore-buffer-context, vc-resynch-buffer, vc-start-entry)
(vc-finish-steal, vc-checkin, vc-finish-logentry, vc-rename-file):
Use with-current-buffer.
(vc-buffer-sync): Use unless.
(vc-next-action-on-file): If the file is 'edited by read-only,
make it read-write instead of trying to commit.
(vc-version-diff, vc-update-change-log): Use `setq
default-directory' rather than `cd'.
(vc-log-edit): Don't forget to set default-directory in the
buffer.
(vc-checkout): Don't do anything special for ange-ftp
files since ange-ftp already has vc-registered return nil.
(vc-do-command): Use file-relative-name.
(vc-responsible-backend): Use vc-backend if possible.
(vc-create-snapshot): Improve the `interactive' spec. Add support
for branches and dispatch to backend-specific `create-snapshot'.
(vc-default-create-snapshot): New function, containing the bulk of
the old vc-create-snapshot.
(vc-retrieve-snapshot): Improve the interactive spec.
(vc-do-command): Get rid of the `last' argument.
(vc-header-alist): Remove, replaced by vc-X-header.
(vc-insert-headers): Use vc-X-header instead of vc-header-alist.
(vc-dired-hook): Use expand-file-name instead of concat.
(vc-directory): Use file-name-as-directory.
(vc-snapshot-precondition, vc-create-snapshot)
(vc-retrieve-snapshot): Allow the command to operate on any
directory.
 Update Copyright and add a crude list of backend funs.
(vc-writable-p): New function.
(with-vc-file): Use vc-writable-p.
(vc-next-action-on-file): Update call to vc-steal-lock and
cleanup.
(vc-register): Avoid vc-name.
(vc-locking-user): Remove.
(vc-steal-lock): Make the `owner' arg non-optional.
(vc-merge): Use vc-writable-p instead of vc-locking-user and
vc-checkout-model.
(vc-default-dired-state-info): Use vc-state instead of
vc-locking-user and return special strings for special states.
(vc-dired-hook): Use vc-up-to-date-p instead of vc-locking-user
and get rid of one of the special CVS cases.
(vc-cancel-version): prettify error message with \\[...].
(vc-rename-master): New function.
(vc-rename-file): Use vc-BACKEND-rename-file (which might in turn
use vc-rename-master) instead of vc-BACKEND-record-rename.  Make
the CVS special case generic.
(vc-default-record-rename): Remove.
(vc-file-tree-walk-internal): Only call FUNC for files that are
under control of some VC backend and replace `concat' with
expand-file-name.
(vc-file-tree-walk): Update docstring.
(vc-version-diff, vc-snapshot-precondition, vc-create-snapshot)
(vc-retrieve-snapshot): Update call to vc-file-tree-walk.
(vc-version-diff): Expand file name read from the
minibuffer.  Handle the case when a previous version number can't
be guessed.  Give suitable messages when there were no differences
found.
(vc-clear-headers): Call backend-specific implementation, if one
exists.
(vc-cancel-version): Made error checks generic.  When done, clear
headers generically, too.
(vc-locking-user): Moved from vc-hooks.el.
(vc-version-diff): Left out a vc- in call to
vc-call-backend.
(vc-default-dired-state-info, vc-default-record-rename)
(vc-default-merge-news): Update for the new backend argument.
(vc-merge): Use vc-find-backend-function.
(vc-register): Put a FIXME note for a newly found bug.
Call vc-call-backend without the leading vc-.
(vc-responsible-backend, vc-finish-logentry, vc-annotate)
(vc-check-headers): Call vc-call-backend without the leading vc-.
(vc-annotate-time-span): Replace confusing use of `cond' with
`or'.
(vc-annotate-display): Replace confusing use of `cond' with `or'.
Call vc-call-backend without the leading vc-.
(vc-process-filter): New function.
(vc-do-command): Setup `vc-process-filter' for the async process.
(vc-maybe-resolve-conflicts): New function to reduce
code-duplication.  Additionally, it puts the buffer in
`smerge-mode' if applicable.
(vc-next-action-on-file): Use `vc-maybe-resolve-conflicts' after
calling `merge-news'.
(vc-merge): Use `vc-maybe-resolve-conflicts' after calling
`merge'.
(vc-log-edit): New function.  Replacement for `vc-log-mode' by
interfacing to log-edit.el.
(vc-start-entry): Call `vc-log-edit' instead of `vc-log-mode' if
log-edit is available.
(vc-resolve-conflicts): Delegate to `smerge-ediff' if available.
(vc-register): Remove `vc-buffer-backend' setup.
(vc-log-mode-map): New name for vc-log-entry-mode and merge the
defvar and the initialization.
(vc-log-mode): Minor docstring fix and use vc-log-mode-map.
(vc-file-clear-masterprops): Removed.
(vc-checkin, vc-revert-buffer): Removed calls to the above.
(vc-version-diff): Use buffer-size without argument.
(vc-register): Heed vc-initial-comment.
(vc-workfile-unchanged-p): Remove unused argument
`want-differences-if-changed' and simplify.
(vc-next-action-on-file) [needs-merge]: Resynch the buffer.
(vc-revert-buffer): Use `unchanged-p' rather than vc-diff's status
output (which is invalid for async vc-diff) to decide whether to
do the revert silently or not.
(with-vc-file, vc-next-action, vc-version-diff)
(vc-dired-mark-locked): Replaced usage of vc-locking-user with
vc-state or vc-up-to-date-p.
(vc-merge): Use vc-backend-defines to check whether merging is
possible.  Set state to 'edited after successful merge.
(vc-recompute-state, vc-next-action-on-file): Update to
new `vc-state' semantics.
(vc-finish-steal): Set 'vc-state to 'edited rather than setting
'vc-locking-user to the current user.
(vc-merge): Inline vc-backend-merge.  Comment out code that I
don't understand and hence can't adapt to the new `vc-state' and
`vc-locking-user' semantics.
(vc-backend-merge): Remove.
(vc-do-command): kill-all-local-variables, to reset any
major-mode in which the buffer might have been put earlier.  Use
`remove' and `when'.  Allow `okstatus' to be `async' and use
`start-process' in this case.
(vc-version-diff): Handle the case where the diff looks empty
because of the use of an async process.
(vc-next-action-on-file): Removed optional parameter
`simple'.  Recompute state unconditionally.
(vc-default-toggle-read-only): Removed.
(vc-backend-dispatch, vc-annotate-mode-syntax-table):
Remove.
(vc-prefix-map): Move from vc-hooks.el and make autoloaded.
(vc-release-greater-or-equal-p): Move to vc-rcs.el.
(vc-file-clear-masterprops): Braindead "fix".  It was a nop and
still is. So maybe it should be removed.
(vc-head-version, vc-find-binary): Remove.
(vc-recompute-state): Move from vc-hooks.el.
(vc-next-action-on-file): Add a `simple' argument to allow
avoiding the `recompute' step (use for vc-cvs-simple-toggle).
(vc-default-toggle-read-only, vc-default-record-rename): New
functions.
(vc-next-action, vc-dired-hook): Use vc-state instead of
vc-cvs-status.
(vc-dired-mode-map): Properly defvar it.
(vc-print-log): Call log-view-mode if available.
(small-temporary-file-directory): defvar instead of use boundp.
(vc-merge-news): Moved to vc-cvs.el.
(vc-default-merge-news): New function.
(function' quotes.
(vc-annotate-mode-map, vc-annotate-mode-syntax-table): Initialize
directly in the defvar.
(vc-do-command): Bind inhibit-read-only so as to properly handle
the case where the destination buffer has been made read-only.
(vc-diff): Delegate to vc-version-diff in all cases.
(vc-version-diff): Setup the *vc-diff* buffer as was done in
vc-diff.
(vc-annotate-mode-variables): Removed (code moved partly to
defvars and partly to vc-annotate-add-menu).
(vc-annotate-mode): Turned into a derived-mode.
(vc-annotate-add-menu): Moved in code in
vc-annotate-mode-variables.
(vc-update-change-log): Use make-temp-file if available.
(vc-next-action-on-file): Added handling of state
`unlocked-changes'.
(vc-checkout-carefully): Is now practically obsolete, unless the
above is too slow to be enabled unconditionally.
(vc-update-change-log): Fixed typo.
(vc-responsible-backend): New function.
(vc-register): Largely rewritten.
(vc-admin): Removed (implementation moved into vc-register).
(vc-checkin): Redocumented.
(vc-finish-logentry): If no backend defined yet (because we are in
the process of registering), use the responsible backend.
 Updated callers of `vc-checkout-required' to use
`vc-checkout-model'.
(vc-backend-release, vc-backend-release-p): Functions
moved into vc-rcs.el
(vc-backend-revert): Function moved into `vc-revert';
`vc-next-action' must be updated to accomodate this change.
(vc-backend-steal): Function moved into `vc-finish-steal'.
(vc-backend-logentry-check): Function moved into
`vc-finish-logentry'.
(vc-backend-printlog): Function moved into `vc-print-log'.
(vc-backend-uncheck): Function moved into `vc-cancel-version'.
(vc-backend-assign-name): Function moved into
`vc-create-snapshot'.
(vc-workfile-unchanged-p,vc-diff,vc-version-diff): Updated
to use the vc-BACKEND-diff functions instead; `vc-diff' is now
working.
 Typo fixed.  This checkin is made with our new VC code
base for the very first time.  A simple `(vc-checkin
(buffer-file-name))' was used to perform it.
(vc-checkin): Merged with `vc-backend-checkin' and updated
to match the split into various backends.
(vc-backend-checkin): Removed.  Merged with `vc-checkin'.
(vc-retrieve-snapshot): Bug fix.
(vc-next-action-on-file): Bug found and fixed.
(vc-checkout, vc-version-other-window, vc-retrieve-snapshot)
(vc-cancel-version): Handle of vc-BACKEND-checkout updated.
(vc-next-action-on-file): Rewritten for the new state model.
(vc-backend-merge-news): Renamed to `vc-merge-news'.  (Specific parts
still need to be split, and implemented for RCS).
(vc-admin): Updated to handle selection of appropriate
backend.  Current implementation is crufty and need re-thinking.
(vc-annotate-get-backend, vc-annotate-display-default)
(vc-annotate-add-menu, vc-annotate, vc-annotate-display): Annotate
functionality updated quite a lot to support multiple backends.
Variables `vc-annotate-mode', `vc-annotate-buffers',
`vc-annotate-backend' added.
 Renamed
`vc-uses-locking' to `vc-checkout-required'.  Renamed the `locked'
state to `reserved'.
(vc-update-change-log): Use small-temporary-file-directory,
if defined.  (Merged from main line, slightly adapted.)
 Split the annotate feature into a BACKEND specific part
and moved it from the vc-cvs.el file to this one.
(vc-resynch-window): Added TODO comment: check for
interaction with view mode according to recent RCS change.
(vc-backend-merge-news): Merged "CMUP" patch from mainline.
 Converted the remaining function comments to
documentation strings.
(vc-backend-release, vc-release-greater-or-equal)
(vc-backend-release-p, vc-trunk-p, vc-branch-p, vc-branch-part)
(vc-minor-part, vc-previous-version): Functions that operate and
compare revision numbers got proper documentation.  Comments added
about their possible removal.
(vc-latest-on-branch-p): Function removed and replaced in
the vc-backend.el files.
(vc-backend-diff): Function removed and placed in the
backend files.
(vc-backend-checkout): Function removed and replaced in
the vc-backend.el files.
(vc-backend-admin): Removed and replaced in the
vc-backend.el files.
(Martin): Removed all the annotate functionality since it
is CVS backend specific.
 [Merged from mainline.]
(vc-dired-mode): Make the dired-move-to-filename-regexp
regexp match the date, to avoid treating date as file size.
Add YYYY S option to WESTERN/
 Require `compile' when compiling.
(vc-logentry-check-hook): New option.
(vc-steal-lock): Use compose-mail.
(vc-dired-mode-map): Defvar when compiling.
(vc-add-triple, vc-record-rename, vc-lookup-triple): Moved to
vc-sccs.el and renamed.  Callers changed.
(vc-backend-checkout, vc-backend-logentry-check)
(vc-backend-merge-news): Doc fix.
(vc-default-logentry-check): New function.
(vc-backend-checkin, vc-backend-revert, vc-backend-steal)
(vc-backend-uncheck, vc-backend-print-log, vc-backend-assign-name)
(vc-backend-merge): Doc fix.  Use backend functions.
(vc-check-headers): Use backend functions.
(vc-backend-release): Call vc-system-release.
(vc-rcs-release, vc-cvs-release, vc-sccs-release): Moved to
backend files.
(vc-backend-release): Dispatch to backend functions.
(vc-backend-release-p): Don't mention CVS, RCS.  [The SCCS case
probably needs attention.]
(vc-dired-mode, vc-dired-reformat-line, vc-dired-purge):
Doc fix.
(vc-fetch-cvs-status): Moved to vc-cvs.el and renamed.
(vc-default-dired-state-info): New function.
(vc-dired-state-info): Dispatch to backends.
(vc-dired-hook): Doc fix.  Simplify, pending removal of CVS specifics.
(vc-file-clear-masterprops, vc-latest-on-branch-p)
(vc-version-other-window, vc-backend-assign-name): Removed
references to vc-latest-version; sometimes changed into
vc-workfile-version.
(with-vc-file, vc-next-action-on-file, vc-merge)
(vc-backend-checkout): Changed calls to `vc-checkout-model' to
`vc-uses-locking'.
(vc-fetch-cvs-status): Use renamed vc-cvs-parse-status.
 Some doc fixes for autoloaded and interactive functions.
Fix compilation warnings from ediff stuff.
(vc-rcs-release, vc-cvs-release, vc-sccs-release): Custom fix.
 This is 1999-03-13T05:04:24Z!kwzh@gnu.org from the emacs sources

1 files changed, 1391 insertions, 1966 deletions

diff --git a/lisp/vc.el b/lisp/vc.el
index 250084402e6..6415619acb3 100644
--- a/lisp/vc.el
+++ b/lisp/vc.el
@@ -1,11 +1,11 @@
 ;;; vc.el --- drive a version-control system from within Emacs
 
-;; Copyright (C) 1992, 93, 94, 95, 96, 97, 1998 Free Software Foundation, Inc.
+;; Copyright (C) 1992,93,94,95,96,97,98,2000  Free Software Foundation, Inc.
 
-;; Author:     Eric S. Raymond <esr@snark.thyrsus.com>
-;; Maintainer: Andre Spiegel <spiegel@inf.fu-berlin.de>
+;; Author:     FSF (see below for full credits)
+;; Maintainer: Andre Spiegel <spiegel@gnu.org>
 
-;; $Id: vc.el,v 1.259 2000/01/26 10:31:13 gerd Exp $
+;; $Id: vc.el,v 1.1 2000/09/04 19:35:57 gerd Exp gerd $
 
 ;; This file is part of GNU Emacs.
 
@@ -24,29 +24,36 @@
 ;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
 ;; Boston, MA 02111-1307, USA.
 
+;;; Credits:
+
+;; VC was initially designed and implemented by Eric S. Raymond
+;; <esr@snark.thyrsus.com>.  Over the years, many people have
+;; contributed substantial amounts of work to VC.  These include:
+;;   Per Cederqvist <ceder@lysator.liu.se>
+;;   Paul Eggert <eggert@twinsun.com>
+;;   Sebastian Kremer <sk@thp.uni-koeln.de>
+;;   Martin Lorentzson <martinl@gnu.org>
+;;   Dave Love <d.love@dl.ac.uk>
+;;   Stefan Monnier <monnier@cs.yale.edu>
+;;   Andre Spiegel <spiegel@gnu.org>
+;;   Richard Stallman <rms@gnu.org>
+;;   ttn@netcom.com
+
 ;;; Commentary:
 
 ;; This mode is fully documented in the Emacs user's manual.
 ;;
-;; This was designed and implemented by Eric Raymond <esr@snark.thyrsus.com>.
-;; Paul Eggert <eggert@twinsun.com>, Sebastian Kremer <sk@thp.uni-koeln.de>,
-;; and Richard Stallman contributed valuable criticism, support, and testing.
-;; CVS support was added by Per Cederqvist <ceder@lysator.liu.se>
-;; in Jan-Feb 1994.  Further enhancements came from ttn@netcom.com and
-;; Andre Spiegel <spiegel@inf.fu-berlin.de>.
-;;
 ;; Supported version-control systems presently include SCCS, RCS, and CVS.
 ;;
 ;; Some features will not work with old RCS versions.  Where
 ;; appropriate, VC finds out which version you have, and allows or
-;; disallows those features (stealing locks, for example, works only 
+;; disallows those features (stealing locks, for example, works only
 ;; from 5.6.2 onwards).
 ;; Even initial checkins will fail if your RCS version is so old that ci
 ;; doesn't understand -t-; this has been known to happen to people running
-;; NExTSTEP 3.0. 
+;; NExTSTEP 3.0.
 ;;
-;; You can support the RCS -x option by adding pairs to the 
-;; vc-master-templates list.
+;; You can support the RCS -x option by customizing vc-rcs-master-templates.
 ;;
 ;; Proper function of the SCCS diff commands requires the shellscript vcdiff
 ;; to be installed somewhere on Emacs's path for executables.
@@ -54,11 +61,6 @@
 ;; If your site uses the ChangeLog convention supported by Emacs, the
 ;; function vc-comment-to-change-log should prove a useful checkin hook.
 ;;
-;; This code depends on call-process passing back the subprocess exit
-;; status.  Thus, you need Emacs 18.58 or later to run it.  For the
-;; vc-directory command to work properly as documented, you need 19.
-;; You also need Emacs 19's ring.el.
-;;
 ;; The vc code maintains some internal state in order to reduce expensive
 ;; version-control operations to a minimum.  Some names are only computed
 ;; once.  If you perform version control operations with RCS/SCCS/CVS while
@@ -70,32 +72,90 @@
 
 ;;; Code:
 
+;;;;;;;;;;;;;;;;; Backend-specific functions ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;;
+;; for each operation FUN, the backend should provide a function vc-BACKEND-FUN.
+;; Operations marked with a `-' instead of a `*' have a sensible default
+;; behavior.
+
+;; * registered (file)
+;; * state (file)
+;; - state-heuristic (file)
+;;     The default behavior delegates to `state'.
+;; - dir-state (dir)
+;; * checkout-model (file)
+;; - mode-line-string (file)
+;; * workfile-version (file)
+;; * revert (file)
+;; * merge-news (file)
+;; * merge (file rev1 rev2)
+;; * steal-lock (file &optional version)
+;; * register (file rev comment)
+;; * responsible-p (file)
+;;     Should also work if FILE is a directory (ends with a slash).
+;; - could-register (file)
+;; * checkout (file writable &optional rev destfile)
+;;     Checkout revision REV of FILE into DESTFILE.
+;;     DESTFILE defaults to FILE.
+;;     The file should be made writable if WRITABLE is non-nil.
+;;     REV can be nil (BASE) or "" (HEAD) or any other revision.
+;; * checkin (file rev comment)
+;; - logentry-check ()
+;; * diff (file &optional rev1 rev2)
+;;     Insert the diff for FILE into the current buffer.
+;;     REV1 should default to workfile-version.
+;;     REV2 should default to the current workfile
+;;     Return a status of either 0 (i.e. no diff) or 1 (i.e. either non-empty
+;;     diff or the diff is run asynchronously).
+;; - workfile-unchanged-p (file)
+;;     Return non-nil if FILE is unchanged from its current workfile version.
+;;     This function should do a brief comparison of FILE's contents
+;;     with those of the master version.  If the backend does not have
+;;     such a brief-comparison feature, the default implementation of this
+;;     function can be used, which delegates to a full vc-BACKEND-diff.
+;; - clear-headers ()
+;; * check-headers ()
+;; - dired-state-info (file)
+;; - create-snapshot (dir name branchp)
+;;     Take a snapshot of the current state of files under DIR and name it NAME.
+;;     This should make sure that files are up-to-date before proceeding
+;;     with the action.
+;;     DIR can also be a file and if BRANCHP is specified, NAME
+;;     should be created as a branch and DIR should be checked out under
+;;     this new branch.  The default behavior does not support branches
+;;     but does a sanity check, a tree traversal and for each file calls
+;;     `assign-name'.
+;; * assign-name (file name)
+;;     Give name NAME to the current version of FILE, assuming it is
+;;     up-to-date.  Only used by the default version of `create-snapshot'.
+;; - retrieve-snapshot (dir name update)
+;;     Retrieve a named snapshot of all registered files at or below DIR.
+;;     If UPDATE is non-nil, then update buffers of any files in the snapshot 
+;;     that are currently visited.
+;; * print-log (file)
+;;     Insert the revision log of FILE into the current buffer.
+;; - show-log-entry (version)
+;; - update-changelog (files)
+;;     Find changelog entries for FILES, or for all files at or below
+;;     the default-directory if FILES is nil.
+;; * latest-on-branch-p (file)
+;;     Only used for sanity check before calling `uncheck'.
+;; * uncheck (file target)
+;; * rename-file (old new)
+;; * annotate-command (file buf)
+;; * annotate-difference (pos)
+
 (require 'vc-hooks)
 (require 'ring)
-(eval-when-compile (require 'dired))    ; for dired-map-over-marks macro
+(eval-when-compile
+  (require 'compile)
+  (require 'dired))     ; for dired-map-over-marks macro
 
 (if (not (assoc 'vc-parent-buffer minor-mode-alist))
     (setq minor-mode-alist
           (cons '(vc-parent-buffer vc-parent-buffer-name)
                 minor-mode-alist)))
 
-;; To implement support for a new version-control system, add another
-;; branch to the vc-backend-dispatch macro and fill it in in each
-;; call.  The variable vc-master-templates in vc-hooks.el will also
-;; have to change.
-
-(defmacro vc-backend-dispatch (f s r c)
-  "Execute FORM1, FORM2 or FORM3 for SCCS, RCS or CVS respectively.
-If FORM3 is `RCS', use FORM2 for CVS as well as RCS.
-\(CVS shares some code with RCS)."
-  (list 'let (list (list 'type (list 'vc-backend f)))
-        (list 'cond
-              (list (list 'eq 'type (quote 'SCCS)) s)   ;; SCCS
-              (list (list 'eq 'type (quote 'RCS)) r)    ;; RCS
-              (list (list 'eq 'type (quote 'CVS))       ;; CVS
-                    (if (eq c 'RCS) r c))
-              )))
-
 ;; General customization
 
 (defgroup vc nil
@@ -122,7 +182,7 @@ preserve the setting."
 
 (defcustom vc-default-init-version "1.1"
   "*A string used as the default version number when a new file is registered.
-This can be overriden by giving a prefix argument to \\[vc-register]."
+This can be overridden by giving a prefix argument to \\[vc-register]."
   :type 'string
   :group 'vc
   :version "20.3")
@@ -162,6 +222,12 @@ These are passed to the checkin program by \\[vc-register]."
                          string))
   :group 'vc)
 
+(defcustom vc-dired-listing-switches "-al"
+  "*Switches passed to `ls' for vc-dired.  MUST contain the `l' option."
+  :type 'string
+  :group 'vc
+  :version "21.0")
+
 (defcustom vc-dired-recurse t
   "*If non-nil, show directory trees recursively in VC Dired."
   :type 'boolean
@@ -184,8 +250,31 @@ These are passed to the checkin program by \\[vc-register]."
 
 ;;; This is duplicated in diff.el.
 (defvar diff-switches "-c"
-  "*A string or list of strings specifying switches to be be passed to diff.")
+  "*A string or list of strings specifying switches to be passed to diff.")
+
+;;;###autoload
+(defcustom vc-checkin-hook nil
+  "*Normal hook (list of functions) run after a checkin is done.
+See `run-hooks'."
+  :type 'hook
+  :options '(vc-comment-to-change-log)
+  :group 'vc)
+
+;;;###autoload
+(defcustom vc-before-checkin-hook nil
+  "*Normal hook (list of functions) run before a file gets checked in.
+See `run-hooks'."
+  :type 'hook
+  :group 'vc)
+
+(defcustom vc-logentry-check-hook nil
+  "*Normal hook run by `vc-backend-logentry-check'.
+Use this to impose your own rules on the entry in addition to any the
+version control backend imposes itself."
+  :type 'hook
+  :group 'vc)
 
+;; Annotate customization
 (defcustom vc-annotate-color-map
   '(( 26.3672 . "#FF0000")
     ( 52.7344 . "#FF3800")
@@ -207,7 +296,7 @@ These are passed to the checkin program by \\[vc-register]."
   "*Association list of age versus color, for \\[vc-annotate].
 Ages are given in units of 2**-16 seconds.
 Default is eighteen steps using a twenty day increment."
-  :type 'sexp
+  :type 'alist
   :group 'vc)
 
 (defcustom vc-annotate-very-old-color "#0046FF"
@@ -224,52 +313,30 @@ Default color is used if nil."
 (defcustom vc-annotate-menu-elements '(2 0.5 0.1 0.01)
   "*Menu elements for the mode-specific menu of VC-Annotate mode.
 List of factors, used to expand/compress the time scale.  See `vc-annotate'."
-  :type 'sexp
+  :type '(repeat number)
   :group 'vc)
 
-;;;###autoload
-(defcustom vc-checkin-hook nil
-  "*Normal hook (list of functions) run after a checkin is done.
-See `run-hooks'."
-  :type 'hook
-  :options '(vc-comment-to-change-log)
-  :group 'vc)
+;; vc-annotate functionality (CVS only).
+(defvar vc-annotate-mode nil
+  "Variable indicating if VC-Annotate mode is active.")
 
-;;;###autoload
-(defcustom vc-before-checkin-hook nil
-  "*Normal hook (list of functions) run before a file gets checked in.  
-See `run-hooks'."
-  :type 'hook
-  :group 'vc)
+(defvar vc-annotate-mode-map
+  (let ((m (make-sparse-keymap)))
+    (define-key m [menu-bar] (make-sparse-keymap "VC-Annotate"))
+    m)
+  "Local keymap used for VC-Annotate mode.")
 
-;;;###autoload
-(defcustom vc-annotate-mode-hook nil
-  "*Hooks to run when VC-Annotate mode is turned on."
-  :type 'hook
-  :group 'vc)
+(defvar vc-annotate-mode-menu nil
+  "Local keymap used for VC-Annotate mode's menu bar menu.")
 
 ;; Header-insertion hair
 
-(defcustom vc-header-alist
-  '((SCCS "\%W\%") (RCS "\$Id\$") (CVS "\$Id\$"))
-  "*Header keywords to be inserted by `vc-insert-headers'.
-Must be a list of two-element lists, the first element of each must
-be `RCS', `CVS', or `SCCS'.  The second element is the string to
-be inserted for this particular backend."
-  :type '(repeat (list :format "%v"
-                       (choice :tag "System"
-                               (const SCCS)
-                               (const RCS)
-                               (const CVS))
-                       (string :tag "Header")))
-  :group 'vc)
-
 (defcustom vc-static-header-alist
   '(("\\.c$" .
      "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n#endif /* lint */\n"))
-  "*Associate static header string templates with file types.  A \%s in the
-template is replaced with the first string associated with the file's
-version-control type in `vc-header-alist'."
+  "*Associate static header string templates with file types.
+A \%s in the template is replaced with the first string associated with
+the file's version-control type in `vc-header-alist'."
   :type '(repeat (cons :format "%v"
                        (regexp :tag "File Type")
                        (string :tag "Header String")))
@@ -288,6 +355,9 @@ is sensitive to blank lines."
   :group 'vc)
 
 ;; Default is to be extra careful for super-user.
+;; TODO: This variable is no longer used; the corresponding checks  
+;;       are always done now.  If that turns out to be fast enough, 
+;;       the variable can be obsoleted.
 (defcustom vc-checkout-carefully (= (user-uid) 0)
   "*Non-nil means be extra-careful in checkout.
 Verify that the file really is not locked
@@ -295,44 +365,61 @@ and that its contents match what the master file says."
   :type 'boolean
   :group 'vc)
 
-(defcustom vc-rcs-release nil
-  "*The release number of your RCS installation, as a string.
-If nil, VC itself computes this value when it is first needed."
-  :type '(choice (const :tag "Auto" nil)
-                 string 
-                 (const :tag "Unknown" unknown))
-  :group 'vc)
-
-(defcustom vc-sccs-release nil
-  "*The release number of your SCCS installation, as a string.
-If nil, VC itself computes this value when it is first needed."
-  :type '(choice (const :tag "Auto" nil)
-                 string 
-                 (const :tag "Unknown" unknown))
-  :group 'vc)
+
+;;; The main keymap
+
+(defvar vc-prefix-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map "a" 'vc-update-change-log)
+    (define-key map "c" 'vc-cancel-version)
+    (define-key map "d" 'vc-directory)
+    (define-key map "g" 'vc-annotate)
+    (define-key map "h" 'vc-insert-headers)
+    (define-key map "i" 'vc-register)
+    (define-key map "l" 'vc-print-log)
+    (define-key map "m" 'vc-merge)
+    (define-key map "r" 'vc-retrieve-snapshot)
+    (define-key map "s" 'vc-create-snapshot)
+    (define-key map "u" 'vc-revert-buffer)
+    (define-key map "v" 'vc-next-action)
+    (define-key map "=" 'vc-diff)
+    (define-key map "~" 'vc-version-other-window)
+    map))
+(fset 'vc-prefix-map vc-prefix-map)
 
-(defcustom vc-cvs-release nil
-  "*The release number of your CVS installation, as a string.
-If nil, VC itself computes this value when it is first needed."
-  :type '(choice (const :tag "Auto" nil)
-                 string 
-                 (const :tag "Unknown" unknown))
-  :group 'vc)
+;; Initialization code, to be done just once at load-time
+(defvar vc-log-mode-map
+  (let ((map (make-sparse-keymap)))
+    (define-key map "\M-n" 'vc-next-comment)
+    (define-key map "\M-p" 'vc-previous-comment)
+    (define-key map "\M-r" 'vc-comment-search-reverse)
+    (define-key map "\M-s" 'vc-comment-search-forward)
+    (define-key map "\C-c\C-c" 'vc-finish-logentry)
+    map))
+;; Compatibility with old name.  Should we bother ?
+(defvar vc-log-entry-mode vc-log-mode-map)
 
+
 ;; Variables the user doesn't need to know about.
-(defvar vc-log-entry-mode nil)
 (defvar vc-log-operation nil)
 (defvar vc-log-after-operation-hook nil)
 (defvar vc-checkout-writable-buffer-hook 'vc-checkout-writable-buffer)
+(defvar vc-annotate-buffers nil
+  "An association list of current \"Annotate\" buffers and their
+corresponding backends.  The keys are \(BUFFER . BACKEND\).  See also
+`vc-annotate-get-backend'.")
 ;; In a log entry buffer, this is a local variable
 ;; that points to the buffer for which it was made
 ;; (either a file, or a VC dired buffer).
 (defvar vc-parent-buffer nil)
+(put 'vc-parent-buffer 'permanent-local t)
 (defvar vc-parent-buffer-name nil)
+(put 'vc-parent-buffer-name 'permanent-local t)
 
 (defvar vc-log-file)
 (defvar vc-log-version)
 
+;; FIXME: only used in vc-sccs.el
 (defconst vc-name-assoc-file "VC-names")
 
 (defvar vc-dired-mode nil)
@@ -340,93 +427,30 @@ If nil, VC itself computes this value when it is first needed."
 
 (defvar vc-comment-ring (make-ring vc-maximum-comment-ring-size))
 (defvar vc-comment-ring-index nil)
-(defvar vc-last-comment-match nil)
-
-;;; Find and compare backend releases
-
-(defun vc-backend-release (backend)
-  ;; Returns which backend release is installed on this system.
-  (cond
-   ((eq backend 'RCS)
-    (or vc-rcs-release
-        (and (zerop (vc-do-command nil nil "rcs" nil nil "-V"))
-             (save-excursion
-               (set-buffer (get-buffer "*vc*"))
-               (setq vc-rcs-release
-                     (car (vc-parse-buffer
-                           '(("^RCS version \\([0-9.]+ *.*\\)" 1)))))))
-        (setq vc-rcs-release 'unknown)))
-   ((eq backend 'CVS)
-    (or vc-cvs-release
-        (and (zerop (vc-do-command nil 1 "cvs" nil nil "-v"))
-             (save-excursion
-               (set-buffer (get-buffer "*vc*"))
-               (setq vc-cvs-release
-                     (car (vc-parse-buffer
-                           '(("^Concurrent Versions System (CVS) \\([0-9.]+\\)"
-                              1)))))))
-        (setq vc-cvs-release 'unknown)))
-     ((eq backend 'SCCS)
-      vc-sccs-release)))
-
-(defun vc-release-greater-or-equal (r1 r2)
-  ;; Compare release numbers, represented as strings.
-  ;; Release components are assumed cardinal numbers, not decimal
-  ;; fractions (5.10 is a higher release than 5.9).  Omitted fields
-  ;; are considered lower (5.6.7 is earlier than 5.6.7.1).
-  ;; Comparison runs till the end of the string is found, or a
-  ;; non-numeric component shows up (5.6.7 is earlier than "5.6.7 beta",
-  ;; which is probably not what you want in some cases).
-  ;;   This code is suitable for existing RCS release numbers.  
-  ;; CVS releases are handled reasonably, too (1.3 < 1.4* < 1.5).
-  (let (v1 v2 i1 i2)
-    (catch 'done
-      (or (and (string-match "^\\.?\\([0-9]+\\)" r1)
-               (setq i1 (match-end 0))
-               (setq v1 (string-to-number (match-string 1 r1)))
-               (or (and (string-match "^\\.?\\([0-9]+\\)" r2)
-                        (setq i2 (match-end 0))
-                        (setq v2 (string-to-number (match-string 1 r2)))
-                        (if (> v1 v2) (throw 'done t)
-                          (if (< v1 v2) (throw 'done nil)
-                            (throw 'done
-                                   (vc-release-greater-or-equal
-                                    (substring r1 i1)
-                                    (substring r2 i2)))))))
-                   (throw 'done t)))
-          (or (and (string-match "^\\.?\\([0-9]+\\)" r2)
-                   (throw 'done nil))
-              (throw 'done t)))))
-
-(defun vc-backend-release-p (backend release)
-  ;; Return t if we have RELEASE of BACKEND or better
-  (let (i r (ri 0) (ii 0) is rs (installation (vc-backend-release backend)))
-    (if (not (eq installation 'unknown))
-        (cond
-         ((or (eq backend 'RCS) (eq backend 'CVS))
-          (vc-release-greater-or-equal installation release))))))
-
-;;; functions that operate on RCS revision numbers
+(defvar vc-last-comment-match "")
 
+;;; functions that operate on RCS revision numbers.  This code should
+;;; also be moved into the backends.  It stays for now, however, since
+;;; it is used in code below.
 (defun vc-trunk-p (rev)
-  ;; return t if REV is a revision on the trunk
+  "Return t if REV is a revision on the trunk"
   (not (eq nil (string-match "\\`[0-9]+\\.[0-9]+\\'" rev))))
 
 (defun vc-branch-p (rev)
-  ;; return t if REV is a branch revision
+  "Return t if REV is a branch revision"
   (not (eq nil (string-match "\\`[0-9]+\\(\\.[0-9]+\\.[0-9]+\\)*\\'" rev))))
 
 (defun vc-branch-part (rev)
-  ;; return the branch part of a revision number REV
+  "return the branch part of a revision number REV"
   (substring rev 0 (string-match "\\.[0-9]+\\'" rev)))
 
 (defun vc-minor-part (rev)
-  ;; return the minor version number of a revision number REV
+  "Return the minor version number of a revision number REV"
   (string-match "[0-9]+\\'" rev)
   (substring rev (match-beginning 0) (match-end 0)))
 
 (defun vc-previous-version (rev)
-  ;; guess the previous version number
+  "Guess the previous version number"
   (let ((branch (vc-branch-part rev))
         (minor-num (string-to-number (vc-minor-part rev))))
     (if (> minor-num 1)
@@ -450,86 +474,36 @@ If nil, VC itself computes this value when it is first needed."
   ;; log buffer with a nonzero local value of vc-comment-ring-index.
   (setq vc-comment-ring (make-ring vc-maximum-comment-ring-size)))
 
-(defun vc-file-clear-masterprops (file)
-  ;; clear all properties of FILE that were retrieved
-  ;; from the master file
-  (vc-file-setprop file 'vc-latest-version nil)
-  (vc-file-setprop file 'vc-your-latest-version nil)
-  (vc-backend-dispatch file
-     (progn   ;; SCCS
-       (vc-file-setprop file 'vc-master-locks nil))
-     (progn   ;; RCS
-       (vc-file-setprop file 'vc-default-branch nil)
-       (vc-file-setprop file 'vc-head-version nil)
-       (vc-file-setprop file 'vc-master-workfile-version nil)
-       (vc-file-setprop file 'vc-master-locks nil))
-     (progn
-       (vc-file-setprop file 'vc-cvs-status nil))))
-
-(defun vc-head-version (file)
-  ;; Return the RCS head version of FILE 
-  (cond ((vc-file-getprop file 'vc-head-version))
-        (t (vc-fetch-master-properties file)
-           (vc-file-getprop file 'vc-head-version))))
-
 ;; Random helper functions
 
-(defun vc-latest-on-branch-p (file)
-  ;; return t iff the current workfile version of FILE is
-  ;; the latest on its branch.
-  (vc-backend-dispatch file
-     ;; SCCS
-     (string= (vc-workfile-version file) (vc-latest-version file)) 
-     ;; RCS
-     (let ((workfile-version (vc-workfile-version file)) tip-version)
-       (if (vc-trunk-p workfile-version) 
-           (progn 
-             ;; Re-fetch the head version number.  This is to make
-             ;; sure that no-one has checked in a new version behind
-             ;; our back.
-             (vc-fetch-master-properties file)
-             (string= (vc-file-getprop file 'vc-head-version)
-                      workfile-version))
-         ;; If we are not on the trunk, we need to examine the
-         ;; whole current branch.  (vc-master-workfile-version 
-         ;; is not what we need.)
-         (save-excursion
-           (set-buffer (get-buffer-create "*vc-info*"))
-           (vc-insert-file (vc-name file) "^desc")
-           (setq tip-version (car (vc-parse-buffer (list (list 
-             (concat "^\\(" (regexp-quote (vc-branch-part workfile-version))
-                     "\\.[0-9]+\\)\ndate[ \t]+\\([0-9.]+\\);") 1 2)))))
-           (if (get-buffer "*vc-info*") 
-               (kill-buffer (get-buffer "*vc-info*")))
-           (string= tip-version workfile-version))))
-     ;; CVS
-     t))
+(defsubst vc-editable-p (file)
+  (or (eq (vc-checkout-model file) 'implicit)
+      (eq (vc-state file) 'edited)
+      (eq (vc-state file) 'needs-merge)))
 
 ;;; Two macros for elisp programming
 ;;;###autoload
 (defmacro with-vc-file (file comment &rest body)
-  "Execute BODY, checking out a writable copy of FILE first if necessary.
-After BODY has been executed, check-in FILE with COMMENT (a string).  
-FILE is passed through `expand-file-name'; BODY executed within 
-`save-excursion'.  If FILE is not under version control, or locked by 
+  "Check out a writable copy of FILE if necessary and execute the body.
+Check in FILE with COMMENT (a string) after BODY has been executed.
+FILE is passed through `expand-file-name'; BODY executed within
+`save-excursion'.  If FILE is not under version control, or locked by
 somebody else, signal error."
   `(let ((file (expand-file-name ,file)))
      (or (vc-registered file)
          (error (format "File not under version control: `%s'" file)))
-     (let ((locking-user (vc-locking-user file)))
-       (cond ((and (not locking-user)
-                   (eq (vc-checkout-model file) 'manual))
-              (vc-checkout file t))
-             ((and (stringp locking-user)
-                   (not (string= locking-user (vc-user-login-name))))
-              (error (format "`%s' is locking `%s'" locking-user file)))))
+     (unless (vc-editable-p file)
+       (let ((state (vc-state file)))
+         (if (stringp state) (error (format "`%s' is locking `%s'" state file))
+           (vc-checkout file t))))
      (save-excursion
        ,@body)
      (vc-checkin file nil ,comment)))
 
 ;;;###autoload
 (defmacro edit-vc-file (file comment &rest body)
-  "Edit FILE under version control, executing BODY.  Checkin with COMMENT.
+  "Edit FILE under version control, executing body.
+Checkin with COMMENT after executing BODY.
 This macro uses `with-vc-file', passing args to it.
 However, before executing BODY, find FILE, and after BODY, save buffer."
   `(with-vc-file
@@ -539,7 +513,8 @@ However, before executing BODY, find FILE, and after BODY, save buffer."
     (save-buffer)))
 
 (defun vc-ensure-vc-buffer ()
-  ;; Make sure that the current buffer visits a version-controlled file.
+  "Make sure that the current buffer visits a version-controlled
+file."
   (if vc-dired-mode
       (set-buffer (find-file-noselect (dired-get-filename)))
     (while vc-parent-buffer
@@ -554,111 +529,131 @@ However, before executing BODY, find FILE, and after BODY, save buffer."
   (if (memq system-type '(ms-dos windows-nt))
       '(".exe" ".com" ".bat" ".cmd" ".btm" "")
     '("")))
-(defun vc-find-binary (name)
-  "Look for a command anywhere on the subprocess-command search path."
-  (or (cdr (assoc name vc-binary-assoc))
-      (catch 'found
-        (mapcar
-         (function 
-          (lambda (s)
-            (if s
-                (let ((full (concat s "/" name))
-                      (suffixes vc-binary-suffixes)
-                      candidate)
-                  (while suffixes
-                    (setq candidate (concat full (car suffixes)))
-                    (if (and (file-executable-p candidate)
-                             (not (file-directory-p candidate)))
-                        (progn
-                          (setq vc-binary-assoc
-                                (cons (cons name candidate) vc-binary-assoc))
-                          (throw 'found candidate))
-                      (setq suffixes (cdr suffixes))))))))
-         exec-path)
-        nil)))
-
-(defun vc-do-command (buffer okstatus command file last &rest flags)
+
+(defun vc-process-filter (p s)
+  "An alternative output filter for async processes.
+The only difference with the default filter is to insert S after markers."
+  (with-current-buffer (process-buffer p)
+    (save-excursion
+      (let ((inhibit-read-only t))
+        (goto-char (process-mark p))
+        (insert s)
+        (set-marker (process-mark p) (point))))))
+
+(defun vc-setup-buffer (&optional buf)
+  "prepare BUF for executing a VC command and make it the current buffer.
+BUF defaults to \"*vc*\", can be a string and will be created if necessary."
+  (unless buf (setq buf "*vc*"))
+  (let ((camefrom (current-buffer))
+        (olddir default-directory))
+    (set-buffer (get-buffer-create buf))
+    (kill-all-local-variables)
+    (set (make-local-variable 'vc-parent-buffer) camefrom)
+    (set (make-local-variable 'vc-parent-buffer-name)
+         (concat " from " (buffer-name camefrom)))
+    (setq default-directory olddir)
+    (let ((inhibit-read-only t))
+      (erase-buffer))))
+
+(defun vc-exec-after (code)
+  "Eval CODE when the current buffer's process is done.
+If the current buffer has no process, just evaluate CODE.
+Else, add CODE to the process' sentinel."
+  (let ((proc (get-buffer-process (current-buffer))))
+    (cond
+     ;; If there's no background process, just execute the code.
+     ((null proc) (eval code))
+     ;; If the background process has exited, reap it and try again
+     ((eq (process-status proc) 'exit)
+      (delete-process proc)
+      (vc-exec-after code))
+     ;; If a process is running, add CODE to the sentinel
+     ((eq (process-status proc) 'run)
+      (let ((sentinel (process-sentinel proc)))
+        (set-process-sentinel proc
+          `(lambda (p s)
+             (with-current-buffer ',(current-buffer)
+               (goto-char (process-mark p))
+               ,@(append (cdr (cdr (cdr ;strip off `with-current-buffer buf 
+                                        ;             (goto-char...)'
+                           (car (cdr (cdr ;strip off `lambda (p s)'
+                            sentinel))))))
+                         (list `(vc-exec-after ',code))))))))
+     (t (error "Unexpected process state"))))
+  nil)
+
+(defvar vc-post-command-functions nil
+  "Hook run at the end of `vc-do-command'.
+Each function is called inside the buffer in which the command was run
+and is passed 3 argument: the COMMAND, the FILE and the FLAGS.")
+
+(defun vc-do-command (buffer okstatus command file &rest flags)
   "Execute a version-control command, notifying user and checking for errors.
-Output from COMMAND goes to BUFFER, or *vc* if BUFFER is nil.  The
+Output from COMMAND goes to BUFFER, or *vc* if BUFFER is nil or the current
+buffer (which is assumed to be properly setup) if BUFFER is t.  The
 command is considered successful if its exit status does not exceed
-OKSTATUS (if OKSTATUS is nil, that means to ignore errors).  FILE is
+OKSTATUS (if OKSTATUS is nil, that means to ignore errors, if it is 'async,
+that means not to wait for termination of the subprocess).  FILE is
 the name of the working file (may also be nil, to execute commands
-that don't expect a file name).  If FILE is non-nil, the argument LAST
-indicates what filename should actually be passed to the command: if
-it is `MASTER', the name of FILE's master file is used, if it is
-`WORKFILE', then FILE is passed through unchanged.  If an optional
-list of FLAGS is present, that is inserted into the command line
-before the filename."
+that don't expect a file name).  If an optional list of FLAGS is present, 
+that is inserted into the command line before the filename."
   (and file (setq file (expand-file-name file)))
-  (if (not buffer) (setq buffer "*vc*"))
   (if vc-command-messages
       (message "Running %s on %s..." command file))
-  (let ((obuf (current-buffer)) (camefrom (current-buffer))
-        (squeezed nil)
-        (olddir default-directory)
-        vc-file status)
-    (set-buffer (get-buffer-create buffer))
-    (set (make-local-variable 'vc-parent-buffer) camefrom)
-    (set (make-local-variable 'vc-parent-buffer-name)
-         (concat " from " (buffer-name camefrom)))
-    (setq default-directory olddir)
-    
-    (erase-buffer)
-
-    (mapcar
-     (function (lambda (s) (and s (setq squeezed (append squeezed (list s))))))
-     flags)
-    (if (and (eq last 'MASTER) file (setq vc-file (vc-name file)))
-        (setq squeezed (append squeezed (list vc-file))))
-    (if (and file (eq last 'WORKFILE))
-        (progn
-          (let* ((pwd (expand-file-name default-directory))
-                 (preflen (length pwd)))
-            (if (string= (substring file 0 preflen) pwd)
-                (setq file (substring file preflen))))
-          (setq squeezed (append squeezed (list file)))))
-    (let ((exec-path (append vc-path exec-path))
-          ;; Add vc-path to PATH for the execution of this command.
-          (process-environment
-           (cons (concat "PATH=" (getenv "PATH")
-                         path-separator
-                         (mapconcat 'identity vc-path path-separator))
-                 process-environment))
-          (w32-quote-process-args t))
-      (setq status (apply 'call-process command nil t nil squeezed)))
-    (goto-char (point-max))
-    (set-buffer-modified-p nil)
-    (forward-line -1)
-    (if (or (not (integerp status)) (and okstatus (< okstatus status)))
-        (progn
-          (pop-to-buffer buffer)
-          (goto-char (point-min))
-          (shrink-window-if-larger-than-buffer)
-          (error "Running %s...FAILED (%s)" command
-                 (if (integerp status)
-                     (format "status %d" status)
-                   status))
-          )
-      (if vc-command-messages
-          (message "Running %s...OK" command))
-      )
-    (set-buffer obuf)
-    status)
-  )
+  (save-current-buffer
+    (unless (eq buffer t) (vc-setup-buffer buffer))
+    (let ((squeezed nil)
+          (inhibit-read-only t)
+          (status 0))
+      (setq squeezed (delq nil (copy-sequence flags)))
+      (when file
+        ;; FIXME: file-relative-name can return a bogus result because
+        ;; it doesn't look at the actual file-system to see if symlinks
+        ;; come into play.
+        (setq squeezed (append squeezed (list (file-relative-name file)))))
+      (let ((exec-path (append vc-path exec-path))
+            ;; Add vc-path to PATH for the execution of this command.
+            (process-environment
+             (cons (concat "PATH=" (getenv "PATH")
+                           path-separator
+                           (mapconcat 'identity vc-path path-separator))
+                   process-environment))
+            (w32-quote-process-args t))
+        (if (eq okstatus 'async)
+            (let ((proc (apply 'start-process command (current-buffer) command
+                               squeezed)))
+              (message "Running %s in the background..." command)
+              ;;(set-process-sentinel proc (lambda (p msg) (delete-process p)))
+              (set-process-filter proc 'vc-process-filter)
+              (vc-exec-after
+               `(message "Running %s in the background... done" ',command)))
+          (setq status (apply 'call-process command nil t nil squeezed))
+          (when (or (not (integerp status)) (and okstatus (< okstatus status)))
+            (pop-to-buffer (current-buffer))
+            (goto-char (point-min))
+            (shrink-window-if-larger-than-buffer)
+            (error "Running %s...FAILED (%s)" command
+                   (if (integerp status) (format "status %d" status) status))))
+        (if vc-command-messages
+            (message "Running %s...OK" command)))
+      (vc-exec-after
+       `(run-hook-with-args 'vc-post-command-functions ',command ',file ',flags))
+      status)))
 
-;;; Save a bit of the text around POSN in the current buffer, to help
-;;; us find the corresponding position again later.  This works even
-;;; if all markers are destroyed or corrupted.
-;;; A lot of this was shamelessly lifted from Sebastian Kremer's rcs.el mode.
 (defun vc-position-context (posn)
+  "Save a bit of the text around POSN in the current buffer, to help
+us find the corresponding position again later.  This works even if
+all markers are destroyed or corrupted."
+  ;; A lot of this was shamelessly lifted from Sebastian Kremer's
+  ;; rcs.el mode.
   (list posn
         (buffer-size)
         (buffer-substring posn
                           (min (point-max) (+ posn 100)))))
 
-;;; Return the position of CONTEXT in the current buffer, or nil if we
-;;; couldn't find it.
 (defun vc-find-position-by-context (context)
+  "Return the position of CONTEXT in the current buffer, or nil if we
+couldn't find it."
   (let ((context-string (nth 2 context)))
     (if (equal "" context-string)
         (point-max)
@@ -677,7 +672,7 @@ before the filename."
               (- (point) (length context-string))))))))
 
 (defun vc-context-matches-p (posn context)
-  ;; Returns t if POSN matches CONTEXT, nil otherwise.
+  "Returns t if POSN matches CONTEXT, nil otherwise."
   (let* ((context-string (nth 2 context))
          (len (length context-string))
          (end (+ posn len)))
@@ -686,8 +681,8 @@ before the filename."
       (string= context-string (buffer-substring posn end)))))
 
 (defun vc-buffer-context ()
-  ;; Return a list '(point-context mark-context reparse); from which
-  ;; vc-restore-buffer-context can later restore the context.
+  "Return a list '(point-context mark-context reparse); from which
+vc-restore-buffer-context can later restore the context."
   (let ((point-context (vc-position-context (point)))
         ;; Use mark-marker to avoid confusion in transient-mark-mode.
         (mark-context  (if (eq (marker-buffer (mark-marker)) (current-buffer))
@@ -701,8 +696,7 @@ before the filename."
                         ;; iff that buffer is a compilation output buffer
                         ;; that contains markers into the current buffer.
                         (save-excursion
-                          (mapcar (function
-                                   (lambda (buffer)
+                          (mapcar (lambda (buffer)
                                     (set-buffer buffer)
                                     (let ((errors (or
                                                    compilation-old-error-list
@@ -716,21 +710,20 @@ before the filename."
                                                   (cdr (car errors))))
                                              (setq buffer-error-marked-p t))
                                         (setq errors (cdr errors)))
-                                      (if buffer-error-marked-p buffer))))
+                                      (if buffer-error-marked-p buffer)))
                                   (buffer-list)))))))
     (list point-context mark-context reparse)))
 
 (defun vc-restore-buffer-context (context)
-  ;; Restore point/mark, and reparse any affected compilation buffers.
-  ;; CONTEXT is that which vc-buffer-context returns.
+  "Restore point/mark, and reparse any affected compilation buffers.
+CONTEXT is that which vc-buffer-context returns."
   (let ((point-context (nth 0 context))
         (mark-context (nth 1 context))
         (reparse (nth 2 context)))
     ;; Reparse affected compilation buffers.
     (while reparse
       (if (car reparse)
-          (save-excursion
-            (set-buffer (car reparse))
+          (with-current-buffer (car reparse)
             (let ((compilation-last-buffer (current-buffer)) ;select buffer
                   ;; Record the position in the compilation buffer of
                   ;; the last error next-error went to.
@@ -755,211 +748,191 @@ before the filename."
          (let ((new-mark (vc-find-position-by-context mark-context)))
            (if new-mark (set-mark new-mark))))))
 
-;; Maybe this "smart mark preservation" could be added directly
-;; to revert-buffer since it can be generally useful.  -sm
 (defun vc-revert-buffer1 (&optional arg no-confirm)
-  ;; Revert buffer, try to keep point and mark where user expects them in spite
-  ;; of changes because of expanded version-control key words.
-  ;; This is quite important since otherwise typeahead won't work as expected.
+  "Revert buffer, try to keep point and mark where user expects them
+in spite of changes because of expanded version-control key words.
+This is quite important since otherwise typeahead won't work as
+expected."
   (interactive "P")
   (widen)
   (let ((context (vc-buffer-context)))
     ;; Use save-excursion here, because it may be able to restore point
     ;; and mark properly even in cases where vc-restore-buffer-context
-    ;; would fail.  However, save-excursion might also get it wrong -- 
+    ;; would fail.  However, save-excursion might also get it wrong --
     ;; in this case, vc-restore-buffer-context gives it a second try.
     (save-excursion
-      ;; t means don't call normal-mode; 
+      ;; t means don't call normal-mode;
       ;; that's to preserve various minor modes.
       (revert-buffer arg no-confirm t))
     (vc-restore-buffer-context context)))
 
 
 (defun vc-buffer-sync (&optional not-urgent)
-  ;; Make sure the current buffer and its working file are in sync
-  ;; NOT-URGENT means it is ok to continue if the user says not to save.
+  "Make sure the current buffer and its working file are in sync
+NOT-URGENT means it is ok to continue if the user says not to save."
   (if (buffer-modified-p)
       (if (or vc-suppress-confirm
               (y-or-n-p (format "Buffer %s modified; save it? " (buffer-name))))
           (save-buffer)
-        (if not-urgent
-            nil
+        (unless not-urgent
           (error "Aborted")))))
 
-
-(defun vc-workfile-unchanged-p (file &optional want-differences-if-changed)
-  ;; Has the given workfile changed since last checkout?
+(defun vc-workfile-unchanged-p (file)
+  "Has the given workfile changed since last checkout?"
   (let ((checkout-time (vc-file-getprop file 'vc-checkout-time))
-        (lastmod (nth 5 (file-attributes file))))
-    (or (equal checkout-time lastmod)
-        (and (or (not checkout-time) want-differences-if-changed)
-             (let ((unchanged (zerop (vc-backend-diff file nil nil
-                                          (not want-differences-if-changed)))))
-               ;; 0 stands for an unknown time; it can't match any mod time.
-               (vc-file-setprop file 'vc-checkout-time (if unchanged lastmod 0))
-               unchanged)))))
+        (lastmod (nth 5 (file-attributes file))))
+    (if checkout-time
+        (equal checkout-time lastmod)
+      (let ((unchanged (vc-call workfile-unchanged-p file)))
+        (vc-file-setprop file 'vc-checkout-time (if unchanged lastmod 0))
+        unchanged))))
+      
+(defun vc-default-workfile-unchanged-p (file)
+  "Default check whether workfile is unchanged: diff against master version."
+  (zerop (vc-call diff file (vc-workfile-version file))))
 
-(defun vc-next-action-on-file (file verbose &optional comment)
-  ;;; If comment is specified, it will be used as an admin or checkin comment.
-  (let ((vc-type (vc-backend file))
-        owner version buffer)
-    (cond
+(defun vc-recompute-state (file)
+  "Force a recomputation of the version control state of FILE.
+The state is computed using the exact, and possibly expensive
+function `vc-BACKEND-state', not the heuristic."
+  (vc-file-setprop file 'vc-state (vc-call state file)))
 
-     ;; If the file is not under version control, register it
-     ((not vc-type)
-      (vc-register verbose comment))
-
-     ;; CVS: changes to the master file need to be 
-     ;; merged back into the working file
-     ((and (eq vc-type 'CVS)
-           (or (eq (vc-cvs-status file) 'needs-checkout)
-               (eq (vc-cvs-status file) 'needs-merge)))
-      (if (or vc-dired-mode
-              (yes-or-no-p 
-               (format "%s is not up-to-date.  Merge in changes now? "
-                       (buffer-name))))
-          (progn
-            (if vc-dired-mode
-                (and (setq buffer (get-file-buffer file))
-                     (buffer-modified-p buffer)
-                     (switch-to-buffer-other-window buffer)
-                     (vc-buffer-sync t))
-              (setq buffer (current-buffer))
-              (vc-buffer-sync t))
-            (if (and buffer (buffer-modified-p buffer)
-                     (not (yes-or-no-p 
-                           (format 
-                            "Buffer %s modified; merge file on disc anyhow? " 
-                            (buffer-name buffer)))))
-                (error "Merge aborted"))
-            (let ((status (vc-backend-merge-news file)))
-              (and buffer
-                   (vc-resynch-buffer file t 
-                                      (not (buffer-modified-p buffer))))
-              (if (not (zerop status))
-                  (if (y-or-n-p "Conflicts detected.  Resolve them now? ")
-                      (vc-resolve-conflicts)))))
-        (error "%s needs update" (buffer-name))))
-
-     ;; For CVS files with implicit checkout: if unmodified, don't do anything
-     ((and (eq vc-type 'CVS)
-           (eq (vc-checkout-model file) 'implicit)
-           (not (vc-locking-user file))
-           (not verbose))
-      (message "%s is up to date" (buffer-name)))
-
-     ;; If there is no lock on the file, assert one and get it.
-     ((not (setq owner (vc-locking-user file)))
-      ;; With implicit checkout, make sure not to lose unsaved changes.
-      (and (eq (vc-checkout-model file) 'implicit)
-           (buffer-modified-p buffer)
-           (vc-buffer-sync))
-      (if (and vc-checkout-carefully
-               (not (vc-workfile-unchanged-p file t)))
-          (if (save-window-excursion
-                (pop-to-buffer "*vc-diff*")
-                (goto-char (point-min))
-                (insert-string (format "Changes to %s since last lock:\n\n"
-                                       file))
-                (not (beep))
-                (yes-or-no-p
-                      (concat "File has unlocked changes, "
-                       "claim lock retaining changes? ")))
-              (progn (vc-backend-steal file)
-                     (vc-mode-line file))
-            (if (not (yes-or-no-p "Revert to checked-in version, instead? "))
-                (error "Checkout aborted")
-              (vc-revert-buffer1 t t)
-              (vc-checkout-writable-buffer file))
-            )
-        (if verbose 
-            (if (not (eq vc-type 'SCCS))
-                (vc-checkout file nil 
-                   (read-string "Branch or version to move to: "))
-              (error "Sorry, this is not implemented for SCCS"))
-          (if (vc-latest-on-branch-p file)
-              (vc-checkout-writable-buffer file)
-            (if (yes-or-no-p 
-                 "This is not the latest version.  Really lock it?  ")
-                (vc-checkout-writable-buffer file)
-              (if (yes-or-no-p "Lock the latest version instead? ")
-                  (vc-checkout-writable-buffer file
-                     (if (vc-trunk-p (vc-workfile-version file)) 
-                         ""  ;; this means check out latest on trunk
-                       (vc-branch-part (vc-workfile-version file)))))))
-          )))
-
-     ;; a checked-out version exists, but the user may not own the lock
-     ((and (not (eq vc-type 'CVS))
-           (not (string-equal owner (vc-user-login-name))))
-      (if comment
-          (error "Sorry, you can't steal the lock on %s this way" file))
-      (and (eq vc-type 'RCS)
-           (not (vc-backend-release-p 'RCS "5.6.2"))
-           (error "File is locked by %s" owner))
-      (vc-steal-lock
-       file
-       (if verbose (read-string "Version to steal: ")
-         (vc-workfile-version file))
-       owner))
-
-     ;; OK, user owns the lock on the file
-     (t
-          (if vc-dired-mode 
-              (find-file-other-window file) 
-            (find-file file))
-
-          ;; If the file on disk is newer, then the user just
-          ;; said no to rereading it.  So the user probably wishes to
-          ;; overwrite the file with the buffer's contents, and check 
-          ;; that in.
-          (if (not (verify-visited-file-modtime (current-buffer)))
-              (if (yes-or-no-p "Replace file on disk with buffer contents? ")
-                  (write-file (buffer-file-name))
-                (error "Aborted"))
-            ;; if buffer is not saved, give user a chance to do it
-            (vc-buffer-sync))
-
-          ;; Revert if file is unchanged and buffer is too.
-          ;; If buffer is modified, that means the user just said no
-          ;; to saving it; in that case, don't revert,
-          ;; because the user might intend to save
-          ;; after finishing the log entry.
-          (if (and (vc-workfile-unchanged-p file) 
-                   (not (buffer-modified-p)))
-               ;; DO NOT revert the file without asking the user!
-              (cond 
-               ((yes-or-no-p "Revert to master version? ")
-                (vc-backend-revert file)
-                (vc-resynch-window file t t)))
-
-            ;; user may want to set nonstandard parameters
-            (if verbose
-                (setq version (read-string "New version level: ")))
-
-            ;; OK, let's do the checkin
-            (vc-checkin file version comment)
-            )))))
+(defun vc-next-action-on-file (file verbose &optional comment)
+  "Do The Right Thing for a given version-controlled FILE.
+If COMMENT is specified, it will be used as an admin or checkin comment.
+If VERBOSE is non-nil, query the user rather than using default parameters."
+  (let ((visited (get-file-buffer file))
+        state version)
+    (when visited
+      ;; Check relation of buffer and file, and make sure
+      ;; user knows what he's doing.  First, finding the file
+      ;; will check whether the file on disk is newer.
+      (if vc-dired-mode
+          (find-file-other-window file)
+        (find-file file))
+      (if (not (verify-visited-file-modtime (current-buffer)))
+          (if (yes-or-no-p "Replace file on disk with buffer contents? ")
+              (write-file (buffer-file-name))
+            (error "Aborted"))
+        ;; Now, check if we have unsaved changes.
+        (vc-buffer-sync t)
+        (if (buffer-modified-p)
+            (or (y-or-n-p "Operate on disk file, keeping modified buffer? ")
+                (error "Aborted")))))
+    
+    ;; Do the right thing
+    (if (not (vc-registered file))
+        (vc-register verbose comment)
+      (vc-recompute-state file)
+      (setq state (vc-state file))
+      (cond
+       ;; up-to-date
+       ((or (eq state 'up-to-date)
+            (and verbose (eq state 'needs-patch)))
+        (cond
+         (verbose
+          ;; go to a different version
+          (setq version (read-string "Branch or version to move to: "))
+          (vc-checkout file (eq (vc-checkout-model file) 'implicit) version))
+         ((not (eq (vc-checkout-model file) 'implicit))
+          ;; check the file out
+          (vc-checkout file t))
+         (t
+          ;; do nothing
+          (message "%s is up-to-date" file))))
+       
+       ;; Abnormal: edited but read-only
+       ((and visited (eq state 'edited) buffer-read-only)
+        ;; Make the file+buffer read-write.  If the user really wanted to
+        ;; commit, he'll get a chance to do that next time around, anyway.
+        (message "File is edited but read-only; making it writable")
+        (set-file-modes buffer-file-name
+                        (logior (file-modes buffer-file-name) 128))
+        (toggle-read-only -1))
+       
+       ;; edited
+       ((eq state 'edited)
+        (cond 
+         ;; For files with locking, if the file does not contain
+         ;; any changes, just let go of the lock, i.e. revert.
+         ((and (not (eq (vc-checkout-model file) 'implicit))
+               (vc-workfile-unchanged-p file)
+               ;; If buffer is modified, that means the user just
+               ;; said no to saving it; in that case, don't revert,
+               ;; because the user might intend to save after
+               ;; finishing the log entry.
+               (not (and visited (buffer-modified-p))))
+          ;; DO NOT revert the file without asking the user!
+          (if (not visited) (find-file-other-window file))
+          (if (yes-or-no-p "Revert to master version? ")
+              (vc-revert-buffer)))
+         (t ;; normal action
+          (if verbose (setq version (read-string "New version: ")))
+          (vc-checkin file version comment))))
+       
+       ;; locked by somebody else
+       ((stringp state)
+        (if comment
+            (error "Sorry, you can't steal the lock on %s this way"
+                   (file-name-nondirectory file)))
+        (vc-steal-lock file
+                       (if verbose (read-string "Version to steal: ")
+                         (vc-workfile-version file))
+                       state))
+       
+       ;; needs-patch
+       ((eq state 'needs-patch)
+        (if (yes-or-no-p (format 
+                          "%s is not up-to-date.  Get latest version? "
+                          (file-name-nondirectory file)))
+            (vc-checkout file (eq (vc-checkout-model file) 'implicit) "")
+          (if (and (not (eq (vc-checkout-model file) 'implicit))
+                   (yes-or-no-p "Lock this version? "))
+              (vc-checkout file t)
+            (error "Aborted"))))
+       
+       ;; needs-merge
+       ((eq state 'needs-merge)
+        (if (yes-or-no-p (format 
+                          "%s is not up-to-date.  Merge in changes now? "
+                          (file-name-nondirectory file)))
+            (vc-maybe-resolve-conflicts file (vc-call merge-news file))
+          (error "Aborted")))
+       
+       ;; unlocked-changes
+       ((eq state 'unlocked-changes)
+        (if (not visited) (find-file-other-window file))
+        (if (save-window-excursion
+              (vc-version-diff file (vc-workfile-version file) nil)
+              (goto-char (point-min))
+              (insert-string (format "Changes to %s since last lock:\n\n"
+                                     file))
+              (not (beep))
+              (yes-or-no-p (concat "File has unlocked changes.  "
+                                   "Claim lock retaining changes? ")))
+            (progn (vc-call steal-lock file)
+                   ;; Must clear any headers here because they wouldn't
+                   ;; show that the file is locked now.
+                   (vc-clear-headers file)
+                   (vc-mode-line file))
+          (if (not (yes-or-no-p
+                    "Revert to checked-in version, instead? "))
+              (error "Checkout aborted")
+            (vc-revert-buffer1 t t)
+            (vc-checkout file t))))))))
 
 (defvar vc-dired-window-configuration)
 
 (defun vc-next-action-dired (file rev comment)
-  ;; Do a vc-next-action-on-file on all the marked files, possibly 
-  ;; passing on the log comment we've just entered.
+  "Do a vc-next-action-on-file on all the marked files, possibly
+passing on the log comment we've just entered."
   (let ((dired-buffer (current-buffer))
         (dired-dir default-directory))
     (dired-map-over-marks
      (let ((file (dired-get-filename)))
        (message "Processing %s..." file)
-       ;; Adjust the default directory so that checkouts
-       ;; go to the right place.
-       (let ((default-directory (file-name-directory file)))
-         (vc-next-action-on-file file nil comment)
-         (set-buffer dired-buffer))
-       ;; Make sure that files don't vanish
-       ;; after they are checked in.
-       (let ((vc-dired-terse-mode nil))
-         (dired-do-redisplay file))
+       (vc-next-action-on-file file nil comment)
+       (set-buffer dired-buffer)
        (set-window-configuration vc-dired-window-configuration)
        (message "Processing %s...done" file))
     nil t))
@@ -970,14 +943,17 @@ before the filename."
 ;;;###autoload
 (defun vc-next-action (verbose)
   "Do the next logical checkin or checkout operation on the current file.
-   If you call this from within a VC dired buffer with no files marked,
+
+If you call this from within a VC dired buffer with no files marked,
 it will operate on the file in the current line.
-   If you call this from within a VC dired buffer, and one or more
+
+If you call this from within a VC dired buffer, and one or more
 files are marked, it will accept a log message and then operate on
 each one.  The log message will be used as a comment for any register
 or checkin operations, but ignored when doing checkouts.  Attempted
 lock steals will raise an error.
-   A prefix argument lets you specify the version number to use.
+
+A prefix argument lets you specify the version number to use.
 
 For RCS and SCCS files:
    If the file is not already registered, this registers it for version
@@ -1012,14 +988,10 @@ merge in the changes into your working copy."
         (let ((files (dired-get-marked-files)))
           (set (make-local-variable 'vc-dired-window-configuration)
                (current-window-configuration))
-          (if (string= "" 
+          (if (string= ""
                  (mapconcat
-                     (function (lambda (f)
-                         (if (eq (vc-backend f) 'CVS)
-                             (if (or (eq (vc-cvs-status f) 'locally-modified)
-                                     (eq (vc-cvs-status f) 'locally-added))
-                                 "@" "")
-                           (if (vc-locking-user f) "@" ""))))
+                     (lambda (f)
+                       (if (not (vc-up-to-date-p f)) "@" ""))
                      files ""))
                 (vc-next-action-dired nil nil "dummy")
               (vc-start-entry nil nil nil
@@ -1040,17 +1012,25 @@ merge in the changes into your working copy."
   )
 
 ;;;###autoload
-(defun vc-register (&optional override comment)
-  "Register the current file into your version-control system."
+(defun vc-register (&optional set-version comment)
+  "Register the current file into a version-control system.
+With prefix argument SET-VERSION, allow user to specify initial version 
+level.  If COMMENT is present, use that as an initial comment.
+
+The version-control system to use is found by cycling through the list
+`vc-handled-backends'.  The first backend in that list which declares
+itself responsible for the file (usually because other files in that
+directory are already registered under that backend) will be used to
+register the file.  If no backend declares itself responsible, the
+first backend that could register the file is used."
   (interactive "P")
   (or buffer-file-name
       (error "No visited file"))
-  (let ((master (vc-name buffer-file-name)))
-    (and master (file-exists-p master)
-         (error "This file is already registered"))
-    (and master
-         (not (y-or-n-p "Previous master file has vanished.  Make a new one? "))
-         (error "This file is already registered")))
+  (when (vc-backend buffer-file-name)
+    (if (vc-registered buffer-file-name)
+        (error "This file is already registered")
+      (unless (y-or-n-p "Previous master file has vanished.  Make a new one? ")
+        (error "Aborted"))))
   ;; Watch out for new buffers of size 0: the corresponding file
   ;; does not exist yet, even though buffer-modified-p is nil.
   (if (and (not (buffer-modified-p))
@@ -1058,32 +1038,66 @@ merge in the changes into your working copy."
            (not (file-exists-p buffer-file-name)))
       (set-buffer-modified-p t))
   (vc-buffer-sync)
-  (cond ((not vc-make-backup-files)
-         ;; inhibit backup for this buffer
-         (make-local-variable 'backup-inhibited)
-         (setq backup-inhibited t)))
-  (vc-admin
-   buffer-file-name
-   (or (and override
-            (read-string
-             (format "Initial version level for %s: " buffer-file-name)))
-       vc-default-init-version)
-   comment)
-  ;; Recompute backend property (it may have been set to nil before).
-  (setq vc-buffer-backend (vc-backend (buffer-file-name)))
-  )
+  
+  (vc-start-entry buffer-file-name
+                  (if set-version
+                      (read-string "Initial version level for %s: "
+                                   (buffer-name))
+                    ;; TODO: Use backend-specific init version.
+                    vc-default-init-version)
+                  (or comment (not vc-initial-comment))
+                  "Enter initial comment."
+                  (lambda (file rev comment)
+                    (message "Registering %s... " file)
+                    (let ((backend (vc-responsible-backend file)))
+                      (vc-call-backend backend 'register file rev comment)
+                      (vc-file-setprop file 'vc-backend backend)
+                      (unless vc-make-backup-files
+                        (make-local-variable 'backup-inhibited)
+                        (setq backup-inhibited t)))
+                    (message "Registering %s... done" file))))
+
+(defun vc-responsible-backend (file &optional register)
+  "Return the name of the backend system that is responsible for FILE.
+If no backend in variable `vc-handled-backends' declares itself
+responsible, the first backend in that list will be returned (if optional
+arg REGISTER is non-nil, return the first backend that could register the 
+file).
+FILE can also be a directory name (ending with a slash)."
+  (if (null vc-handled-backends)
+      (error "Cannot register, no backends in `vc-handled-backends'"))
+  (or (and (not (file-directory-p file)) (vc-backend file))
+      (catch 'found
+        (mapcar (lambda (backend)
+                  (if (vc-call-backend backend 'responsible-p file)
+                      (throw 'found backend)))
+                vc-handled-backends)
+        (if register
+            (mapcar (lambda (backend)
+                      (if (vc-call-backend backend 'could-register file)
+                          (throw 'found backend)))
+                    vc-handled-backends)
+          (car vc-handled-backends)))))
+
+(defun vc-default-could-register (backend file)
+  "Return non-nil if BACKEND could be used to register FILE.  
+The default implementation returns t for all files."
+  t)
 
 (defun vc-resynch-window (file &optional keep noquery)
-  ;; If the given file is in the current buffer,
-  ;; either revert on it so we see expanded keywords,
-  ;; or unvisit it (depending on vc-keep-workfiles)
-  ;; NOQUERY if non-nil inhibits confirmation for reverting.
-  ;; NOQUERY should be t *only* if it is known the only difference
-  ;; between the buffer and the file is due to RCS rather than user editing!
+  "If the given file is in the current buffer, either revert on it so
+we see expanded keywords, or unvisit it (depending on
+vc-keep-workfiles) NOQUERY if non-nil inhibits confirmation for
+reverting.  NOQUERY should be t *only* if it is known the only
+difference between the buffer and the file is due to version control
+rather than user editing!"
   (and (string= buffer-file-name file)
        (if keep
            (progn
              (vc-revert-buffer1 t noquery)
+             ;; TODO: Adjusting view mode might no longer be necessary
+             ;; after RMS change to files.el of 1999-08-08.  Investigate
+             ;; this when we install the new VC.
              (and view-read-only
                   (if (file-writable-p file)
                       (and view-mode
@@ -1096,26 +1110,25 @@ merge in the changes into your working copy."
          (kill-buffer (current-buffer)))))
 
 (defun vc-resynch-buffer (file &optional keep noquery)
-  ;; if FILE is currently visited, resynch its buffer
+  "If FILE is currently visited, resynch its buffer."
   (if (string= buffer-file-name file)
       (vc-resynch-window file keep noquery)
     (let ((buffer (get-file-buffer file)))
       (if buffer
-          (save-excursion
-            (set-buffer buffer)
-            (vc-resynch-window file keep noquery))))))
+          (with-current-buffer buffer
+            (vc-resynch-window file keep noquery)))))
+  (vc-dired-resynch-file file))
 
 (defun vc-start-entry (file rev comment msg action &optional after-hook)
-  ;; Accept a comment for an operation on FILE revision REV.  If COMMENT
-  ;; is nil, pop up a VC-log buffer, emit MSG, and set the
-  ;; action on close to ACTION; otherwise, do action immediately.
-  ;; Remember the file's buffer in vc-parent-buffer (current one if no file).
-  ;; AFTER-HOOK specifies the local value for vc-log-operation-hook.
+  "Accept a comment for an operation on FILE revision REV.  If COMMENT
+is nil, pop up a VC-log buffer, emit MSG, and set the action on close
+to ACTION; otherwise, do action immediately.  Remember the file's
+buffer in vc-parent-buffer (current one if no file).  AFTER-HOOK
+specifies the local value for vc-log-operation-hook."
   (let ((parent (if file (find-file-noselect file) (current-buffer))))
     (if vc-before-checkin-hook
         (if file
-            (save-excursion 
-              (set-buffer parent)
+            (with-current-buffer parent
               (run-hooks 'vc-before-checkin-hook))
           (run-hooks 'vc-before-checkin-hook)))
     (if comment
@@ -1125,7 +1138,7 @@ merge in the changes into your working copy."
     (set (make-local-variable 'vc-parent-buffer-name)
          (concat " from " (buffer-name vc-parent-buffer)))
     (if file (vc-mode-line file))
-    (vc-log-mode file)
+    (if (fboundp 'log-edit) (vc-log-edit file) (vc-log-mode file))
     (make-local-variable 'vc-log-after-operation-hook)
     (if after-hook
         (setq vc-log-after-operation-hook after-hook))
@@ -1138,44 +1151,41 @@ merge in the changes into your working copy."
               (vc-finish-logentry t)
             (insert comment)
             (vc-finish-logentry nil)))
-      (message "%s  Type C-c C-c when done." msg))))
-
-(defun vc-admin (file rev &optional comment)
-  "Check a file into your version-control system.
-FILE is the unmodified name of the file.  REV should be the base version
-level to check it in under.  COMMENT, if specified, is the checkin comment."
-  (vc-start-entry file rev
-                  (or comment (not vc-initial-comment))
-                  "Enter initial comment." 'vc-backend-admin
-                  nil))
+      (message "%s  Type C-c C-c when done" msg))))
 
 (defun vc-checkout (file &optional writable rev)
   "Retrieve a copy of the latest version of the given file."
-  ;; If ftp is on this system and the name matches the ange-ftp format
-  ;; for a remote file, the user is trying something that won't work.
-  (if (and (string-match "^/[^/:]+:" file) (vc-find-binary "ftp"))
-      (error "Sorry, you can't check out files over FTP"))
-  (vc-backend-checkout file writable rev)
+  (condition-case err
+      (vc-call checkout file writable rev)
+    (file-error
+     ;; Maybe the backend is not installed ;-(
+     (when writable
+       (let ((buf (get-file-buffer file)))
+         (when buf (with-current-buffer buf (toggle-read-only -1)))))
+     (signal (car err) (cdr err))))
+  (vc-file-setprop file 'vc-state
+                   (if (or (eq (vc-checkout-model file) 'implicit)
+                           (not writable))
+                       (if (vc-call latest-on-branch-p file)
+                           'up-to-date
+                         'needs-patch)
+                     'edited))
+  (vc-file-setprop file 'vc-checkout-time (nth 5 (file-attributes file)))
   (vc-resynch-buffer file t t))
 
-(defun vc-steal-lock (file rev &optional owner)
+(defun vc-steal-lock (file rev owner)
   "Steal the lock on the current workfile."
   (let (file-description)
-    (if (not owner)
-        (setq owner (vc-locking-user file)))
     (if rev
         (setq file-description (format "%s:%s" file rev))
       (setq file-description file))
     (if (not (yes-or-no-p (format "Steal the lock on %s from %s? "
                                   file-description owner)))
-        (error "Steal cancelled"))
-    (pop-to-buffer (get-buffer-create "*VC-mail*"))
+        (error "Steal canceled"))
+    (compose-mail owner (format "Stolen lock on %s" file-description)
+                  nil nil nil nil
+                  (list (list 'vc-finish-steal file rev)))
     (setq default-directory (expand-file-name "~/"))
-    (auto-save-mode auto-save-default)
-    (mail-mode)
-    (erase-buffer)
-    (mail-setup owner (format "Stolen lock on %s" file-description) nil nil nil
-                (list (list 'vc-finish-steal file rev)))
     (goto-char (point-max))
     (insert
      (format "I stole the lock on %s, " file-description)
@@ -1183,27 +1193,40 @@ level to check it in under.  COMMENT, if specified, is the checkin comment."
      ".\n")
     (message "Please explain why you stole the lock.  Type C-c C-c when done.")))
 
-;; This is called when the notification has been sent.
 (defun vc-finish-steal (file version)
-  (vc-backend-steal file version)
-  (if (get-file-buffer file)
-      (save-excursion
-        (set-buffer (get-file-buffer file))
-        (vc-resynch-window file t t))))
+  ;; This is called when the notification has been sent.
+  (message "Stealing lock on %s..." file)
+  (vc-call steal-lock file version)
+  (vc-file-setprop file 'vc-state 'edited)
+  (vc-resynch-buffer file t t)
+  (message "Stealing lock on %s...done" file))
 
 (defun vc-checkin (file &optional rev comment)
-  "Check in the file specified by FILE.
-The optional argument REV may be a string specifying the new version level
-\(if nil increment the current level).  The file is either retained with write
-permissions zeroed, or deleted (according to the value of `vc-keep-workfiles').
-If the back-end is CVS, a writable workfile is always kept.
-COMMENT is a comment string; if omitted, a buffer is popped up to accept a
-comment.
+  "Check in FILE.  
+The optional argument REV may be a string specifying the new version
+level (if nil increment the current level).  COMMENT is a comment
+string; if omitted, a buffer is popped up to accept a comment.
+
+If `vc-keep-workfiles' is nil, FILE is deleted afterwards, provided
+that the version control system supports this mode of operation.
 
 Runs the normal hook `vc-checkin-hook'."
-  (vc-start-entry file rev comment
-                  "Enter a change comment." 'vc-backend-checkin
-                  'vc-checkin-hook))
+  (vc-start-entry 
+   file rev comment
+   "Enter a change comment." 
+   (lambda (file rev comment)
+     (message "Checking in %s..." file)
+     ;; "This log message intentionally left almost blank".
+     ;; RCS 5.7 gripes about white-space-only comments too.
+     (or (and comment (string-match "[^\t\n ]" comment))
+         (setq comment "*** empty log message ***"))
+     ;; Change buffers to get local value of vc-checkin-switches.
+     (with-current-buffer (or (get-file-buffer file) (current-buffer))
+       (vc-call checkin file rev comment))
+     (vc-file-setprop file 'vc-state 'up-to-date)
+     (vc-file-setprop file 'vc-checkout-time (nth 5 (file-attributes file)))
+     (message "Checking in %s...done" file))
+   'vc-checkin-hook))
 
 (defun vc-comment-to-change-log (&optional whoami file-name)
   "Enter last VC comment into change log file for current buffer's file.
@@ -1256,19 +1279,22 @@ May be useful as a `vc-checkin-hook' to update change logs automatically."
   "Complete the operation implied by the current log entry."
   (interactive)
   ;; Check and record the comment, if any.
-  (if (not nocomment)
-      (progn
-        ;; Comment too long?
-        (vc-backend-logentry-check vc-log-file)
-        ;; Record the comment in the comment ring
-        (ring-insert vc-comment-ring (buffer-string))
-        ))
+  (unless nocomment
+    ;; Comment too long?
+    (vc-call-backend (or (and vc-log-file (vc-backend vc-log-file))
+                         (vc-responsible-backend default-directory))
+                     'logentry-check)
+    (run-hooks 'vc-logentry-check-hook)
+    ;; Record the comment in the comment ring
+    (let ((comment (buffer-string)))
+      (unless (and (ring-p vc-comment-ring)
+                   (not (ring-empty-p vc-comment-ring))
+                   (equal comment (ring-ref vc-comment-ring 0)))
+        (ring-insert vc-comment-ring comment))))
   ;; Sync parent buffer in case the user modified it while editing the comment.
   ;; But not if it is a vc-dired buffer.
-  (save-excursion
-    (set-buffer vc-parent-buffer)
-    (or vc-dired-mode
-        (vc-buffer-sync)))
+  (with-current-buffer vc-parent-buffer
+    (or vc-dired-mode (vc-buffer-sync)))
   (if (not vc-log-operation) (error "No log operation is pending"))
   ;; save the parameters held in buffer-local variables
   (let ((log-operation vc-log-operation)
@@ -1280,7 +1306,7 @@ May be useful as a `vc-checkin-hook' to update change logs automatically."
     (pop-to-buffer vc-parent-buffer)
     ;; OK, do it to it
     (save-excursion
-      (funcall log-operation 
+      (funcall log-operation
                log-file
                log-version
                log-entry))
@@ -1296,79 +1322,69 @@ May be useful as a `vc-checkin-hook' to update change logs automatically."
                (pop-to-buffer tmp-vc-parent-buffer))))
     ;; Now make sure we see the expanded headers
     (if buffer-file-name
-        (vc-resynch-window buffer-file-name vc-keep-workfiles t))
-    (if vc-dired-mode 
+        (vc-resynch-buffer buffer-file-name vc-keep-workfiles t))
+    (if vc-dired-mode
         (dired-move-to-filename))
     (run-hooks after-hook 'vc-finish-logentry-hook)))
 
 ;; Code for access to the comment ring
 
+(defun vc-new-comment-index (stride len)
+  (mod (cond
+        (vc-comment-ring-index (+ vc-comment-ring-index stride))
+        ;; Initialize the index on the first use of this command
+        ;; so that the first M-p gets index 0, and the first M-n gets
+        ;; index -1.
+        ((> stride 0) (1- stride))
+        (t stride))
+       len))
+
 (defun vc-previous-comment (arg)
   "Cycle backwards through comment history."
   (interactive "*p")
   (let ((len (ring-length vc-comment-ring)))
-    (cond ((<= len 0)
-           (message "Empty comment ring")
-           (ding))
-          (t
-           (erase-buffer)
-           ;; Initialize the index on the first use of this command
-           ;; so that the first M-p gets index 0, and the first M-n gets
-           ;; index -1.
-           (if (null vc-comment-ring-index)
-               (setq vc-comment-ring-index
-                     (if (> arg 0) -1
-                         (if (< arg 0) 1 0))))
-           (setq vc-comment-ring-index
-                 (mod (+ vc-comment-ring-index arg) len))
-           (message "%d" (1+ vc-comment-ring-index))
-           (insert (ring-ref vc-comment-ring vc-comment-ring-index))))))
+    (if (<= len 0)
+        (progn (message "Empty comment ring") (ding))
+      (erase-buffer)
+      (setq vc-comment-ring-index (vc-new-comment-index arg len))
+      (message "Comment %d" (1+ vc-comment-ring-index))
+      (insert (ring-ref vc-comment-ring vc-comment-ring-index)))))
 
 (defun vc-next-comment (arg)
   "Cycle forwards through comment history."
   (interactive "*p")
   (vc-previous-comment (- arg)))
 
-(defun vc-comment-search-reverse (str)
+(defun vc-comment-search-reverse (str &optional stride)
   "Searches backwards through comment history for substring match."
-  (interactive "sComment substring: ")
+  ;; Why substring rather than regexp ?   -sm
+  (interactive
+   (list (read-string "Comment substring: " nil nil vc-last-comment-match)))
+  (unless stride (setq stride 1))
   (if (string= str "")
       (setq str vc-last-comment-match)
     (setq vc-last-comment-match str))
-  (if (null vc-comment-ring-index)
-      (setq vc-comment-ring-index -1))
-  (let ((str (regexp-quote str))
-        (len (ring-length vc-comment-ring))
-        (n (1+ vc-comment-ring-index)))
-    (while (and (< n len) (not (string-match str (ring-ref vc-comment-ring n))))
-      (setq n (+ n 1)))
-    (cond ((< n len)
-           (vc-previous-comment (- n vc-comment-ring-index)))
-          (t (error "Not found")))))
+  (let* ((str (regexp-quote str))
+         (len (ring-length vc-comment-ring))
+         (n (vc-new-comment-index stride len)))
+    (while (progn (when (or (>= n len) (< n 0)) (error "Not found"))
+                  (not (string-match str (ring-ref vc-comment-ring n))))
+      (setq n (+ n stride)))
+    (setq vc-comment-ring-index n)
+    (vc-previous-comment 0)))
 
 (defun vc-comment-search-forward (str)
   "Searches forwards through comment history for substring match."
-  (interactive "sComment substring: ")
-  (if (string= str "")
-      (setq str vc-last-comment-match)
-    (setq vc-last-comment-match str))
-  (if (null vc-comment-ring-index)
-      (setq vc-comment-ring-index 0))
-  (let ((str (regexp-quote str))
-        (len (ring-length vc-comment-ring))
-        (n vc-comment-ring-index))
-    (while (and (>= n 0) (not (string-match str (ring-ref vc-comment-ring n))))
-      (setq n (- n 1)))
-    (cond ((>= n 0)
-           (vc-next-comment (- n vc-comment-ring-index)))
-          (t (error "Not found")))))
+  (interactive
+   (list (read-string "Comment substring: " nil nil vc-last-comment-match)))
+  (vc-comment-search-reverse str -1))
 
 ;; Additional entry points for examining version histories
 
 ;;;###autoload
 (defun vc-diff (historic &optional not-urgent)
   "Display diffs between file versions.
-Normally this compares the current file and buffer with the most recent 
+Normally this compares the current file and buffer with the most recent
 checked in version of that file.  This uses no arguments.
 With a prefix argument, it reads the file name to use
 and two version designators specifying which versions to compare."
@@ -1376,36 +1392,17 @@ and two version designators specifying which versions to compare."
   (vc-ensure-vc-buffer)
   (if historic
       (call-interactively 'vc-version-diff)
-    (let ((file buffer-file-name)
-          unchanged)
+    (let ((file buffer-file-name))
       (vc-buffer-sync not-urgent)
-      (setq unchanged (vc-workfile-unchanged-p buffer-file-name))
-      (if unchanged
-          (message "No changes to %s since latest version" file)
-        (vc-backend-diff file)
-        ;; Ideally, we'd like at this point to parse the diff so that
-        ;; the buffer effectively goes into compilation mode and we
-        ;; can visit the old and new change locations via next-error.
-        ;; Unfortunately, this is just too painful to do.  The basic
-        ;; problem is that the `old' file doesn't exist to be
-        ;; visited.  This plays hell with numerous assumptions in
-        ;; the diff.el and compile.el machinery.
-        (set-buffer "*vc-diff*")
-        (setq default-directory (file-name-directory file))
-        (if (= 0 (buffer-size))
-            (progn
-              (setq unchanged t)
-              (message "No changes to %s since latest version" file))
-          (pop-to-buffer "*vc-diff*")
-          (goto-char (point-min))
-          (shrink-window-if-larger-than-buffer)))
-      (not unchanged))))
+      (if (vc-workfile-unchanged-p buffer-file-name)
+          (message "No changes to %s since latest version" file)
+        (vc-version-diff file nil nil)))))
 
 (defun vc-version-diff (file rel1 rel2)
   "For FILE, report diffs between two stored versions REL1 and REL2 of it.
 If FILE is a directory, generate diffs between versions for all registered
 files in or below it."
-  (interactive 
+  (interactive
    (let ((file (expand-file-name
                 (read-file-name (if buffer-file-name
                                     "File or dir to diff: (default visited file) "
@@ -1414,18 +1411,19 @@ files in or below it."
          (rel1-default nil) (rel2-default nil))
      ;; compute default versions based on the file state
      (cond
-      ;; if it's a directory, don't supply any version defauolt
-      ((file-directory-p file) 
+      ;; if it's a directory, don't supply any version default
+      ((file-directory-p file)
        nil)
-      ;; if the file is locked, use current version as older version
-      ((vc-locking-user file)
+      ;; if the file is not up-to-date, use current version as older version
+      ((not (vc-up-to-date-p file))
        (setq rel1-default (vc-workfile-version file)))
       ;; if the file is not locked, use last and previous version as default
       (t
        (setq rel1-default (vc-previous-version (vc-workfile-version file)))
+       (if (string= rel1-default "") (setq rel1-default nil))
        (setq rel2-default (vc-workfile-version file))))
      ;; construct argument list
-     (list file 
+     (list file
            (read-string (if rel1-default
                             (concat "Older version: (default "
                                     rel1-default ") ")
@@ -1438,52 +1436,58 @@ files in or below it."
                         nil nil rel2-default))))
   (if (string-equal rel1 "") (setq rel1 nil))
   (if (string-equal rel2 "") (setq rel2 nil))
+  (vc-setup-buffer "*vc-diff*")
   (if (file-directory-p file)
-      (let ((camefrom (current-buffer)))
-        (set-buffer (get-buffer-create "*vc-status*"))
-        (set (make-local-variable 'vc-parent-buffer) camefrom)
-        (set (make-local-variable 'vc-parent-buffer-name)
-             (concat " from " (buffer-name camefrom)))
-        (erase-buffer)
+      (let ((inhibit-read-only t))
         (insert "Diffs between "
                 (or rel1 "last version checked in")
                 " and "
                 (or rel2 "current workfile(s)")
                 ":\n\n")
-        (set-buffer (get-buffer-create "*vc-diff*"))
-        (cd file)
+        (setq default-directory (file-name-as-directory file))
+        ;; FIXME: this should do a single exec in CVS.
         (vc-file-tree-walk
          default-directory
-         (function (lambda (f)
-                     (message "Looking at %s" f)
-                     (and
-                      (not (file-directory-p f))
-                      (vc-registered f)
-                      (vc-backend-diff f rel1 rel2)
-                      (append-to-buffer "*vc-status*" (point-min) (point-max)))
-                     )))
-        (pop-to-buffer "*vc-status*")
-        (insert "\nEnd of diffs.\n")
-        (goto-char (point-min))
-        (set-buffer-modified-p nil)
-        )
-    (if (zerop (vc-backend-diff file rel1 rel2))
-        (message "No changes to %s between %s and %s." file rel1 rel2)
-      (pop-to-buffer "*vc-diff*"))))
+         (lambda (f)
+           (vc-exec-after
+            `(progn
+               (message "Looking at %s" ',f)
+               (vc-call-backend ',(vc-backend file) 'diff ',f ',rel1 ',rel2)))))
+        (vc-exec-after `(let ((inhibit-read-only t))
+                          (insert "\nEnd of diffs.\n"))))
+    
+    (cd (file-name-directory file))
+    (vc-call diff file rel1 rel2))
+  (if (and (zerop (buffer-size))
+           (not (get-buffer-process (current-buffer))))
+      (progn
+        (if rel1
+            (if rel2
+                (message "No changes to %s between %s and %s" file rel1 rel2)
+              (message "No changes to %s since %s" file rel1))
+          (message "No changes to %s since latest version" file))
+        nil)
+    (pop-to-buffer (current-buffer))
+    ;; Gnus-5.8.5 sets up an autoload for diff-mode, even if it's
+    ;; not available.  Work around that.
+    (if (require 'diff-mode nil t) (diff-mode))
+    (vc-exec-after '(progn (goto-char (point-min))
+                           (shrink-window-if-larger-than-buffer)))
+    t))
 
 ;;;###autoload
 (defun vc-version-other-window (rev)
   "Visit version REV of the current buffer in another window.
 If the current buffer is named `F', the version is named `F.~REV~'.
 If `F.~REV~' already exists, it is used instead of being re-created."
-  (interactive "sVersion to visit (default is latest version): ")
+  (interactive "sVersion to visit (default is workfile version): ")
   (vc-ensure-vc-buffer)
   (let* ((version (if (string-equal rev "")
-                      (vc-latest-version buffer-file-name)
+                      (vc-workfile-version buffer-file-name)
                     rev))
          (filename (concat buffer-file-name ".~" version "~")))
     (or (file-exists-p filename)
-        (vc-backend-checkout buffer-file-name nil version filename))
+        (vc-call checkout buffer-file-name nil version filename))
     (find-file-other-window filename)))
 
 ;; Header-insertion code
@@ -1492,7 +1496,7 @@ If `F.~REV~' already exists, it is used instead of being re-created."
 (defun vc-insert-headers ()
   "Insert headers in a file for use with your version-control system.
 Headers desired are inserted at point, and are pulled from
-the variable `vc-header-alist'."
+the variable `vc-BACKEND-header'."
   (interactive)
   (vc-ensure-vc-buffer)
   (save-excursion
@@ -1504,83 +1508,99 @@ the variable `vc-header-alist'."
             (let* ((delims (cdr (assq major-mode vc-comment-alist)))
                    (comment-start-vc (or (car delims) comment-start "#"))
                    (comment-end-vc (or (car (cdr delims)) comment-end ""))
-                   (hdstrings (cdr (assoc (vc-backend (buffer-file-name)) vc-header-alist))))
-              (mapcar (function (lambda (s)
-                                  (insert comment-start-vc "\t" s "\t"
-                                          comment-end-vc "\n")))
+                   (hdsym (vc-make-backend-sym (vc-backend (buffer-file-name))
+                                               'header))
+                   (hdstrings (and (boundp hdsym) (symbol-value hdsym))))
+              (mapcar (lambda (s)
+                        (insert comment-start-vc "\t" s "\t"
+                                comment-end-vc "\n"))
                       hdstrings)
               (if vc-static-header-alist
-                  (mapcar (function (lambda (f)
-                                      (if (string-match (car f) buffer-file-name)
-                                          (insert (format (cdr f) (car hdstrings))))))
+                  (mapcar (lambda (f)
+                            (if (string-match (car f) buffer-file-name)
+                                (insert (format (cdr f) (car hdstrings)))))
                           vc-static-header-alist))
               )
             )))))
 
-(defun vc-clear-headers ()
-  ;; Clear all version headers in the current buffer, i.e. reset them 
-  ;; to the nonexpanded form.  Only implemented for RCS, yet.
-  ;; Don't lose point and mark during this.
-  (let ((context (vc-buffer-context))
-        (case-fold-search nil))
-    ;; save-excursion may be able to relocate point and mark properly.
-    ;; If it fails, vc-restore-buffer-context will give it a second try.
-    (save-excursion
-      (goto-char (point-min))
-      (while (re-search-forward 
-              (concat "\\$\\(Author\\|Date\\|Header\\|Id\\|Locker\\|Name\\|"
-                      "RCSfile\\|Revision\\|Source\\|State\\): [^$\n]+\\$")
-              nil t)
-        (replace-match "$\\1$")))
-    (vc-restore-buffer-context context)))
+(defun vc-clear-headers (&optional file)
+  "Clear all version headers in the current buffer (or FILE), i.e. reset them 
+to the non-expanded form."
+  (let* ((filename (or file buffer-file-name))
+         (visited (find-buffer-visiting filename))
+         (backend (vc-backend filename)))
+    (when (vc-find-backend-function backend 'clear-headers)
+        (if visited 
+            (let ((context (vc-buffer-context)))
+              ;; save-excursion may be able to relocate point and mark
+              ;; properly.  If it fails, vc-restore-buffer-context
+              ;; will give it a second try.
+              (save-excursion
+                (vc-call-backend backend 'clear-headers))
+              (vc-restore-buffer-context context))
+          (find-file filename)
+          (vc-call-backend backend 'clear-headers)
+          (kill-buffer filename)))))
 
 ;;;###autoload
-(defun vc-merge ()
-  (interactive)
+(defun vc-merge (&optional merge-news)
+  "Merge changes between two revisions into the work file.
+With prefix arg, merge news, i.e. recent changes from the current branch.
+
+See Info node `Merging'."
+  (interactive "P")
   (vc-ensure-vc-buffer)
   (vc-buffer-sync)
   (let* ((file buffer-file-name)
          (backend (vc-backend file))
-         first-version second-version locking-user)
-    (if (eq backend 'SCCS)
-        (error "Sorry, merging is not implemented for SCCS")
-      (setq locking-user (vc-locking-user file))
-      (if (eq (vc-checkout-model file) 'manual)
-          (if (not locking-user)
-              (if (not (y-or-n-p 
-                        (format "File must be %s for merging.  %s now? "
-                                (if (eq backend 'RCS) "locked" "writable")
-                                (if (eq backend 'RCS) "Lock" "Check out"))))
-                  (error "Merge aborted")
-                (vc-checkout file t))
-            (if (not (string= locking-user (vc-user-login-name)))
-                (error "File is locked by %s" locking-user))))
+         (state (vc-state file))
+         first-version second-version)
+    (cond
+     ((not (vc-find-backend-function backend 
+                                     (if merge-news 'merge-news 'merge)))
+      (error "Sorry, merging is not implemented for %s" backend))
+     ((stringp state)
+      (error "File is locked by %s" state))
+     ((not (vc-editable-p file))
+      (if (y-or-n-p
+           "File must be checked out for merging.  Check out now? ")
+          (vc-checkout file t)
+        (error "Merge aborted"))))
+    (unless merge-news
       (setq first-version (read-string "Branch or version to merge from: "))
       (if (and (>= (elt first-version 0) ?0)
-               (<= (elt first-version 0) ?9))
-          (if (not (vc-branch-p first-version))
-              (setq second-version 
-                    (read-string "Second version: " 
-                                 (concat (vc-branch-part first-version) ".")))
-            ;; We want to merge an entire branch.  Set versions
-            ;; accordingly, so that vc-backend-merge understands us.
-            (setq second-version first-version)
-            ;; first-version must be the starting point of the branch
-            (setq first-version (vc-branch-part first-version))))
-      (let ((status (vc-backend-merge file first-version second-version)))
-        (if (and (eq (vc-checkout-model file) 'implicit)
-                 (not (vc-locking-user file)))
-            (vc-file-setprop file 'vc-locking-user nil))
-        (vc-resynch-buffer file t t)
-        (if (not (zerop status))
-            (if (y-or-n-p "Conflicts detected.  Resolve them now? ")
-                (vc-resolve-conflicts "WORKFILE" "MERGE SOURCE")
-              (message "File contains conflict markers"))
-          (message "Merge successful"))))))
+               (<= (elt first-version 0) ?9))
+          (if (not (vc-branch-p first-version))
+              (setq second-version 
+                    (read-string "Second version: " 
+                                 (concat (vc-branch-part first-version) ".")))
+            ;; We want to merge an entire branch.  Set versions
+            ;; accordingly, so that vc-backend-merge understands us.
+            (setq second-version first-version)
+            ;; first-version must be the starting point of the branch
+            (setq first-version (vc-branch-part first-version)))))
+    (let ((status (if merge-news
+                      (vc-call merge-news file)
+                    (vc-call merge file first-version second-version))))
+      (vc-maybe-resolve-conflicts file status "WORKFILE" "MERGE SOURCE"))))
+
+(defun vc-maybe-resolve-conflicts (file status &optional name-A name-B)
+  (vc-resynch-buffer file t (not (buffer-modified-p)))
+  (if (zerop status) (message "Merge successful")
+    (if (fboundp 'smerge-mode) (smerge-mode 1))
+    (if (y-or-n-p "Conflicts detected.  Resolve them now? ")
+        (if (fboundp 'smerge-ediff)
+            (smerge-ediff)
+          (vc-resolve-conflicts name-A name-B))
+      (message "File contains conflict markers"))))
 
 (defvar vc-ediff-windows)
 (defvar vc-ediff-result)
-
+(eval-when-compile
+  (defvar ediff-buffer-A)
+  (defvar ediff-buffer-B)
+  (defvar ediff-buffer-C)
+  (require 'ediff-util))
 ;;;###autoload
 (defun vc-resolve-conflicts (&optional name-A name-B)
   "Invoke ediff to resolve conflicts in the current buffer.
@@ -1589,19 +1609,19 @@ The conflicts must be marked with rcsmerge conflict markers."
   (vc-ensure-vc-buffer)
   (let* ((found nil)
          (file-name (file-name-nondirectory buffer-file-name))
-         (your-buffer   (generate-new-buffer 
-                         (concat "*" file-name 
+         (your-buffer   (generate-new-buffer
+                         (concat "*" file-name
                                  " " (or name-A "WORKFILE") "*")))
-         (other-buffer  (generate-new-buffer 
-                         (concat "*" file-name 
+         (other-buffer  (generate-new-buffer
+                         (concat "*" file-name
                                  " " (or name-B "CHECKED-IN") "*")))
          (result-buffer (current-buffer)))
-    (save-excursion 
+    (save-excursion
       (set-buffer your-buffer)
       (erase-buffer)
       (insert-buffer result-buffer)
       (goto-char (point-min))
-      (while (re-search-forward (concat "^<<<<<<< " 
+      (while (re-search-forward (concat "^<<<<<<< "
                                         (regexp-quote file-name) "\n") nil t)
         (setq found t)
         (replace-match "")
@@ -1621,7 +1641,7 @@ The conflicts must be marked with rcsmerge conflict markers."
       (erase-buffer)
       (insert-buffer result-buffer)
       (goto-char (point-min))
-      (while (re-search-forward (concat "^<<<<<<< " 
+      (while (re-search-forward (concat "^<<<<<<< "
                                         (regexp-quote file-name) "\n") nil t)
         (let ((start (match-beginning 0)))
         (if (not (re-search-forward "^=======\n" nil t))
@@ -1643,25 +1663,24 @@ The conflicts must be marked with rcsmerge conflict markers."
         (make-local-variable 'vc-ediff-windows)
         (setq vc-ediff-windows config)
         (make-local-variable 'vc-ediff-result)
-        (setq vc-ediff-result result-buffer)        
+        (setq vc-ediff-result result-buffer)
         (make-local-variable 'ediff-quit-hook)
         (setq ediff-quit-hook 
-              (function 
-               (lambda ()
-                 (let ((buffer-A ediff-buffer-A)
-                       (buffer-B ediff-buffer-B)
-                       (buffer-C ediff-buffer-C)
-                       (result vc-ediff-result)
-                       (windows vc-ediff-windows))
-                   (ediff-cleanup-mess)
-                   (set-buffer result)
-                   (erase-buffer)
-                   (insert-buffer buffer-C)
-                   (kill-buffer buffer-A)
-                   (kill-buffer buffer-B)
-                   (kill-buffer buffer-C)
-                   (set-window-configuration windows)
-                   (message "Conflict resolution finished; you may save the buffer")))))
+              (lambda ()
+                (let ((buffer-A ediff-buffer-A)
+                      (buffer-B ediff-buffer-B)
+                      (buffer-C ediff-buffer-C)
+                      (result vc-ediff-result)
+                      (windows vc-ediff-windows))
+                  (ediff-cleanup-mess)
+                  (set-buffer result)
+                  (erase-buffer)
+                  (insert-buffer buffer-C)
+                  (kill-buffer buffer-A)
+                  (kill-buffer buffer-B)
+                  (kill-buffer buffer-C)
+                  (set-window-configuration windows)
+                  (message "Conflict resolution finished; you may save the buffer"))))
         (message "Please resolve conflicts now; exit ediff when done")
         nil))))
 
@@ -1671,14 +1690,27 @@ The conflicts must be marked with rcsmerge conflict markers."
 (defvar vc-dired-switches)
 (defvar vc-dired-terse-mode)
 
+(defvar vc-dired-mode-map
+  (let ((map (make-sparse-keymap))
+        (vmap (make-sparse-keymap)))
+    (set-keymap-parent map dired-mode-map)
+    (define-key map "\C-xv" vc-prefix-map)
+    (define-key map "v" vmap)
+    (set-keymap-parent vmap vc-prefix-map)
+    (define-key vmap "t" 'vc-dired-toggle-terse-mode)
+    map))
+
 (define-derived-mode vc-dired-mode dired-mode "Dired under VC"
-  "The major mode used in VC directory buffers.  It works like Dired,
-but lists only files under version control, with the current VC state of 
-each file being indicated in the place of the file's link count, owner, 
-group and size.  Subdirectories are also listed, and you may insert them 
-into the buffer as desired, like in Dired.
-  All Dired commands operate normally, with the exception of `v', which
-is redefined as the version control prefix, so that you can type 
+  "The major mode used in VC directory buffers.
+
+It works like Dired, but lists only files under version control, with
+the current VC state of each file being indicated in the place of the
+file's link count, owner, group and size.  Subdirectories are also
+listed, and you may insert them into the buffer as desired, like in
+Dired.
+
+All Dired commands operate normally, with the exception of `v', which
+is redefined as the version control prefix, so that you can type
 `vl', `v=' etc. to invoke `vc-print-log', `vc-diff', and the like on
 the file named in the current Dired buffer line.  `vv' invokes
 `vc-next-action' on this file, or on all files currently marked.
@@ -1688,12 +1720,12 @@ There is a special command, `*l', to mark all files currently locked."
   ;; The following is slightly modified from dired.el,
   ;; because file lines look a bit different in vc-dired-mode.
   (set (make-local-variable 'dired-move-to-filename-regexp)
-       (let* 
+       (let*
           ((l "\\([A-Za-z]\\|[^\0-\177]\\)")
            ;; In some locales, month abbreviations are as short as 2 letters,
            ;; and they can be padded on the right with spaces.
            (month (concat l l "+ *"))
-           ;; Recognize any non-ASCII character.  
+           ;; Recognize any non-ASCII character.
            ;; The purpose is to match a Kanji character.
            (k "[^\0-\177]")
            ;; (k "[^\x00-\x7f\x80-\xff]")
@@ -1705,7 +1737,8 @@ There is a special command, `*l', to mark all files currently locked."
            (western (concat "\\(" month s dd "\\|" dd s month "\\)"
                             s "\\(" HH:MM "\\|" s yyyy"\\|" yyyy s "\\)"))
            (japanese (concat mm k s dd k s "\\(" s HH:MM "\\|" yyyy k "\\)")))
-         (concat s "\\(" western "\\|" japanese "\\)" s)))
+         ;; the .* below ensures that we find the last match on a line
+         (concat ".*" s "\\(" western "\\|" japanese "\\)" s)))
   (and (boundp 'vc-dired-switches)
        vc-dired-switches
        (set (make-local-variable 'dired-actual-switches)
@@ -1713,9 +1746,6 @@ There is a special command, `*l', to mark all files currently locked."
   (set (make-local-variable 'vc-dired-terse-mode) vc-dired-terse-display)
   (setq vc-dired-mode t))
 
-(define-key vc-dired-mode-map "\C-xv" vc-prefix-map)
-(define-key vc-dired-mode-map "v" vc-prefix-map)
-
 (defun vc-dired-toggle-terse-mode ()
   "Toggle terse display in VC Dired."
   (interactive)
@@ -1726,53 +1756,30 @@ There is a special command, `*l', to mark all files currently locked."
         (vc-dired-hook)
       (revert-buffer))))
 
-(define-key vc-dired-mode-map "vt" 'vc-dired-toggle-terse-mode)
-
 (defun vc-dired-mark-locked ()
   "Mark all files currently locked."
   (interactive)
   (dired-mark-if (let ((f (dired-get-filename nil t)))
                    (and f
                         (not (file-directory-p f))
-                        (vc-locking-user f)))
+                        (not (vc-up-to-date-p f))))
                  "locked file"))
 
 (define-key vc-dired-mode-map "*l" 'vc-dired-mark-locked)
 
-(defun vc-fetch-cvs-status (dir)
-  (let ((default-directory dir))
-    ;; Don't specify DIR in this command, the default-directory is
-    ;; enough.  Otherwise it might fail with remote repositories.
-    (vc-do-command "*vc-info*" 0 "cvs" nil nil "status" "-l")
-    (save-excursion
-      (set-buffer (get-buffer "*vc-info*"))
-      (goto-char (point-min))
-      (while (re-search-forward "^=+\n\\([^=\n].*\n\\|\n\\)+" nil t)
-        (narrow-to-region (match-beginning 0) (match-end 0))
-        (vc-parse-cvs-status)
-        (goto-char (point-max))
-        (widen)))))
-
-(defun vc-dired-state-info (file)
-  ;; Return the string that indicates the version control status
-  ;; on a VC dired line.
-  (let* ((cvs-state (and (eq (vc-backend file) 'CVS)
-                         (vc-cvs-status file)))
-         (state 
-          (if cvs-state
-              (cond ((eq cvs-state 'up-to-date) nil)
-                    ((eq cvs-state 'needs-checkout)      "patch")
-                    ((eq cvs-state 'locally-modified)    "modified")
-                    ((eq cvs-state 'needs-merge)         "merge")
-                    ((eq cvs-state 'unresolved-conflict) "conflict")
-                    ((eq cvs-state 'locally-added)       "added"))
-            (vc-locking-user file))))
-    (if state (concat "(" state ")"))))
+(defun vc-default-dired-state-info (backend file)
+  (let ((state (vc-state file)))
+    (cond
+     ((stringp state) (concat "(" state ")"))
+     ((eq state 'edited) (concat "(" (vc-user-login-name) ")"))
+     ((eq state 'needs-merge) "(merge)")
+     ((eq state 'needs-patch) "(patch)")
+     ((eq state 'unlocked-changes) "(stale)"))))
 
 (defun vc-dired-reformat-line (x)
-  ;; Reformat a directory-listing line, replacing various columns with 
-  ;; version control information.
-  ;; This code, like dired, assumes UNIX -l format.
+  "Reformat a directory-listing line.
+Replace various columns with version control information.
+This code, like dired, assumes UNIX -l format."
   (beginning-of-line)
   (let ((pos (point)) limit perm date-and-file)
     (end-of-line)
@@ -1782,9 +1789,9 @@ There is a special command, `*l', to mark all files currently locked."
         (or
          (re-search-forward  ;; owner and group
           "^\\(..[drwxlts-]+ \\) *[0-9]+ [^ ]+ +[^ ]+ +[0-9]+\\( .*\\)"
-          limit t)       
+          limit t)
          (re-search-forward  ;; only owner displayed
-          "^\\(..[drwxlts-]+ \\) *[0-9]+ [^ ]+ +[0-9]+\\( .*\\)" 
+          "^\\(..[drwxlts-]+ \\) *[0-9]+ [^ ]+ +[0-9]+\\( .*\\)"
           limit t)
          (re-search-forward  ;; OS/2 -l format, no links, owner, group
           "^\\(..[drwxlts-]+ \\) *[0-9]+\\( .*\\)"
@@ -1795,34 +1802,32 @@ There is a special command, `*l', to mark all files currently locked."
       (replace-match (concat perm x date-and-file)))))
 
 (defun vc-dired-hook ()
-  ;; Called by dired after any portion of a vc-dired buffer has been read in.
-  ;; Reformat the listing according to version control.
+  "Reformat the listing according to version control.
+Called by dired after any portion of a vc-dired buffer has been read in."
   (message "Getting version information... ")
   (let (subdir filename (buffer-read-only nil) cvs-dir)
     (goto-char (point-min))
-    (while (not (eq (point) (point-max)))
-      (cond 
+    (while (not (eobp))
+      (cond
        ;; subdir header line
        ((setq subdir (dired-get-subdir))
-        (if (file-directory-p (concat subdir "/CVS"))
-            (progn
-              (vc-fetch-cvs-status (file-name-as-directory subdir))
-              (setq cvs-dir t))
-          (setq cvs-dir nil))
+        ;; if the backend supports it, get the state
+        ;; of all files in this directory at once
+        (let ((backend (vc-responsible-backend subdir)))
+          (if (vc-find-backend-function backend 'dir-state)
+              (vc-call-backend backend 'dir-state subdir)))
         (forward-line 1)
         ;; erase (but don't remove) the "total" line
-        (let ((start (point)))
-          (end-of-line)
-          (delete-region start (point))
-          (beginning-of-line)
-          (forward-line 1)))
-       ;; directory entry
+        (delete-region (point) (line-end-position))
+        (beginning-of-line)
+        (forward-line 1))
+       ;; file line
        ((setq filename (dired-get-filename nil t))
         (cond
          ;; subdir
          ((file-directory-p filename)
-          (cond 
-           ((member (file-name-nondirectory filename) 
+          (cond
+           ((member (file-name-nondirectory filename)
                     vc-directory-exclusion-list)
             (let ((pos (point)))
               (dired-kill-tree filename)
@@ -1832,7 +1837,7 @@ There is a special command, `*l', to mark all files currently locked."
             ;; Don't show directories in terse mode.  Don't use
             ;; dired-kill-line to remove it, because in recursive listings,
             ;; that would remove the directory contents as well.
-            (delete-region (progn (beginning-of-line) (point))
+            (delete-region (line-beginning-position)
                            (progn (forward-line 1) (point))))
            ((string-match "\\`\\.\\.?\\'" (file-name-nondirectory filename))
             (dired-kill-line))
@@ -1840,16 +1845,12 @@ There is a special command, `*l', to mark all files currently locked."
             (vc-dired-reformat-line nil)
             (forward-line 1))))
          ;; ordinary file
-         ((if cvs-dir 
-              (and (eq (vc-file-getprop filename 'vc-backend) 'CVS)
-                   (or (not vc-dired-terse-mode)
-                       (not (eq (vc-cvs-status filename) 'up-to-date))))
-            (and (vc-backend filename)
-                 (or (not vc-dired-terse-mode)
-                     (vc-locking-user filename))))
-          (vc-dired-reformat-line (vc-dired-state-info filename))
+         ((and (vc-backend filename)
+               (not (and vc-dired-terse-mode
+                         (vc-up-to-date-p filename))))
+          (vc-dired-reformat-line (vc-call dired-state-info filename))
           (forward-line 1))
-         (t 
+         (t
           (dired-kill-line))))
        ;; any other line
        (t (forward-line 1))))
@@ -1862,7 +1863,7 @@ There is a special command, `*l', to mark all files currently locked."
            (message "No files locked under %s" default-directory)))))
 
 (defun vc-dired-purge ()
-  ;; Remove empty subdirs
+  "Remove empty subdirs."
   (let (subdir)
     (goto-char (point-min))
     (while (setq subdir (dired-get-subdir))
@@ -1881,139 +1882,136 @@ There is a special command, `*l', to mark all files currently locked."
               (goto-char (point-max))))))
     (goto-char (point-min))))
 
+(defun vc-dired-buffers-for-dir (dir)
+  "Return a list of all vc-dired buffers that currently display DIR."
+  (let (result)
+    (mapcar (lambda (buffer)
+              (with-current-buffer buffer
+                (if vc-dired-mode
+                    (setq result (append result (list buffer))))))
+            (dired-buffers-for-dir dir))
+    result))
+
+(defun vc-dired-resynch-file (file)
+  "Update the entries for FILE in any VC Dired buffers that list it."
+  (let ((buffers (vc-dired-buffers-for-dir (file-name-directory file))))
+    (when buffers
+      (mapcar (lambda (buffer)
+                (with-current-buffer buffer
+                  (if (dired-goto-file file)
+                      ;; bind vc-dired-terse-mode to nil so that
+                      ;; files won't vanish when they are checked in
+                      (let ((vc-dired-terse-mode nil))
+                        (dired-do-redisplay 1)))))
+              buffers))))
+
 ;;;###autoload
-(defun vc-directory (dirname read-switches)
+(defun vc-directory (dir read-switches)
+  "Create a buffer in VC Dired Mode for directory DIR.
+
+See Info node `VC Dired Mode'.
+
+With prefix arg READ-SWITCHES, specify a value to override
+`dired-listing-switches' when generating the listing."
   (interactive "DDired under VC (directory): \nP")
-  (let ((vc-dired-switches (concat dired-listing-switches
+  (let ((vc-dired-switches (concat vc-dired-listing-switches
                                    (if vc-dired-recurse "R" ""))))
-    (if read-switches 
+    (if read-switches
         (setq vc-dired-switches
               (read-string "Dired listing switches: "
                            vc-dired-switches)))
     (require 'dired)
     (require 'dired-aux)
-    ;; force a trailing slash
-    (if (not (eq (elt dirname (1- (length dirname))) ?/))
-        (setq dirname (concat dirname "/")))
-    (switch-to-buffer 
-     (dired-internal-noselect (expand-file-name dirname)
-                              (or vc-dired-switches dired-listing-switches)
+    (switch-to-buffer
+     (dired-internal-noselect (expand-file-name (file-name-as-directory dir))
+                              vc-dired-switches
                               'vc-dired-mode))))
 
-;; Named-configuration support for SCCS
-
-(defun vc-add-triple (name file rev)
-  (save-excursion
-    (find-file (expand-file-name
-                vc-name-assoc-file
-                (file-name-directory (vc-name file))))
-    (goto-char (point-max))
-    (insert name "\t:\t" file "\t" rev "\n")
-    (basic-save-buffer)
-    (kill-buffer (current-buffer))
-    ))
-
-(defun vc-record-rename (file newname)
-  (save-excursion
-    (find-file
-     (expand-file-name
-      vc-name-assoc-file
-      (file-name-directory (vc-name file))))
-    (goto-char (point-min))
-    ;; (replace-regexp (concat ":" (regexp-quote file) "$") (concat ":" newname))
-    (while (re-search-forward (concat ":" (regexp-quote file) "$") nil t)
-      (replace-match (concat ":" newname) nil nil))
-    (basic-save-buffer)
-    (kill-buffer (current-buffer))
-    ))
-
-(defun vc-lookup-triple (file name)
-  ;; Return the numeric version corresponding to a named snapshot of file
-  ;; If name is nil or a version number string it's just passed through
-  (cond ((null name) name)
-        ((let ((firstchar (aref name 0)))
-           (and (>= firstchar ?0) (<= firstchar ?9)))
-         name)
-        (t
-         (save-excursion
-           (set-buffer (get-buffer-create "*vc-info*"))
-           (vc-insert-file
-            (expand-file-name
-             vc-name-assoc-file
-             (file-name-directory (vc-name file))))
-           (prog1
-               (car (vc-parse-buffer
-                     (list (list (concat name "\t:\t" file "\t\\(.+\\)") 1))))
-             (kill-buffer "*vc-info*"))))
-         ))
 
 ;; Named-configuration entry points
 
-(defun vc-snapshot-precondition ()
-  ;; Scan the tree below the current directory.
-  ;; If any files are locked, return the name of the first such file.
-  ;; (This means, neither snapshot creation nor retrieval is allowed.)
-  ;; If one or more of the files are currently visited, return `visited'.
-  ;; Otherwise, return nil.
+(defun vc-snapshot-precondition (dir)
+  "Scan the tree below the current directory.  If any files are
+locked, return the name of the first such file.  \(This means, neither
+snapshot creation nor retrieval is allowed.\) If one or more of the
+files are currently visited, return `visited'.  Otherwise, return
+nil."
   (let ((status nil))
     (catch 'vc-locked-example
       (vc-file-tree-walk
-       default-directory
-       (function (lambda (f)
-                   (and (vc-registered f)
-                        (if (vc-locking-user f) (throw 'vc-locked-example f)
-                          (if (get-file-buffer f) (setq status 'visited)))))))
+       dir
+       (lambda (f)
+         (if (not (vc-up-to-date-p f)) (throw 'vc-locked-example f)
+           (if (get-file-buffer f) (setq status 'visited)))))
       status)))
 
 ;;;###autoload
-(defun vc-create-snapshot (name)
-  "Make a snapshot called NAME.
-The snapshot is made from all registered files at or below the current
-directory.  For each file, the version level of its latest
-version becomes part of the named configuration."
-  (interactive "sNew snapshot name: ")
-  (let ((result (vc-snapshot-precondition)))
+(defun vc-create-snapshot (dir name branchp)
+  "Descending recursively from DIR, make a snapshot called NAME.  
+For each registered file, the version level of its latest version
+becomes part of the named configuration.  If the prefix argument
+BRANCHP is given, the snapshot is made as a new branch and the files
+are checked out in that new branch."
+  (interactive
+   (list (read-file-name "Directory: " default-directory default-directory t)
+         (read-string "New snapshot name: ")
+         current-prefix-arg))
+  (message "Making %s... " (if branchp "branch" "snapshot"))
+  (if (file-directory-p dir) (setq dir (file-name-as-directory dir)))
+  (vc-call-backend (vc-responsible-backend dir)
+                   'create-snapshot dir name branchp)
+  (message "Making %s... done" (if branchp "branch" "snapshot")))
+
+(defun vc-default-create-snapshot (backend dir name branchp)
+  (when branchp 
+    (error "VC backend %s does not support module branches" backend))
+  (let ((result (vc-snapshot-precondition dir)))
     (if (stringp result)
-        (error "File %s is locked" result)
+        (error "File %s is not up-to-date" result)
       (vc-file-tree-walk
-       default-directory
-       (function (lambda (f) (and
-                              (vc-name f)
-                              (vc-backend-assign-name f name)))))
-      )))
+       dir
+       (lambda (f)
+         (vc-call assign-name f name))))))
 
 ;;;###autoload
-(defun vc-retrieve-snapshot (name)
-  "Retrieve the snapshot called NAME, or latest versions if NAME is empty.
-When retrieving a snapshot, there must not be any locked files at or below
-the current directory.  If none are locked, all registered files are 
-checked out (unlocked) at their version levels in the snapshot NAME.
-If NAME is the empty string, all registered files that are not currently 
-locked are updated to the latest versions."
-  (interactive "sSnapshot name to retrieve (default latest versions): ")
-  (let ((update (yes-or-no-p "Update any affected buffers? ")))
-    (if (string= name "")
-        (progn 
-          (vc-file-tree-walk 
-           default-directory
-           (function (lambda (f) (and
-                                  (vc-registered f)
-                                  (not (vc-locking-user f))
-                                  (vc-error-occurred
-                                   (vc-backend-checkout f nil "")
-                                   (if update (vc-resynch-buffer f t t))))))))
-      (let ((result (vc-snapshot-precondition)))
-        (if (stringp result)
-            (error "File %s is locked" result)
-          (setq update (and (eq result 'visited) update))
-          (vc-file-tree-walk
-           default-directory
-           (function (lambda (f) (and
-                                  (vc-name f)
-                                  (vc-error-occurred
-                                   (vc-backend-checkout f nil name)
-                                   (if update (vc-resynch-buffer f t t)))))))
-          )))))
+(defun vc-retrieve-snapshot (dir name)
+  "Descending recursively from DIR, retrieve the snapshot called NAME,
+or latest versions if NAME is empty.  If locking is used for the files
+in DIR, then there must not be any locked files at or below DIR (but
+if NAME is empty, locked files are allowed and simply skipped)."
+  (interactive
+   (list (read-file-name "Directory: " default-directory default-directory t)
+         (read-string "Snapshot name to retrieve (default latest versions): ")))
+  (let ((update (yes-or-no-p "Update any affected buffers? "))
+        (msg (if (or (not name) (string= name ""))
+                 (format "Updating %s... " (abbreviate-file-name dir))
+               (format "Retrieving snapshot into %s... "
+                       (abbreviate-file-name dir)))))
+    (message msg)
+    (vc-call-backend (vc-responsible-backend dir)
+                     'retrieve-snapshot dir name update)
+    (message (concat msg "done"))))
+
+(defun vc-default-retrieve-snapshot (backend dir name update)
+  (if (string= name "")
+      (progn
+        (vc-file-tree-walk
+         dir
+         (lambda (f) (and
+                      (vc-up-to-date-p f)
+                      (vc-error-occurred
+                       (vc-call checkout f nil "")
+                       (if update (vc-resynch-buffer f t t)))))))
+    (let ((result (vc-snapshot-precondition dir)))
+      (if (stringp result)
+          (error "File %s is locked" result)
+        (setq update (and (eq result 'visited) update))
+        (vc-file-tree-walk
+         dir
+         (lambda (f) (and
+                      (vc-error-occurred
+                       (vc-call checkout f nil name)
+                       (if update (vc-resynch-buffer f t t))))))))))
 
 ;; Miscellaneous other entry points
 
@@ -2023,73 +2021,60 @@ locked are updated to the latest versions."
   (interactive)
   (vc-ensure-vc-buffer)
   (let ((file buffer-file-name))
-    (vc-backend-print-log file)
-    (pop-to-buffer (get-buffer-create "*vc*"))
+    (vc-setup-buffer nil)
     (setq default-directory (file-name-directory file))
-    (goto-char (point-max)) (forward-line -1)
-    (while (looking-at "=*\n")
-      (delete-char (- (match-end 0) (match-beginning 0)))
-      (forward-line -1))
-    (goto-char (point-min))
-    (if (looking-at "[\b\t\n\v\f\r ]+")
-        (delete-char (- (match-end 0) (match-beginning 0))))
-    (shrink-window-if-larger-than-buffer)
-    ;; move point to the log entry for the current version
-    (and (not (eq (vc-backend file) 'SCCS))
-         (re-search-forward
-          ;; also match some context, for safety
-          (concat "----\nrevision " (vc-workfile-version file)
-                  "\\(\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)))))))
+    (vc-call print-log file)
+    (pop-to-buffer (current-buffer))
+    (if (fboundp 'log-view-mode) (log-view-mode))
+    (vc-exec-after
+     `(progn
+        (goto-char (point-max)) (forward-line -1)
+        (while (looking-at "=*\n")
+          (delete-char (- (match-end 0) (match-beginning 0)))
+          (forward-line -1))
+        (goto-char (point-min))
+        (if (looking-at "[\b\t\n\v\f\r ]+")
+            (delete-char (- (match-end 0) (match-beginning 0))))
+        (shrink-window-if-larger-than-buffer)
+        ;; move point to the log entry for the current version
+        (if (fboundp 'log-view-goto-rev)
+            (log-view-goto-rev ',(vc-workfile-version file))
+          (if (vc-find-backend-function ',(vc-backend file) 'show-log-entry)
+              (vc-call-backend ',(vc-backend file) 
+                               'show-log-entry 
+                               ',(vc-workfile-version file))))))))
 
 ;;;###autoload
 (defun vc-revert-buffer ()
   "Revert the current buffer's file back to the version it was based on.
 This asks for confirmation if the buffer contents are not identical
-to that version.  Note that for RCS and CVS, this function does not 
-automatically pick up newer changes found in the master file; 
-use C-u \\[vc-next-action] RET to do so."
+to that version.  Note that for RCS and CVS, this function does not
+automatically pick up newer changes found in the master file;
+use \\[universal-argument] \\[vc-next-action] to do so."
   (interactive)
   (vc-ensure-vc-buffer)
   (let ((file buffer-file-name)
         ;; This operation should always ask for confirmation.
         (vc-suppress-confirm nil)
-        (obuf (current-buffer)) (changed (vc-diff nil t)))
-    (if changed
-        (unwind-protect
-            (if (not (yes-or-no-p "Discard changes? "))
-                (error "Revert cancelled"))
-          (if (and (window-dedicated-p (selected-window))
-                   (one-window-p t 'selected-frame))
-              (make-frame-invisible (selected-frame))
-            (delete-window))))
+        (obuf (current-buffer)))
+    (unless (vc-workfile-unchanged-p file)
+      (vc-diff nil t)
+      (vc-exec-after `(message nil))
+      (unwind-protect
+          (if (not (yes-or-no-p "Discard changes? "))
+              (error "Revert canceled"))
+        (if (or (window-dedicated-p (selected-window))
+                (one-window-p t 'selected-frame))
+            (make-frame-invisible (selected-frame))
+          (delete-window))))
     (set-buffer obuf)
-    (vc-backend-revert file)
-    (vc-resynch-window file t t)))
+    ;; Do the reverting
+    (message "Reverting %s..." file)
+    (vc-call revert file)
+    (vc-file-setprop file 'vc-state 'up-to-date)
+    (vc-file-setprop file 'vc-checkout-time (nth 5 (file-attributes file)))
+    (vc-resynch-buffer file t t)
+    (message "Reverting %s...done" file)))
 
 ;;;###autoload
 (defun vc-cancel-version (norevert)
@@ -2097,21 +2082,26 @@ use C-u \\[vc-next-action] RET to do so."
 A prefix argument means do not revert the buffer afterwards."
   (interactive "P")
   (vc-ensure-vc-buffer)
-  (cond 
-   ((eq (vc-backend (buffer-file-name)) 'CVS)
-    (error "Unchecking files under CVS is dangerous and not supported in VC"))
-   ((vc-locking-user (buffer-file-name))
-    (error "This version is locked; use vc-revert-buffer to discard changes"))
-   ((not (vc-latest-on-branch-p (buffer-file-name)))
-    (error "This is not the latest version--VC cannot cancel it")))
-  (let* ((target (vc-workfile-version (buffer-file-name)))
+  (let* ((backend (vc-backend (buffer-file-name)))
+         (target (vc-workfile-version (buffer-file-name)))
          (recent (if (vc-trunk-p target) "" (vc-branch-part target)))
          (config (current-window-configuration)) done)
+    (cond
+     ((not (vc-find-backend-function backend 'uncheck))
+      (error "Sorry, canceling versions is not supported under %s" backend))
+     ((not (vc-call latest-on-branch-p (buffer-file-name)))
+      (error "This is not the latest version; VC cannot cancel it"))
+     ((not (vc-up-to-date-p (buffer-file-name)))
+      (error (substitute-command-keys "File is not up to date; use \\[vc-revert-buffer] to discard changes"))))
     (if (null (yes-or-no-p (format "Remove version %s from master? " target)))
         nil
-      (setq norevert (or norevert (not 
-           (yes-or-no-p "Revert buffer to most recent remaining version? "))))
-      (vc-backend-uncheck (buffer-file-name) target)
+      (setq norevert (or norevert (not
+          (yes-or-no-p "Revert buffer to most recent remaining version? "))))
+
+      (message "Removing last change from %s..." (buffer-file-name))
+      (vc-call uncheck (buffer-file-name) target)
+      (message "Removing last change from %s...done" (buffer-file-name))
+
       ;; Check out the most recent remaining version.  If it fails, because
       ;; the whole branch got deleted, do a double-take and check out the
       ;; version where the branch started.
@@ -2119,15 +2109,16 @@ A prefix argument means do not revert the buffer afterwards."
         (condition-case err
             (progn
               (if norevert
-                  ;; Check out locked, but only to disc, and keep 
+                  ;; Check out locked, but only to disk, and keep
                   ;; modifications in the buffer.
-                  (vc-backend-checkout (buffer-file-name) t recent)
+                  (vc-call checkout (buffer-file-name) t recent)
                 ;; Check out unlocked, and revert buffer.
                 (vc-checkout (buffer-file-name) nil recent))
               (setq done t))
           ;; If the checkout fails, vc-do-command signals an error.
           ;; We catch this error, check the reason, correct the
           ;; version number, and try a second time.
+          ;; FIXME: This is still RCS-only code.
           (error (set-buffer "*vc*")
                  (goto-char (point-min))
                  (if (search-forward "no side branches present for" nil t)
@@ -2146,12 +2137,41 @@ A prefix argument means do not revert the buffer afterwards."
                 ;; inhibit backup for this buffer
                 (progn (make-local-variable 'backup-inhibited)
                        (setq backup-inhibited t)))
-            (if (eq (vc-backend (buffer-file-name)) 'RCS)
-                (progn (setq buffer-read-only nil)
-                       (vc-clear-headers)))
+            (setq buffer-read-only nil)
+            (vc-clear-headers)
             (vc-mode-line (buffer-file-name))))
-      (message "Version %s has been removed from the master" target)
-      )))
+      (message "Version %s has been removed from the master" target))))
+
+(defun vc-rename-master (oldmaster newfile templates)
+  "Rename OLDMASTER to be the master file for NEWFILE based on TEMPLATES."
+  (let* ((dir (file-name-directory (expand-file-name oldmaster)))
+         (newdir (or (file-name-directory newfile) ""))
+         (newbase (file-name-nondirectory newfile))
+         (masters
+          ;; List of potential master files for `newfile'
+          (mapcar
+           (lambda (s) (vc-possible-master s newdir newbase))
+           templates)))
+    (if (or (file-symlink-p oldmaster)
+            (file-symlink-p (file-name-directory oldmaster)))
+        (error "This unsafe in the presence of symbolic links"))
+    (rename-file
+     oldmaster
+     (catch 'found
+       ;; If possible, keep the master file in the same directory.
+       (mapcar (lambda (f)
+                 (if (and f (string= (file-name-directory (expand-file-name f))
+                                     dir))
+                     (throw 'found f)))
+               masters)
+       ;; If not, just use the first possible place.
+       (mapcar (lambda (f)
+                 (and f
+                      (or (not (setq dir (file-name-directory f)))
+                          (file-directory-p dir))
+                      (throw 'found f)))
+               masters)
+       (error "New file lacks a version control directory")))))
 
 ;;;###autoload
 (defun vc-rename-file (old new)
@@ -2163,77 +2183,42 @@ A prefix argument means do not revert the buffer afterwards."
   ;; consider to be wrong.  When the famous, long-awaited rename database is
   ;; implemented things might change for the better.  This is unlikely to occur
   ;; until CVS 2.0 is released.  --ceder 1994-01-23 21:27:51
-  (if (eq (vc-backend old) 'CVS)
-      (error "Renaming files under CVS is dangerous and not supported in VC"))
-  (let ((oldbuf (get-file-buffer old)))
+  (let ((oldbuf (get-file-buffer old))
+        (backend (vc-backend old)))
+    (unless (or (null backend) (vc-find-backend-function backend 'rename-file))
+      (error "Renaming files under %s is not supported in VC" backend))
     (if (and oldbuf (buffer-modified-p oldbuf))
         (error "Please save files before moving them"))
     (if (get-file-buffer new)
         (error "Already editing new file name"))
     (if (file-exists-p new)
         (error "New file already exists"))
-    (let ((oldmaster (vc-name old)) newmaster)
-      (if oldmaster
-          (progn
-            (if (vc-locking-user old)
-                (error "Please check in files before moving them"))
-            (if (or (file-symlink-p oldmaster)
-                    ;; This had FILE, I changed it to OLD. -- rms.
-                    (file-symlink-p (vc-backend-subdirectory-name old)))
-                (error "This is not a safe thing to do in the presence of symbolic links"))
-            (setq newmaster
-                  (let ((backend (vc-backend old))
-                        (newdir (or (file-name-directory new) ""))
-                        (newbase (file-name-nondirectory new)))
-                    (catch 'found
-                      (mapcar
-                       (function
-                        (lambda (s)
-                          (if (eq backend (cdr s))
-                              (let* ((newmaster (format (car s) newdir newbase))
-                                     (newmasterdir (file-name-directory newmaster)))
-                                (if (or (not newmasterdir)
-                                        (file-directory-p newmasterdir))
-                                    (throw 'found newmaster))))))
-                       vc-master-templates)
-                      (error "New file lacks a version control directory"))))
-            ;; Handle the SCCS PROJECTDIR feature.  It is odd that this 
-            ;; is a special case, but a more elegant solution would require
-            ;; significant changes in other parts of VC.
-            (if (eq (vc-backend old) 'SCCS)
-                (let ((project-dir (vc-sccs-project-dir)))
-                  (if project-dir
-                      (setq newmaster 
-                            (concat project-dir 
-                                    (file-name-nondirectory newmaster))))))
-            (rename-file oldmaster newmaster)))
-      (if (or (not oldmaster) (file-exists-p old))
-          (rename-file old new)))
-; ?? Renaming a file might change its contents due to keyword expansion.
-; We should really check out a new copy if the old copy was precisely equal
-; to some checked in version.  However, testing for this is tricky....
+    (when backend
+      (if (and backend (not (vc-up-to-date-p old)))
+          (error "Please check in files before moving them"))
+      (vc-call-backend backend 'rename-file old new))
+    ;; Move the actual file (unless the backend did it already)
+    (if (or (not backend) (file-exists-p old))
+        (rename-file old new))
+    ;; ?? Renaming a file might change its contents due to keyword expansion.
+    ;; We should really check out a new copy if the old copy was precisely equal
+    ;; to some checked in version.  However, testing for this is tricky....
     (if oldbuf
-        (save-excursion
-          (set-buffer oldbuf)
+        (with-current-buffer oldbuf
           (let ((buffer-read-only buffer-read-only))
             (set-visited-file-name new))
           (vc-backend new)
           (vc-mode-line new)
-          (set-buffer-modified-p nil))))
-  ;; This had FILE, I changed it to OLD. -- rms.
-  (vc-backend-dispatch old
-                       (vc-record-rename old new) ;SCCS
-                       nil              ;RCS
-                       nil              ;CVS
-                       )
-  )
+          (set-buffer-modified-p nil)))))
+
+;; Only defined in very recent Emacsen
+(defvar small-temporary-file-directory nil)
 
 ;;;###autoload
 (defun vc-update-change-log (&rest args)
-  "Find change log file and add entries from recent RCS/CVS logs.
+  "Find change log file and add entries from recent version control logs.
 Normally, find log entries for all registered files in the default
-directory using `rcs2log', which finds CVS logs preferentially.
-The mark is left at the end of the text prepended to the change log.
+directory.
 
 With prefix arg of C-u, only find log entries for the current buffer's file.
 
@@ -2241,9 +2226,8 @@ With any numeric prefix arg, find log entries for all currently visited
 files that are under version control.  This puts all the entries in the
 log for the default directory, which may not be appropriate.
 
-From a program, any arguments are assumed to be filenames and are
-passed to the `rcs2log' script after massaging to be relative to the
-default directory."
+From a program, any arguments are assumed to be filenames for which
+log entries should be gathered."
   (interactive
    (cond ((consp current-prefix-arg)    ;C-u
           (list buffer-file-name))
@@ -2258,13 +2242,22 @@ default directory."
               (setq buffers (cdr buffers)))
             files))
          (t
-          ;; `rcs2log' will find the relevant RCS or CVS files
-          ;; relative to the curent directory if none supplied.
+          ;; Don't supply any filenames to backend; this means
+          ;; it should find all relevant files relative to
+          ;; the default-directory.
           nil)))
+  (vc-call-backend (vc-responsible-backend default-directory)
+                   'update-changelog args))
+
+(defun vc-default-update-changelog (backend files)
+  "Default implementation of update-changelog; uses `rcs2log' which only
+works for RCS and CVS."
+  ;; FIXME: We (c|sh)ould add support for cvs2cl
   (let ((odefault default-directory)
         (changelog (find-change-log))
         ;; Presumably not portable to non-Unixy systems, along with rcs2log:
-        (tempfile (make-temp-file
+        (tempfile (funcall
+                   (if (fboundp 'make-temp-file) 'make-temp-file 'make-temp-name)
                    (expand-file-name "vc"
                                      (or small-temporary-file-directory
                                          temporary-file-directory))))
@@ -2284,93 +2277,74 @@ default directory."
     (message "Computing change log entries... %s"
              (unwind-protect
                  (progn
-                   (cd odefault)
-                   (if (eq 0 (apply 'call-process
-                                    (expand-file-name "rcs2log" exec-directory)
-                                    nil
-                                    (list t tempfile) nil
-                                    "-c" changelog
-                                    "-u" (concat (vc-user-login-name)
-                                                 "\t" full-name
-                                                 "\t" mailing-address)
-                                    (mapcar
-                                     (function
-                                      (lambda (f)
-                                        (file-relative-name
-                                         (if (file-name-absolute-p f)
-                                             f
-                                           (concat odefault f)))))
-                                     args)))
-                       "done"
+                   (setq default-directory odefault)
+                   (if (eq 0 (apply 'call-process 
+                                    (expand-file-name "rcs2log" 
+                                                      exec-directory) 
+                                    nil (list t tempfile) nil
+                                    "-c" changelog
+                                    "-u" (concat (vc-user-login-name)
+                                                 "\t" full-name
+                                                 "\t" mailing-address)
+                                    (mapcar
+                                     (lambda (f)
+                                       (file-relative-name
+                                        (if (file-name-absolute-p f)
+                                            f
+                                          (concat odefault f))))
+                                     files)))
+                       "done"
                      (pop-to-buffer
                       (set-buffer (get-buffer-create "*vc*")))
                      (erase-buffer)
                      (insert-file tempfile)
                      "failed"))
-               (cd (file-name-directory changelog))
+               (setq default-directory (file-name-directory changelog))
                (delete-file tempfile)))))
-
-;; vc-annotate functionality (CVS only).
-(defvar vc-annotate-mode-map nil
-  "Local keymap used for VC-Annotate mode.")
 
-(defvar vc-annotate-mode-menu nil
-  "Local keymap used for VC-Annotate mode's menu bar menu.")
-
-;; Syntax Table
-(defvar vc-annotate-mode-syntax-table nil
-  "Syntax table used in VC-Annotate mode buffers.")
+;;; Annotate functionality
 
 ;; Declare globally instead of additional parameter to
 ;; temp-buffer-show-function (not possible to pass more than one
 ;; parameter).
-(defvar vc-annotate-ratio nil)
-
-(defun vc-annotate-mode-variables ()
-  (if (not vc-annotate-mode-syntax-table)
-      (progn   (setq vc-annotate-mode-syntax-table (make-syntax-table))
-               (set-syntax-table vc-annotate-mode-syntax-table)))
-  (if (not vc-annotate-mode-map)
-      (setq vc-annotate-mode-map (make-sparse-keymap)))
-  (setq vc-annotate-mode-menu (make-sparse-keymap "Annotate"))
-  (define-key vc-annotate-mode-map [menu-bar]
-    (make-sparse-keymap "VC-Annotate"))
-  (define-key vc-annotate-mode-map [menu-bar vc-annotate-mode]
-    (cons "VC-Annotate" vc-annotate-mode-menu)))
+(defvar vc-annotate-ratio nil "Global variable")
+(defvar vc-annotate-backend nil "Global variable")
+
+(defun vc-annotate-get-backend (buffer)
+  "Return the backend matching \"Annotate\" buffer BUFFER.  Return NIL
+if no match made.  Associations are made based on
+`vc-annotate-buffers'."
+  (cdr (assoc buffer vc-annotate-buffers)))
 
-(defun vc-annotate-mode ()
-  "Major mode for buffers displaying output from the CVS `annotate' command.
+(define-derived-mode vc-annotate-mode fundamental-mode "Annotate"
+  "Major mode for buffers displaying output from the `annotate' command.
 
 You can use the mode-specific menu to alter the time-span of the used
 colors.  See variable `vc-annotate-menu-elements' for customizing the
 menu items."
-  (interactive)
-  (kill-all-local-variables)            ; Recommended by RMS.
-  (vc-annotate-mode-variables)          ; This defines various variables.
-  (use-local-map vc-annotate-mode-map)  ; This provides the local keymap.
-  (set-syntax-table vc-annotate-mode-syntax-table)
-  (setq major-mode 'vc-annotate-mode)   ; This is how `describe-mode'
-                                        ;   finds out what to describe.
-  (setq mode-name "Annotate")           ; This goes into the mode line.
-  (run-hooks 'vc-annotate-mode-hook)
   (vc-annotate-add-menu))
 
 (defun vc-annotate-display-default (&optional event)
   "Use the default color spectrum for VC Annotate mode."
-  (interactive)
+  (interactive "e")
   (message "Redisplaying annotation...")
-  (vc-annotate-display (get-buffer (buffer-name)))
+  (vc-annotate-display (current-buffer)
+                       nil 
+                       (vc-annotate-get-backend (current-buffer)))
   (message "Redisplaying annotation...done"))
 
 (defun vc-annotate-add-menu ()
-  "Adds the menu 'Annotate' to the menu bar in VC-Annotate mode."
+  "Add the menu 'Annotate' to the menu bar in VC-Annotate mode."
+  (setq vc-annotate-mode-menu (make-sparse-keymap "Annotate"))
+  (define-key vc-annotate-mode-map [menu-bar vc-annotate-mode]
+    (cons "VC-Annotate" vc-annotate-mode-menu))
   (define-key vc-annotate-mode-menu [default]
     '("Default" . vc-annotate-display-default))
   (let ((menu-elements vc-annotate-menu-elements))
     (while menu-elements
       (let* ((element (car menu-elements))
-             (days (round (* element 
-                             (vc-annotate-car-last-cons vc-annotate-color-map) 
+             (days (round (* element
+                             (vc-annotate-car-last-cons vc-annotate-color-map)
                              0.7585))))
         (setq menu-elements (cdr menu-elements))
         (define-key vc-annotate-mode-menu
@@ -2383,14 +2357,21 @@ menu items."
                    (message "Redisplaying annotation...")
                    (vc-annotate-display
                     (get-buffer (buffer-name))
-                    (vc-annotate-time-span vc-annotate-color-map ,element))
+                    (vc-annotate-time-span vc-annotate-color-map ,element)
+                    (vc-annotate-get-backend (current-buffer)))
                    (message "Redisplaying annotation...done"))))))))
 
+
+;;;; (defun vc-BACKEND-annotate-command (file buffer) ...)
+;;;;  Execute "annotate" on FILE by using `call-process' and insert
+;;;;  the contents in BUFFER.
+
 ;;;###autoload
 (defun vc-annotate (ratio)
-  "Display the result of the CVS `annotate' command using colors.
-New lines are displayed in red, old in blue.
-A prefix argument specifies a factor for stretching the time scale.
+  "Display the result of the \"Annotate\" command using colors.
+\"Annotate\" is defined by `vc-BACKEND-annotate-command'.  New lines
+are displayed in red, old in blue.  A prefix argument specifies a
+factor for stretching the time scale.
 
 `vc-annotate-menu-elements' customizes the menu elements of the
 mode-specific menu. `vc-annotate-color-map' and
@@ -2398,17 +2379,23 @@ mode-specific menu. `vc-annotate-color-map' and
 colors. `vc-annotate-background' specifies the background color."
   (interactive "p")
   (vc-ensure-vc-buffer)
-  (if (not (eq (vc-backend (buffer-file-name)) 'CVS))
-      (error "Sorry, vc-annotate is only implemented for CVS"))
   (message "Annotating...")
-  (let ((temp-buffer-name (concat "*cvs annotate " (buffer-name) "*"))
+  (let ((temp-buffer-name (concat "*Annotate " (buffer-name) "*"))
         (temp-buffer-show-function 'vc-annotate-display)
-        (vc-annotate-ratio ratio))
-    (with-output-to-temp-buffer temp-buffer-name
-      (call-process "cvs" nil (get-buffer temp-buffer-name) nil
-                    "annotate" (file-name-nondirectory (buffer-file-name)))))
+        (vc-annotate-ratio ratio)
+        (vc-annotate-backend (vc-backend (buffer-file-name))))
+    (with-output-to-temp-buffer temp-buffer-name 
+      (vc-call-backend vc-annotate-backend 'annotate-command
+                       (file-name-nondirectory (buffer-file-name))
+                       (get-buffer temp-buffer-name)))
+    ;; Don't use the temp-buffer-name until the buffer is created
+    ;; (only after `with-output-to-temp-buffer'.)
+    (setq vc-annotate-buffers 
+          (append vc-annotate-buffers
+                  (list (cons (get-buffer temp-buffer-name) vc-annotate-backend)))))
   (message "Annotating... done"))
 
+
 (defun vc-annotate-car-last-cons (a-list)
   "Return car of last cons in association list A-LIST."
   (if (not (eq nil (cdr a-list)))
@@ -2416,21 +2403,21 @@ colors. `vc-annotate-background' specifies the background color."
     (car (car a-list))))
 
 (defun vc-annotate-time-span (a-list span &optional quantize)
-"Return an association list with factor SPAN applied to the time-span
-of association list A-LIST.  Optionaly quantize to the factor of
-QUANTIZE."
+"Apply factor SPAN  to the time-span of association list A-LIST
+Return the new alist.
+Optionally quantize to the factor of QUANTIZE."
   ;; Apply span to each car of every cons
-  (if (not (eq nil a-list)) 
+  (if (not (eq nil a-list))
       (append (list (cons (* (car (car a-list)) span)
                           (cdr (car a-list))))
-              (vc-annotate-time-span (nthcdr (cond (quantize) ; optional
-                                                   (1)) ; Default to cdr
+              (vc-annotate-time-span (nthcdr (or quantize ; optional
+                                                 1) ; Default to cdr
                                              a-list) span quantize))))
 
 (defun vc-annotate-compcar (threshold a-list)
-  "Test successive cons cells of association list A-LIST against
-THRESHOLD.  Return the first cons cell which car is not less than
-THRESHOLD, nil otherwise"
+  "Test successive cons cells of association list A-LIST against THRESHOLD.
+Return the first cons cell which car is not less than THRESHOLD,
+nil otherwise"
  (let ((i 1)
        (tmp-cons (car a-list)))
    (while (and tmp-cons (< (car tmp-cons) threshold))
@@ -2439,649 +2426,91 @@ THRESHOLD, nil otherwise"
    tmp-cons))                           ; Return the appropriate value
 
 
-(defun vc-annotate-display (buffer &optional color-map)
-  "Do the VC-Annotate display in BUFFER using COLOR-MAP."
+;;;; (defun vc-BACKEND-annotate-difference (point) ...)
+;;;;
+;;;;  Return the difference between the age of the line at point and
+;;;;  the current time.  Return NIL if there is no more comparison to
+;;;;  be made in the buffer.  Return value as defined for
+;;;;  `current-time'.  You can safely assume that point is placed at
+;;;;  the beginning of each line, starting at `point-min'.  The buffer
+;;;;  that point is placed in is the Annotate output, as defined by
+;;;;  the relevant backend.
+
+(defun vc-annotate-display (buffer &optional color-map backend)
+  "Do the VC-Annotate display in BUFFER using COLOR-MAP.  The original
+Annotating file is supposed to be handled by BACKEND.  If BACKEND is
+NIL, variable VC-ANNOTATE-BACKEND is used instead.  This function is
+destructive on VC-ANNOTATE-BACKEND when BACKEND is non-nil."
 
   ;; Handle the case of the global variable vc-annotate-ratio being
   ;; set. This variable is used to pass information from function
   ;; vc-annotate since it is not possible to use another parameter
-  ;; (see temp-buffer-show-function). 
+  ;; (see temp-buffer-show-function).
   (if (and (not color-map) vc-annotate-ratio)
       ;; This will only be true if called from vc-annotate with ratio
       ;; being non-nil.
       (setq color-map (vc-annotate-time-span vc-annotate-color-map
                                              vc-annotate-ratio)))
-      
-  ;; We need a list of months and their corresponding numbers.
-  (let* ((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))))
-    (set-buffer buffer)
-    (display-buffer buffer)
-    (or (eq major-mode 'vc-annotate-mode) ; Turn on vc-annotate-mode if not done
-        (vc-annotate-mode))
-    ;; Delete old overlays
-    (mapcar
-     (lambda (overlay)
-       (if (overlay-get overlay 'vc-annotation)
-           (delete-overlay overlay)))
-     (overlays-in (point-min) (point-max)))
-    (goto-char (point-min))             ; Position at the top of the buffer.
-    (while (re-search-forward
-            "^\\S-+\\s-+\\S-+\\s-+\\([0-9]+\\)-\\(\\sw+\\)-\\([0-9]+\\)): "
-;;          "^[0-9]+\\(\.[0-9]+\\)*\\s-+(\\sw+\\s-+\\([0-9]+\\)-\\(\\sw+\\)-\\([0-9]+\\)): "
-            nil t)
-
-      (let* (;; Unfortunately, order is important. match-string will
-             ;; be corrupted by extent functions in XEmacs. Access
-             ;; string-matches first.
-             (day (string-to-number (match-string 1)))
-             (month (cdr (assoc (match-string 2) 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))
-             (high (- (car (current-time))
-                      (car (encode-time 0 0 0 day month year))))
-             (color (cond ((vc-annotate-compcar high (cond (color-map)
-                                                           (vc-annotate-color-map))))
-                          ((cons nil vc-annotate-very-old-color))))
-             ;; substring from index 1 to remove any leading `#' in the name
-             (face-name (concat "vc-annotate-face-" (substring (cdr color) 1)))
-             ;; Make the face if not done.
-             (face (cond ((intern-soft face-name))
-                         ((let ((tmp-face (make-face (intern face-name))))
-                            (set-face-foreground tmp-face (cdr color))
-                            (if vc-annotate-background
-                                (set-face-background tmp-face vc-annotate-background))
-                            tmp-face)))) ; Return the face
-             (point (point))
-             overlay)
-
+  (set-buffer buffer)
+  (display-buffer buffer)
+  (if (not vc-annotate-mode)            ; Turn on vc-annotate-mode if not done
+      (vc-annotate-mode))
+  (goto-char (point-min))               ; Position at the top of the buffer.
+  ;; Delete old overlays
+  (mapcar
+   (lambda (overlay)
+     (if (overlay-get overlay 'vc-annotation)
+         (delete-overlay overlay)))
+   (overlays-in (point-min) (point-max)))
+  (goto-char (point-min))               ; Position at the top of the buffer.
+
+  (if backend (setq vc-annotate-backend backend)) ; Destructive on `vc-annotate-backend'
+
+  (let ((difference (vc-call-backend vc-annotate-backend 'annotate-difference (point))))
+    (while difference
+      (let*
+          ((color (or (vc-annotate-compcar
+                       difference (or color-map vc-annotate-color-map))
+                      (cons nil vc-annotate-very-old-color)))
+           ;; substring from index 1 to remove any leading `#' in the name
+           (face-name (concat "vc-annotate-face-" (substring (cdr color) 1)))
+           ;; Make the face if not done.
+           (face (or (intern-soft face-name)
+                     (let ((tmp-face (make-face (intern face-name))))
+                       (set-face-foreground tmp-face (cdr color))
+                       (if vc-annotate-background
+                           (set-face-background tmp-face vc-annotate-background))
+                       tmp-face)))      ; Return the face
+           (point (point))
+           overlay)
         (forward-line 1)
         (setq overlay (make-overlay point (point)))
         (overlay-put overlay 'face face)
-        (overlay-put overlay 'vc-annotation t)))))
+        (overlay-put overlay 'vc-annotation t))
+      (setq difference (vc-call-backend vc-annotate-backend 'annotate-difference (point))))))
 
 
 ;; Collect back-end-dependent stuff here
 
-(defun vc-backend-admin (file &optional rev comment)
-  ;; Register a file into the version-control system
-  ;; Automatically retrieves a read-only version of the file with
-  ;; keywords expanded if vc-keep-workfiles is non-nil, otherwise
-  ;; it deletes the workfile.
-  (vc-file-clearprops file)
-  (or vc-default-back-end
-      (setq vc-default-back-end (if (vc-find-binary "rcs") 'RCS 'SCCS)))
-  (message "Registering %s..." file)
-  (let* ((switches
-          (if (stringp vc-register-switches)
-              (list vc-register-switches)
-            vc-register-switches))
-         (project-dir)
-         (backend
-          (cond
-           ((file-exists-p (vc-backend-subdirectory-name)) vc-default-back-end)
-           ((file-exists-p "RCS") 'RCS)
-           ((file-exists-p "CVS") 'CVS)
-           ((file-exists-p "SCCS") 'SCCS)
-           ((setq project-dir (vc-sccs-project-dir)) 'SCCS)
-           (t vc-default-back-end))))
-    (cond ((eq backend 'SCCS)
-           (let ((vc-name
-                  (if project-dir (concat project-dir 
-                                          "s." (file-name-nondirectory file))
-                    (format
-                     (car (rassq 'SCCS vc-master-templates))
-                     (or (file-name-directory file) "")
-                     (file-name-nondirectory file)))))
-             (apply 'vc-do-command nil 0 "admin" nil nil        ;; SCCS
-                                   (and rev (concat "-r" rev))
-                                   "-fb"
-                                   (concat "-i" file)
-                                   (and comment (concat "-y" comment))
-                                   vc-name
-                                   switches))
-           (delete-file file)
-           (if vc-keep-workfiles
-               (vc-do-command nil 0 "get" file 'MASTER)))
-          ((eq backend 'RCS)
-           (apply 'vc-do-command nil 0 "ci" file 'WORKFILE      ;; RCS
-                                 ;; if available, use the secure registering option
-                                 (and (vc-backend-release-p 'RCS "5.6.4") "-i")
-                                 (concat (if vc-keep-workfiles "-u" "-r") rev)
-                                 (and comment (concat "-t-" comment))
-                                 switches))
-          ((eq backend 'CVS)
-           (apply 'vc-do-command nil 0 "cvs" file 'WORKFILE ;; CVS
-                                 "add"
-                                 (and comment (string-match "[^\t\n ]" comment)
-                                      (concat "-m" comment))
-                                 switches)
-           )))
-  (message "Registering %s...done" file)
-  )
+(defalias 'vc-default-logentry-check 'ignore)
 
-(defun vc-backend-checkout (file &optional writable rev workfile)
-  ;; Retrieve a copy of a saved version into a 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))
-          (vc-backend-dispatch file
-            (progn  ;; SCCS
-              (and rev (string= rev "") (setq rev nil))
-              (if workfile  
-                  ;; Some SCCS implementations allow checking out directly to a
-                  ;; file using the -G option, but then some don't so use the
-                  ;; least common denominator approach and use the -p option
-                  ;; ala RCS.
-                  (let ((vc-modes (logior (file-modes (vc-name file))
-                                          (if writable 128 0)))
-                        (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 "get" file 'MASTER
-                                     "-s" ;; suppress diagnostic output
-                                     (if writable "-e")
-                                     "-p" 
-                                     (and rev
-                                          (concat "-r" 
-                                                  (vc-lookup-triple file rev)))
-                                     switches)))
-                          (set-file-modes filename
-                                          (logior (file-modes (vc-name file))
-                                                  (if writable 128 0)))
-                          (setq failed nil))
-                      (and failed (file-exists-p filename) 
-                           (delete-file filename))))
-                (apply 'vc-do-command nil 0 "get" file 'MASTER   ;; SCCS
-                       (if writable "-e")
-                       (and rev (concat "-r" (vc-lookup-triple file rev)))
-                       switches)
-                (vc-file-setprop file 'vc-workfile-version nil)))
-            (if workfile  ;; RCS
-                ;; RCS doesn't let us check out into arbitrary file names directly.
-                ;; Use `co -p' and make stdout point to the correct file.
-                (let ((vc-modes (logior (file-modes (vc-name file))
-                                        (if writable 128 0)))
-                      (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 "co" file 'MASTER
-                                   "-q" ;; suppress diagnostic output
-                                   (if writable "-l")
-                                   (concat "-p" rev)
-                                   switches)))
-                        (set-file-modes filename 
-                                        (logior (file-modes (vc-name file))
-                                                (if writable 128 0)))
-                        (setq failed nil))
-                    (and failed (file-exists-p filename) (delete-file filename))))
-              (let (new-version)
-                ;; if we should go to the head of the trunk, 
-                ;; clear the default branch first
-                (and rev (string= rev "") 
-                     (vc-do-command nil 0 "rcs" file 'MASTER "-b"))
-                ;; now do the checkout
-                (apply 'vc-do-command
-                       nil 0 "co" file 'MASTER
-                       ;; If locking is not strict, force to overwrite
-                       ;; the writable workfile.
-                       (if (eq (vc-checkout-model file) 'implicit) "-f")
-                       (if writable "-l")
-                       (if rev (concat "-r" rev)
-                         ;; if no explicit revision was specified,
-                         ;; check out that of the working file
-                         (let ((workrev (vc-workfile-version file)))
-                           (if workrev (concat "-r" workrev)
-                             nil)))
-                       switches)
-                ;; determine the new workfile version
-                (save-excursion
-                  (set-buffer "*vc*")
-                  (goto-char (point-min))
-                  (setq new-version 
-                        (if (re-search-forward "^revision \\([0-9.]+\\).*\n" nil t)
-                            (buffer-substring (match-beginning 1) (match-end 1)))))
-                (vc-file-setprop file 'vc-workfile-version new-version)
-                ;; if necessary, adjust the default branch
-                (and rev (not (string= rev ""))
-                     (vc-do-command nil 0 "rcs" file 'MASTER 
-                        (concat "-b" (if (vc-latest-on-branch-p file)
-                                         (if (vc-trunk-p new-version) nil
-                                           (vc-branch-part new-version))
-                                       new-version))))))
-            (if workfile  ;; CVS
-                ;; CVS is much like RCS
-                (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 'WORKFILE 
-                                   "-Q" ;; suppress diagnostic output
-                                   "update"
-                                   (concat "-r" rev)
-                                   "-p"
-                                   switches)))
-                        (setq failed nil))
-                    (and failed (file-exists-p filename) (delete-file filename))))
-              ;; default for verbose checkout: clear the sticky tag
-              ;; so that the actual update will get the head of the trunk
-              (and rev (string= rev "")
-                   (vc-do-command nil 0 "cvs" file 'WORKFILE "update" "-A"))
-              ;; If a revision was specified, check that out.
-              (if rev
-                  (apply 'vc-do-command nil 0 "cvs" file 'WORKFILE 
-                         (and writable (eq (vc-checkout-model file) 'manual) "-w")
-                         "update"
-                         (and rev (not (string= rev ""))
-                              (concat "-r" rev))
-                         switches)
-                ;; If no revision was specified, call "cvs edit" to make
-                ;; the file writeable.
-                (and writable (eq (vc-checkout-model file) 'manual)
-                     (vc-do-command nil 0 "cvs" file 'WORKFILE "edit")))
-              (if rev (vc-file-setprop file 'vc-workfile-version nil))))
-          (cond 
-           ((not workfile)
-            (vc-file-clear-masterprops file)
-            (if writable 
-                (vc-file-setprop file 'vc-locking-user (vc-user-login-name)))
-            (vc-file-setprop file
-                             'vc-checkout-time (nth 5 (file-attributes file)))))
-          (message "Checking out %s...done" filename))))))
-
-(defun vc-backend-logentry-check (file)
-  (vc-backend-dispatch file
-   (if (>= (buffer-size) 512)   ;; SCCS
-       (progn
-         (goto-char 512)
-         (error
-          "Log must be less than 512 characters; point is now at pos 512")))
-   nil    ;; RCS
-   nil)   ;; CVS
-  )
-
-(defun vc-backend-checkin (file rev comment)
-  ;; Register changes to FILE as level REV with explanatory COMMENT.
-  ;; Automatically retrieves a read-only version of the file with
-  ;; keywords expanded if vc-keep-workfiles is non-nil, otherwise
-  ;; it deletes the workfile.
-  ;;   Adaptation for RCS branch support: if this is an explicit checkin,
-  ;; or if the checkin creates a new branch, set the master file branch
-  ;; accordingly.
-  (message "Checking in %s..." file)
-  ;; "This log message intentionally left almost blank".
-  ;; RCS 5.7 gripes about white-space-only comments too.
-  (or (and comment (string-match "[^\t\n ]" comment))
-      (setq comment "*** empty log message ***"))
-  (save-excursion
-    ;; Change buffers to get local value of vc-checkin-switches.
-    (set-buffer (or (get-file-buffer file) (current-buffer)))
-    (let ((switches
-           (if (stringp vc-checkin-switches)
-               (list vc-checkin-switches)
-             vc-checkin-switches)))
-      ;; Clear the master-properties.  Do that here, not at the
-      ;; end, because if the check-in fails we want them to get
-      ;; re-computed before the next try.
-      (vc-file-clear-masterprops file)
-      (vc-backend-dispatch file
-        ;; SCCS
-        (progn
-          (apply 'vc-do-command nil 0 "delta" file 'MASTER
-                 (if rev (concat "-r" rev))
-                 (concat "-y" comment)
-                 switches)
-          (vc-file-setprop file 'vc-locking-user 'none)
-          (vc-file-setprop file 'vc-workfile-version nil)
-          (if vc-keep-workfiles
-              (vc-do-command nil 0 "get" file 'MASTER))
-          )
-        ;; RCS
-        (let ((old-version (vc-workfile-version file)) new-version)
-          (apply 'vc-do-command nil 0 "ci" file 'MASTER
-                 ;; if available, use the secure check-in option
-                 (and (vc-backend-release-p 'RCS "5.6.4") "-j")
-                 (concat (if vc-keep-workfiles "-u" "-r") rev)
-                 (concat "-m" comment)
-                 switches)
-          (vc-file-setprop file 'vc-locking-user 'none)
-          (vc-file-setprop file 'vc-workfile-version nil)
-
-          ;; determine the new workfile version
-          (set-buffer "*vc*")
-          (goto-char (point-min))
-          (if (or (re-search-forward 
-                   "new revision: \\([0-9.]+\\);" nil t)
-                  (re-search-forward 
-                   "reverting to previous revision \\([0-9.]+\\)" nil t))
-              (progn (setq new-version (buffer-substring (match-beginning 1)
-                                                         (match-end 1)))
-                     (vc-file-setprop file 'vc-workfile-version new-version)))
-
-          ;; if we got to a different branch, adjust the default
-          ;; branch accordingly
-          (cond 
-           ((and old-version new-version
-                 (not (string= (vc-branch-part old-version)
-                               (vc-branch-part new-version))))
-            (vc-do-command nil 0 "rcs" file 'MASTER 
-                           (if (vc-trunk-p new-version) "-b"
-                             (concat "-b" (vc-branch-part new-version))))
-            ;; If this is an old RCS release, we might have 
-            ;; to remove a remaining lock.
-            (if (not (vc-backend-release-p 'RCS "5.6.2"))
-                ;; exit status of 1 is also accepted.
-                ;; It means that the lock was removed before.
-                (vc-do-command nil 1 "rcs" file 'MASTER 
-                               (concat "-u" old-version))))))
-        ;; CVS
-        (progn
-          ;; explicit check-in to the trunk requires a 
-          ;; double check-in (first unexplicit) (CVS-1.3)
-          (condition-case nil
-              (progn
-                (if (and rev (vc-trunk-p rev))
-                    (apply 'vc-do-command nil 0 "cvs" file 'WORKFILE 
-                           "ci" "-m" "intermediate"
-                           switches))
-                (apply 'vc-do-command nil 0 "cvs" file 'WORKFILE 
-                       "ci" (if rev (concat "-r" rev))
-                       (concat "-m" comment)
-                       switches))
-            (error (if (eq (vc-cvs-status file) 'needs-merge)
-                       ;; The CVS output will be on top of this message.
-                       (error "Type C-x 0 C-x C-q to merge in changes")
-                     (error "Check-in failed"))))
-          ;; determine and store the new workfile version
-          (set-buffer "*vc*")
-          (goto-char (point-min))
-          (if (re-search-forward 
-               "^\\(new\\|initial\\) revision: \\([0-9.]+\\)" nil t)
-              (vc-file-setprop file 'vc-workfile-version 
-                               (buffer-substring (match-beginning 2)
-                                                 (match-end 2)))
-            (vc-file-setprop file 'vc-workfile-version nil))
-          ;; if this was an explicit check-in, remove the sticky tag
-          (if rev
-              (vc-do-command nil 0 "cvs" file 'WORKFILE "update" "-A"))
-          ;; Forget the checkout model, because we might have assumed
-          ;; a wrong one when we found the file.  After commit, we can
-          ;; tell it from the permissions of the file 
-          ;; (see vc-checkout-model).
-          (vc-file-setprop file 'vc-checkout-model nil)
-          (vc-file-setprop file 'vc-locking-user 'none)
-          (vc-file-setprop file 'vc-checkout-time 
-                           (nth 5 (file-attributes file)))))))
-  (message "Checking in %s...done" file))
-
-(defun vc-backend-revert (file)
-  ;; Revert file to the version it was based on.
-  (message "Reverting %s..." file)
-  (vc-file-clear-masterprops file)
-  (vc-backend-dispatch
-   file
-   ;; SCCS
-   (progn
-     (vc-do-command nil 0 "unget" file 'MASTER nil)
-     (vc-do-command nil 0 "get" file 'MASTER nil)
-     ;; Checking out explicit versions is not supported under SCCS, yet.
-     ;; We always "revert" to the latest version; therefore 
-     ;; vc-workfile-version is cleared here so that it gets recomputed.
-     (vc-file-setprop file 'vc-workfile-version nil))
-   ;; RCS
-   (vc-do-command nil 0 "co" file 'MASTER
-                  "-f" (concat "-u" (vc-workfile-version file)))
-   ;; CVS
-   (progn
-     ;; Check out via standard output (caused by the final argument 
-     ;; FILE below), so that no sticky tag is set.      
-     (vc-backend-checkout file nil (vc-workfile-version file) file)
-     ;; If "cvs edit" was used to make the file writeable,
-     ;; call "cvs unedit" now to undo that.
-     (if (eq (vc-checkout-model file) 'manual)
-         (vc-do-command nil 0 "cvs" file 'WORKFILE "unedit"))))
-  (vc-file-setprop file 'vc-locking-user 'none)
-  (vc-file-setprop file 'vc-checkout-time (nth 5 (file-attributes file)))
-  (message "Reverting %s...done" file)
-  )
-
-(defun vc-backend-steal (file &optional rev)
-  ;; Steal the lock on the current workfile.  Needs RCS 5.6.2 or later for -M.
-  (message "Stealing lock on %s..." file)
-  (vc-backend-dispatch file
-   (progn                               ;SCCS
-     (vc-do-command nil 0 "unget" file 'MASTER "-n" (if rev (concat "-r" rev)))
-     (vc-do-command nil 0 "get" file 'MASTER "-g" (if rev (concat "-r" rev)))
-     )
-   (vc-do-command nil 0 "rcs" file 'MASTER      ;RCS
-                  "-M" (concat "-u" rev) (concat "-l" rev))
-   (error "You cannot steal a CVS lock; there are no CVS locks to steal") ;CVS
-   )
-  (vc-file-setprop file 'vc-locking-user (vc-user-login-name))
-  (message "Stealing lock on %s...done" file)
-  )  
-
-(defun vc-backend-uncheck (file target)
-  ;; Undo the latest checkin.
-  (message "Removing last change from %s..." file)
-  (vc-backend-dispatch file
-   (vc-do-command nil 0 "rmdel" file 'MASTER (concat "-r" target))
-   (vc-do-command nil 0 "rcs" file 'MASTER (concat "-o" target))
-   nil  ;; this is never reached under CVS
-   )
-  (message "Removing last change from %s...done" file)
-  )
-
-(defun vc-backend-print-log (file)
-  ;; Get change log associated with FILE.
-  (vc-backend-dispatch 
-   file
-   (vc-do-command nil 0 "prs" file 'MASTER)
-   (vc-do-command nil 0 "rlog" file 'MASTER)
-   (vc-do-command nil 0 "cvs" file 'WORKFILE "log")))
-
-(defun vc-backend-assign-name (file name)
-  ;; Assign to a FILE's latest version a given NAME.
-  (vc-backend-dispatch file
-   (vc-add-triple name file (vc-latest-version file))              ;; SCCS
-   (vc-do-command nil 0 "rcs" file 'MASTER (concat "-n" name ":")) ;; RCS
-   (vc-do-command nil 0 "cvs" file 'WORKFILE "tag" name)           ;; CVS
-   )
-  )
-
-(defun vc-backend-diff (file &optional oldvers newvers cmp)
-  ;; Get a difference report between two versions of FILE.
-  ;; Get only a brief comparison report if CMP, a difference report otherwise.
-  (let ((backend (vc-backend file)) options status
-        (diff-switches-list (if (listp diff-switches) 
-                                diff-switches 
-                              (list diff-switches))))
-    (cond
-     ((eq backend 'SCCS)
-      (setq oldvers (vc-lookup-triple file oldvers))
-      (setq newvers (vc-lookup-triple file newvers))
-      (setq options (append (list (and cmp "--brief") "-q"
-                                  (and oldvers (concat "-r" oldvers))
-                                  (and newvers (concat "-r" newvers)))
-                            (and (not cmp) diff-switches-list)))
-      (apply 'vc-do-command "*vc-diff*" 1 "vcdiff" file 'MASTER options))
-     ((eq backend 'RCS)
-      (if (not oldvers) (setq oldvers (vc-workfile-version file)))
-      ;; If we know that --brief is not supported, don't try it.
-      (setq cmp (and cmp (not (eq vc-rcsdiff-knows-brief 'no))))
-      (setq options (append (list (and cmp "--brief") "-q"
-                                  (concat "-r" oldvers)
-                                  (and newvers (concat "-r" newvers)))
-                            (and (not cmp) diff-switches-list)))
-      (setq status (apply 'vc-do-command "*vc-diff*" 2 
-                          "rcsdiff" file 'WORKFILE options))
-      ;; If --brief didn't work, do a double-take and remember it 
-      ;; for the future.
-      (if (eq status 2)
-          (setq status
-                (prog1
-                    (apply 'vc-do-command "*vc-diff*" 1 "rcsdiff" file 'WORKFILE
-                           (if cmp (cdr options) options))
-                  (if cmp (setq vc-rcsdiff-knows-brief 'no))))
-        ;; If --brief DID work, remember that, too.
-        (and cmp (not vc-rcsdiff-knows-brief)
-             (setq vc-rcsdiff-knows-brief 'yes))
-        status))
-     ;; CVS is different.  
-     ((eq backend 'CVS)
-      (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)
-            (if cmp 1 ;; file is added but not committed, 
-                      ;; we regard this as "changed".
-              ;; diff it against /dev/null.
-              (apply 'vc-do-command
-                     "*vc-diff*" 1 "diff" file 'WORKFILE
-                     (append diff-switches-list '("/dev/null")))))
-        ;; cmp is not yet implemented -- we always do a full diff.
-        (apply 'vc-do-command
-               "*vc-diff*" 1 "cvs" file 'WORKFILE "diff"
-               (and oldvers (concat "-r" oldvers))
-               (and newvers (concat "-r" newvers))
-               diff-switches-list))))))
-
-(defun vc-backend-merge-news (file)
-  ;; Merge in any new changes made to FILE.
-  (message "Merging changes into %s..." file)
-  (prog1
-      (vc-backend-dispatch 
-       file
-       (error "vc-backend-merge-news not meaningful for SCCS files") ;SCCS
-       (error "vc-backend-merge-news not meaningful for RCS files")     ;RCS
-       (save-excursion  ; CVS
-         (vc-file-clear-masterprops file)
-         (vc-file-setprop file 'vc-workfile-version nil)
-         (vc-file-setprop file 'vc-locking-user nil)
-         (vc-file-setprop file 'vc-checkout-time nil)
-         (vc-do-command nil 0 "cvs" file 'WORKFILE "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)))
-         ;; get file status
-         (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 (string= (match-string 2) "U")
-                   (string= (match-string 2) "P")
-                   ;; Special case: file contents in sync with
-                   ;; repository anyhow:
-                   (match-string 3))
-               (vc-file-setprop file 'vc-locking-user 'none)
-               (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 2) "M")
-               (vc-file-setprop file 'vc-locking-user (vc-file-owner file))
-               (vc-file-setprop file 'vc-checkout-time 0)
-               0) ;; indicate success to the caller
-              ;; Conflicts detected!
-              ((string= (match-string 2) "C")
-               (vc-file-setprop file 'vc-locking-user (vc-file-owner file))
-               (vc-file-setprop file 'vc-checkout-time 0)
-               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-backend-merge (file first-version &optional second-version)
-  ;; Merge the changes between FIRST-VERSION and SECOND-VERSION into
-  ;; the current working copy of FILE.  It is assumed that FILE is
-  ;; locked and writable (vc-merge ensures this).
-  (vc-backend-dispatch file
-   ;; SCCS
-   (error "Sorry, merging is not implemented for SCCS")
-   ;; RCS
-   (vc-do-command nil 1 "rcsmerge" file 'MASTER
-                  "-kk" ;; ignore keyword conflicts
-                  (concat "-r" first-version)
-                  (if second-version (concat "-r" second-version)))
-   ;; CVS
-   (progn
-     (vc-do-command nil 0 "cvs" file 'WORKFILE
-                    "update" "-kk"
-                    (concat "-j" first-version)
-                    (concat "-j" second-version))
-     (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-default-merge-news (backend file)
+  (error "vc-merge-news not meaningful for %s files" backend))
 
 (defun vc-check-headers ()
   "Check if the current file has any headers in it."
   (interactive)
-  (save-excursion
-    (goto-char (point-min))
-    (vc-backend-dispatch buffer-file-name
-     (re-search-forward  "%[MIRLBSDHTEGUYFPQCZWA]%" nil t)      ;; SCCS
-     (re-search-forward "\\$[A-Za-z\300-\326\330-\366\370-\377]+\\(: [\t -#%-\176\240-\377]*\\)?\\$" nil t)             ;; RCS
-     'RCS                               ;; CVS works like RCS in this regard.
-     )
-    ))
+  (vc-call-backend (vc-backend buffer-file-name) 'check-headers))
 
 ;; Back-end-dependent stuff ends here.
 
 ;; Set up key bindings for use while editing log messages
 
 (defun vc-log-mode (&optional file)
-  "Minor mode for driving version-control tools.
+  "Major mode for editing VC log entries.
 These bindings are added to the global keymap when you enter this mode:
 \\[vc-next-action]              perform next logical version-control operation on current file
-\\[vc-register]                 register current file
+\\[vc-register]         register current file
 \\[vc-toggle-read-only]         like next-action, but won't register files
 \\[vc-insert-headers]           insert version-control headers in current file
 \\[vc-print-log]                display change history of current file
@@ -3090,7 +2519,7 @@ These bindings are added to the global keymap when you enter this mode:
 \\[vc-diff]             show diffs between file versions
 \\[vc-version-other-window]             visit old version in another window
 \\[vc-directory]                show all files locked by any user in or below .
-\\[vc-annotate]         colorful display of the cvs annotate command 
+\\[vc-annotate]         colorful display of the cvs annotate command
 \\[vc-update-change-log]                add change log entry from recent checkins
 
 While you are entering a change log message for a version, the following
@@ -3106,39 +2535,39 @@ saved comments.  These can be recalled as follows:
 \\[vc-comment-search-reverse]   search backward for regexp in the comment ring
 \\[vc-comment-search-forward]   search backward for regexp in the comment ring
 
-Entry to the change-log submode calls the value of text-mode-hook, then
-the value of vc-log-mode-hook.
+Entry to the change-log submode calls the value of `text-mode-hook', then
+the value of `vc-log-mode-hook'.
 
 Global user options:
-        vc-initial-comment      If non-nil, require user to enter a change
+        `vc-initial-comment'    If non-nil, require user to enter a change
                                 comment upon first checkin of the file.
 
-        vc-keep-workfiles       Non-nil value prevents workfiles from being
+        `vc-keep-workfiles'     Non-nil value prevents workfiles from being
                                 deleted when changes are checked in
 
-        vc-suppress-confirm     Suppresses some confirmation prompts,
+        `vc-suppress-confirm'   Suppresses some confirmation prompts,
                                 notably for reversions.
 
-        vc-header-alist         Which keywords to insert when adding headers
+        vc-BACKEND-header       Which keywords to insert when adding headers
                                 with \\[vc-insert-headers].  Defaults to
-                                '(\"\%\W\%\") under SCCS, '(\"\$Id\$\") under 
+                                '(\"\%\W\%\") under SCCS, '(\"\$Id\$\") under
                                 RCS and CVS.
 
-        vc-static-header-alist  By default, version headers inserted in C files
+        `vc-static-header-alist' By default, version headers inserted in C files
                                 get stuffed in a static string area so that
                                 ident(RCS/CVS) or what(SCCS) can see them in
                                 the compiled object code.  You can override
                                 this by setting this variable to nil, or change
                                 the header template by changing it.
 
-        vc-command-messages     if non-nil, display run messages from the
+        `vc-command-messages'   if non-nil, display run messages from the
                                 actual version-control utilities (this is
                                 intended primarily for people hacking vc
                                 itself).
 "
   (interactive)
   (set-syntax-table text-mode-syntax-table)
-  (use-local-map vc-log-entry-mode)
+  (use-local-map vc-log-mode-map)
   (setq local-abbrev-table text-mode-abbrev-table)
   (setq major-mode 'vc-log-mode)
   (setq mode-name "VC-Log")
@@ -3148,43 +2577,39 @@ Global user options:
   (make-local-variable 'vc-comment-ring-index)
   (set-buffer-modified-p nil)
   (setq buffer-file-name nil)
-  (run-hooks 'text-mode-hook 'vc-log-mode-hook)
-)
-
-;; Initialization code, to be done just once at load-time
-(if vc-log-entry-mode
-    nil
-  (setq vc-log-entry-mode (make-sparse-keymap))
-  (define-key vc-log-entry-mode "\M-n" 'vc-next-comment)
-  (define-key vc-log-entry-mode "\M-p" 'vc-previous-comment)
-  (define-key vc-log-entry-mode "\M-r" 'vc-comment-search-reverse)
-  (define-key vc-log-entry-mode "\M-s" 'vc-comment-search-forward)
-  (define-key vc-log-entry-mode "\C-c\C-c" 'vc-finish-logentry)
-  )
+  (run-hooks 'text-mode-hook 'vc-log-mode-hook))
+
+(defun vc-log-edit (file)
+  "Interface between VC and `log-edit'."
+  (setq default-directory (file-name-directory file))
+  (log-edit 'vc-finish-logentry nil
+            `(lambda () ',(list (file-name-nondirectory file))))
+  (set (make-local-variable 'vc-log-file) file)
+  (make-local-variable 'vc-log-version)
+  (setq buffer-file-name nil))
 
 ;;; These things should probably be generally available
 
 (defun vc-file-tree-walk (dirname func &rest args)
   "Walk recursively through DIRNAME.
-Invoke FUNC f ARGS on each non-directory file f underneath it."
+Invoke FUNC f ARGS on each VC-managed file f underneath it."
   (vc-file-tree-walk-internal (expand-file-name dirname) func args)
   (message "Traversing directory %s...done" dirname))
 
 (defun vc-file-tree-walk-internal (file func args)
   (if (not (file-directory-p file))
-      (apply func file args)
+      (if (vc-backend file) (apply func file args))
     (message "Traversing directory %s..." (abbreviate-file-name file))
     (let ((dir (file-name-as-directory file)))
       (mapcar
-       (function
-        (lambda (f) (or
-                     (string-equal f ".")
-                     (string-equal f "..")
-                     (member f vc-directory-exclusion-list)
-                     (let ((dirf (concat dir f)))
-                        (or
-                         (file-symlink-p dirf) ;; Avoid possible loops
-                         (vc-file-tree-walk-internal dirf func args))))))
+       (lambda (f) (or
+                    (string-equal f ".")
+                    (string-equal f "..")
+                    (member f vc-directory-exclusion-list)
+                    (let ((dirf (expand-file-name f dir)))
+                      (or
+                       (file-symlink-p dirf);; Avoid possible loops
+                       (vc-file-tree-walk-internal dirf func args)))))
        (directory-files dir)))))
 
 (provide 'vc)
@@ -3195,61 +2620,61 @@ Invoke FUNC f ARGS on each non-directory file f underneath it."
 ;;; (Note that this information corresponds to versions 5.x. Some of it
 ;;; might have been invalidated by the additions to support branching
 ;;; and RCS keyword lookup. AS, 1995/03/24)
-;;; 
+;;;
 ;;; A fundamental problem in VC is that there are time windows between
 ;;; vc-next-action's computations of the file's version-control state and
 ;;; the actions that change it.  This is a window open to lossage in a
 ;;; multi-user environment; someone else could nip in and change the state
 ;;; of the master during it.
-;;; 
+;;;
 ;;; The performance problem is that rlog/prs calls are very expensive; we want
 ;;; to avoid them as much as possible.
-;;; 
+;;;
 ;;; ANALYSIS:
-;;; 
+;;;
 ;;; The performance problem, it turns out, simplifies in practice to the
-;;; problem of making vc-locking-user fast.  The two other functions that call
+;;; problem of making vc-state fast.  The two other functions that call
 ;;; prs/rlog will not be so commonly used that the slowdown is a problem; one
 ;;; makes snapshots, the other deletes the calling user's last change in the
 ;;; master.
-;;; 
+;;;
 ;;; The race condition implies that we have to either (a) lock the master
 ;;; during the entire execution of vc-next-action, or (b) detect and
 ;;; recover from errors resulting from dispatch on an out-of-date state.
-;;; 
+;;;
 ;;; Alternative (a) appears to be infeasible.  The problem is that we can't
 ;;; guarantee that the lock will ever be removed.  Suppose a user starts a
 ;;; checkin, the change message buffer pops up, and the user, having wandered
 ;;; off to do something else, simply forgets about it?
-;;; 
+;;;
 ;;; Alternative (b), on the other hand, works well with a cheap way to speed up
-;;; vc-locking-user.  Usually, if a file is registered, we can read its locked/
+;;; vc-state.  Usually, if a file is registered, we can read its locked/
 ;;; unlocked state and its current owner from its permissions.
-;;; 
+;;;
 ;;; This shortcut will fail if someone has manually changed the workfile's
 ;;; permissions; also if developers are munging the workfile in several
 ;;; directories, with symlinks to a master (in this latter case, the
 ;;; permissions shortcut will fail to detect a lock asserted from another
 ;;; directory).
-;;; 
+;;;
 ;;; Note that these cases correspond exactly to the errors which could happen
 ;;; because of a competing checkin/checkout race in between two instances of
 ;;; vc-next-action.
-;;; 
+;;;
 ;;; For VC's purposes, a workfile/master pair may have the following states:
-;;; 
+;;;
 ;;; A. Unregistered.  There is a workfile, there is no master.
-;;; 
+;;;
 ;;; B. Registered and not locked by anyone.
-;;; 
+;;;
 ;;; C. Locked by calling user and unchanged.
-;;; 
+;;;
 ;;; D. Locked by the calling user and changed.
-;;; 
+;;;
 ;;; E. Locked by someone other than the calling user.
-;;; 
+;;;
 ;;; This makes for 25 states and 20 error conditions.  Here's the matrix:
-;;; 
+;;;
 ;;; VC's idea of state
 ;;;  |
 ;;;  V  Actual state   RCS action              SCCS action          Effect
@@ -3259,280 +2684,280 @@ Invoke FUNC f ARGS on each non-directory file f underneath it."
 ;;;  C 9  10 .  11 12  co -u              unget; get              revert
 ;;;  D 13 14 15 .  16  ci -u -m<comment>  delta -y<comment>; get  checkin
 ;;;  E 17 18 19 20 .   rcs -u -M -l       unget -n ; get -g       steal lock
-;;; 
+;;;
 ;;; All commands take the master file name as a last argument (not shown).
-;;; 
+;;;
 ;;; In the discussion below, a "self-race" is a pathological situation in
 ;;; which VC operations are being attempted simultaneously by two or more
 ;;; Emacsen running under the same username.
-;;; 
+;;;
 ;;; The vc-next-action code has the following windows:
-;;; 
+;;;
 ;;; Window P:
 ;;;    Between the check for existence of a master file and the call to
 ;;; admin/checkin in vc-buffer-admin (apparent state A).  This window may
 ;;; never close if the initial-comment feature is on.
-;;; 
+;;;
 ;;; Window Q:
 ;;;    Between the call to vc-workfile-unchanged-p in and the immediately
 ;;; following revert (apparent state C).
-;;; 
+;;;
 ;;; Window R:
 ;;;    Between the call to vc-workfile-unchanged-p in and the following
 ;;; checkin (apparent state D).  This window may never close.
-;;; 
+;;;
 ;;; Window S:
 ;;;    Between the unlock and the immediately following checkout during a
 ;;; revert operation (apparent state C).  Included in window Q.
-;;; 
+;;;
 ;;; Window T:
-;;;    Between vc-locking-user and the following checkout (apparent state B).
-;;; 
+;;;    Between vc-state and the following checkout (apparent state B).
+;;;
 ;;; Window U:
-;;;    Between vc-locking-user and the following revert (apparent state C).
+;;;    Between vc-state and the following revert (apparent state C).
 ;;; Includes windows Q and S.
-;;; 
+;;;
 ;;; Window V:
-;;;    Between vc-locking-user and the following checkin (apparent state
+;;;    Between vc-state and the following checkin (apparent state
 ;;; D).  This window may never be closed if the user fails to complete the
 ;;; checkin message.  Includes window R.
-;;; 
+;;;
 ;;; Window W:
-;;;    Between vc-locking-user and the following steal-lock (apparent
+;;;    Between vc-state and the following steal-lock (apparent
 ;;; state E).  This window may never close if the user fails to complete
 ;;; the steal-lock message.  Includes window X.
-;;; 
+;;;
 ;;; Window X:
 ;;;    Between the unlock and the immediately following re-lock during a
-;;; steal-lock operation (apparent state E).  This window may never cloce
+;;; steal-lock operation (apparent state E).  This window may never close
 ;;; if the user fails to complete the steal-lock message.
-;;; 
+;;;
 ;;; Errors:
-;;; 
+;;;
 ;;; Apparent state A ---
 ;;;
 ;;; 1. File looked unregistered but is actually registered and not locked.
-;;; 
+;;;
 ;;;    Potential cause: someone else's admin during window P, with
 ;;; caller's admin happening before their checkout.
-;;; 
+;;;
 ;;;    RCS: Prior to version 5.6.4, ci fails with message
 ;;;         "no lock set by <user>".  From 5.6.4 onwards, VC uses the new
 ;;;         ci -i option and the message is "<file>,v: already exists".
 ;;;    SCCS: admin will fail with error (ad19).
-;;; 
+;;;
 ;;;    We can let these errors be passed up to the user.
-;;; 
+;;;
 ;;; 2. File looked unregistered but is actually locked by caller, unchanged.
-;;; 
+;;;
 ;;;    Potential cause: self-race during window P.
-;;; 
+;;;
 ;;;    RCS: Prior to version 5.6.4, reverts the file to the last saved
 ;;;         version and unlocks it.  From 5.6.4 onwards, VC uses the new
 ;;;         ci -i option, failing with message "<file>,v: already exists".
 ;;;    SCCS: will fail with error (ad19).
-;;; 
+;;;
 ;;;    Either of these consequences is acceptable.
-;;; 
+;;;
 ;;; 3. File looked unregistered but is actually locked by caller, changed.
-;;; 
+;;;
 ;;;    Potential cause: self-race during window P.
-;;; 
-;;;    RCS: Prior to version 5.6.4, VC registers the caller's workfile as 
-;;;         a delta with a null change comment (the -t- switch will be 
+;;;
+;;;    RCS: Prior to version 5.6.4, VC registers the caller's workfile as
+;;;         a delta with a null change comment (the -t- switch will be
 ;;;         ignored). From 5.6.4 onwards, VC uses the new ci -i option,
 ;;;         failing with message "<file>,v: already exists".
 ;;;    SCCS: will fail with error (ad19).
-;;; 
+;;;
 ;;; 4. File looked unregistered but is locked by someone else.
-;;; 
+;;;
 ;;;    Potential cause: someone else's admin during window P, with
 ;;; caller's admin happening *after* their checkout.
-;;; 
-;;;    RCS: Prior to version 5.6.4, ci fails with a 
-;;;         "no lock set by <user>" message.  From 5.6.4 onwards, 
-;;;         VC uses the new ci -i option, failing with message 
+;;;
+;;;    RCS: Prior to version 5.6.4, ci fails with a
+;;;         "no lock set by <user>" message.  From 5.6.4 onwards,
+;;;         VC uses the new ci -i option, failing with message
 ;;;         "<file>,v: already exists".
 ;;;    SCCS: will fail with error (ad19).
-;;; 
+;;;
 ;;;    We can let these errors be passed up to the user.
-;;; 
+;;;
 ;;; Apparent state B ---
 ;;;
 ;;; 5. File looked registered and not locked, but is actually unregistered.
-;;; 
+;;;
 ;;;    Potential cause: master file got nuked during window P.
-;;; 
+;;;
 ;;;    RCS: will fail with "RCS/<file>: No such file or directory"
 ;;;    SCCS: will fail with error ut4.
-;;; 
+;;;
 ;;;    We can let these errors be passed up to the user.
-;;; 
+;;;
 ;;; 6. File looked registered and not locked, but is actually locked by the
 ;;; calling user and unchanged.
-;;; 
+;;;
 ;;;    Potential cause: self-race during window T.
-;;; 
+;;;
 ;;;    RCS: in the same directory as the previous workfile, co -l will fail
 ;;; with "co error: writable foo exists; checkout aborted".  In any other
 ;;; directory, checkout will succeed.
 ;;;    SCCS: will fail with ge17.
-;;; 
+;;;
 ;;;    Either of these consequences is acceptable.
-;;; 
+;;;
 ;;; 7. File looked registered and not locked, but is actually locked by the
 ;;; calling user and changed.
-;;; 
+;;;
 ;;;    As case 6.
-;;; 
+;;;
 ;;; 8. File looked registered and not locked, but is actually locked by another
 ;;; user.
-;;; 
+;;;
 ;;;    Potential cause: someone else checks it out during window T.
-;;; 
+;;;
 ;;;    RCS: co error: revision 1.3 already locked by <user>
 ;;;    SCCS: fails with ge4 (in directory) or ut7 (outside it).
-;;; 
+;;;
 ;;;    We can let these errors be passed up to the user.
-;;; 
+;;;
 ;;; Apparent state C ---
 ;;;
 ;;; 9. File looks locked by calling user and unchanged, but is unregistered.
-;;; 
+;;;
 ;;;    As case 5.
-;;; 
+;;;
 ;;; 10. File looks locked by calling user and unchanged, but is actually not
 ;;; locked.
-;;; 
+;;;
 ;;;    Potential cause: a self-race in window U, or by the revert's
 ;;; landing during window X of some other user's steal-lock or window S
 ;;; of another user's revert.
-;;; 
+;;;
 ;;;    RCS: succeeds, refreshing the file from the identical version in
 ;;; the master.
 ;;;    SCCS: fails with error ut4 (p file nonexistent).
 ;;;
 ;;;    Either of these consequences is acceptable.
-;;; 
+;;;
 ;;; 11. File is locked by calling user.  It looks unchanged, but is actually
 ;;; changed.
-;;; 
+;;;
 ;;;    Potential cause: the file would have to be touched by a self-race
 ;;; during window Q.
-;;; 
+;;;
 ;;;    The revert will succeed, removing whatever changes came with
 ;;; the touch.  It is theoretically possible that work could be lost.
-;;; 
+;;;
 ;;; 12. File looks like it's locked by the calling user and unchanged, but
 ;;; it's actually locked by someone else.
-;;; 
+;;;
 ;;;    Potential cause: a steal-lock in window V.
-;;; 
+;;;
 ;;;    RCS: co error: revision <rev> locked by <user>; use co -r or rcs -u
 ;;;    SCCS: fails with error un2
-;;; 
+;;;
 ;;;    We can pass these errors up to the user.
-;;; 
+;;;
 ;;; Apparent state D ---
 ;;;
 ;;; 13. File looks like it's locked by the calling user and changed, but it's
 ;;; actually unregistered.
-;;; 
+;;;
 ;;;    Potential cause: master file got nuked during window P.
-;;; 
-;;;    RCS: Prior to version 5.6.4, checks in the user's version as an 
+;;;
+;;;    RCS: Prior to version 5.6.4, checks in the user's version as an
 ;;;         initial delta.  From 5.6.4 onwards, VC uses the new ci -j
 ;;;         option, failing with message "no such file or directory".
 ;;;    SCCS: will fail with error ut4.
 ;;;
 ;;;    This case is kind of nasty.  Under RCS prior to version 5.6.4,
 ;;; VC may fail to detect the loss of previous version information.
-;;; 
+;;;
 ;;; 14. File looks like it's locked by the calling user and changed, but it's
 ;;; actually unlocked.
-;;; 
+;;;
 ;;;    Potential cause: self-race in window V, or the checkin happening
 ;;; during the window X of someone else's steal-lock or window S of
 ;;; someone else's revert.
-;;; 
+;;;
 ;;;    RCS: ci will fail with "no lock set by <user>".
 ;;;    SCCS: delta will fail with error ut4.
-;;; 
+;;;
 ;;; 15. File looks like it's locked by the calling user and changed, but it's
 ;;; actually locked by the calling user and unchanged.
-;;; 
+;;;
 ;;;    Potential cause: another self-race --- a whole checkin/checkout
 ;;; sequence by the calling user would have to land in window R.
-;;; 
+;;;
 ;;;    SCCS: checks in a redundant delta and leaves the file unlocked as usual.
 ;;;    RCS: reverts to the file state as of the second user's checkin, leaving
 ;;; the file unlocked.
 ;;;
 ;;;    It is theoretically possible that work could be lost under RCS.
-;;; 
+;;;
 ;;; 16. File looks like it's locked by the calling user and changed, but it's
 ;;; actually locked by a different user.
-;;; 
+;;;
 ;;;    RCS: ci error: no lock set by <user>
 ;;;    SCCS: unget will fail with error un2
-;;; 
+;;;
 ;;;    We can pass these errors up to the user.
-;;; 
+;;;
 ;;; Apparent state E ---
 ;;;
 ;;; 17. File looks like it's locked by some other user, but it's actually
 ;;; unregistered.
-;;; 
+;;;
 ;;;    As case 13.
-;;; 
+;;;
 ;;; 18. File looks like it's locked by some other user, but it's actually
 ;;; unlocked.
-;;; 
+;;;
 ;;;    Potential cause: someone released a lock during window W.
-;;; 
+;;;
 ;;;    RCS: The calling user will get the lock on the file.
 ;;;    SCCS: unget -n will fail with cm4.
-;;; 
+;;;
 ;;;    Either of these consequences will be OK.
-;;; 
+;;;
 ;;; 19. File looks like it's locked by some other user, but it's actually
 ;;; locked by the calling user and unchanged.
-;;; 
+;;;
 ;;;    Potential cause: the other user relinquishing a lock followed by
 ;;; a self-race, both in window W.
-;;; 
+;;;
 ;;;     Under both RCS and SCCS, both unlock and lock will succeed, making
 ;;; the sequence a no-op.
-;;; 
+;;;
 ;;; 20. File looks like it's locked by some other user, but it's actually
 ;;; locked by the calling user and changed.
-;;; 
+;;;
 ;;;     As case 19.
-;;; 
+;;;
 ;;; PROBLEM CASES:
-;;; 
+;;;
 ;;;    In order of decreasing severity:
-;;; 
+;;;
 ;;;    Cases 11 and 15 are the only ones that potentially lose work.
 ;;; They would require a self-race for this to happen.
-;;; 
+;;;
 ;;;    Case 13 in RCS loses information about previous deltas, retaining
 ;;; only the information in the current workfile.  This can only happen
 ;;; if the master file gets nuked in window P.
-;;; 
+;;;
 ;;;    Case 3 in RCS and case 15 under SCCS insert a redundant delta with
 ;;; no change comment in the master.  This would require a self-race in
 ;;; window P or R respectively.
-;;; 
+;;;
 ;;;    Cases 2, 10, 19 and 20 do extra work, but make no changes.
-;;; 
+;;;
 ;;;    Unfortunately, it appears to me that no recovery is possible in these
 ;;; cases.  They don't yield error messages, so there's no way to tell that
 ;;; a race condition has occurred.
-;;; 
+;;;
 ;;;    All other cases don't change either the workfile or the master, and
 ;;; trigger command errors which the user will see.
-;;; 
+;;;
 ;;;    Thus, there is no explicit recovery code.
 
 ;;; vc.el ends here