3 files changed, 34 insertions, 32 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 7aae8fd7854..d7004237adf 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,12 @@
 2012-09-07  Chong Yidong  <cyd@gnu.org>
 
+        * subr.el (read-char-choice): Allow quitting via ESC ESC.
+
+        * userlock.el (ask-user-about-supersession-threat): Use
+        read-char-choice (Bug#12093).
+
+2012-09-07  Chong Yidong  <cyd@gnu.org>
+
         * subr.el (buffer-narrowed-p): New function.
 
         * ses.el (ses-widen):
diff --git a/lisp/subr.el b/lisp/subr.el
index 621622e70eb..a3e0897e9fe 100644
--- a/lisp/subr.el
+++ b/lisp/subr.el
@@ -2237,7 +2237,8 @@ keyboard-quit events while waiting for a valid input."
     (error "Called `read-char-choice' without valid char choices"))
   (let (char done show-help (helpbuf " *Char Help*"))
     (let ((cursor-in-echo-area t)
-          (executing-kbd-macro executing-kbd-macro))
+          (executing-kbd-macro executing-kbd-macro)
+          (esc-flag nil))
       (save-window-excursion          ; in case we call help-form-show
         (while (not done)
           (unless (get-text-property 0 'face prompt)
@@ -2261,8 +2262,12 @@ keyboard-quit events while waiting for a valid input."
             ;; there are no more events in the macro.  Attempt to
             ;; get an event interactively.
             (setq executing-kbd-macro nil))
-           ((and (not inhibit-keyboard-quit) (eq char ?\C-g))
-            (keyboard-quit))))))
+           ((not inhibit-keyboard-quit)
+            (cond
+             ((and (null esc-flag) (eq char ?\e))
+              (setq esc-flag t))
+             ((memq char '(?\C-g ?\e))
+              (keyboard-quit))))))))
     ;; Display the question with the answer.  But without cursor-in-echo-area.
     (message "%s%s" prompt (char-to-string char))
     char))
diff --git a/lisp/userlock.el b/lisp/userlock.el
index 705d9588249..4c003e423aa 100644
--- a/lisp/userlock.el
+++ b/lisp/userlock.el
@@ -108,37 +108,27 @@ You can rewrite this to use any criterion you like to choose which one to do.
 The buffer in question is current when this function is called."
   (discard-input)
   (save-window-excursion
-    (let (answer)
+    (let ((prompt
+           (format "%s changed on disk; \
+really edit the buffer? (y, n, r or C-h) "
+                   (file-name-nondirectory fn)))
+          (choices '(?y ?n ?r ?? ?\C-h))
+          answer)
       (while (null answer)
-        (message "%s changed on disk; really edit the buffer? (y, n, r or C-h) "
-                 (file-name-nondirectory fn))
-        (let ((tem (downcase (let ((cursor-in-echo-area t))
-                               (read-char-exclusive)))))
-          (setq answer
-                (if (= tem help-char)
-                    'help
-                  (cdr (assoc tem '((?n . yield)
-                                    (?\C-g . yield)
-                                    (?y . proceed)
-                                    (?r . revert)
-                                    (?? . help))))))
-          (cond ((null answer)
-                 (beep)
-                 (message "Please type y, n or r; or ? for help")
-                 (sit-for 3))
-                ((eq answer 'help)
-                 (ask-user-about-supersession-help)
-                 (setq answer nil))
-                ((eq answer 'revert)
-                 (revert-buffer nil (not (buffer-modified-p)))
-                                        ; ask confirmation if buffer modified
-                 (signal 'file-supersession
-                         (list "File reverted" fn)))
-                ((eq answer 'yield)
-                 (signal 'file-supersession
-                         (list "File changed on disk" fn))))))
+        (setq answer (read-char-choice prompt choices))
+        (cond ((memq answer '(?? ?\C-h))
+               (ask-user-about-supersession-help)
+               (setq answer nil))
+              ((eq answer ?r)
+               ;; Ask for confirmation if buffer modified
+               (revert-buffer nil (not (buffer-modified-p)))
+               (signal 'file-supersession
+                       (list "File reverted" fn)))
+              ((eq answer ?n)
+               (signal 'file-supersession
+                       (list "File changed on disk" fn)))))
       (message
-        "File on disk now will become a backup file if you save these changes.")
+       "File on disk now will become a backup file if you save these changes.")
       (setq buffer-backed-up nil))))
 
 (defun ask-user-about-supersession-help ()