* allout.el (allout-encrypt-unencrypted-on-saves): Do not provide insecure

exception for current topic.  Also note that auto-saves are handled
differently.

(allout-auto-save-temporarily-disabled), (allout-just-did-undo): State
variables for tracking auto-save inhibition situation.

(allout-write-contents-hook-handler): Rename from
'allout-write-file-hook-handler', and describe how it depends on
write-contents-functions sensitivity to non-nil value to prevent file
write.

(allout-auto-save-hook-handler): Remove.  auto-save does not check this in
individual buffers, only in the starting buffer, so this is not the right
way for us to inhibit auto-save in a buffer according to its condition.

(allout-mode): Use new allout-write-contents-hook-handler, and only with
write-contents-functions.  Remove auto-save provisions - they're
implemented elsewhere.

(allout-before-change-handler): If undo is in progress, note that for
attention of allout-post-command-business.

(allout-post-command-business): If the command we're following was an undo,
check for change in the status of encrypted items and adjust auto-save
inhibitions accordingly.

(allout-toggle-subtree-encryption): Adjust auto-save inhibition according
to whether there are or aren't any plain-text topics pending encryption.

(allout-inhibit-auto-save-info-for-decryption): Adjust buffer-saved-size
and some allout state to inhibit auto-saves if there are plain-text topics
pending encryption.

(allout-maybe-resume-auto-save-info-after-encryption): Adjust
buffer-saved-size and some allout state to not inhibit auto-saves if there
are no longer any plain-text topics pending encryption.

(allout-next-topic-pending-encryption), (allout-encrypt-decrypted): No
longer provide for exemption of the current topic.

2 files changed, 164 insertions, 88 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index d7def506d98..71fc929308b 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,49 @@
+2011-07-04  Ken Manheimer  <ken.manheimer@gmail.com>
+
+        * allout.el (allout-encrypt-unencrypted-on-saves): Do not provide
+        insecure exception for current topic.  Also note that auto-saves
+        are handled differently.
+
+        (allout-auto-save-temporarily-disabled), (allout-just-did-undo):
+        State variables for tracking auto-save inhibition situation.
+
+        (allout-write-contents-hook-handler): Rename from
+        'allout-write-file-hook-handler', and describe how it depends on
+        write-contents-functions sensitivity to non-nil value to prevent
+        file write.
+
+        (allout-auto-save-hook-handler): Remove.  auto-save does not check
+        this in individual buffers, only in the starting buffer, so this
+        is not the right way for us to inhibit auto-save in a buffer
+        according to its condition.
+
+        (allout-mode): Use new allout-write-contents-hook-handler, and
+        only with write-contents-functions.  Remove auto-save provisions -
+        they're implemented elsewhere.
+
+        (allout-before-change-handler): If undo is in progress, note that
+        for attention of allout-post-command-business.
+
+        (allout-post-command-business): If the command we're following was
+        an undo, check for change in the status of encrypted items and
+        adjust auto-save inhibitions accordingly.
+
+        (allout-toggle-subtree-encryption): Adjust auto-save inhibition
+        according to whether there are or aren't any plain-text topics
+        pending encryption.
+
+        (allout-inhibit-auto-save-info-for-decryption): Adjust
+        buffer-saved-size and some allout state to inhibit auto-saves if
+        there are plain-text topics pending encryption.
+
+        (allout-maybe-resume-auto-save-info-after-encryption): Adjust
+        buffer-saved-size and some allout state to not inhibit auto-saves
+        if there are no longer any plain-text topics pending encryption.
+
+        (allout-next-topic-pending-encryption),
+        (allout-encrypt-decrypted): No longer provide for exemption of the
+        current topic.
+
 2011-07-04  Juri Linkov  <juri@jurta.org>
 
         Add 7z operations to delete and save changed members (bug#8968).
diff --git a/lisp/allout.el b/lisp/allout.el
index d238745df17..5b8a7a7de1a 100644
--- a/lisp/allout.el
+++ b/lisp/allout.el
@@ -823,37 +823,32 @@ formatted copy."
   :group 'allout-encryption)
 ;;;_  = allout-encrypt-unencrypted-on-saves
 (defcustom allout-encrypt-unencrypted-on-saves t
-  "When saving, should topics pending encryption be encrypted?
-
-The idea is to prevent file-system exposure of any un-encrypted stuff, and
-mostly covers both deliberate file writes and auto-saves.
-
- - Yes: encrypt all topics pending encryption, even if it's the one
-        currently being edited.  (In that case, the currently edited topic
-        will be automatically decrypted before any user interaction, so they
-        can continue editing but the copy on the file system will be
-        encrypted.)
-        Auto-saves will use the \"All except current topic\" mode if this
-        one is selected, to avoid practical difficulties -- see below.
- - All except current topic: skip the topic currently being edited, even if
-       it's pending encryption.  This may expose the current topic on the
-       file sytem, but avoids the nuisance of prompts for the encryption
-       passphrase in the middle of editing for, eg, autosaves.
-       This mode is used for auto-saves for both this option and \"Yes\".
- - No: leave it to the user to encrypt any unencrypted topics.
-
-For practical reasons, auto-saves always use the 'except-current policy
-when auto-encryption is enabled.  (Otherwise, spurious passphrase prompts
-and unavoidable timing collisions are too disruptive.)  If security for a
-file requires that even the current topic is never auto-saved in the clear,
-disable auto-saves for that file."
-
-  :type '(choice (const :tag "Yes" t)
-                 (const :tag "All except current topic" except-current)
-                 (const :tag "No" nil))
-  :version "22.1"
+  "If non-nil, topics pending encryption are encrypted during buffer saves.
+
+This provents file-system exposure of un-encrypted contents of
+items marked for encryption.
+
+When non-nil, if the topic currently being edited is decrypted,
+it will be encrypted for saving but automatically decrypted
+before any subsequent user interaction, so it is once again clear
+text for editing though the file system copy is encrypted.
+
+\(Auto-saves are handled differently.  Buffers with plain-text
+exposed encrypted topics are exempted from auto saves until all
+such topics are encrypted.)"
+
+  :type 'boolean
+  :version "23.1"
   :group 'allout-encryption)
 (make-variable-buffer-local 'allout-encrypt-unencrypted-on-saves)
+(defvar allout-auto-save-temporarily-disabled nil
+  "True while topic encryption is pending and auto-saving was active.
+
+The value of buffer-saved-size at the time of decryption is used,
+for restoring when all encryptions are established.")
+(defvar allout-just-did-undo nil
+  "True just after undo commands, until allout-post-command-business.")
+(make-variable-buffer-local 'allout-just-did-undo)
 
 ;;;_ + Developer
 ;;;_  = allout-developer group
@@ -1564,39 +1559,43 @@ See `allout-encryption-ciphertext-rejection-regexps' for rejection reasons.")
 (defmacro allout-mode-p ()
   "Return t if `allout-mode' is active in current buffer."
   'allout-mode)
-;;;_   > allout-write-file-hook-handler ()
-(defun allout-write-file-hook-handler ()
-  "Implement `allout-encrypt-unencrypted-on-saves' policy for file writes."
+;;;_   > allout-write-contents-hook-handler ()
+(defun allout-write-contents-hook-handler ()
+  "Implement `allout-encrypt-unencrypted-on-saves' for file writes
+
+Return nil if all goes smoothly, or else return an informative
+message if an error is encountered.  The message will serve as a
+non-nil return on `write-contents-functions' to prevent saving of
+the buffer while it has decrypted content.
+
+This behavior depends on emacs versions that implement the
+`write-contents-functions' hook."
 
   (if (or (not (allout-mode-p))
           (not (boundp 'allout-encrypt-unencrypted-on-saves))
           (not allout-encrypt-unencrypted-on-saves))
       nil
-    (let ((except-mark (and (equal allout-encrypt-unencrypted-on-saves
-                                   'except-current)
-                            (point-marker))))
-      (if (save-excursion (goto-char (point-min))
-                          (allout-next-topic-pending-encryption except-mark))
-          (progn
-            (message "auto-encrypting pending topics")
-            (sit-for 0)
-            (condition-case failure
+    (if (save-excursion (goto-char (point-min))
+                        (allout-next-topic-pending-encryption))
+        (progn
+          (message "auto-encrypting pending topics")
+          (sit-for 0)
+          (condition-case failure
+              (progn
                 (setq allout-after-save-decrypt
-                      (allout-encrypt-decrypted except-mark))
-              (error (message
-                      "allout-write-file-hook-handler suppressing error %s"
-                      failure)
-                     (sit-for 2)))))
-      ))
-  nil)
-;;;_   > allout-auto-save-hook-handler ()
-(defun allout-auto-save-hook-handler ()
-  "Implement `allout-encrypt-unencrypted-on-saves' policy for auto save."
-
-  (if (and (allout-mode-p) allout-encrypt-unencrypted-on-saves)
-      ;; Always implement 'except-current policy when enabled.
-      (let ((allout-encrypt-unencrypted-on-saves 'except-current))
-        (allout-write-file-hook-handler))))
+                      (allout-encrypt-decrypted))
+                ;; aok - return nil:
+                nil)
+            (error
+             ;; whoops - probably some still-decrypted items, return non-nil:
+             (let ((text (format (concat "%s contents write inhibited due to"
+                                         " encrypted topic encryption error:"
+                                         " %s")
+                                 (buffer-name (current-buffer))
+                                 failure)))
+               (message text)(sit-for 2)
+               text)))))
+    ))
 ;;;_   > allout-after-saves-handler ()
 (defun allout-after-saves-handler ()
   "Decrypt topic encrypted for save, if it's currently being edited.
@@ -1960,12 +1959,7 @@ OPEN:	A TOPIC that is not CLOSED, though its OFFSPRING or BODY may be."
   :lighter " Allout"
   :keymap 'allout-mode-map
 
-  (let ((write-file-hook-var-name (cond ((boundp 'write-file-functions)
-                                         'write-file-functions)
-                                        ((boundp 'write-file-hooks)
-                                         'write-file-hooks)
-                                        (t 'local-write-file-hooks)))
-        (use-layout (if (listp allout-layout)
+  (let ((use-layout (if (listp allout-layout)
                         allout-layout
                       allout-default-layout)))
 
@@ -1984,9 +1978,8 @@ OPEN:	A TOPIC that is not CLOSED, though its OFFSPRING or BODY may be."
           (remove-hook 'post-command-hook 'allout-post-command-business t)
           (remove-hook 'before-change-functions 'allout-before-change-handler t)
           (remove-hook 'isearch-mode-end-hook 'allout-isearch-end-handler t)
-          (remove-hook write-file-hook-var-name
-                       'allout-write-file-hook-handler t)
-          (remove-hook 'auto-save-hook 'allout-auto-save-hook-handler t)
+          (remove-hook 'write-contents-functions
+                       'allout-write-contents-hook-handler t)
 
           (remove-overlays (point-min) (point-max)
                            'category 'allout-exposure-category))
@@ -2019,9 +2012,8 @@ OPEN:	A TOPIC that is not CLOSED, though its OFFSPRING or BODY may be."
       (add-hook 'post-command-hook 'allout-post-command-business nil t)
       (add-hook 'before-change-functions 'allout-before-change-handler nil t)
       (add-hook 'isearch-mode-end-hook 'allout-isearch-end-handler nil t)
-      (add-hook write-file-hook-var-name 'allout-write-file-hook-handler
+      (add-hook 'write-contents-functions 'allout-write-contents-hook-handler
                 nil t)
-      (add-hook 'auto-save-hook 'allout-auto-save-hook-handler nil t)
 
       ;; Stash auto-fill settings and adjust so custom allout auto-fill
       ;; func will be used if auto-fill is active or activated.  (The
@@ -2154,8 +2146,10 @@ internal functions use this feature cohesively bunch changes."
 
 See `allout-overlay-interior-modification-handler' for details."
 
-  (when (and (allout-mode-p) undo-in-progress (allout-hidden-p))
-    (allout-show-children))
+  (when (and (allout-mode-p) undo-in-progress)
+    (setq allout-just-did-undo t)
+    (if (allout-hidden-p)
+        (allout-show-children)))
 
   ;; allout-overlay-interior-modification-handler on an overlay handles
   ;; this in other emacs, via `allout-exposure-category's 'modification-hooks.
@@ -3308,12 +3302,29 @@ coordinating with allout activity.")
 - Implement (and clear) `allout-post-goto-bullet', for hot-spot
   outline commands.
 
+- If the command we're following was an undo, check for change in
+  the status of encrypted items and adjust auto-save inhibitions
+  accordingly.
+
 - Decrypt topic currently being edited if it was encrypted for a save."
 
-                                        ; Apply any external change func:
   (if (not (allout-mode-p))             ; In allout-mode.
       nil
 
+    (when allout-just-did-undo
+      (setq allout-just-did-undo nil)
+      (cond ((and (= buffer-saved-size -1)
+                  allout-auto-save-temporarily-disabled)
+             ;; user possibly undid a decryption, deinhibit auto-save:
+             (allout-maybe-resume-auto-save-info-after-encryption))
+            ((save-excursion
+               (save-restriction
+                 (widen)
+                 (goto-char (point-min))
+                 (not (allout-next-topic-pending-encryption))))
+             ;; plain-text encrypted items are present, inhibit auto-save:
+             (allout-inhibit-auto-save-info-for-decryption (buffer-size)))))
+
     (if (and (boundp 'allout-after-save-decrypt)
              allout-after-save-decrypt)
         (allout-after-saves-handler))
@@ -5899,6 +5910,8 @@ See `allout-toggle-current-subtree-encryption' for more details."
                        " shift it in to make it encryptable")))
 
     (let* ((allout-buffer (current-buffer))
+           ;; for use with allout-auto-save-temporarily-disabled, if necessary:
+           (was-buffer-saved-size buffer-saved-size)
            ;; Assess location:
            (bullet-pos allout-recent-prefix-beginning)
            (after-bullet-pos (point))
@@ -5978,6 +5991,12 @@ See `allout-toggle-current-subtree-encryption' for more details."
            ;; Add the is-encrypted bullet qualifier:
            (goto-char after-bullet-pos)
            (insert "*"))))
+
+      ;; adjust buffer's auto-save eligibility:
+      (if was-encrypted
+          (allout-inhibit-auto-save-info-for-decryption was-buffer-saved-size)
+        (allout-maybe-resume-auto-save-info-after-encryption))
+
       (run-hook-with-args 'allout-structure-added-hook
                           bullet-pos subtree-end))))
 ;;;_  > allout-encrypt-string (text decrypt allout-buffer keymode-cue
@@ -6029,6 +6048,7 @@ signal."
                         (epg-context-set-passphrase-callback
                          context #'epa-passphrase-callback-function)
                         context))
+
          (encoding (with-current-buffer allout-buffer
                      buffer-file-coding-system))
          (multibyte (with-current-buffer allout-buffer
@@ -6150,8 +6170,29 @@ signal."
                          result-text))
       (error (concat "Encryption produced non-armored text, which"
                      "conflicts with allout mode -- reconfigure!")))
-
      (t result-text))))
+;;;_  > allout-inhibit-auto-save-info-for-decryption
+(defun allout-inhibit-auto-save-info-for-decryption (was-buffer-saved-size)
+  "Temporarily prevent auto-saves in this buffer when an item is decrypted.
+
+WAS-BUFFER-SAVED-SIZE is the value of buffer-saved-size *before*
+the decryption."
+  (when (not (or (= buffer-saved-size -1) (= was-buffer-saved-size -1)))
+    (setq allout-auto-save-temporarily-disabled was-buffer-saved-size
+          buffer-saved-size -1)))
+;;;_  > allout-maybe-resume-auto-save-info-after-encryption ()
+(defun allout-maybe-resume-auto-save-info-after-encryption ()
+  "Restore auto-save info, *if* there are no topics pending encryption."
+  (when (and allout-auto-save-temporarily-disabled
+             (= buffer-saved-size -1)
+             (save-excursion
+               (save-restriction
+                 (widen)
+                 (goto-char (point-min))
+                 (not (allout-next-topic-pending-encryption)))))
+    (setq buffer-saved-size allout-auto-save-temporarily-disabled
+          allout-auto-save-temporarily-disabled nil)))
+
 ;;;_  > allout-encrypted-topic-p ()
 (defun allout-encrypted-topic-p ()
   "True if the current topic is encryptable and encrypted."
@@ -6162,14 +6203,10 @@ signal."
          (save-match-data (looking-at "\\*")))
     )
   )
-;;;_  > allout-next-topic-pending-encryption (&optional except-mark)
-(defun allout-next-topic-pending-encryption (&optional except-mark)
+;;;_  > allout-next-topic-pending-encryption ()
+(defun allout-next-topic-pending-encryption ()
   "Return the point of the next topic pending encryption, or nil if none.
 
-EXCEPT-MARK identifies a point whose containing topics should be excluded
-from encryption.  This supports 'except-current mode of
-`allout-encrypt-unencrypted-on-saves'.
-
 Such a topic has the `allout-topic-encryption-bullet' without an
 immediately following '*' that would mark the topic as being encrypted.  It
 must also have content."
@@ -6204,10 +6241,7 @@ must also have content."
                (setq content-beg (point))
                (backward-char 1)
                (allout-end-of-subtree)
-               (if (or (<= (point) content-beg)
-                       (and except-mark
-                            (<= content-beg except-mark)
-                            (>= (point) except-mark)))
+               (if (<= (point) content-beg)
                    ;; Continue looking
                    (setq got nil)
                  ;; Got it!
@@ -6219,14 +6253,10 @@ must also have content."
       )
     )
   )
-;;;_  > allout-encrypt-decrypted (&optional except-mark)
-(defun allout-encrypt-decrypted (&optional except-mark)
+;;;_  > allout-encrypt-decrypted ()
+(defun allout-encrypt-decrypted ()
   "Encrypt topics pending encryption except those containing exemption point.
 
-EXCEPT-MARK identifies a point whose containing topics should be excluded
-from encryption.  This supports the `except-current' mode of
-`allout-encrypt-unencrypted-on-saves'.
-
 If a topic that is currently being edited was encrypted, we return a list
 containing the location of the topic and the location of the cursor just
 before the topic was encrypted.  This can be used, eg, to decrypt the topic
@@ -6242,7 +6272,7 @@ save.  See `allout-encrypt-unencrypted-on-saves' for more info."
              bo-subtree
              editing-topic editing-point)
         (goto-char (point-min))
-        (while (allout-next-topic-pending-encryption except-mark)
+        (while (allout-next-topic-pending-encryption)
           (setq was-modified (buffer-modified-p))
           (when (save-excursion
                   (and (boundp 'allout-encrypt-unencrypted-on-saves)