Record "safe themes" as sha1 hashes, as suggested by Stefan Monnier.

* lisp/custom.el (custom-safe-themes): Rename from
custom-safe-theme-files.  Add :risky tag.
(load-theme, custom-theme-load-confirm): Save sha1 hashes to
custom-safe-themes, not filenames.  Suggested by Stefan Monnier.

3 files changed, 81 insertions, 71 deletions

diff --git a/etc/NEWS b/etc/NEWS
index 0fd74252601..2db17e550d0 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -219,9 +219,10 @@ Emacs no longer looks for custom themes in `load-path'.  The default
 is to search in `custom-theme-directory', followed by a built-in theme
 directory named "themes/" in `data-directory'.
 
-*** New option `custom-safe-theme-files' lists known-safe theme files.
-If a theme is not in this list, Emacs queries before loading it.
-The default value treats all themes included in Emacs as safe.
+*** New option `custom-safe-themes' records known-safe theme files.
+If a theme is not in this list, Emacs queries before loading it, and
+offers to save the theme to `custom-safe-themes' automatically.  By
+default, all themes included in Emacs are treated as safe.
 
 ** The user option `remote-file-name-inhibit-cache' controls whether
 the remote file-name cache is used for read access.
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 1a1f9205793..c09c89a5efa 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,5 +1,12 @@
 2011-01-09  Chong Yidong  <cyd@stupidchicken.com>
 
+        * custom.el (custom-safe-themes): Rename from
+        custom-safe-theme-files.  Add :risky tag.
+        (load-theme, custom-theme-load-confirm): Save sha1 hashes to
+        custom-safe-themes, not filenames.  Suggested by Stefan Monnier.
+
+2011-01-09  Chong Yidong  <cyd@stupidchicken.com>
+
         * tool-bar.el (tool-bar-setup): Remove Help button.  Remove label
         from Search and add a label to Undo.
 
diff --git a/lisp/custom.el b/lisp/custom.el
index f984d132dd1..6a0beae749e 100644
--- a/lisp/custom.el
+++ b/lisp/custom.el
@@ -1105,14 +1105,16 @@ property `theme-feature' (which is usually a symbol created by
     (let ((custom-enabling-themes t))
       (enable-theme 'user))))
 
-(defcustom custom-safe-theme-files '(default)
-  "List of theme files that are considered safe to load.
-Each list element should be either an absolute file name, or the
-symbol `default', which stands for the built-in Emacs theme
-directory (a directory named \"themes\" in `data-directory'."
+(defcustom custom-safe-themes '(default)
+  "List of themes that are considered safe to load.
+Each list element should be the `sha1' hash of a theme file, or
+the symbol `default', which stands for any theme in the built-in
+Emacs theme directory (a directory named \"themes\" in
+`data-directory')."
   :type '(repeat
-          (choice file (const :tag "Built-in theme directory" default)))
+          (choice string (const :tag "Built-in themes" default)))
   :group 'customize
+  :risky t
   :version "24.1")
 
 (defvar safe-functions) ; From unsafep.el
@@ -1140,74 +1142,74 @@ in one of the directories specified by `custom-theme-load-path'."
     (put theme 'theme-documentation nil))
   (let ((fn (locate-file (concat (symbol-name theme) "-theme.el")
                          (custom-theme--load-path)
-                         '("" "c"))))
+                         '("" "c")))
+        hash)
     (unless fn
       (error "Unable to find theme file for `%s'." theme))
-    ;; Check file safety.
-    (when (or (and (memq 'default custom-safe-theme-files)
-                   (equal (file-name-directory fn)
-                          (expand-file-name "themes/" data-directory)))
-              (member fn custom-safe-theme-files)
-              ;; If the file is not in the builtin theme directory or
-              ;; in `custom-safe-theme-files', check it with unsafep.
-              (with-temp-buffer
-                (require 'unsafep)
-                (insert-file-contents fn)
-                (let ((safe-functions (append '(provide-theme deftheme
-                                                custom-theme-set-variables
-                                                custom-theme-set-faces)
-                                              safe-functions))
-                      unsafep form)
-                  (while (and (setq form (condition-case nil
-                                             (let ((read-circle nil))
-                                               (read (current-buffer)))
-                                           (end-of-file nil)))
-                              (null (setq unsafep (unsafep form)))))
-                  (or (null unsafep)
-                      (custom-theme-load-confirm fn)))))
-      (let ((custom--inhibit-theme-enable no-enable))
-        (load fn)))))
-
-(defun custom-theme-load-confirm (filename)
+    (with-temp-buffer
+      (insert-file-contents fn)
+      (setq hash (sha1 (current-buffer)))
+      ;; Check file safety.
+      (when (or (and (memq 'default custom-safe-themes)
+                     (equal (file-name-directory fn)
+                            (expand-file-name "themes/" data-directory)))
+                (member hash custom-safe-themes)
+                ;; If the theme is not in `custom-safe-themes', check
+                ;; it with unsafep.
+                (progn
+                  (require 'unsafep)
+                  (let ((safe-functions
+                         (append '(provide-theme deftheme
+                                   custom-theme-set-variables
+                                   custom-theme-set-faces)
+                                 safe-functions))
+                        unsafep form)
+                    (while (and (setq form (condition-case nil
+                                               (let ((read-circle nil))
+                                                 (read (current-buffer)))
+                                             (end-of-file nil)))
+                                (null (setq unsafep (unsafep form)))))
+                    (or (null unsafep)
+                        (custom-theme-load-confirm hash)))))
+        (let ((custom--inhibit-theme-enable no-enable))
+          (eval-buffer))))))
+
+(defun custom-theme-load-confirm (hash)
+  "Query the user about loading a Custom theme that may not be safe.
+The theme should be in the current buffer.  If the user agrees,
+query also about adding HASH to `custom-safe-themes'."
   (if noninteractive
       nil
-    (let ((existing-buffer (find-buffer-visiting filename))
-          (exit-chars '(?y ?n ?\s ?\C-g))
+    (let ((exit-chars '(?y ?n ?\s))
           prompt char)
       (save-window-excursion
-        (if existing-buffer
-            (pop-to-buffer existing-buffer)
-          (find-file filename))
-        (unwind-protect
-            (progn
-              (setq prompt
-                    (format "This theme is not guaranteed to be safe.  Really load? %s"
-                            (if (< (line-number-at-pos (point-max))
-                                   (window-body-height))
-                                "(y or n) "
-                              (push ?\C-v exit-chars)
-                              "Type y or n, or C-v to scroll: ")))
-              (goto-char (point-min))
-              (while (null char)
-                (setq char (read-char-choice prompt exit-chars t))
-                (when (eq char ?\C-v)
-                  (condition-case nil
-                      (scroll-up)
-                    (error (goto-char (point-min))))
-                  (setq char nil)))
-              (when (memq char '(?\s ?y))
-                (push filename custom-safe-theme-files)
-                ;; Offer to save to `custom-safe-theme-files'.
-                (and (or custom-file user-init-file)
-                     (y-or-n-p "Treat %s as safe for future loads? "
-                               (file-name-nondirectory filename))
-                     (let ((coding-system-for-read nil))
-                       (customize-save-variable
-                        'custom-safe-theme-files
-                        custom-safe-theme-files)))
-                t))
-          ;; Unwind form.
-          (unless existing-buffer (kill-buffer)))))))
+        (rename-buffer "*Custom Theme*" t)
+        (emacs-lisp-mode)
+        (display-buffer (current-buffer))
+        (setq prompt
+              (format "This theme is not guaranteed to be safe.  Really load? %s"
+                      (if (< (line-number-at-pos (point-max))
+                             (window-body-height))
+                          "(y or n) "
+                        (push ?\C-v exit-chars)
+                        "Type y or n, or C-v to scroll: ")))
+        (goto-char (point-min))
+        (while (null char)
+          (setq char (read-char-choice prompt exit-chars))
+          (when (eq char ?\C-v)
+            (condition-case nil
+                (scroll-up)
+              (error (goto-char (point-min))))
+            (setq char nil)))
+        (when (memq char '(?\s ?y))
+          (push hash custom-safe-themes)
+          ;; Offer to save to `custom-safe-themes'.
+          (and (or custom-file user-init-file)
+               (y-or-n-p "Treat this theme as safe for future loads? ")
+               (let ((coding-system-for-read nil))
+                 (customize-save-variable 'custom-safe-themes
+                                          custom-safe-themes)))
+          t)))))
 
 (defun custom-theme-name-valid-p (name)
   "Return t if NAME is a valid name for a Custom theme, nil otherwise.