;;;; unsafep.el -- Determine whether a Lisp form is safe to evaluate
-;; Copyright (C)2002 Free Software Foundation, Inc.
+;; Copyright (C) 2002-2011 Free Software Foundation, Inc.
;; Author: Jonathan Yavner <jyavner@member.fsf.org>
;; Maintainer: Jonathan Yavner <jyavner@member.fsf.org>
;; This file is part of GNU Emacs.
-;; GNU Emacs is free software; you can redistribute it and/or modify
+;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
-;; the Free Software Foundation; either version 2, or (at your option)
-;; any later version.
+;; the Free Software Foundation, either version 3 of the License, or
+;; (at your option) any later version.
;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; GNU General Public License for more details.
;; You should have received a copy of the GNU General Public License
-;; along with GNU Emacs; see the file COPYING. If not, write to the
-;; Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-;; Boston, MA 02111-1307, USA.
+;; along with GNU Emacs. If not, see <http://www.gnu.org/licenses/>.
;;; Commentary:
;; passed a circular list to `assoc', Emacs would crash. Historically,
;; problems of this kind have been few and short-lived.
+;;; Code:
+
(provide 'unsafep)
(require 'byte-opt) ;Set up the `side-effect-free' properties
(defcustom safe-functions nil
- "t to disable `unsafep', or a list of assumed-safe functions."
+ "A list of assumed-safe functions, or t to disable `unsafep'."
:group 'lisp
:type '(choice (const :tag "No" nil) (const :tag "Yes" t) hook))
(dolist (x '(;;Special forms
and catch if or prog1 prog2 progn while unwind-protect
;;Safe subrs that have some side-effects
- ding error message minibuffer-message random read-minibuffer
- signal sleep-for string-match throw y-or-n-p yes-or-no-p
+ ding error random signal sleep-for string-match throw
;;Defsubst functions from subr.el
caar cadr cdar cddr
;;Macros from subr.el
- save-match-data unless when with-temp-message
+ save-match-data unless when
;;Functions from subr.el that have side effects
- read-passwd split-string replace-regexp-in-string
- play-sound-file))
+ split-string replace-regexp-in-string play-sound-file))
(put x 'safe-function t))
;;;###autoload
(defun unsafep (form &optional unsafep-vars)
- "Return nil if evaluating FORM couldn't possibly do any harm;
-otherwise result is a reason why FORM is unsafe. UNSAFEP-VARS is a list
-of symbols with local bindings."
+ "Return nil if evaluating FORM couldn't possibly do any harm.
+Otherwise result is a reason why FORM is unsafe.
+UNSAFEP-VARS is a list of symbols with local bindings."
(catch 'unsafep
(if (or (eq safe-functions t) ;User turned off safety-checking
(atom form)) ;Atoms are never unsafe
((eq fun 'lambda)
;;First arg is temporary bindings
(mapc #'(lambda (x)
- (let ((y (unsafep-variable x t)))
- (if y (throw 'unsafep y)))
(or (memq x '(&optional &rest))
- (push x unsafep-vars)))
+ (let ((y (unsafep-variable x t)))
+ (if y (throw 'unsafep y))
+ (push x unsafep-vars))))
(cadr form))
(unsafep-progn (cddr form)))
((eq fun 'let)
(dolist (x (nthcdr 3 form))
(setq reason (unsafep-progn (cdr x)))
(if reason (throw 'unsafep reason))))))
+ ((eq fun '\`)
+ ;; Backquoted form - safe if its expansion is.
+ (unsafep (cdr (backquote-process (cadr form)))))
(t
;;First unsafep-function call above wasn't nil, no special case applies
reason)))))
(defun unsafep-function (fun)
- "Return nil if FUN is a safe function
-\(either a safe lambda or a symbol that names a safe function). Otherwise
-result is a reason code."
+ "Return nil if FUN is a safe function.
+\(Either a safe lambda or a symbol that names a safe function).
+Otherwise result is a reason code."
(cond
((eq (car-safe fun) 'lambda)
(unsafep fun unsafep-vars))
`(function ,fun))))
(defun unsafep-progn (list)
- "Return nil if all forms in LIST are safe, or the reason
-for the first unsafe form."
+ "Return nil if all forms in LIST are safe.
+Else, return the reason for the first unsafe form."
(catch 'unsafep-progn
(let (reason)
(dolist (x list)
(if reason (throw 'unsafep-progn reason))))))
(defun unsafep-let (clause)
- "CLAUSE is a let-binding, either SYM or (SYM) or (SYM VAL). Checks VAL
-and throws a reason to `unsafep' if unsafe. Returns SYM."
+ "Check the safety of a let binding.
+CLAUSE is a let-binding, either SYM or (SYM) or (SYM VAL).
+Check VAL and throw a reason to `unsafep' if unsafe.
+Return SYM."
(let (reason sym)
(if (atom clause)
(setq sym clause)
(if reason (throw 'unsafep reason))
sym))
-(defun unsafep-variable (sym global-okay)
- "Returns nil if SYM is safe as a let-binding sym
-\(because it already has a temporary binding or is a non-risky buffer-local
-variable), otherwise a reason why it is unsafe. Failing to be locally bound
-is okay if GLOBAL-OKAY is non-nil."
+(defun unsafep-variable (sym to-bind)
+ "Return nil if SYM is safe to set or bind, or a reason why not.
+If TO-BIND is nil, check whether SYM is safe to set.
+If TO-BIND is t, check whether SYM is safe to bind."
(cond
((not (symbolp sym))
`(variable ,sym))
((risky-local-variable-p sym nil)
`(risky-local-variable ,sym))
- ((not (or global-okay
+ ((not (or to-bind
(memq sym unsafep-vars)
(local-variable-p sym)))
`(global-variable ,sym))))
-;;; arch-tag: 6216f98b-eb8f-467a-9c33-7a7644f50658
-;; unsafep.el ends here.
+;;; unsafep.el ends here