From 083940a93df17c6e50d6523e30d56ca3d179f688 Mon Sep 17 00:00:00 2001 From: Paul Eggert Date: Sun, 9 Jul 2017 16:04:02 -0700 Subject: Fix core dump in substitute-object-in-subtree MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Without this fix, (substitute-object-in-subtree #0=(#0# 'a) 'a) would dump core, since the C code would recurse indefinitely through the infinite structure. This patch adds an argument to the function, and renames it to lread--substitute-object-in-subtree as the function is not general-purpose and should not be relied on by outside code. See Bug#23660. * src/intervals.c (traverse_intervals_noorder): ARG is now void *, not Lisp_Object, so that callers need not cons unnecessarily. All callers changed. Also, remove related #if-0 code that was “temporary” in the early 1990s and has not been compilable for some time. * src/lread.c (struct subst): New type, for substitution closure data. (seen_list): Remove this static var, as this info is now part of struct subst. All uses removed. (Flread__substitute_object_in_subtree): Rename from Fsubstitute_object_in_subtree, and give it a 3rd arg so that it doesn’t dump core when called from the top level with an already-cyclic structure. All callers changed. (SUBSTITUTE): Remove. All callers expanded and then simplified. (substitute_object_recurse): Take a single argument SUBST rather than a pair OBJECT and PLACEHOLDER, so that its address can be passed around as part of a closure; this avoids the need for an AUTO_CONS call. All callers changed. If the COMPLETED component is t, treat every subobject as potentially circular. (substitute_in_interval): Take a struct subst * rather than a Lisp_Object, for the closure data. All callers changed. * test/src/lread-tests.el (lread-lread--substitute-object-in-subtree): New test, to check that the core dump does not reoccur. --- lisp/emacs-lisp/edebug.el | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'lisp/emacs-lisp') diff --git a/lisp/emacs-lisp/edebug.el b/lisp/emacs-lisp/edebug.el index 65e30f86778..1494ed1d9c3 100644 --- a/lisp/emacs-lisp/edebug.el +++ b/lisp/emacs-lisp/edebug.el @@ -906,7 +906,7 @@ circular objects. Let `read' read everything else." ;; with the object itself, wherever it occurs. (forward-char 1) (let ((obj (edebug-read-storing-offsets stream))) - (substitute-object-in-subtree obj placeholder) + (lread--substitute-object-in-subtree obj placeholder t) (throw 'return (setf (cdr elem) obj))))) ((eq ?# (following-char)) ;; #n# returns a previously read object. -- cgit v1.2.3