From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 26 Sep 2011 15:27:22 +0000 (-0700)
Subject: * floatfns.c (Fexpt): Avoid undefined signed * signed overflow.
X-Git-Tag: emacs-24.2.90~471^2~6^2~187
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=125b3835e556b6c7d967148f09ed15c0a4747d14;p=emacs.git

* floatfns.c (Fexpt): Avoid undefined signed * signed overflow.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index ff0972fd0f1..9857461143a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -286,6 +286,7 @@
 	(Fdo_auto_save, Fset_buffer_auto_saved)
 	(Fclear_buffer_auto_save_failure):
 	Don't assume time_t is signed, or that it fits in int.
+	* floatfns.c (Fexpt): Avoid undefined signed * signed overflow.
 	* fns.c (Fcompare_strings, Fstring_lessp, struct textprop_rec, concat)
 	(string_char_byte_cache_charpos, string_char_byte_cache_bytepos)
 	(string_char_to_byte, string_byte_to_char)
diff --git a/src/floatfns.c b/src/floatfns.c
index 2011b4d942d..6158b9bd26d 100644
--- a/src/floatfns.c
+++ b/src/floatfns.c
@@ -484,7 +484,8 @@ DEFUN ("expt", Fexpt, Sexpt, 2, 2, 0,
       && INTEGERP (arg2)   /* don't promote, if both are ints, and */
       && 0 <= XINT (arg2)) /* we are sure the result is not fractional */
     {				/* this can be improved by pre-calculating */
-      EMACS_INT acc, x, y;	/* some binary powers of x then accumulating */
+      EMACS_INT y;		/* some binary powers of x then accumulating */
+      EMACS_UINT acc, x;  /* Unsigned so that overflow is well defined.  */
       Lisp_Object val;
 
       x = XINT (arg1);