From ec6e26742cd467b210c8d2935edb1a0dcb26e0dd Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Wed, 18 Jul 2007 07:57:45 +0000
Subject: [PATCH] * bignum.c (rb_big_pow): refine overflow check. 
 [ruby-dev:31242]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@12813 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 ChangeLog | 4 ++++
 bignum.c  | 4 +++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index aaf31fd7ed..5465281c35 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Jul 18 16:57:41 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* bignum.c (rb_big_pow): refine overflow check.  [ruby-dev:31242]
+
 Wed Jul 18 09:19:07 2007  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* parse.y (rb_parser_append_print, rb_parser_while_loop): moved check
diff --git a/bignum.c b/bignum.c
index 39403a980d..fc4b79883a 100644
--- a/bignum.c
+++ b/bignum.c
@@ -1675,8 +1675,10 @@ rb_big_pow(VALUE x, VALUE y)
 	if (yy > 0) {
 	    VALUE z = 0;
 	    SIGNED_VALUE mask;
+	    const long BIGLEN_LIMIT = 1024*1024 / SIZEOF_BDIGITS;
 
-	    if (RBIGNUM(x)->len * SIZEOF_BDIGITS * yy > 1024*1024) {
+	    if ((RBIGNUM(x)->len > BIGLEN_LIMIT) ||
+		(RBIGNUM(x)->len > BIGLEN_LIMIT / yy)) {
 		rb_warn("in a**b, b may be too big");
 		d = (double)yy;
 		break;