* bignum.c (big2str_karatsuba): Don't allocate new temporary buffer

  if the buffer is enough for current invocation.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@42364 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

2 files changed, 9 insertions, 3 deletions

diff --git a/ChangeLog b/ChangeLog
index aff5a024a2..fc0a391c08 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Aug  4 00:57:58 2013  Tanaka Akira  <akr@fsij.org>
+
+	* bignum.c (big2str_karatsuba): Don't allocate new temporary buffer
+	  if the buffer is enough for current invocation.
+
 Sun Aug  4 00:22:34 2013  Tanaka Akira  <akr@fsij.org>
 
 	* bignum.c (bary2bdigitdbl): New function.
diff --git a/bignum.c b/bignum.c
index a3e4a0be91..f7599c3449 100644
--- a/bignum.c
+++ b/bignum.c
@@ -4383,12 +4383,13 @@ big2str_karatsuba(struct big2str_struct *b2s, BDIGIT *xds, size_t xn,
             memset(b2s->ptr, '0', len);
             b2s->ptr += len;
         }
-        if (wn < bn * 4 + BIGDIVREM_EXTRA_WORDS) {
+        rn = bn;
+        qn = xn+BIGDIVREM_EXTRA_WORDS;
+        if (wn < rn + qn) {
             wn = bn * 4 + BIGDIVREM_EXTRA_WORDS;
+            assert(rn + qn <= wn);
             wds = ALLOCV_N(BDIGIT, tmpw, wn);
         }
-        rn = bn;
-        qn = xn+BIGDIVREM_EXTRA_WORDS;
         rds = wds;
         qds = wds+rn;
         bary_divmod(qds, qn, rds, rn, xds, xn, bds, bn);