* string.c (rb_str_substr): offset movement bug. a patch from

  Vincent Isambart <vincent.isambart at gmail.com> in
  [ruby-core:14647].  [ruby-core:14644]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@14825 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 2 insertions, 2 deletions

diff --git a/string.c b/string.c
index d569ce5447..87f61a3321 100644
--- a/string.c
+++ b/string.c
@@ -832,10 +832,10 @@ rb_str_substr(VALUE str, long beg, long len)
 	if (len > -beg) len = -beg;
 	if (-beg * rb_enc_mbmaxlen(enc) < RSTRING_LEN(str) / 8) {
 	    beg = -beg;
-	    while (len++ < beg && (e = rb_enc_prev_char(s, e, enc)) != 0);
+	    while (beg-- > len && (e = rb_enc_prev_char(s, e, enc)) != 0);
 	    p = e;
 	    if (!p) return Qnil;
-	    while (beg-- > 0 && (p = rb_enc_prev_char(s, p, enc)) != 0);
+	    while (len-- > 0 && (p = rb_enc_prev_char(s, p, enc)) != 0);
 	    if (!p) return Qnil;
 	    len = e - p;
 	    goto sub;