* string.c (rb_str_rindex): use rb_enc_prev_char instead of repeated str_nth.

patched by Michael Selig [ruby-core:32498]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@29331 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+2010-09-24  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* string.c (rb_str_rindex): use rb_enc_prev_char instead of repeated str_nth.
+	  patched by Michael Selig [ruby-core:32498]
+
 Fri Sep 24 14:19:12 2010  URABE Shyouhei  <shyouhei@ruby-lang.org>
 
 	* test/test_pty.rb: Same as 229281; existence of PTY class do not

string.c

@@ -2488,14 +2488,14 @@ rb_str_rindex(VALUE str, VALUE sub, long pos)
     e = RSTRING_END(str);
     t = RSTRING_PTR(sub);
     slen = RSTRING_LEN(sub);
-    for (;;) {
-	s = str_nth(sbeg, e, pos, enc, singlebyte);
-	if (!s) return -1;
+    s = str_nth(sbeg, e, pos, enc, singlebyte);
+    while (s) {
 	if (memcmp(s, t, slen) == 0) {
 	    return pos;
 	}
 	if (pos == 0) break;
 	pos--;
+	s = rb_enc_prev_char(sbeg, s, e, enc);
     }
     return -1;
 }