ext/cgi/escape: preserve String subclass in result

* ext/cgi/escape/escape.c (optimized_escape_html): use rb_str_new_with_class
  (optimized_unescape_html): ditto
  (optimized_escape): ditto
  (optimized_unescape): ditto
* test/cgi/test_cgi_util.rb (test_escape_string_subclass): new test
  [ruby-core:86847] [Bug #14732]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63328 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/cgi/escape/escape.c

@@ -59,7 +59,7 @@ optimized_escape_html(VALUE str)
 	  case '<':
 	  case '>':
 	    if (!dest) {
-		dest = rb_str_buf_new(len);
+		dest = rb_str_new_with_class(str, 0, 0);
 	    }
 
 	    rb_str_cat(dest, cstr + beg, i - beg);
@@ -151,7 +151,7 @@ optimized_unescape_html(VALUE str)
 	    i += clen;
 	    if (overflow || cc >= charlimit || cstr[i] != ';') continue;
 	    if (!dest) {
-		dest = rb_str_buf_new(len);
+		dest = rb_str_new_with_class(str, 0, 0);
 	    }
 	    rb_str_cat(dest, cstr + beg, plen);
 	    if (charlimit > 256) {
@@ -168,7 +168,7 @@ optimized_unescape_html(VALUE str)
 	    continue;
 	}
 	if (!dest) {
-	    dest = rb_str_buf_new(len);
+	    dest = rb_str_new_with_class(str, 0, 0);
 	}
 	rb_str_cat(dest, cstr + beg, plen);
 	rb_str_cat(dest, &c, 1);
@@ -219,7 +219,7 @@ optimized_escape(VALUE str)
 	const unsigned char c = (unsigned char)cstr[i];
 	if (!url_unreserved_char(c)) {
 	    if (!dest) {
-		dest = rb_str_buf_new(len);
+		dest = rb_str_new_with_class(str, 0, 0);
 	    }
 
 	    rb_str_cat(dest, cstr + beg, i - beg);
@@ -278,7 +278,7 @@ optimized_unescape(VALUE str, VALUE encoding)
 	}
 
 	if (!dest) {
-	    dest = rb_str_buf_new(len);
+	    dest = rb_str_new_with_class(str, 0, 0);
 	}
 
 	rb_str_cat(dest, cstr + beg, i - beg);

test/cgi/test_cgi_util.rb

@@ -197,4 +197,25 @@ class CGIUtilTest < Test::Unit::TestCase
     assert_equal('&lt;BR&gt;<A HREF="url"></A>', unescape_element(escapeHTML('<BR><A HREF="url"></A>'), "A", "IMG"))
     assert_equal('&lt;BR&gt;<A HREF="url"></A>', unescape_element(escapeHTML('<BR><A HREF="url"></A>'), ["A", "IMG"]))
   end
+
+  def test_escape_string_subclass
+    sc = Class.new(String).freeze
+    str = sc.new('>')
+    msg = '[ruby-core:86847] [Bug #14732]'
+    assert_not_instance_of String, str
+
+    html = escapeHTML(str)
+    assert_instance_of sc, html, msg
+    assert_equal '&gt;', html
+    orig = unescapeHTML(html)
+    assert_instance_of sc, orig, msg
+    assert_equal '>', orig
+
+    url = escape(str)
+    assert_instance_of sc, url, msg
+    assert_equal '%3E', url
+    orig = unescape(url)
+    assert_instance_of sc, orig, msg
+    assert_equal '>', orig
+  end
 end