stringio.c: use rb_str_append other than ASCII-8BIT

* ext/stringio/stringio.c (strio_write): use rb_str_append to
  reuse coderange bits other than ASCII-8BIT, and keep
  taintedness.  [ruby-dev:48118] [Bug #9769]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@45677 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 18 insertions, 0 deletions

diff --git a/test/stringio/test_stringio.rb b/test/stringio/test_stringio.rb
index c7db91aae1..3fbe2f7eca 100644
--- a/test/stringio/test_stringio.rb
+++ b/test/stringio/test_stringio.rb
@@ -119,6 +119,24 @@ class TestStringIO < Test::Unit::TestCase
     f.close unless f.closed?
   end
 
+  def test_write_infection
+    bug9769 = '[ruby-dev:48118] [Bug #9769]'
+    s = "".untaint
+    f = StringIO.new(s, "w")
+    f.print("bar".taint)
+    f.close
+    assert_predicate(s, :tainted?, bug9769)
+  ensure
+    f.close unless f.closed?
+  end
+
+  def test_write_encoding
+    s = "".force_encoding(Encoding::UTF_8)
+    f = StringIO.new(s)
+    f.print("\u{3053 3093 306b 3061 306f ff01}".b)
+    assert_equal(Encoding::UTF_8, s.encoding, "honor the original encoding over ASCII-8BIT")
+  end
+
   def test_mode_error
     f = StringIO.new("", "r")
     assert_raise(IOError) { f.write("foo") }