io.c: fix stack smashing

* io.c (parse_mode_enc): fix buffer overflow.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@53083 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 13 insertions, 0 deletions

diff --git a/test/ruby/test_io_m17n.rb b/test/ruby/test_io_m17n.rb
index ea68219184..63eb4b7d88 100644
--- a/test/ruby/test_io_m17n.rb
+++ b/test/ruby/test_io_m17n.rb
@@ -2082,6 +2082,19 @@ EOT
     }
   end
 
+  def test_bom_too_long_utfname
+    assert_separately([], <<-'end;') # do
+      assert_warn(/Unsupported encoding/) {
+        open(IO::NULL, "r:bom|utf-" + "x" * 10000) {}
+      }
+    end;
+    assert_separately([], <<-'end;') # do
+      assert_warn(/Unsupported encoding/) {
+        open(IO::NULL, encoding: "bom|utf-" + "x" * 10000) {}
+      }
+    end;
+  end
+
   def test_cbuf
     with_tmpdir {
       fn = "tst"