file.c: chardev is loadable

* file.c (ruby_is_fd_loadable): allow character devices to load,
  e.g., `ruby /dev/null` exits successfully.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63143 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

file.c

@@ -5959,7 +5959,7 @@ ruby_is_fd_loadable(int fd)
     if (S_ISREG(st.st_mode))
 	return 1;
 
-    if (S_ISFIFO(st.st_mode))
+    if (S_ISFIFO(st.st_mode) || S_ISCHR(st.st_mode))
 	return -1;
 
     if (S_ISDIR(st.st_mode))

test/ruby/test_rubyoptions.rb

@@ -1020,4 +1020,9 @@ class TestRubyOptions < Test::Unit::TestCase
       end
     end
   end
+
+  def test_null_script
+    skip "#{IO::NULL} is not a character device" unless File.chardev?(IO::NULL)
+    assert_in_out_err([IO::NULL], success: true)
+  end
 end