prelude.c.tmpl: require_relative

* template/prelude.c.tmpl (Prelude#translate): support for
  require_relative and comments followed by #.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48708 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

template/prelude.c.tmpl

@@ -42,10 +42,14 @@ class Prelude
     result = [@preludes.size, @vpath.strip(filename), lines, sub]
     @vpath.foreach(filename) do |line|
       @preludes[filename] ||= result
-      line.sub!(/(?:^|\s+)\#(?:$|\s.*)/, '')
-      line.sub!(/require\s*\(?\s*(["'])(.*?)\1\)?/) do
-        orig, path = $&, $2
-        path = translate(path, true) rescue nil
+      line.sub!(/(?:^|\s+)\#(?:$|[#\s].*)/, '')
+      line.sub!(/require(_relative)?\s*\(?\s*(["'])(.*?)(?:\.rb)?\2\)?/) do
+        orig, rel, path = $&, $2, $3
+        if rel
+          path = File.join(File.dirname(filename), path)
+          nil while path.gsub!(%r'(\A|/)(?!\.\.?/)[^/]+/\.\.(?:/|\z)', '')
+        end
+        path = translate("#{path}.rb", true) rescue nil
         if path
           @have_sublib = true
           "TMP_RUBY_PREFIX.require(#{path[0]})"