Ensure finalizer order in Tempfile

The Closer and Remover finalizers are defined on different objects in
Tempfile. The Closer is defined on the Tempfile object while the Remover
is defined on the finalizer_obj. This means that there is no guarantee
of the finalizer order.

On Windows, we must close the file before removing it because we cannot
remove an open file. But since the order is not guaranteed, the GC may
run the Remover finalizer first, which will fail with an Errno::EACCES
(Permission denied @ apply2files).

This commit changes it so that both the Closer and Remover finalizers
are defined on the finalizer_obj, which guarantees the order that it is
ran.

Author: peterzhu2118

lib/tempfile.rb

@@ -228,22 +228,25 @@ def initialize(basename="", tmpdir=nil, mode: 0, **options)
       tmpfile = File.open(tmpname, @mode, **opts)
       @opts = opts.freeze
     end
-    ObjectSpace.define_finalizer(@finalizer_obj, Remover.new(tmpfile.path))
-    ObjectSpace.define_finalizer(self, Closer.new(tmpfile))
 
     super(tmpfile)
+
+    define_finalizers
+  end
+
+  private def define_finalizers
+    ObjectSpace.define_finalizer(@finalizer_obj, Closer.new(__getobj__))
+    ObjectSpace.define_finalizer(@finalizer_obj, Remover.new(__getobj__.path))
   end
 
   def initialize_dup(other) # :nodoc:
     initialize_copy_iv(other)
     super(other)
-    ObjectSpace.define_finalizer(self, Closer.new(__getobj__))
   end
 
   def initialize_clone(other) # :nodoc:
     initialize_copy_iv(other)
     super(other)
-    ObjectSpace.define_finalizer(self, Closer.new(__getobj__))
   end
 
   private def initialize_copy_iv(other) # :nodoc:
@@ -256,10 +259,13 @@ def initialize_clone(other) # :nodoc:
   # Opens or reopens the file with mode "r+".
   def open
     _close
-    ObjectSpace.undefine_finalizer(self)
+
     mode = @mode & ~(File::CREAT|File::EXCL)
     __setobj__(File.open(__getobj__.path, mode, **@opts))
-    ObjectSpace.define_finalizer(self, Closer.new(__getobj__))
+
+    ObjectSpace.undefine_finalizer(@finalizer_obj)
+    define_finalizers
+
     __getobj__
   end
 
@@ -327,7 +333,10 @@ def unlink
       # may not be able to unlink on Windows; just ignore
       return
     end
+
     ObjectSpace.undefine_finalizer(@finalizer_obj)
+    ObjectSpace.define_finalizer(@finalizer_obj, Closer.new(__getobj__))
+
     @unlinked = true
   end
   alias delete unlink