From: Brian Marick <marick@...>
Date: 2003-12-01T11:32:57+09:00
Subject: Marshal.load EOF on loading subclass of Array (1.8.1)

I think I have found a bug in marshaling in version "ruby 1.8.1
(2003-10-31) [powerpc-darwin]". It's difficult to describe in
words, but I have a failing test.

It seems to require a subclass of Array that adds an instance
variable, an object of that class, and another object that refers to
the first object. Change any of those facts, and you do *not* get this
failure upon loading the marshaled data:

   1) Error:
test_marshaling(SessionTests):
EOFError: End of file reached
     /Users/marick/src/timeclock/timeclock/server/marshal-test.rb:32:in 
`load'
     /Users/marick/src/timeclock/timeclock/server/marshal-test.rb:32:in 
`load'
     /Users/marick/src/timeclock/timeclock/server/marshal-test.rb:31:in 
`open'
     /Users/marick/src/timeclock/timeclock/server/marshal-test.rb:31:in 
`load'
     /Users/marick/src/timeclock/timeclock/server/marshal-test.rb:52:in 
`test_marshaling'

Here is the Test::Unit test. I hope it's reasonably clear. It's a
drastically stripped-down version of the original code+test.

Is this a true bug?

========== snip ================


require 'pp'

# Inherit from some user-defined class, and the test passes
class RecordList < Array
   def initialize
     super
     @next_record_id = 0  # Delete this line, and the test passes.
   end
end

class ActiveJobManager
   def initialize(all_records)
     @all_records = all_records # Delete this line, and the test passes
   end
end


class Session
   def initialize(user)
     @user = user
     @records = RecordList.new
     # Use the following instead of the above, and the test passes.
     # @records = []
     @active_job_manager = ActiveJobManager.new(@records)
     # Use the following instead of the above, and the test passes.
     # @active_job_manager = ActiveJobManager.new([])
   end

   def load
     @records, @active_job_manager = File.open(@user, "r") { | f |
       Marshal.load(f)
     }
   end

   def save
     File.open(@user, "w") { | f |
       Marshal.dump([@records, @active_job_manager], f)
     }
   end
end


class SessionTests < Test::Unit::TestCase

   TEST_USER = "marshal-test-data"

   def test_marshaling
     File.delete(TEST_USER) if FileTest.exists?(TEST_USER)
     @session = Session.new(TEST_USER)
     @session.save
     pp @session.load
   end
end



-----
Brian Marick
Consulting, training, contracting, and research
Focused on the intersection of testing, programming, and design
marick@testing.com, marick@visibleworkings.com
www.testing.com, www.visibleworkings.com