From: nobu@...
Date: 2014-03-26T01:41:32+00:00
Subject: [ruby-core:61684] [ruby-trunk - Bug #9675] [Rejected] Marshal.load fails with recursive structures and user defined hash method

Issue #9675 has been updated by Nobuyoshi Nakada.

Status changed from Open to Rejected

Cody Cutrer wrote:
> It seems like the hash should be constructed during loading *without* calling #hash, and then after the load has completed, call #rehash on all of the loaded hashes. This should fix any form of nested data structures.

Before the hash get constructed, you can't access `@b['id']`.

You should use `marshal_dump` and `marshal_load` instead.

~~~ruby
class A
  attr_accessor :a, :b
  def hash
    @b ? @b['id'].hash : super
  end

  def marshal_dump
    [@a, @b]
  end
  def marshal_load((a, b))
    @a = a
    @b = b
    a.rehash if a
  end
end

a = A.new
a.a = nil
a.b = {'id' => 1}
a.a = {a => 1}

Marshal.load(Marshal.dump(a))
~~~

----------------------------------------
Bug #9675: Marshal.load fails with recursive structures and user defined hash method
https://bugs.ruby-lang.org/issues/9675#change-45936

* Author: Cody Cutrer
* Status: Rejected
* Priority: Normal
* Assignee: 
* Category: 
* Target version: 
* ruby -v: ruby 2.1.0p0 (2013-12-25 revision 44422) [x86_64-darwin13.0]
* Backport: 2.0.0: UNKNOWN, 2.1: UNKNOWN
----------------------------------------
If a user class redefines hash to something that depends on instance variables, and the object is loaded both before a hash, and as a key of a hash of one of its own instance variables (that's loaded *before* the instance variables needed for the #hash method), it will fail.

It seems like the hash should be constructed during loading *without* calling #hash, and then after the load has completed, call #rehash on all of the loaded hashes. This should fix any form of nested data structures.

I can repro in 1.9.3p286, 1.9.3p484, and 2.1.0p0 at the least.  I discovered when upgrading a far more complicated application from 1.9.3p286 to 1.9.3p484 caused a change in the order of instance variables, thereby triggering the issue. My reduced test case (attached) hits the issue in both versions, though.

---Files--------------------------------
marshal_crash.rb (228 Bytes)


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