[Win32utils-devel] [ win32utils-Bugs-10589 ] Bug in win32-mmap

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Bugs item #10589, was opened at 2007-05-04 12:01
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Category: win32-mmap
Group: Code
>Status: Closed
>Resolution: Accepted
Priority: 3
Submitted By: Daniel Berger (djberg96)
Assigned to: Daniel Berger (djberg96)
Summary: Bug in win32-mmap

Initial Comment:
Ruby 1.8.6
win32-mmap 0.2.1

Assigning the value 0 to a dynamic setter causes the corresponding getter to fail. This small script demonstrates the problem:

require 'win32/mmap'
include Win32

mm = MMap.new(:size => 1024, :name => 'test')
mm.gvalue = 0
p mm.gvalue
mm.close

The result is:

C:/ruby/lib/ruby/gems/1.8/gems/win32-mmap-0.2.0/lib/win32/mmap.rb:335:in `load': marshal data too short (ArgumentError)
        from C:/ruby/lib/ruby/gems/1.8/gems/win32-mmap-0.2.0/lib/win32/mmap.rb:335:in `method_missing'
        from mmap_test.rb:6

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>Comment By: Daniel Berger (djberg96)
Date: 2007-05-16 09:58

Message:
Thanks, that was it!

Dan

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Comment By: Park Heesob  (phasis68)
Date: 2007-05-16 09:03

Message:
I wish this is the right solution:

  marshal = memcpy(buf, @address, @size) 

should be 

  memcpy(buf, @address, @size) 
  marshal = buf

Regards,
Park Heesob

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Comment By: Daniel Berger (djberg96)
Date: 2007-05-16 00:58

Message:
I added the explicit "\0" in CVS, but then I noticed that it fails elsewhere:

mm = Win32::MMap.new(:size => 24, :name => 'test')
mm.bar = 7
mm.baz = 0
p mm.bar # Boom!
p mm.baz
mm.close

mmap.rb:336:in `load': marshal data too short (ArgumentError)
        from mmap.rb:336:in `method_missing'
        from mmap.rb:399

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Comment By: Park Heesob  (phasis68)
Date: 2007-05-10 08:57

Message:
It's because the return type of the MemcpyXXX is 'P'.

Quick and dirty solution is like this:

marshal = memcpy(buf, @address, @size) + "\0"

Regards,
Park Heesob


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Comment By: Daniel Berger (djberg96)
Date: 2007-05-07 20:47

Message:
(FYI to myself)

This is caused by memcpy() truncating marshalled data that ends with "\000" because it treats it as a null. One solution might be to use wmemcpy() instead, but I'm not sure how to get at that function, since msvcrt doesn't appear to export it.

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