From: Erik Terpstra <erik@...>
Date: 2008-08-15T00:15:46+09:00
Subject: Re: Is it possible to extract data out of memory using Ruby?

So if you would like to look at the 'in memory' representation of a Ruby 
String how would that work?

  require "dl"

  ptr = DL::PtrData.new 0
  ptr.struct! "L", "val"
  size = ptr.size

  str = 'Hello world!'
  address = str.object_id * 2
  value = ptr[ address, size ]

  puts [address, value].inspect

TIA,

Erik.

Pit Capitain wrote:
> 2008/8/14 Erik Terpstra <erik@ruby-lang.nl>:
>> Is it possible to extract data out of memory using Ruby?
> 
> Erik, to read and write longs (4 bytes) I use the DL standard library
> with the following code:
> 
>   require "dl"
> 
>   ptr = DL::PtrData.new 0
>   ptr.struct! "L", "val"
>   size = ptr.size
> 
>   # read
>   ptr[ address, size ].unpack( "L" )[ 0 ]
> 
>   # write
>   ptr[ address, size ] = [ val ].pack( "L" )
> 
> For reading and writing bytes you have to change the "L" to something
> else. See the docs for the DL standard library.
> 
> Regards,
> Pit

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