[WARNING!]SqueakMap problems

John M McIntosh johnmci at smalltalkconsulting.com
Tue Nov 19 20:49:23 UTC 2002


On Tuesday, November 19, 2002, at 11:58  AM, Ned Konz wrote:

> On Tuesday 19 November 2002 11:48 am, I wrote:
>> We should probably have a plugin that does this properly.
>
> There is a UUIDPlugin that's not complete (under Linux, anyway).
> We could flush it out on the various platforms with platform-specific  
> code.
>
> The platform-specific code could get the MAC address(es)
> and use it/them as part of a standard UUID generation scheme.
> Isn't there a standard for this anyway?

Ya, look here

http://hegel.ittc.ukans.edu/topics/internet/internet-drafts/draft-l/ 
draft-leach-uuids-guids-01.txt

I'll point out as the author of the UUID generator my fallback position  
was to generate type 4 UUID based
on the only accessible squeak random number generator. Which someone  
can confirm that the
flaw is the failure to save the Random instance entropy causes repeats  
of the UUID generation after image
crashes because that Random entropy is not swizzled at image startup  
time.  Closer reading will show that after
every 10,000 iterations I create another Random instance in hopes of  
reducing the probability of UUID duplication (Tho
testing this theory is difficult).

I'd rather not suggest one goes off and create a type 3 generator,  
rather use some of the existing C code
you can find on the internet, or use a system support api for this. If  
you use some anonymous C code ensure things about
licensing are clear, and if it really does generate a proper type 3  
UUID based on your perusal of the doc. I'll note it's a
draft, can find a final version, only comments about "where the heck is  
the final version?"

I believe for windows and  the macintosh the VM uses the hosting OS  
UUID generation which is type 3.

Of course window is different, they use have a different version number  
set of bits which I've not found docs for, and
I believe depending on which api you use they perform a one-way hash  
(Hah homeland security comes to mind) on the IP information so
that an UUID isn't 'traceable' to a particular IP by the public.  Just  
in case someone is expecting to see their IP number in the UUID info,  
then again maybe that generator isn't invoked and perhaps it's windows  
OS different.


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John M. McIntosh <johnmci at smalltalkconsulting.com> 1-800-477-2659
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