[iyonix-support] Re: Memphis oddity.

On 10 Aug 2006  Martin Wuerthner <lists@xxxxxxxxxxxxxxx> wrote:

> In message <171e46544e.pnyoung@xxxxxxxxxxxxxxxxxxxx>
>           Dr Peter Young <pnyoung@xxxxxxxxxxxx> wrote:
> 
>> I'm not sure whether this is the right list (it happens on RISC OS
>> 5.11); if not, will someone tell me, but politely, please? :-) I just
>> wonder whether it has some relevance to a previous thread when people
>> were getting lines across the screen, which seemed to be due to
>> applications' memory leaking out of their allotted spaces.
> 
> No, this is unrelated.
> 
>> [...]I'm a great addict of playing Klondike, courtesy of
>> SuperPatience, and I save the current game in Memphis. On my peeping
>> into some of these saved files, they contain fragments of e-mails (I
>> use Hermes/NetFetch and Messenger Pro); no e-mails are stored in
>> Memphis, and no corruption of e-mails is apparent (I think they're all
>> deleted e-mails, but it's difficult to tell, as they are all
>> fragmented, and, perhaps relevantly, appear to be only parts of
>> headers).
>> 
>> This doesn't seem to affect how the game plays, but I'm sure these
>> bits shouldn't be there. Should I be worried? And does anyone out
>> there have any idea how this happens?
> 
> This is perfectly normal under RISC OS. If an application releases a
> page of memory and that page is later given to some other application
> its contents are not deleted inbetween. So, if the second application
> does not overwrite all of the newly allocated memory (and this happens
> frequently, e.g., if the application reserves 256 bytes for a string
> and then only writes a short string to it), then some random remaining
> data from some other application remains and might even be saved to
> disc as part of the second application's files.
> 
> Technically, this is perfectly safe (after all, the memory was
> released by the first application) but has privacy issues (and maybe
> security issues, too, if the memory contained passwords, for
> instance).

Many thanks for this clear and comprehensive explanation. I'll now 
stop worrying.

With best wishes,

Peter.

-- 
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Anne     \ / __            __  \                              England.
and       / /  \ | | |\ | /  _  \     http://pnyoung.orpheusweb.co.uk
family   /  \__/ \_/ | \| \__/   \______________ pnyoung@xxxxxxxxxxxxx
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