[iyonix-support] Re: Memphis oddity.

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).

Martin
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Martin Wuerthner           MW Software          lists@xxxxxxxxxxxxxxx
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