Re: shared memory

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# The following was supposedly scribed by
# Andr=E9 Warnier
# on Tuesday 15 March 2005 05:26 pm:

>On the other hand, mod_perl seems to have some deep interactions with
>the innards of the Apache server, for example direct manipulation of
> the "bucket brigades". =A0How come no-one has come up yet with some
> scheme to "hijack" one of these bucket brigades (or some other
> internal Apache memory area) to provide such a capability ?
>
>Also, for instance, the DBI module and it's companion Apache::DBI
>provide persistent connections to databases. And to my knowledge, they
>are available under Unix as well as Windows. =A0For doing this, there
> must be some form of memory sharing at work, isn't it so ?

The answer to these and all related "why" questions probably contains=20
the word "security".

Any kind of memory sharing between apache processes is a potential hole,=20
so you have to be really careful about how you code it.

I think that what you propose is certainly possible, but it would be a=20
big task to cover all of the vulnerabilities.  So, your best bet is to=20
use something that already exists, and there's been a lot of work done=20
by a lot of people on the DBI, so that's probably where you'll get the=20
most mileage.

You keep saying that you want to share memory, but what you really want=20
to do is share data.  In terms of security, stability, etc. you solve a=20
lot of problems by avoiding shared memory.  With that in mind, try to=20
reframe your problem and you'll probably find that DBI will be the path=20
of least resistance.  There are a few wrapper modules that simplify the=20
interface (some even tied to hashes?) so maybe you want to use one of=20
those if your frustrated by having to speak in SQL to talk to your data=20
structure.

=2D-Eric
=2D-=20
"Left to themselves, things tend to go from bad to worse."=20
                                       -- Murphy's Corollary
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