On Fri, Dec 08, 2006 at 01:26:53AM +0200, Alon Bar-Lev wrote:
> On 12/8/06, Joe Orton <[EMAIL PROTECTED]> wrote:
> >You say the KDE QCA code can be used as a library.  So in that case:
> >what happens when both QCA code and some other pkcs11h_*-using code are
> >linked into the same process, and both register a token prompt hook?
> >
> >There can only be one callback registered for the process so it can't be
> >handled by both the QCA code and any other user, right?
> 
> True.
> And what happens if I register OpenSSL locking hooks, modify its
> engines unloading alogirthmim while using neon?

You discover why process-global state in the OpenSSL libraries is bad? 
:)

> Or application that uses pkcs11-helper, and decides to access the
> PKCS#11 provider directly?
> 
> Or using operating system to read/write files and access directly to 
> /dev/sda?

Right!  These are exactly the same class of problem - a hardware 
resource for which you need to arbitrate shared access.  The solution is 
always the same: you invent an abstraction layer and arbitrate access 
through an intermediary.

"the filesystem" is the abstraction used to share access to disks, the 
OS arbitrates as the intermediary.

"the X Window System" is an abstraction used to arbitrate access to the 
display+IO devices: a daemon (the X server) acts as the intermediary and 
apps talk to that daemon via a library over a socket.  That's exactly 
analogous to the idea I talked about by no coincidence.

Regards,

joe
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