Re: Access a perl dll's function on Win32

----- Original Message ----- 
From: "Marvin Humphrey" <[email protected]>
To: <[email protected]>
Cc: <[email protected]>
Sent: Thursday, September 04, 2008 2:15 AM
Subject: Re: Access a perl dll's function on Win32


> [reply cross-posted to Module::Build list; reply-to header set to 
> [email protected] ]
>
> On Sep 3, 2008, at 6:23 AM, Sisyphus wrote:
>
>> Basically, if you have a perl dll (by which I mean, eg, the  Digest::SHA 
>> dll) and you want to directly access a function from  within that dll 
>> using XS or Inline::C, how do you do that ?
>
> The brute-force way is cram function addresses through Perl variables,  as 
> suggested at <http://www.perlmonks.org/?node_id=691174> and  described in 
> the Time::HiRes POD documentation at 
> <http://perldoc.perl.org/Time/HiRes.html#C-API

Yes - I've used that approach before (with the help of that very same 
perlmonks thread) - though only in a proof-of-concept exercise (in which I 
also did an XS Boot) and it works beautifully. In this particular instance, 
however, I was thinking more of how to access the dll's functionality 
*without* recompiling it to include the additional functions that would be 
necessary for that approach to work. (Sorry - I should have made that 
restriction clearer.)

I think that Jan's suggestion of doing a callback is probably the sane way 
to go. I was thinking more in terms of accessing the dll in isolation (ie 
without actually loading the module - which would rule out callbacks), but 
in reality that's probably a silly condition to be imposing anyway.

I thought it might be fun to try out Reini's idea - and I've got an 
Inline::C script all set to go to access a function in the Math::GMPf dll. 
(That dll has a function that takes no args and returns an int - which keeps 
things really simple for me.) Only problem is I couldn't find a way to get 
any useful address information at all using nm, objdump or dumpbin. I was, 
of course, able to get the address of _boot_Math__GMPf/boot_Math__GMPf using 
GetProcAddress, but that's the only address I could get hold of. No matter 
.... it was, after all, just something I was going to try out for the heck 
of it ;-)

Thanks guys.

Cheers,
Rob