From: Jos Backus <jos@...>
Date: 2004-07-14T03:03:39+09:00
Subject: Re: win32api: how to access NetFileEnum results?

    Hi daz,

On Tue, Jul 13, 2004 at 04:32:23PM +0900, daz wrote:
[snip]
> However bufptr (from NetFileEnum) is a POINTER_to_address (POINTER_POINTER),
> so Win32API is *not* required to convert this parameter into a POINTER.
> Passed as a L(ONG), it fulfils the requirement that it's a POINTER already.
> 
> What this often leads to is multiple definitions such as:
> 
>     Pmemcpy1 = Win32API.new('msvcrt', 'memcpy', 'PLL'], 'L')
>     Pmemcpy2 = Win32API.new('msvcrt', 'memcpy', 'LPL'], 'L')
> 
> for use in cases such as yours.
> 
> Call with:
> 
>     Pmemcpy1.call(dest ruby string,     src POINTER_POINTER, length)
>     Pmemcpy2.call(dest POINTER_POINTER, src ruby string,     length)
> 
> 
> Hope that's OK.  Haven't tried ... (I'm not NT)

Thanks for the info. I did indeed overlook the `*' after the LPBYTE typename.

Next question is: using Pmemcpy1, how do I initialize the src POINTER_POINTER
argument (i.e.  bufptr)? Setting it to 0 causes ruby to segfault (both 1.8.1
and today's 1.8.2 snapshot installed using the one-click installer) and
setting it to "\0" * 4 causes a TypeError as the template specifies a Long
and I'm supplying a String.

Thanks,
-- 
Jos Backus                       _/  _/_/_/      Sunnyvale, CA
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jos at catnook.com        _/_/   _/_/_/          require 'std/disclaimer'