Re: Lua Alien library

["J.Jørgen von Bargen" <jjvb.primus@...>]

Am 24.04.2010 12:00, schrieb Attila:
> After your help, I was able to load it, and  almost works perfectly. 
> Currently I want to use GetVolumeInformationA, which prototype is the 
> following:
> BOOL ::GetVolumeInformation(LPCWSTR lpRootPathName, LPWSTR 
> lpVolumaNameBuffer, DWORD nVolumeNameSize, LPDWORD 
> lpVolumeSerialNumber,LPDWORD lpMaximumComponentLength, LPDWORD 
> lpFileSystemFlag, LPWSTR lpFileSystemNameBuffer,DWORD 
> nFileSystemNameSize)
> LPDWORD is unsigned long* , so I should pass a referenced value to get 
> the value, but I can't, because only ref char, ref int and ref double 
> are available, but ref long isn't. What can I do to make this working?
> I Googled a lot, but there is only one working Windows example on the 
> stackoverflow forum. Can somebody mention some places where I can find 
> more?
> Thanks: Attila
I would try the following.
Prototype the argument as "pointer"
    your_function:types{ret="int",abi="stdcall","pointer"}
allocate a buffer
    local one_long=alien.array('long',1)
pass the buffer as argument
    your_function(one_long.buffer)
get the result
    local result=one_long[1]

In your case for GetVolumeInformation you must declare one "pointer" and 
allocate one buffer for each LPDWORD argument.
Hope this helps
regards Jørgen