Import Structure from unmanaged DLL (not function!)

[vk000]

Hi,

There is a constant structure with predefined fields values located in WinScard.dll. I am trying to get access to this structure
values in my C# code. Is there any way I can do that?

Basically I just need to obtain a memory reference like IntPtr to location of the structure in DLL, since I know the structure
layout.

I know that [DllImport()...] attribute works great for functions but looks like there is no instruction/attribute to associate
IntPtr and structure from an unmanaged DLL.

In my case I am trying to get access to
g_rgSCardT0Pci,
g_rgSCardT1Pci,
g_rgSCardRawPci
structures from WinScard.dll

Please help!

--
Regards,

Victor.
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"Be nice to the people you meet on the way up, because you'll be meeting the same people on the way down."

 

[jdmartinez]

Hmm ... the way I'd probably do that is to write my own unmanaged dll
to obtain the reference to that, then p/invoke that ...

Joel Martinez
http://www.onetug.org - Orlando .NET User Group
http://www.codecube.net - blog

 

[Philip Coveney]

Victor,

Try this:

[StructLayout(LayoutKing.Explicit, Size=#bytes)]
internal class SCardInfo (sic)
{
[FieldOffset(0)] public int g_rgSCardT0Pci;
[FieldOffset(4)] public int g_rgSCardT1Pci;
[FieldOffset(8)] public int g_rgSCardRawPci;
}

Basically, you tell .NET exactly how to marshal the structure. Then use
DllImport as you probably already are, roughly:

[DllImport("foo,dll", EntryPoint="MyFunc")]
static extern int GetCardInfo (SCardInfo cardInfo);

(Obviously, I don't know the names/signatures for the functions in your
DLL, but you get the idea.)

Finally, call the sucker:

SCardInfo temp = new SCardInfo();
int result = GetCardInfo(temp);

Good luck,

PC

 

[Mattias Sjögren]

Is there any way I can do that?

I believe you can use GetProcAddress to get the pointers.



Mattias