Message-ID: <4548FF03.50403@cygwin.com>
Date: Wed, 01 Nov 2006 15:09:39 -0500
From: "Larry Hall (Cygwin)" <reply-to-list-only-lh AT cygwin DOT com>
Reply-To: cygwin AT cygwin DOT com
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To: cygwin AT cygwin DOT com
Subject: Re: Possible to use pinvoke to call DLL built with cygwin
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Sammy Yu wrote:
> Hi guys,
>    I'm trying to port an application onto Windows that was originally
> developed for UNIX using rpc, pthreads, and AF_UNIX sockets.  I have
> used cygwin to compile this application successfully.  One of the
> components built is a DLL which I want to invoke from a C Sharp
> application.  However, the application crashes whenever I call this
> DLL via pinvoke in C Sharp.
> 
> 
> ************** Exception Text **************
> System.DllNotFoundException: Unable to load DLL 'perm.dll': Invalid
> access to memory location. (Exception from HRESULT: 0x800703E6)
>    at WinPcapRedirectorUI.Perm.meme ()
>    at WinPcapRedirectorUI.MainForm.statisticsButton_Click(Object
> sender, EventArgs e) in
> C:\eclipse\workspace\winperm\WinPcapRedirectorUI\MainForm.cs:line 74
>    at System.Windows.Forms.Control.OnClick (EventArgs e)
>    at System.Windows.Forms.Button.OnClick(EventArgs e)
>    at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
>    at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons
> button, Int32 clicks)
> 
> 
> I verified that the cygwin*.dll are in the path.   I made a strip down
> version of a dll, it exhibited the same behavior.  Next, I compiled
> the
> library with -mno-cygwin flag which surprisingly worked.  I suspect
> that cygwin1.dll does not work with pinvoke.  Can anybody confirm this
> is true?  I prefer not to have to port the native application to
> Visual C or mingw32 as there are a lot of rpc and AF_UNIX sockets.
> Are there any other alternatives?  Thanks in advance for your help!


You need to initialize the DLL.  Loading the Cygwin DLL from a non-Cygwin
app doesn't initialize it automatically.  Only Cygwin apps do that.  Off
the top of my head, I don't recall the details but this has been discussed
before in the email archives, if you want to poke around a bit for the
procedure.


-- 
Larry Hall                              http://www.rfk.com
RFK Partners, Inc.                      (508) 893-9779 - RFK Office
216 Dalton Rd.                          (508) 893-9889 - FAX
Holliston, MA 01746

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