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Mail Archives: cygwin/2002/08/19/21:47:34

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Message-ID: <3D5F1721.2808F1A3@gmx.net>
Date: Sun, 18 Aug 2002 05:40:17 +0100
From: Lostmind <lostmind AT gmx DOT net>
X-Accept-Language: de,en
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Problems exporting my DLL functions...

Hi,
first: I'm a newbe in C programming, so don't eat me if the mistake is
too simple - but at least it's not mentioned in the FAQ or in the short
text on the Cygwin homepage about DLL stuff...

Ok, what I want is to write a simple DLL...

I definined two functions inside the DLL code, like this (I leave out
the initialization code here):

#ifdef __cplusplus
#define EXPORT extern "C" __declspec (dllexport)
#else
#define EXPORT __declspec (dllexport)
#endif

EXPORT int CALLBACK CreateKeyboardHook (HWND receiver);
EXPORT int CALLBACK DestroyKeyboardHook ();

//...

EXPORT int CALLBACK CreateKeyboardHook (HWND receiver)
{
//...
}

EXPORT int CALLBACK DestroyKeyboardHook ()
{
//...
}

main()
{
}

To compile I used the following instructions - based on the text from
the Cywin homepage, but a bit modified (I wrote them in a .bat file):

gcc -c khook.c -mno-cygwin -s -O3
gcc -Wl,--base-file,khook.base -o khook.dll khook.o
-Wl,-e,_mydll_init AT 12 -mno-cygwin -O3 -s -luser32
dlltool --base-file khook.base --def khook.def --output-exp khook.exp
--dllname khook.dll
gcc -Wl,--base-file,khook.base,khook.exp -o khook.dll khook.o
-Wl,-e,_mydll_init AT 12 -mno-cygwin -O3 -s -luser32
dlltool --base-file khook.base --def khook.def --output-exp khook.exp
--dllname khook.dll
gcc -Wl,khook.exp -o khook.dll khook.o -Wl,-e,_mydll_init AT 12 -mno-cygwin
-O3 -s -luser32
dlltool --def khook.def --dllname khook.dll --output-lib khook.a

My .def file looks like this:

EXPORTS
CreateKeyboardHook @1
DestroyKeyboardHook @2

When I run the batch, the first 3 instructions work fine but then gcc
reports:

khook.exp(.edata+0x34):fake: undefined reference to `CreateKeyboardHook'
khook.exp(.edata+0x38):fake: undefined reference to
`DestroyKeyboardHook'
collect2: ld returned 1 exit status

What's my mistake? Thanx for every answer... Klaus.

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