Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com
Message-ID: <4163EA68.6030407@x-ray.at>
Date: Wed, 06 Oct 2004 14:51:52 +0200
From: Reini Urban <rurban AT x-ray DOT at>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; de-AT; rv:1.8a3) Gecko/20040817
MIME-Version: 1.0
To: Jani Tiainen <redetin AT luukku DOT com>
CC: cygwin AT cygwin DOT com
Subject: Re: Building plugin that is used from multiple executables
References: <1529c46304100604132bced4d1 AT mail DOT gmail DOT com> <ck0o9b$i39$1 AT sea DOT gmane DOT org>
In-Reply-To: <ck0o9b$i39$1@sea.gmane.org>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
X-IsSubscribed: yes

Jani Tiainen schrieb:
> Maarten Boekhold wrote:
>> Suppose I have a plugin library that contains calls that reside in the
>> executable that dlopen()'s that plugin. You can link such a plugin by
>> using a .def file that contains something like:
>>
>> IMPORTS
>> symbol = executable.exe.symbol
>>
>> Now if I need to be able to use the *same* plugin from *two*
>> executables, how do I resolve that??? Can I use a .def file that
>> contains:
>>
>> IMPORTS
>> symbol = executable_1.exe.symbol
>> symbol = executable_2.exe.symbol
>>
>> My gut feeling says 'no', but hope against hope...
> 
> 
> Well, shortly... You can't do that. Since windows exports are binded to 
> name of library (application) and symbol...
> 
> Long way: You can do it, but you need to take alternative route.
> 
> You need one extra DLL that has imports symbol from executable and 
> ex-exports symbol you need forward to plugin:
> 
> for plugin you need to do following:
> 
> IMPORT
> symbol = helper.dll.symbol
> 
> and for both apps you create own helper.dll:
> 
> app1.exe create helper.dll:
> IMPORT
> symbol = app1.exe.symbol
> 
> EXPORT
> symbol
> 
> app2.exe create helper.dll:
> IMPORT
> symbol = app2.exe.symbol
> 
> EXPORT
> symbol
> 
> And finally...
> 
> Or even better, DTRT in windoze world is to pass needed symbol pointers 
> as arguments to plugin function, since windows libraries and 
> applications doesn't allow unresolved symbols in linktime (so called 
> backlinking issue)...

hmm,
stubs:
   (intermediate dll, which dlopen's dependent on
   various issues another dll. platform, release, required feature se: 
pro/basic, language)

lazy linking:
   resolve at run-time. as soon as it will be added to ld.
-- 
Reini Urban
http://xarch.tu-graz.ac.at/home/rurban/

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/