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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Wed, 30 Jul 2003 21:03:26 -0400 (EDT)
From: Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: vikramshrowty AT fastmail DOT fm
cc: cygwin AT cygwin DOT com
Subject: Re: linking with non-cygwin dll
In-Reply-To: <Pine.LNX.4.50.0307301737210.22806-100000@hidis.cjb.net>
Message-ID: <Pine.GSO.4.44.0307302101310.15840-100000@slinky.cs.nyu.edu>
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On Wed, 30 Jul 2003 vikramshrowty AT yahoo DOT com wrote:

> Hi,
>         I had posted a query earlier about a cygwin program linking
> with a non-cygwin dll. Based on the very helpful responses and some googling
> around, I learnt that this is possible. But...
>
> heres a main.c that links with cygwin1.dll
>
> int main(void)
> {
>   printf("CYGWIN\n");
>   test_dll();
>   return(0);
> }
>
> where test_dll is in a dll compiled with -mno-cygwin and is defined
> like this...
>
> __declspec(dllexport) __stdcall void test_dll(void)
> {
>   printf("MSFT %d\n",i);
>   fflush(stdout);
> }
>
> This works perfectly. But, notice the fflush. If this is removed,
> "MSFT" doesnt get printf'ed. I assuming that this is because the
> stdout buffer in the microsoft c-library isnt getting flushed
> automatically at program exit.
>
> Any ideas on why?? ..and how to remedy this??
> --Vikram

Well, gcc links the Cygwin executable with its own C runtime.  MSVCRT is
another C runtime.  So, when you call the DLL, you have 2 C runtimes
competing for the same output stream.  This can't be good (in fact, the
results are unspecified, IIRC).  Thus, the simple remedy is: don't do
that.  Either only use one runtime for output (whichever one), or fflush
and pray.
	Igor
-- 
				http://cs.nyu.edu/~pechtcha/
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ZZZzz /,`.-'`'    -.  ;-;;,_		igor AT watson DOT ibm DOT com
     |,4-  ) )-,_. ,\ (  `'-'		Igor Pechtchanski, Ph.D.
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

"I have since come to realize that being between your mentor and his route
to the bathroom is a major career booster."  -- Patrick Naughton


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