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Date: Mon, 02 Nov 2009 20:05:52 -0700
From: Eric Blake <ebb9 AT byu DOT net>
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To: cygwin AT cygwin DOT com
Subject: Re: Shall dlopen("foo") succeeed if only "foo.dll" exists?
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According to Corinna Vinschen on 11/2/2009 9:48 AM:
> Weird question, right?
> 
> Here's the problem.
> 
> Assume you have a file "foo.so" on Linux.  If you call
> 
>   dlopen ("./foo.so", RTLD_LAZY);
> 
> it succeeds, but
> 
>   dlopen ("./foo", RTLD_LAZY);
> 
> fails because the dlopen function never adds any suffixes like .so
> automatically.

And POSIX says "If file contains a <slash> character, the file argument is
used as the pathname for the file. Otherwise, file is used in an
implementation-defined manner to yield a pathname."  So I think we are
better off NOT adding an implicit .dll.

> While we tend to change the implementation to be more Linux-like,
> there could be some tools out there which erroneously depend on the
> Windows-like behaviour of Cygwin's dlopen().

My only worry is whether libtool depends on this behavior.  But a quick
look at the source code (although not a definitive one) shows that libtool
is already adding a trailing dot on its own, in order to bypass window's
automatic .dll appending.  So if anything, I'm guessing that not adding an
implicit suffix is actually what libtool would prefer.

- --
Don't work too hard, make some time for fun as well!

Eric Blake             ebb9 AT byu DOT net
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