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Date:	Thu, 5 Nov 2009 10:48:21 +0100
From:	Corinna Vinschen <corinna-cygwin AT cygwin DOT com>
To:	cygwin AT cygwin DOT com
Subject:	Re: Shall dlopen("foo") succeeed if only "foo.dll" exists?
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On Nov  4 22:38, Charles Wilson wrote:
> Corinna Vinschen wrote:
> 
> > But what about perl?  It uses the .dll suffix for modules on Cygwin.
> 
> perl uses dl_dlopen.xs on cygwin AFAICT, which basically passes its
> arguments unchanged to the system dlopen.
> 
> > Does it call dlopen("foo.dll") or dlopen("foo")?
> 
> Looking at DynaLoader_pm.PL (this is self-modifying code, used to
> generate the actual DynaLoader.pm, so it's a little odd):
> [...]
> On cygwin:
> use Config; print join("\n",@Config::Config{qw(dlext so dlsrc)});
> dll
> dll
> dl_dlopen.xs
> 
> So it looks like perl itself accepts either a "bare" library name, or a
> properly .dll-decorated one (or even "-lfoo"!) -- but will eventually
> try the .dll extension if "bare" fails.

It looks like perl tries the dll suffix immediately.  I just tried
this:

  $ perl -e 'use Alias;'

under strace and the first access is already to the file called
/usr/lib/perl5/vendor_perl/5.10/i686-cygwin/auto/Alias/Alias.dll

I removed the automatic adding of the .dll suffix, and the above
perl statement still works fine and dlopen succeeds.

I'm going to check this change in.  I think I should prepare a new
Cygwin release quite soon, not only for testing this change, but also
due to the cygpath problem.


Thanks to all of you,
Corinna

-- 
Corinna Vinschen                  Please, send mails regarding Cygwin to
Cygwin Project Co-Leader          cygwin AT cygwin DOT com
Red Hat

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