Re: libltdl on AIX

[Peter O'Gorman]

Tom Epperly wrote:
> We just upgraded to a more recent version of libltdl on my project, and
> the behavior for AIX seems to have changed. In the past, it seems to
> have ignored the results of the LTDL_DLOPEN_SELF_WORKS
> (AC_LIBTOOL_DLOPEN_SELF) test, and now when the test fails it forces a
> lt_dlopen(NULL, ...) to fail.
> 
> In libtool-2.2.4/libltdl/loaders/dlopen.c, the following lines appear:
> 
>   /* On AIX, dlopen(NULL) succeeds but dlsym of symbols fails.
>      In this case, fail here to let the preopen loader do the job. */
> #ifndef LTDL_DLOPEN_SELF_WORKS
>   if (!filename)
>     module = NULL;
>   else
> #endif
>     module = dlopen (filename, module_flags);
> 
> The comment in the code fragment above isn't completely correct.
> dlopen(NULL) works just fine on AIX provided you use -Wl,-bexpall when
> you link your executable. The configure macro that checks whether
> dlopen(NULL) works doesn't use -Wl,-bexpall, so the test fails. Ideally,
> the configure check would add -Wl,-bexpall when testing when
> dlopen(NULL) works on AIX.
> 
> In past versions of libtool, the results from the test didn't matter
> because it seems that libltdl went ahead and called dlopen(NULL) even if
> configure didn't think it would work.  It would be better for us if
> libltdl had the old behavior or if the configure script tried
> -Wl,-bexpall because declaring that dlopen self doesn't work.

Looks like the relevant thread is here:

http://lists.gnu.org/archive/html/bug-libtool/2008-01/msg00021.html

I will probably simply revert that change when I get the chance. Real
life failures being worse than test suite failures :)

Peter
-- 
Peter O'Gorman
http://pogma.com