Add a patch to libltdl so that the preopen loader doesn't mask a real

error if the file-based dloader (e.g., dlopen) fails to load a DSO for
a complex reason (e.g., unresolved symbol).

This has been widely reported upstream to the libltdl maintainers - a
general solution is difficult.  This is very definitely an
OMPI-specific solution.  Since our embedded libltdl is hidden behind
visibility flags, that's ok.

Note that this is a change to autogen.sh, but this commit does not
force re-running autogen.sh.  You'll just get the new functionality
the next time you re-run autogen.sh.

This commit was SVN r22806.

autogen.sh

@@ -490,6 +490,11 @@ EOF
             mv configure.new configure
             chmod a+x configure
         fi
+        echo "   ++ preopen error masking ib libltdl"
+        if test -r opal/libltdl/loaders/preopen.c; then
+            patch -N -p0 < config/libltdl-preopen-error.patch
+            rm -f opal/libltdl/loaders/preopen.c.rej
+        fi
 
         # See
         # http://lists.gnu.org/archive/html/bug-libtool/2008-05/msg00045.html.

config/Makefile.am

@@ -9,7 +9,7 @@
 #                         University of Stuttgart.  All rights reserved.
 # Copyright (c) 2004-2005 The Regents of the University of California.
 #                         All rights reserved.
-# Copyright (c) 2006      Cisco Systems, Inc.  All rights reserved.
+# Copyright (c) 2006-2010 Cisco Systems, Inc.  All rights reserved.
 # $COPYRIGHT$
 # 
 # Additional copyrights may follow
@@ -21,6 +21,7 @@ EXTRA_DIST = \
         distscript.csh \
 	ompi_get_version.m4sh \
 	libltdl_dlopen_global.diff \
+	libltdl-preopen-error.diff \
         lt-sun-fortran.diff \
 	lt1522-pathCC.diff \
 	lt21a-pathCC.diff \

config/libltdl-preopen-error.patch

@@ -0,0 +1,27 @@
+--- opal/libltdl/loaders/preopen.c.~1~	2010-03-03 14:13:28.000000000 -0500
++++ opal/libltdl/loaders/preopen.c	2010-03-05 17:57:11.000000000 -0500
+@@ -185,7 +185,24 @@
+ 	}
+     }
+ 
++#if 0
++  /* Open MPI: This line is commented out because Open MPI does not
++     use the preopen functionality in libltdl at all -- so we never
++     need to see errors from this module.  Additionally, this module
++     is usually invoked last in the sequence when trying to
++     lt_dlopenadvise() a DSO -- so if there was a real error when
++     opening that DSO (e.g., a symbol not found), setting the
++     FILE_NOT_FOUND error here will mask the real error.
++
++     This error has been reported upstream to the Libtool maintainers;
++     they acknowledge that it is a problem but no one has come up with
++     a good general solution yet.  This Open MPI-specific solution is
++     workable for us, but not workable as a general solution.  Hence,
++     we patch in this "if 0" block in autogen.sh after Libtool
++     installs libltdl in the opal/ tree.
++  */
+   LT__SETERROR (FILE_NOT_FOUND);
++#endif
+ 
+  done:
+   return module;