From 8d2092603203d3f565dbb32b86db625bbdd6a415 Mon Sep 17 00:00:00 2001
From: Paul MARTZ <pmartz@skew-matrix.com>
Date: Sun, 22 May 2011 18:49:43 +0000
Subject: [PATCH] 2.8 branch: This is a backport of r11055 from trunk so that
 libosg and libosgDB link against libdl on Linux systems. Backported by Ryan
 Pavlik. Trunk commit messages: "From Jim Brooks, fix for FreeBSD build where
 FIND_LIBRARY(DL_LIBRARY..) return NOT_FOUND. And From Alberto Luaces, "he new
 GNU linker, "gold", is going to replace soon the current ld in almost all
 Linux distributions. Although it is 100% compatible with ld, by default it
 gives an error if a library has unresolved symbols at link time, that is, it
 has set -Wl,--no-undefined by default. Debian folks have found that libosg.so
 and libosgDB.so use some functions belonging to libdl.so
 {dlsym,dlopen,dlclose,dlerror} without linking to it. My changes link those
 two libraries to libdl.so explicitly in the same way it is already done for
 libm.so and librt.so."

---
 CMakeLists.txt           | 6 ++++++
 src/osg/CMakeLists.txt   | 2 +-
 src/osgDB/CMakeLists.txt | 2 +-
 3 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9bb960cdf..75b233cc2 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -153,6 +153,12 @@ IF(UNIX)
     FIND_PACKAGE(X11)
     # Some Unicies need explicit linkage to the Math library or the build fails.
     FIND_LIBRARY(MATH_LIBRARY m)
+
+    FIND_LIBRARY(DL_LIBRARY dl)
+    IF(NOT DL_LIBRARY)
+        SET(DL_LIBRARY "") # change from NOTFOUND to empty when passed to linker
+    ENDIF()
+
 ENDIF(UNIX)
 
 # Make the headers visible to everything
diff --git a/src/osg/CMakeLists.txt b/src/osg/CMakeLists.txt
index 5bb3d96f1..7b5b029a3 100644
--- a/src/osg/CMakeLists.txt
+++ b/src/osg/CMakeLists.txt
@@ -326,7 +326,7 @@ ADD_LIBRARY(${LIB_NAME}
 LINK_INTERNAL(${LIB_NAME}     
     OpenThreads
 )
-LINK_EXTERNAL(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT}    ${MATH_LIBRARY} )
+LINK_EXTERNAL(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT}    ${MATH_LIBRARY} ${DL_LIBRARY})
 LINK_CORELIB_DEFAULT(${LIB_NAME} ${CMAKE_THREAD_LIBS_INIT} ${MATH_LIBRARY} )
 
 INCLUDE(ModuleInstall OPTIONAL)
diff --git a/src/osgDB/CMakeLists.txt b/src/osgDB/CMakeLists.txt
index 300bce174..19bce40b3 100644
--- a/src/osgDB/CMakeLists.txt
+++ b/src/osgDB/CMakeLists.txt
@@ -110,7 +110,7 @@ LINK_INTERNAL(${LIB_NAME}
     osg
     OpenThreads
 )
-LINK_EXTERNAL(${LIB_NAME}     ${OSGDB_PLATFORM_SPECIFIC_LIBRARIES} )
+LINK_EXTERNAL(${LIB_NAME}     ${OSGDB_PLATFORM_SPECIFIC_LIBRARIES} ${DL_LIBRARY})
 LINK_CORELIB_DEFAULT(${LIB_NAME})
 
 INCLUDE(ModuleInstall OPTIONAL)