Added '--enable-dynamic-loading' to autotools-based builds, and

-DENABLE_DYNAMIC_LOADING to cmake-based builds.

This will allow for compatibility with hdf5 1.8.11 builds that
have enabled dynamic building (depends on libdl).

See Jira ticket NCF-258

CMakeLists.txt

@@ -389,6 +389,11 @@ ENDIF()
 # Option to Enable HDF5
 OPTION (USE_SZIP "Use SZip" OFF)
 OPTION (USE_HDF5 "Use HDF5." ${ENABLE_NETCDF_4})
+OPTION (ENABLE_DYNAMIC_LOADING "Enable Dynamic Loading" OFF)
+IF(ENABLE_DYNAMIC_LOADING)
+  SET(USE_LIBDL ON CACHE BOOL "")
+ENDIF()
+
 IF (USE_HDF5 OR ENABLE_NETCDF_4)
   SET(USE_HDF5 ON)
   SET(USE_NETCDF4 ON)
@@ -410,6 +415,24 @@ IF (USE_HDF5 OR ENABLE_NETCDF_4)
   
   INCLUDE_DIRECTORIES(${HDF5_INCLUDE_DIRS})
   
+  # Starting with hdf5 1.8.11, dynamic loading is an option.
+  # In case hdf5 has a dependency on libdl, the user must specify
+  # -DENABLE_DYNAMIC_LOADING=ON when configuring netcdf.
+  IF(USE_LIBDL)
+    FIND_LIBRARY(LIBDL NAMES dl dld)
+    FIND_PATH(LIBDL_INCLUDE_DIR dlfcn.h)
+    IF(NOT LIBDL)
+      MESSAGE(ERROR "Cannot find libdl, but dynamic loading was specified.")
+    ENDIF()
+    IF(NOT LIBDL_INCLUDE_DIR)
+      MESSAGE(ERROR "Cannot find dlfcn.h, but dynamic loading was specified.")
+    ENDIF()
+    MESSAGE(STATUS "Found libdl: ${LIBDL}")
+    SET(HAVE_LIBDL ON)
+    INCLUDE_DIRECTORIES(${LIBDL_INCLUDE_DIR})
+
+  ENDIF()
+
   #Check to see if H5Z_SZIP exists in HDF5_Libraries. If so, we must use szip.
   IF(USE_SZIP)
 	FIND_PACKAGE(SZIP NO_MODULE)

RELEASE_NOTES

@@ -6,6 +6,15 @@ https://www.unidata.ucar.edu/jira/browse/NCF-XXX .
 
 VERSION		COMMENTS
 -------		--------
+4.3.1		Released TBD
+
+		Added support for dynamic loading, to compliment
+		the dynamic loading support introduced in hdf 1.8.11. 
+		Dynamic loading support depends on libdl, and 
+		is enabled as follows: [NCF-258]
+			o autotools-based builds: --enable-dynamic-loading
+			o cmake-based builds: -DENABLE_DYNAMIC_LOADING=ON
+
 4.3		Released 2013-05-03
 
 	       fsync: Changed default in autotools config

RELEASE_NOTES.md

@@ -5,6 +5,14 @@ Releases are in reverse chronological order (most recent first). Recent
 releases include references to Jira issue identifiers for more
 information, where '[NCF-XXX]' refers to https://www.unidata.ucar.edu/jira/browse/NCF-XXX .
 
+### 4.3.1 Released TBD
+
+* Added support for dynamic loading, to compliment the dynamic loading support introduced in hdf 1.8.11.  Dynamic loading support depends on libdl, and is enabled as follows: [NCF-258]
+	* autotools-based builds: --enable-dynamic-loading
+	* cmake-based builds: -DENABLE\_DYNAMIC\_LOADING=ON
+	
+[NCF-258]: https://www.unidata.ucar.edu/jira/browse/NCF-258
+
 ### 4.3.0 Released 2013-04-29
 
 * fsync: Changed default in autotools config file; fsync must now be

config.h.in.cmake

@@ -73,6 +73,7 @@
 #cmakedefine ENABLE_DAP_REMOTE_TESTS 1
 #cmakedefine EXTRA_TESTS
 #cmakedefine USE_NETCDF4 1
+#cmakedefine USE_LIBDL 1
 #cmakedefine USE_HDF4 1
 #cmakedefine USE_HDF5 1
 #cmakedefine USE_FFIO 1
@@ -95,7 +96,8 @@
 #cmakedefine HAVE_DOPRNT
 #cmakedefine HAVE_ALLOCA
 #cmakedefine HAVE_SSIZE_T 1
-#cmakedefine HAVE_LIBPNETCDF
+#cmakedefine HAVE_LIBPNETCDF 1
+#cmakedefine HAVE_LIBDL 1
 
 /* Define to 1 if you have the <alloca.h> header file. */
 #cmakedefine HAVE_ALLOCA_H @HAVE_ALLOCA_H@

configure.ac

@@ -113,6 +113,14 @@ if test "x$enable_netcdf_4" = "x" ; then
   enable_netcdf_4="$enable_netcdf4"
 fi
 
+# Does the user require dynamic loading?
+# This is only for those hdf5 installs that support it.
+AC_MSG_CHECKING([do we require hdf5 dynamic-loading support])
+AC_ARG_ENABLE([dynamic-loading], [AS_HELP_STRING([--enable-dynamic-loading],
+				 [enable dynamic loading for use with supported hdf5 installs (libdl, HDF5 required)])])
+test "x$enable_dynamic_loading" = xyes || enable_dynamic_loading=xno
+AC_MSG_RESULT([$enable_dynamic_loading])
+
 # Does the user want to turn on HDF4 read ability?
 AC_MSG_CHECKING([whether reading of HDF4 SD files is to be enabled])
 AC_ARG_ENABLE([hdf4], [AS_HELP_STRING([--enable-hdf4],
@@ -705,6 +713,17 @@ if test "x$enable_netcdf_4" = xyes; then
   	AC_DEFINE([USE_SZIP], [1], [if true, compile in szip compression in netCDF-4 variables])
    fi
 
+   # The user may have built HDF5 with libdl (dynamic loading support).
+   if test "x$enable_dynamic_loading" = xyes; then
+      AC_CHECK_HEADERS([dlfcn.h], [], [nc_dlfcn_h_missing=yes])
+      if test "x$nc_dlfcn_h_missing" = xyes; then
+      	      AC_MSG_ERROR([Cannot find dlfcn.h, yet --enable-dynamic-loading was used.])
+      fi
+      AC_CHECK_LIB([dl],[dlopen], [], [AC_MSG_ERROR([Can't find or link against libdf. See config.log for errors.])])
+      AC_DEFINE([USE_LIBDL],[1], [if true, enable dynamic loading support])
+   fi
+   
+
    # If the user wants hdf4 built in, check it out.
    if test "x$enable_hdf4" = xyes; then
       AC_CHECK_HEADERS([mfhdf.h], [], [nc_mfhdf_h_missing=yes])	   

liblib/CMakeLists.txt

@@ -44,6 +44,10 @@ SET(TLL_LIBS "")
 
 SET(TLL_LIBS ${TLL_LIBS} ${HAVE_LIBM} ${ZLIB_LIBRARY})
 
+IF(HAVE_LIBDL)
+  SET(TLL_LIBS ${LIBDL} ${TLL_LIBS})
+ENDIF()
+
 IF(USE_HDF5 OR USE_NETCDF4)
 	    SET(TLL_LIBS ${HDF5_LIBRARIES} ${TLL_LIBS} ${SZIP_LIBRARY})	
 ENDIF()