Allow optional use of libxml2

CMakeLists.txt

@@ -1179,6 +1179,15 @@ IF(NOT FOUND_CURL)
   ENDIF()
 ENDIF(NOT FOUND_CURL)
 
+# see if we have libxml2
+find_package(LibXml2)
+IF(LibXml2_FOUND)
+SET(HAVE_LIBXML2 TRUE)
+INCLUDE_DIRECTORIES(${LIBXML2_INCLUDE_DIRS})
+ELSE()
+SET(HAVE_LIBXML2 FALSE)
+ENDIF()
+
 IF(NOT ENABLE_BYTERANGE AND ENABLE_HDF5_ROS3)
     MESSAGE(WARNING "ROS3 support requires ENABLE_BYTERANGE=TRUE; disabling ROS3 support")
     SET(ENABLE_HDF5_ROS3 OFF CACHE BOOL "ROS3 support" FORCE)
@@ -2080,6 +2089,7 @@ ENDIF()
 
 IF(ENABLE_DAP4)
   ADD_SUBDIRECTORY(libdap4)
+  ADD_SUBDIRECTORY(libncxml)
 ENDIF()
 
 IF(ENABLE_PLUGINS)

Makefile.am

@@ -67,6 +67,7 @@ endif
 
 if ENABLE_DAP4
 DAP4 = libdap4
+XML = libncxml
 NCDAP4TESTDIR = dap4_test
 endif #DAP4
 
@@ -112,7 +113,7 @@ endif
 # This is the list of subdirs for which Makefiles will be constructed
 # and run. ncgen must come before ncdump, because their tests
 # depend on it.
-SUBDIRS = include $(H5_TEST_DIR) libdispatch libsrc $(LIBSRC4_DIR)	\
+SUBDIRS = include $(H5_TEST_DIR) ${XML} libdispatch libsrc $(LIBSRC4_DIR)	\
 $(LIBSRCP) $(LIBHDF4) $(LIBHDF5) $(OCLIB) $(DAP2) ${DAP4} \
 ${NCPOCO} ${ZARR} liblib \
 $(NCGEN3) $(NCGEN) $(NCDUMP) ${PLUGIN_DIR} $(TESTDIRS) docs		\

RELEASE_NOTES.md

@@ -7,6 +7,7 @@ This file contains a high-level description of this package's evolution. Release
 
 ## 4.8.2 - TBD
 
+* [Enhancement] Support optional use of libxml2, otherwise default to ezxml. See [Github #2135](https://github.com/Unidata/netcdf-c/pull/2135) -- H/T to [Egbert Eich](https://github.com/e4t).
 * [Enhancement] Support byte-range reading of netcdf-3 files stored in private buckets in S3. See [Github #2134](https://github.com/Unidata/netcdf-c/pull/2134)
 * [Enhancement] Support Amazon S3 access for NCZarr. Also support use of the existing Amazon SDK credentials system. See [Github #2114](https://github.com/Unidata/netcdf-c/pull/2114)
 * [Bug Fix] Fix string allocation error in H5FDhttp.c. See [Github #2127](https://github.com/Unidata/netcdf-c/pull/2127).

config.h.cmake.in

@@ -300,6 +300,9 @@ are set when opening a binary file on Windows. */
 /* Define to 1 if you have the `pnetcdf' library (-lpnetcdf). */
 #cmakedefine HAVE_LIBPNETCDF 1
 
+/* Define to 1 if you have the libxml2 library. */
+#cmakedefine HAVE_LIBXML2 1
+
 /* Define to 1 if you have the <locale.h> header file. */
 #cmakedefine HAVE_LOCALE_H 1
 

configure.ac

@@ -1054,6 +1054,19 @@ if test "x$enable_dap4" = xyes; then
    AC_DEFINE([ENABLE_DAP4], [1], [if true, build DAP4 Client])
 fi
 
+# We can optionally use libxml2 for DAP4, if available
+AC_CHECK_LIB([xml2],[xmlReadMemory],[have_libxml2=yes],[have_libxml2=no])
+if test "x$have_libxml2" = "xyes" ; then
+   AC_SEARCH_LIBS([xmlReadMemory],[xml2 xml2.dll cygxml2.dll], [],[])
+fi
+if test "x$have_libxml2" = xyes; then
+   XML2FLAGS=`xml2-config --cflags`
+   AC_SUBST([XML2FLAGS],${XML2FLAGS})
+   AC_DEFINE([HAVE_LIBXML2], [1], [if true, use libxml2])
+fi
+# Need a condition for this
+AM_CONDITIONAL(HAVE_LIBXML2, [test "x$have_libxml2" = xyes])
+
 # check for useful, but not essential, memio support
 AC_CHECK_FUNCS([memmove getpagesize sysconf])
 
@@ -1875,6 +1888,7 @@ AC_CONFIG_FILES([Makefile
                  libhdf4/Makefile
                  libnczarr/Makefile
                  libncpoco/Makefile
+                 libncxml/Makefile
                  libdispatch/Makefile
                  liblib/Makefile
                  ncdump/cdl/Makefile

include/Makefile.am

@@ -20,7 +20,7 @@ nc4internal.h nctime.h nc3internal.h onstack.h ncrc.h ncauth.h		\
 ncoffsets.h nctestserver.h nc4dispatch.h nc3dispatch.h ncexternl.h	\
 ncpathmgr.h ncindex.h hdf4dispatch.h hdf5internal.h nc_provenance.h	\
 hdf5dispatch.h ncmodel.h isnan.h nccrc.h ncexhash.h ncxcache.h          \
-ncfilter.h ncjson.h ezxml.h ncs3sdk.h
+ncfilter.h ncjson.h ncxml.h ncs3sdk.h
 
 if USE_DAP
 noinst_HEADERS += ncdap.h
@@ -32,10 +32,7 @@ endif
 
 EXTRA_DIST = CMakeLists.txt XGetopt.h netcdf_meta.h.in netcdf_dispatch.h.in
 
-# netcdf_json.h is part of the distribution.
-# If either of the files ncjson.h ../libdispatch/ncjson.c is changed
-# then netcdf_json.h should be reconstructed using this recipe.
-build_netcdf_json.h::
-	sed -e 's/NCJSON_H/NETCDF_JSON_H/' -e '/ncjson.h/d' <${srcdir}/ncjson.h > $@
-	sed -e '/ncjson.h/d' < ${srcdir}/../libdispatch/ncjson.c >> $@
-
+# Give the recipe for rebuilding netcdf_json.h
+makencjson::
+	sed -e 's/NCJSON_H/NETCDF_JSON_H/' -e '/ncjson.h/d' <${srcdir}/ncjson.h > netcdf_json.h
+	sed -e '/ncjson.h/d' < ${srcdir}/../libdispatch/ncjson.c >> netcdf_json.h

include/ncxml.h

@@ -0,0 +1,44 @@
+/* Copyright 2018-2018 University Corporation for Atmospheric
+   Research/Unidata. */
+
+#ifndef NCXML_H
+#define NCXML_H
+
+#ifdef _WIN32
+  #ifdef DLL_EXPORT /* define when building the library */
+    #define DECLSPEC __declspec(dllexport)
+  #else
+    #define DECLSPEC __declspec(dllimport)
+  #endif
+#else
+  #define DECLSPEC
+#endif
+
+typedef void* ncxml_t;
+typedef void* ncxml_attr_t;
+typedef void* ncxml_doc_t;
+
+#if defined(__cplusplus)
+extern "C" {
+#endif
+
+DECLSPEC void ncxml_initialize(void);
+DECLSPEC void ncxml_finalize(void);
+DECLSPEC ncxml_doc_t ncxml_parse(char* contents, size_t len);
+DECLSPEC void ncxml_free(ncxml_doc_t doc0);
+DECLSPEC ncxml_t ncxml_root(ncxml_doc_t doc);
+DECLSPEC const char* ncxml_name(ncxml_t xml0);
+DECLSPEC char* ncxml_attr(ncxml_t xml0, const char* key);
+DECLSPEC ncxml_t ncxml_child(ncxml_t xml0, const char* name);
+DECLSPEC ncxml_t ncxml_next(ncxml_t xml0, const char* name);
+DECLSPEC char* ncxml_text(ncxml_t xml0);
+DECLSPEC int ncxml_attr_pairs(ncxml_t xml0, char*** pairsp);
+/* Nameless versions of child and next */
+DECLSPEC ncxml_t ncxml_child_first(ncxml_t xml0);
+DECLSPEC ncxml_t ncxml_child_next(ncxml_t xml0);
+
+#if defined(__cplusplus)
+}
+#endif
+
+#endif /*NCXML_H*/

libdap4/Makefile.am

@@ -6,6 +6,8 @@
 
 # Put together AM_CPPFLAGS and AM_LDFLAGS.
 include $(top_srcdir)/lib_flags.am
+AM_CPPFLAGS += -I$(top_srcdir)/libncxml
+libdap4_la_CPPFLAGS = ${AM_CPPFLAGS}
 
 # We may have to add to these later.
 DISTCLEANFILES =
@@ -59,7 +61,7 @@ endif
 # Build convenience library
 noinst_LTLIBRARIES = libdap4.la
 libdap4_la_SOURCES = $(SRC) $(HDRS)
-libdap4_la_CPPFLAGS = $(AM_CPPFLAGS)
+libdap4_la_CPPFLAGS += $(AM_CPPFLAGS)
 libdap4_la_LIBADD =
 
 endif # ENABLE_DAP4

libdap4/d4data.c

@@ -6,7 +6,6 @@
 #include "d4includes.h"
 #include <stdarg.h>
 #include <assert.h>
-#include "ezxml.h"
 #include "d4includes.h"
 #include "d4odom.h"
 #include "nccrc.h"

libdap4/d4fix.c

@@ -7,7 +7,6 @@
 #include <assert.h>
 
 #include "d4includes.h"
-#include "ezxml.h"
 
 /*
 The primary purpose of this code is to provide node and data walkers

libdap4/d4meta.c

@@ -7,7 +7,6 @@
 #include <stdarg.h>
 #include "nc4internal.h"
 #include "ncoffsets.h"
-#include "ezxml.h"
 
 /**
  * Build the netcdf-4 metadata from the NCD4node nodes.