Initial handling of calls to static Java methods

Changes mostly include:
* New option `--with{out}-java` for `configure` script
* Runtime support for calling `static void (void)` methods
* Lookup of JVM library when JAVA_HOME is set, and pre-load when
  possible
* Two preliminary tests

Co-authored-by: Nicolas Berthier <[email protected]>
Co-authored-by: Simon Sobisch <[email protected]>

ChangeLog

@@ -1,5 +1,11 @@
+
+2024-07-12  Vedant Tewari <[email protected]>
 
-2023-02-25  Ron Norman <[email protected]> 
+	* ax_prog_java.m4: Added macro for jni check
+	* ax_jni_include_dir.m4: Added macro for jni check
+    	* configure.ac: added support for Java interoperability through JNI
+
+2023-02-25  Ron Norman <[email protected]>
 
 	* configure.ac: Add check for  sys/time.h
 

DEPENDENCIES

@@ -137,6 +137,21 @@ The following libraries ARE required WHEN :
 
     JSON-C is distributed under Expat License.
 
+5) JNI (Java Native Interface) support is used
+
+    BOTH runtime AND development components required.
+
+    Java Development Kit (JDK) 8 or later
+
+    https://openjdk.org/
+
+    The JDK is distributed under various open-source licenses depending
+    on the vendor and version. Common licenses include the GNU General
+    Public License (GPL) and the Oracle Binary Code License Agreement.
+
+    To enable JNI support, ensure that the JDK is installed on your system,
+    and set the appropriate environment variables (e.g., JAVA_HOME) to point
+    to the JDK installation directory.
 
 See HACKING if you wish to hack the GnuCOBOL source or build directly
 from version control as this includes the list of additional tools

DEPENDENCIES.md

@@ -119,3 +119,13 @@ Support for GENERATE JSON is provided by *one* of the following:
 
     JSON-C is distributed under Expat License.
 
+JNI Support
+------------
+
+Support for JNI (Java Native Interface) is provided by:
+
+* [Java Development Kit (JDK)](https://openjdk.java.net/) 8 or later.
+
+    The JDK is distributed under various open-source licenses depending on the vendor and version. Common licenses include the GNU General Public License (GPL) and the Oracle Binary Code License Agreement.
+
+To enable JNI support, ensure that the JDK is installed on your system, and set the appropriate environment variables (e.g., JAVA_HOME) to point to the JDK installation directory.

NEWS

@@ -20,7 +20,7 @@ NEWS - user visible changes				-*- outline -*-
 
 
 * New GnuCOBOL features
-
+** Initial support for Java interoperability through JNI (new optional dependency JDK)
 ** file handling: added backends for ODBC (so far PostgrSQL, MySQL, SQLite,
    MSSQL) and OCI, along with new directory COB_SCHEMA_DIR containing the
    necessary internal schema files to match the file definition to the

cobc/ChangeLog

@@ -1,4 +1,8 @@
 
+2024-08-14  Nicolas Berthier <[email protected]>
+
+	* cobc.c (cobc_print_info): added note for Java interoperability
+
 2024-08-04  David Declerck <[email protected]>
 
 	Adjustments to merge 2022-12-21:

cobc/cobc.c

@@ -2620,6 +2620,12 @@ cobc_print_info (void)
 
 	cobc_var_print (_("JSON library"),		_(WITH_JSON), 0);
 
+#ifdef WITH_JNI
+	cobc_var_print (_("Java interoperability"),	_("enabled"), 0);
+#else
+	cobc_var_print (_("Java interoperability"),	_("disabled"), 0);
+#endif
+
 #ifdef COB_DEBUG_LOG
 	cobc_var_print ("DEBUG_LOG",		_("enabled"), 0);
 #endif

cobc/codegen.c

@@ -1,7 +1,7 @@
 /*
    Copyright (C) 2003-2024 Free Software Foundation, Inc.
    Written by Keisuke Nishida, Roger While, Ron Norman, Simon Sobisch,
-   Edward Hart
+   Edward Hart, Vedant Tewari
 
    This file is part of GnuCOBOL.
 
@@ -147,6 +147,7 @@ static struct literal_list	*literal_cache = NULL;
 static struct field_list	*field_cache = NULL;
 static struct field_list	*local_field_cache = NULL;
 static struct call_list		*call_cache = NULL;
+static struct call_list	*call_java_cache = NULL;
 static struct call_list		*func_call_cache = NULL;
 static struct static_call_list	*static_call_cache = NULL;
 static struct base_list		*base_cache = NULL;
@@ -395,6 +396,22 @@ lookup_source (const char *p)
 	return source_id++;
 }
 
+static void
+lookup_java_call(const char *p)
+{
+	struct call_list *clp;
+
+	for (clp = call_java_cache; clp; clp = clp->next) {
+		if (strcmp (p, clp->call_name) == 0) {
+			return;
+		}
+	}
+	clp = cobc_parse_malloc (sizeof (struct call_list));
+	clp->call_name = p;
+	clp->next = call_java_cache;
+	call_java_cache = clp;
+}
+
 static void
 lookup_call (const char *p)
 {
@@ -1978,6 +1995,11 @@ output_call_cache (void)
 		output_local ("static cob_call_union\tcall_%s;\n",
 			      call->call_name);
 	}
+	call_java_cache = call_list_reverse (call_java_cache);
+	for (call = call_java_cache; call; call = call->next) {
+		output_local ("static cob_java_handle*\tcall_java_%s;\n",
+			      call->call_name);
+	}
 	func_call_cache = call_list_reverse (func_call_cache);
 	for (call = func_call_cache; call; call = call->next) {
 		output_local ("static cob_call_union\tfunc_%s;\n",
@@ -7068,6 +7090,45 @@ output_field_constant (cb_tree x, int n, const char *flagname)
 	output_newline ();
 }
 
+static void
+output_java_call (struct cb_call *p)
+{
+	char* full_name = (char *)CB_LITERAL(p->name)->data; /* Assume java.prefix (enforced in `parser.y`, rule `call_body`)*/
+	char* class_and_method_name = full_name + 5;
+	char *last_dot;
+	char *method_name;
+	const char *class_name;
+	char* mangled;
+
+	mangled = strdup(class_and_method_name);
+	for (size_t i = 0; i < strlen(mangled) + 1; i++) {
+		mangled[i] = (mangled[i] == '.') ? '_' : mangled[i];
+	}
+
+	last_dot = strrchr(class_and_method_name, '.');
+	if (last_dot == NULL) {
+		cobc_err_msg (_("malformed call '%s' to a Java method"), class_and_method_name);
+		COBC_ABORT ();
+	}
+
+	*last_dot = '\0';
+	method_name = last_dot + 1;
+	class_name = class_and_method_name;
+
+	lookup_java_call(mangled);
+	output_line("if (call_java_%s == NULL)", mangled);
+	output_block_open();
+
+	output_prefix();
+	output_line("call_java_%s = ", mangled);
+	output("cob_resolve_java(\"%s\", \"%s\", \"()V\");", class_name, method_name);
+	output_newline ();
+	output_prefix ();
+	output_line("cob_call_java(call_java_%s);\n", mangled);
+	output_newline();
+	output_block_close();
+}
+
 static void
 output_call (struct cb_call *p)
 {
@@ -7097,6 +7158,11 @@ output_call (struct cb_call *p)
 	}
 	system_call = NULL;
 
+	if (p->convention & CB_CONV_JAVA) {
+		output_java_call(p);
+		return;
+	}
+
 #ifdef	_WIN32
 	if (p->convention & CB_CONV_STDCALL) {
 		convention = "_std";

cobc/parser.y

@@ -12253,6 +12253,11 @@ call_body:
 
 	/* Check parameter conformance, if we can work out what is being called. */
 	if (CB_LITERAL_P ($3)) {
+		/* Check for "Java." prefix and set call convention */
+		char* s = (char *)CB_LITERAL ($3)->data;
+	        if (strncasecmp("Java.", s, 5) == 0) {
+		        call_conv = CB_CONV_JAVA;
+                }
 		cb_check_conformance ($3, $7, $8);
 	} else if (CB_REFERENCE_P ($3)) {
 		cb_tree	ref = cb_ref ($3);

cobc/tree.h

@@ -199,6 +199,7 @@ enum cb_tag {
 #define CB_CONV_THUNK_16	(1 << 5)
 #define CB_CONV_STDCALL		(1 << 6)
 #define CB_CONV_COBOL	(1 << 15)
+#define CB_CONV_JAVA    (1 << 16)
 #define CB_CONV_C	(0)
 #define CB_CONV_PASCAL	(CB_CONV_L_TO_R | CB_CONV_CALLEE_STACK)
 

configure.ac

@@ -113,6 +113,8 @@ AH_TEMPLATE([WITH_JSON], [JSON handler])
 AH_TEMPLATE([WITH_CJSON], [Use cJSON library/source as JSON handler])
 AH_TEMPLATE([WITH_JSON_C], [Use JSON-C library as JSON handler])
 
+AH_TEMPLATE([WITH_JNI], [Support for Java calls through JNI])
+
 AH_TEMPLATE([COB_EXPORT_DYN], [Compile/link option for exporting symbols])
 AH_TEMPLATE([COB_PIC_FLAGS], [Compile/link option for PIC code])
 AH_TEMPLATE([COB_DEBUG_FLAGS], [Compile/link option for debugging])
@@ -483,7 +485,6 @@ AC_CHECK_HEADERS([sys/types.h signal.h stddef.h], [],
 # optional:
 AC_CHECK_HEADERS([sys/time.h locale.h fcntl.h dlfcn.h sys/wait.h sys/sysmacros.h])
 
-
 # Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 AC_C_BIGENDIAN
@@ -933,7 +934,56 @@ AS_IF([test "$with_xml2" = "yes" -o "$with_xml2" = "check"], [
 	LIBS="$curr_libs"; CPPFLAGS="$curr_cppflags"
 ])
 
+# Check for JNI
+AC_ARG_WITH([java],
+	    [AS_HELP_STRING([--without-java],
+			    [disable Java Interoperability])])
+cob_has_jni=no
+AS_IF([test "x$with_java" != "xno"], [
+	dnl Find `java` and $JAVA_HOME (we need the latter to locate libjvm).
+	dnl AX_CHECK_JAVA_HOME dnl (<- does not appear to work properly)
+	AX_PROG_JAVA
+	if test "x$JAVA_HOME" = x; then
+		JAVA_HOME="$( $JAVA -XshowSettings:properties -version 2>&1 >/dev/null | \
+			      $SED -e '/^[ ]*java.home/!d' -e 's/.*=[ ]*//' )"
+		AC_MSG_NOTICE([Found Java home: ${JAVA_HOME}])
+	else
+		AC_MSG_NOTICE([Given Java home: ${JAVA_HOME}])
+	fi
 
+	dnl Note: AX_PROG_JAVAC might find a `javac` binary that does
+	dnl not match the version of `$JAVA` found above, so we set
+	dnl its path manually.
+	JAVAC="$JAVA_HOME/bin/javac"
+	AX_PROG_JAVAC_WORKS
+
+	AX_JNI_INCLUDE_DIR
+	AS_IF([test "$JNI_INCLUDE_DIRS" != ""], [
+		for JNI_INCLUDE_DIR in $JNI_INCLUDE_DIRS; do
+		    JNI_CPPFLAGS="$JNI_CPPFLAGS -I$JNI_INCLUDE_DIR"
+		done
+		for _dir in "${JAVA_HOME}/jre/lib" "${JAVA_HOME}/lib"; do
+		    if test -d "$_dir"; then
+			JNI_LIBS="$JNI_LIBS -L$_dir"
+		    fi
+		    if test -d "$_dir/server"; then
+			JNI_LIBS="$JNI_LIBS -L$_dir/server"
+		    fi
+		done
+		curr_LIBS="$LIBS"
+		LIBS="$LIBS $JNI_LIBS"
+		AC_CHECK_LIB([jvm], [JNI_CreateJavaVM], [
+			AC_DEFINE([WITH_JNI], [1])
+			JNI_LDFLAGS="$JNI_LIBS"
+			JNI_LIBS="-ljvm"
+			cob_has_jni=yes
+		])
+		LIBS="$curr_LIBS"
+	])
+])
+AS_IF([test "x$with_java" = "xyes" -a "x$cob_has_jni" != "xyes"], [
+	AC_MSG_ERROR([Java interoperability requested, but JNI was not found])
+])
 
 # Checks for cjson/json-c.
 AC_MSG_NOTICE([Checks for JSON handler])
@@ -2570,6 +2620,8 @@ AM_CONDITIONAL([COB_MAKE_LMDB_LIB], [test "$cob_gen_lmdb" = "yes"])
 
 AM_CONDITIONAL([LOCAL_CJSON],[test "$USE_JSON" = "local"])
 
+AM_CONDITIONAL([COB_HAS_JNI], [test "$cob_has_jni" = "yes"])
+
 unset COB_USES_GCC
 unset COB_USES_GCC_NO_ICC
 unset COB_USES_ICC_ONLY
@@ -2660,6 +2712,11 @@ AC_SUBST([OCI_CFLAGS])
 AC_SUBST([BDB_CFLAGS])
 AC_SUBST([LMDB_CFLAGS])
 
+AC_SUBST([JAVAC])
+AC_SUBST([JNI_LIBS])
+AC_SUBST([JNI_LDFLAGS])
+AC_SUBST([JNI_CPPFLAGS])
+
 dnl was used in bin/Makefile.am - seems not to be needed
 dnl AC_SUBST([COB_EXPORT_DYN])
 
@@ -2683,6 +2740,7 @@ AC_SUBST([COB_HAS_OCEXTFH])
 AC_SUBST([COB_HAS_CURSES])
 AC_SUBST([COB_HAS_XML2])
 AC_SUBST([COB_HAS_JSON])
+AC_SUBST([COB_HAS_JNI])
 AC_SUBST([COB_HAS_64_BIT_POINTER])
 AC_SUBST([COB_PATCH_LEVEL], [$with_patch_level]) # needed for bin/cob-config
 
@@ -2804,4 +2862,6 @@ case "$USE_JSON" in
 	;;
 esac
 
+AC_MSG_NOTICE([ Build with Java interoperability:            ${cob_has_jni}])
+
 unset DEFINE_DL

libcob/ChangeLog

@@ -1,4 +1,14 @@
 
+2024-08-14  Nicolas Berthier <[email protected]>
+
+	* common.c (print_info_detailed): added note for Java interoperability
+
+2024-06-12  Vedant Tewari <[email protected]>
+
+        * Makefile.am: Updated to include JNI-related files
+        * common.h: Added internal state for JNI support
+        * java.c: Implemented JNI support for GnuCOBOL
+
 2024-08-04  David Declerck <[email protected]>
 
 	Adjustments to merge 2022-12-21:

libcob/Makefile.am

@@ -1,8 +1,8 @@
 #
 # Makefile gnucobol/libcob
 #
-# Copyright (C) 2003-2012, 2014, 2017-2023 Free Software Foundation, Inc.
-# Written by Keisuke Nishida, Roger While, Simon Sobisch
+# Copyright (C) 2003-2012, 2014, 2017-2024 Free Software Foundation, Inc.
+# Written by Keisuke Nishida, Roger While, Simon Sobisch, Vedant Tewari
 #
 # This file is part of GnuCOBOL.
 #
@@ -125,8 +125,18 @@ else
 lib_lm =
 endif
 
+if COB_HAS_JNI
+lib_jni = libcobjni.la
+libcobjni_la_LIBADD = libcob.la $(JNI_LIBS)
+libcobjni_la_SOURCES = java.c
+libcobjni_la_LDFLAGS = $(AM_LDFLAGS) $(JNI_LDFLAGS) -version-info 1:0:0
+libcobjni_la_CFLAGS = $(AM_CFLAGS) $(JNI_CPPFLAGS)
+else
+lib_jni =
+endif
+
 lib_LTLIBRARIES = libcob.la $(lib_ci) $(lib_di) $(lib_vb) $(lib_vc) \
-	$(lib_od) $(lib_oc) $(lib_db) $(lib_lm)
+	$(lib_od) $(lib_oc) $(lib_db) $(lib_lm) $(lib_jni)
 
 EXTRA_DIST = fisam.c
 pkgincludedir = $(includedir)/libcob