From c3f882f90540883782e6742c03707b96511805d3 Mon Sep 17 00:00:00 2001
From: Gabe Black <gabe.black@gmail.com>
Date: Thu, 22 Oct 2020 20:01:06 -0700
Subject: [PATCH] util: Embed the JNI library (.so) in the jar file for the
 gem5 ops.

This makes it easier to manage the java wrapper since there's only one
file. This change also splits up the command builder which builds the
java jar since we need to run one step which produces the .h, then a
second step to build the library, and then finally the step that
produces the jar. The first step is left as a command builder since the
scons Java builder still doesn't know about the -h option, but the
second step now uses the Jar builder.

Change-Id: I76e2e5e86bb3153f2ba69a75ad94cd4e065cd33d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/28183
Reviewed-by: Gabe Black <gabe.black@gmail.com>
Maintainer: Gabe Black <gabe.black@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>
---
 util/m5/SConstruct             |  1 +
 util/m5/src/SConscript         | 34 ++++++++++++++++++++++------------
 util/m5/src/java/gem5/Ops.java | 17 ++++++++++++++++-
 3 files changed, 39 insertions(+), 13 deletions(-)

diff --git a/util/m5/SConstruct b/util/m5/SConstruct
index 242bbe7c3..6552bfb9f 100644
--- a/util/m5/SConstruct
+++ b/util/m5/SConstruct
@@ -79,6 +79,7 @@ if not GetOption('verbose'):
     main['ASPPCOMSTR'] = ComStr('ASPP')
     main['ARCOMSTR'] = ComStr('AR')
     main['RANLIBCOMSTR'] = ComStr('RANLIB')
+    main['JARCOMSTR'] = ComStr('JAR')
 
     def MakeAction(action, string, *args, **kwargs):
         def func(target, source, env, executor):
diff --git a/util/m5/src/SConscript b/util/m5/src/SConscript
index b3e057c7f..1105b6037 100644
--- a/util/m5/src/SConscript
+++ b/util/m5/src/SConscript
@@ -105,16 +105,24 @@ if env['HAVE_JAVA']:
     # that the javah tool exists. Java has dropped that tool in favor of a -h
     # option on javac which the Java builder doesn't know how to use. To get
     # around this, we set up our own builder which does the "right thing" here.
-    java_env.Command([ Dir('java').File('gem5_Ops.h'),
-                       Dir('out').Dir('java').File('gem5Ops.jar') ],
-                     srcs,
-                     MakeAction([
-                         '${JAVAC} ${JAVACFLAGS} -d ${OUT} '
-                         '${SOURCES} -h ${JAVA_DIR}',
-                         '${JAR} cvf ${TARGETS[1]} ${CLS_DIR}/*.class' ],
-                        'JAVA'),
-                     CLS_DIR=Dir('out').Dir('java').Dir('gem5'),
-                     OUT=Dir('out').Dir('java'), JAVA_DIR=Dir('java'))
+    jni_header = Dir('java').File('gem5_Ops.h')
+
+    java_files = []
+    class_files = []
+    def check_for_java(arg, dirname, fnames):
+        for filename in fnames:
+            base, extension = os.path.splitext(filename)
+            if extension == '.java':
+                java_files.append(dirname.File(filename))
+                class_files.append(dirname.File(base + '.class'))
+
+    Dir('java').walk(check_for_java, None)
+
+    java_env.Command([ jni_header ] + class_files, java_files,
+                     MakeAction('${JAVAC} ${JAVACFLAGS} -d ${JAVA_DIR} '
+                                '${SOURCES} -h ${JAVA_DIR}',
+                                'JAVA'), JAVA_DIR=Dir('java'))
+
     # Set include paths to the C headers from the JDK which scons found for us.
     java_env.Append(CPPPATH='${JAVAINCLUDES}')
     for ct in all_call_types:
@@ -122,9 +130,11 @@ if env['HAVE_JAVA']:
             java_env.Append(CXXFLAGS=[ '-DCALL_TYPE_DEFAULT=%s' % ct.name ])
         java_env.Append(CXXFLAGS=[ '-DCALL_TYPE_%s_ENABLED=%s' %
                                    (ct.name, '1' if ct.enabled else '0') ])
-    java_env.SharedLibrary('out/java/gem5Ops',
-                           [ jni ] + m5op_shared + m5_mmap_shared)
+    jni_lib = java_env.SharedLibrary(
+            'java/gem5Ops', [ jni ] + m5op_shared + m5_mmap_shared)
 
+    java_env.Jar(Dir('out').File('gem5Ops.jar'),
+                 jni_lib + class_files, JARCHDIR=Dir('java'))
 
 if env['HAVE_LUA51']:
     #
diff --git a/util/m5/src/java/gem5/Ops.java b/util/m5/src/java/gem5/Ops.java
index 44afad976..f6ab178db 100644
--- a/util/m5/src/java/gem5/Ops.java
+++ b/util/m5/src/java/gem5/Ops.java
@@ -37,6 +37,7 @@
 
 package gem5;
 
+import java.io.*;
 import java.util.*;
 
 /**
@@ -53,7 +54,21 @@ public class Ops {
     public static final Map<String, Ops> callTypes;
 
     static {
-        System.loadLibrary("gem5Ops");
+        try {
+            File temp_lib = File.createTempFile("gem5Ops", ".so");
+            temp_lib.deleteOnExit();
+
+            InputStream in = Ops.class.getResourceAsStream("/libgem5Ops.so");
+            byte[] buffer = new byte[in.available()];
+            in.read(buffer);
+            OutputStream out = new FileOutputStream(temp_lib);
+            out.write(buffer);
+
+            System.load(temp_lib.getAbsolutePath());
+        } catch (Exception e) {
+            throw new RuntimeException(e.getMessage());
+        }
+
         setupCallTypes();
         callTypes = Collections.unmodifiableMap(_callTypes);
     }
-- 
2.30.2