Bug 1024: Add fallback for native-jar-file location via classpath

In situations, where the native-jar file is not located within
the same parent URI as it's java-jar file, our location mechanism fails.

This patch adds a classloader based native-jar file location mechanism as a fallback,
requiring the native jar file to be included in the users CLASSPATH.

Classloader based location algorithm in JNILibLoaderBase.addNativeJarLibsImpl(..):
  - Extract the 'module-name' from the given classFromJavaJar's package name,
    i.e. the last package-part: 'jogamp.common.Debug' -> 'common'

    Hence it is important to pass a 'classFromJavaJar',
    which last package segment reflects the module-name!

  - <os.and.arch> -> <os_and_arch_dot>, e.g. linux-amd64 -> linux.amd64 (linux/amd64)

  - Locate class 'jogamp.nativetag.<module-name>.<os_and_arch_dot>.TAG',
    e.g. 'jogamp.nativetag.common.linux.amd64.TAG'

  - Use located class's JarFile URI .. continue as usual

Injection of above mentioned TAG class via gluegen-cpptasks-base.xml macro 'native.tag.jar':
  - Creates dummy TAG.java code
  - Compiles TAG.java
  - Creates the native-jar file

Example:
      <native.tag.jar objdir="${build}/obj"
                      nativejarfile="${build}/gluegen-rt-natives-${os.and.arch}.jar"
                      manifestfile="${build}/Manifest-rt-natives.temp"
                      module="common"
                      includelibs="*gluegen-rt.${native.library.suffix}" />

Note that the manifest file uses a matching Extension-Name:
  Extension-Name: jogamp.nativetag.common

2 files changed, 54 insertions, 6 deletions

diff --git a/src/java/com/jogamp/common/jvm/JNILibLoaderBase.java b/src/java/com/jogamp/common/jvm/JNILibLoaderBase.java
index f69ddd1..4bb68d3 100644
--- a/src/java/com/jogamp/common/jvm/JNILibLoaderBase.java
+++ b/src/java/com/jogamp/common/jvm/JNILibLoaderBase.java
@@ -150,6 +150,8 @@ public class JNILibLoaderBase {
     loaderAction = action;
   }
 
+  private static final String nativeJarTagPackage = "jogamp.nativetag"; // TODO: sync with gluegen-cpptasks-base.xml
+
   /**
    *
    * @param classFromJavaJar
@@ -200,10 +202,17 @@ public class JNILibLoaderBase {
         // We probably have one big-fat jar file, containing java classes
         // and all native platform libraries under 'natives/os.and.arch'!
         final URI nativeJarURI = JarUtil.getJarFileURI(jarUriRoot_s+jarBasename);
-        if( TempJarCache.addNativeLibs(classFromJavaJar, nativeJarURI, nativeLibraryPath) ) {
-            ok = true;
-            if (DEBUG) {
-                System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: fat: %s -> %s\n", jarBasename, nativeJarURI);
+        try {
+            if( TempJarCache.addNativeLibs(classFromJavaJar, nativeJarURI, nativeLibraryPath) ) {
+                ok = true;
+                if (DEBUG) {
+                    System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: fat: %s -> %s%n", jarBasename, nativeJarURI);
+                }
+            }
+        } catch(final Exception e) {
+            if(DEBUG) {
+                System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: Caught %s%n", e.getMessage());
+                e.printStackTrace();
             }
         }
     }
@@ -215,7 +224,46 @@ public class JNILibLoaderBase {
             System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: module: %s -> %s%n", nativeJarBasename, nativeJarURI);
         }
 
-        ok = TempJarCache.addNativeLibs(classFromJavaJar, nativeJarURI, null /* nativeLibraryPath */);
+        try {
+            ok = TempJarCache.addNativeLibs(classFromJavaJar, nativeJarURI, null /* nativeLibraryPath */);
+        } catch(final Exception e) {
+            if(DEBUG) {
+                System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: Caught %s%n", e.getMessage());
+                e.printStackTrace();
+            }
+        }
+    }
+    if (!ok) {
+        // Attempt to find via ClassLoader and Native-Jar-Tag,
+        // assuming one slim native jar file per 'os.and.arch'!
+        final String moduleName;
+        {
+            final String packageName = classFromJavaJar.getPackage().getName();
+            final int idx = packageName.lastIndexOf('.');
+            if( 0 <= idx ) {
+                moduleName = packageName.substring(idx+1);
+            } else {
+                moduleName = packageName;
+            }
+        }
+        final String os_and_arch_dot = PlatformPropsImpl.os_and_arch.replace('-', '.');
+        final String nativeJarTagClassName = nativeJarTagPackage + "." + moduleName + "." + os_and_arch_dot + ".TAG" ; // TODO: sync with gluegen-cpptasks-base.xml
+        try {
+            if(DEBUG) {
+                System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: ClassLoader/TAG: Locating module %s, os.and.arch %s: %s%n",
+                        moduleName, os_and_arch_dot, nativeJarTagClassName);
+            }
+            final URI nativeJarTagClassJarURI = JarUtil.getJarURI(nativeJarTagClassName, cl);
+            if (DEBUG) {
+                System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: ClassLoader/TAG: %s -> %s%n", nativeJarTagClassName, nativeJarTagClassJarURI);
+            }
+            ok = TempJarCache.addNativeLibs(classFromJavaJar, nativeJarTagClassJarURI, null /* nativeLibraryPath */);
+        } catch (final Exception e ) {
+            if(DEBUG) {
+                System.err.printf("JNILibLoaderBase: addNativeJarLibsImpl: Caught %s%n", e.getMessage());
+                e.printStackTrace();
+            }
+        }
     }
 
     if (DEBUG) {
diff --git a/src/java/com/jogamp/common/os/Platform.java b/src/java/com/jogamp/common/os/Platform.java
index b8e3385..12122a2 100644
--- a/src/java/com/jogamp/common/os/Platform.java
+++ b/src/java/com/jogamp/common/os/Platform.java
@@ -200,7 +200,7 @@ public class Platform extends PlatformPropsImpl {
                 // load GluegenRT native library
                 if(_USE_TEMP_JAR_CACHE[0] && TempJarCache.initSingleton()) {
                     try {
-                        JNILibLoaderBase.addNativeJarLibs(new Class<?>[] { Platform.class }, null);
+                        JNILibLoaderBase.addNativeJarLibs(new Class<?>[] { jogamp.common.Debug.class }, null);
                     } catch (final Exception e0) {
                         // IllegalArgumentException, IOException
                         System.err.println("Caught "+e0.getClass().getSimpleName()+": "+e0.getMessage()+", while JNILibLoaderBase.addNativeJarLibs(..)");