8278205: jlink plugins should dump .class file in debug mode

Reviewed-by: jlaskey

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/JlinkTask.java

@@ -78,7 +78,7 @@
  * ## Should use jdk.joptsimple some day.
  */
 public class JlinkTask {
-    static final boolean DEBUG = Boolean.getBoolean("jlink.debug");
+    public static final boolean DEBUG = Boolean.getBoolean("jlink.debug");
 
     // jlink API ignores by default. Remove when signing is implemented.
     static final boolean IGNORE_SIGNING_DEFAULT = true;

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/AbstractPlugin.java

@@ -26,10 +26,16 @@
 package jdk.tools.jlink.internal.plugins;
 
 import jdk.tools.jlink.plugin.Plugin;
+import jdk.tools.jlink.internal.JlinkTask;
 
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 import java.util.Locale;
 import java.util.MissingResourceException;
 import java.util.ResourceBundle;
+import jdk.internal.org.objectweb.asm.ClassReader;
 
 public abstract class AbstractPlugin implements Plugin {
 
@@ -61,6 +67,35 @@ protected AbstractPlugin(String name, ResourceBundle bundle) {
         this.name = name;
         this.pluginsBundle = bundle;
     }
+
+    private void dumpClassFile(String path, byte[] buf) {
+        try {
+            String fullPath = String.format("%d-%s%s%s",
+                 ProcessHandle.current().pid(),
+                 getName(), File.separator,
+                 path.replace('/', File.separatorChar));
+            System.err.printf("Dumping class file %s\n", fullPath);
+            new File(fullPath.substring(0, fullPath.lastIndexOf('/'))).mkdirs();
+            Files.write(Paths.get(fullPath), buf);
+        } catch (IOException ioExp) {
+            System.err.println("writing " + path + " failed");
+            ioExp.printStackTrace();
+        }
+    }
+
+    protected ClassReader newClassReader(String path, byte[] buf) {
+        try {
+            return new ClassReader(buf);
+        } catch (IllegalArgumentException iae) {
+            if (JlinkTask.DEBUG) {
+                System.err.printf("Failed to parse class file: %s\n", path);
+                iae.printStackTrace();
+                dumpClassFile(path, buf);
+            }
+            throw iae;
+        }
+    }
+
     @Override
     public String getName() {
         return name;

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/IncludeLocalesPlugin.java

@@ -158,7 +158,7 @@ public ResourcePool transform(ResourcePool in, ResourcePoolBuilder out) {
                 if (resource != null &&
                     resource.type().equals(ResourcePoolEntry.Type.CLASS_OR_RESOURCE)) {
                     byte[] bytes = resource.contentBytes();
-                    ClassReader cr = new ClassReader(bytes);
+                    ClassReader cr = newClassReader(path, bytes);
                     if (Arrays.stream(cr.getInterfaces())
                         .anyMatch(i -> i.contains(METAINFONAME)) &&
                         stripUnsupportedLocales(bytes, cr)) {

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/StripJavaDebugAttributesPlugin.java

@@ -59,7 +59,7 @@ public ResourcePool transform(ResourcePool in, ResourcePoolBuilder out) {
                     if (path.endsWith("module-info.class")) {
                         // XXX. Do we have debug info? Is Asm ready for module-info?
                     } else {
-                        ClassReader reader = new ClassReader(resource.contentBytes());
+                        ClassReader reader = newClassReader(path, resource.contentBytes());
                         ClassWriter writer = new ClassWriter(ClassWriter.COMPUTE_MAXS);
                         reader.accept(writer, ClassReader.SKIP_DEBUG);
                         byte[] content = writer.toByteArray();

src/jdk.jlink/share/classes/jdk/tools/jlink/internal/plugins/VersionPropsPlugin.java

@@ -96,9 +96,9 @@ public void configure(Map<String, String> config) {
 
     private boolean redefined = false;
 
-    private byte[] redefine(byte[] classFile) {
+    private byte[] redefine(String path, byte[] classFile) {
 
-        var cr = new ClassReader(classFile);
+        var cr = newClassReader(path, classFile);
         var cw = new ClassWriter(0);
 
         cr.accept(new ClassVisitor(Opcodes.ASM7, cw) {
@@ -189,7 +189,7 @@ public ResourcePool transform(ResourcePool in, ResourcePoolBuilder out) {
         in.transformAndCopy(res -> {
                 if (res.type().equals(ResourcePoolEntry.Type.CLASS_OR_RESOURCE)) {
                     if (res.path().equals(VERSION_PROPS_CLASS)) {
-                        return res.copyWithContent(redefine(res.contentBytes()));
+                        return res.copyWithContent(redefine(res.path(), res.contentBytes()));
                     }
                 }
                 return res;