8264774: Implementation of Foreign Function and Memory API (Incubator)

Co-authored-by: Paul Sandoz <psandoz@openjdk.org>
Co-authored-by: Jorn Vernee <jvernee@openjdk.org>
Co-authored-by: Vladimir Ivanov <vlivanov@openjdk.org>
Co-authored-by: Athijegannathan Sundararajan <sundar@openjdk.org>
Co-authored-by: Chris Hegarty <chegar@openjdk.org>
Reviewed-by: psandoz, chegar, mchung, vlivanov

src/java.base/share/classes/java/lang/Module.java

@@ -109,6 +109,8 @@ public final class Module implements AnnotatedElement {
     // the module descriptor
     private final ModuleDescriptor descriptor;
 
+    // true, if this module allows restricted native access
+    private volatile boolean enableNativeAccess;
 
     /**
      * Creates a new named Module. The resulting Module will be defined to the
@@ -133,6 +135,10 @@ public final class Module implements AnnotatedElement {
         String loc = Objects.toString(uri, null);
         Object[] packages = descriptor.packages().toArray();
         defineModule0(this, isOpen, vs, loc, packages);
+        if (loader == null || loader == ClassLoaders.platformClassLoader()) {
+            // boot/builtin modules are always native
+            implAddEnableNativeAccess();
+        }
     }
 
 
@@ -244,6 +250,30 @@ public final class Module implements AnnotatedElement {
         return null;
     }
 
+    /**
+     * Update this module to allow access to restricted methods.
+     */
+    Module implAddEnableNativeAccess() {
+        enableNativeAccess = true;
+        return this;
+    }
+
+    /**
+     * Update all unnamed modules to allow access to restricted methods.
+     */
+    static void implAddEnableNativeAccessAllUnnamed() {
+        ALL_UNNAMED_MODULE.enableNativeAccess = true;
+    }
+
+    /**
+     * Returns true if module m can access restricted methods.
+     */
+    boolean implIsEnableNativeAccess() {
+        return isNamed() ?
+                enableNativeAccess :
+                ALL_UNNAMED_MODULE.enableNativeAccess;
+    }
+
     // --
 
     // special Module to mean "all unnamed modules"

src/java.base/share/classes/java/lang/System.java

@@ -62,7 +62,6 @@ import java.util.Set;
 import java.util.function.Supplier;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Stream;
-
 import jdk.internal.misc.Unsafe;
 import jdk.internal.util.StaticProperty;
 import jdk.internal.module.ModuleBootstrap;
@@ -2274,6 +2273,15 @@ public final class System {
             public boolean isReflectivelyOpened(Module m, String pn, Module other) {
                 return m.isReflectivelyOpened(pn, other);
             }
+            public Module addEnableNativeAccess(Module m) {
+                return m.implAddEnableNativeAccess();
+            }
+            public void addEnableNativeAccessAllUnnamed() {
+                Module.implAddEnableNativeAccessAllUnnamed();
+            }
+            public boolean isEnableNativeAccess(Module m) {
+                return m.implIsEnableNativeAccess();
+            }
             public ServicesCatalog getServicesCatalog(ModuleLayer layer) {
                 return layer.getServicesCatalog();
             }

src/java.base/share/classes/java/lang/invoke/MethodHandleImpl.java

@@ -1467,6 +1467,11 @@ abstract class MethodHandleImpl {
                 return GenerateJLIClassesHelper.generateHolderClasses(traces);
             }
 
+            @Override
+            public void ensureCustomized(MethodHandle mh) {
+                mh.customize();
+            }
+
             @Override
             public VarHandle memoryAccessVarHandle(Class<?> carrier, boolean skipAlignmentMaskCheck, long alignmentMask,
                                                    ByteOrder order) {

src/java.base/share/classes/java/lang/invoke/NativeMethodHandle.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2020, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -58,7 +58,7 @@ import static java.lang.invoke.MethodHandleStatics.newInternalError;
             throw new IllegalArgumentException("Type must only contain primitives: " + type);
 
         if (type != fallback.type())
-            throw new IllegalArgumentException("Type of fallback must match");
+            throw new IllegalArgumentException("Type of fallback must match: " + type + " != " + fallback.type());
 
         LambdaForm lform = preparedLambdaForm(type);
         return new NativeMethodHandle(type, lform, fallback, nep);