1 /*
   2  * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package com.sun.tools.jextract;
  24 
  25 import java.foreign.Libraries;
  26 import java.lang.invoke.MethodHandles;
  27 import java.lang.invoke.MethodHandles.Lookup;
  28 import java.lang.reflect.Method;
  29 import java.util.Collections;
  30 import java.util.HashMap;
  31 import java.util.List;
  32 import java.util.Map;
  33 
  34 import com.sun.tools.jextract.tree.Tree;
  35 import jdk.internal.org.objectweb.asm.FieldVisitor;
  36 import jdk.internal.org.objectweb.asm.ClassWriter;
  37 import jdk.internal.org.objectweb.asm.MethodVisitor;
  38 import jdk.internal.org.objectweb.asm.Type;
  39 import com.sun.tools.jextract.tree.EnumTree;
  40 import com.sun.tools.jextract.tree.FieldTree;
  41 import com.sun.tools.jextract.tree.FunctionTree;
  42 import com.sun.tools.jextract.tree.MacroTree;
  43 import com.sun.tools.jextract.tree.VarTree;
  44 
  45 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_FINAL;
  46 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PUBLIC;
  47 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_PRIVATE;
  48 import static jdk.internal.org.objectweb.asm.Opcodes.ACC_STATIC;
  49 import static jdk.internal.org.objectweb.asm.Opcodes.CHECKCAST;
  50 import static jdk.internal.org.objectweb.asm.Opcodes.GETSTATIC;
  51 import static jdk.internal.org.objectweb.asm.Opcodes.ILOAD;
  52 import static jdk.internal.org.objectweb.asm.Opcodes.INVOKEINTERFACE;
  53 import static jdk.internal.org.objectweb.asm.Opcodes.INVOKESTATIC;
  54 import static jdk.internal.org.objectweb.asm.Opcodes.IRETURN;
  55 import static jdk.internal.org.objectweb.asm.Opcodes.PUTSTATIC;
  56 import static jdk.internal.org.objectweb.asm.Opcodes.RETURN;
  57 import static jdk.internal.org.objectweb.asm.Opcodes.V1_8;
  58 
  59 /**
  60  * This extended factory generates a class with only static methods and fields. A native
  61  * library interface instance (of the given header file) is kept as a static private field.
  62  * One static method is generated for every library interface method. Enum and macro constants
  63  * are mapped to static final fields. By importing the "static forwarder" class, the user code
  64  * looks more or less like C code. Libraries.bind and header interface usage is hidden.
  65  */
  66 final class AsmCodeFactoryExt extends AsmCodeFactory {
  67     private final String headerClassNameDesc;
  68     private final ClassWriter cw;
  69     // suffix for static forwarder class name
  70     private static final String STATICS_CLASS_NAME_SUFFIX = "_h";
  71     // field name for the header interface instance.
  72     private static final String STATICS_LIBRARY_FIELD_NAME = "_theLibrary";
  73 
  74     AsmCodeFactoryExt(Context ctx, HeaderFile header) {
  75         super(ctx, header);
  76         logger.info(() -> "Instantiate StaticForwarderGenerator for " + header.path);
  77         this.headerClassNameDesc = "L" + headerClassName + ";";
  78         this.cw = new ClassWriter(ClassWriter.COMPUTE_FRAMES | ClassWriter.COMPUTE_MAXS);
  79         this.cw.visit(V1_8, ACC_PUBLIC | ACC_FINAL, getClassName(),
  80             null, "java/lang/Object", null);
  81         staticsInitializer();
  82     }
  83 
  84     @Override
  85     public Boolean visitVar(VarTree varTree, JType jt) {
  86         if (super.visitVar(varTree, jt)) {
  87             String fieldName = varTree.name();
  88             assert !fieldName.isEmpty();
  89 
  90             emitStaticForwarder(fieldName + "$get",
  91                 "()" + jt.getDescriptor(), "()" + jt.getSignature(false));
  92 
  93             emitStaticForwarder(fieldName + "$set",
  94                 "(" + jt.getDescriptor() + ")V",
  95                 "(" + jt.getSignature(true) + ")V");
  96             JType ptrType = JType.GenericType.ofPointer(jt);
  97             emitStaticForwarder(fieldName + "$ptr",
  98                 "()" + ptrType.getDescriptor(), "()" + ptrType.getSignature(false));
  99 
 100             return true;
 101         } else {
 102             return false;
 103         }
 104     }
 105 
 106     @Override
 107     public Boolean visitEnum(EnumTree enumTree, JType jt) {
 108         if (super.visitEnum(enumTree, jt)) {
 109             enumTree.constants().forEach(constant -> addEnumConstant(constant));
 110             return true;
 111         } else {
 112             return false;
 113         }
 114     }
 115 
 116     @Override
 117     public Boolean visitFunction(FunctionTree funcTree, JType jt) {
 118         if (super.visitFunction(funcTree, jt)) {
 119             assert (jt instanceof JType.Function);
 120             JType.Function fn = (JType.Function)jt;
 121             logger.fine(() -> "Add method: " + fn.getSignature(false));
 122             emitStaticForwarder(funcTree.name(), fn.getDescriptor(), fn.getSignature(false));
 123             return true;
 124         } else {
 125             return false;
 126         }
 127     }
 128 
 129     @Override
 130     public Boolean visitMacro(MacroTree macroTree, JType jt) {
 131         if (super.visitMacro(macroTree, jt)) {
 132             String name = macroTree.name();
 133             Object value = macroTree.value().get();
 134             logger.fine(() -> "Adding macro " + name);
 135             Class<?> macroType = Utils.unboxIfNeeded(value.getClass());
 136             String sig = Type.getType(macroType).getDescriptor();
 137             FieldVisitor fv = cw.visitField(ACC_PUBLIC | ACC_STATIC, name, sig, null, value);
 138             fv.visitEnd();
 139             return true;
 140         } else {
 141             return false;
 142         }
 143     }
 144 
 145     @Override
 146     public Map<String, byte[]> generateNativeHeader(List<Tree> decls) {
 147         Map<String, byte[]> results = new HashMap<>();
 148         results.putAll(super.generateNativeHeader(decls));
 149         results.put(getClassName(), getClassBytes());
 150         return Collections.unmodifiableMap(results);
 151     }
 152 
 153     // Internals only below this point
 154 
 155     private String getClassName() {
 156         return headerClassName + STATICS_CLASS_NAME_SUFFIX;
 157     }
 158 
 159     // return the generated static forwarder class bytes
 160     private byte[] getClassBytes() {
 161         cw.visitEnd();
 162         return cw.toByteArray();
 163     }
 164 
 165     // map each C enum constant as a static final field of the static forwarder class
 166     private void addEnumConstant(FieldTree fieldTree) {
 167         assert (fieldTree.isEnumConstant());
 168         String name = fieldTree.name();
 169         String desc = headerFile.dictionary().lookup(fieldTree.type()).getDescriptor();
 170         if (desc.length() != 1) {
 171             throw new AssertionError("expected single char descriptor: " + desc);
 172         }
 173         FieldVisitor fv = null;
 174         switch (desc.charAt(0)) {
 175             case 'J':
 176                 long lvalue = fieldTree.enumConstant().get();
 177                 fv = cw.visitField(ACC_PUBLIC | ACC_STATIC, name, desc, null, lvalue);
 178                 break;
 179             case 'I':
 180                 int ivalue = fieldTree.enumConstant().get().intValue();
 181                 fv = cw.visitField(ACC_PUBLIC | ACC_STATIC, name, desc, null, ivalue);
 182                 break;
 183             default:
 184                 throw new AssertionError("should not reach here");
 185         }
 186         fv.visitEnd();
 187     }
 188 
 189     // emit library interface static field and <clinit> initializer for that field
 190     private void staticsInitializer() {
 191         // library interface field
 192         FieldVisitor fv = cw.visitField(ACC_PRIVATE|ACC_STATIC|ACC_FINAL,
 193             STATICS_LIBRARY_FIELD_NAME, headerClassNameDesc, null, null);
 194         fv.visitEnd();
 195 
 196         // <clinit> to bind library interface field
 197         MethodVisitor mv = cw.visitMethod(ACC_STATIC,
 198             "<clinit>", "()V", null, null);
 199         mv.visitCode();
 200 
 201         // MethodHandles.lookup()
 202         Method lookupMethod = null;
 203         try {
 204             lookupMethod = MethodHandles.class.getMethod("lookup");
 205         } catch (NoSuchMethodException nsme) {
 206             throw new RuntimeException(nsme);
 207         }
 208         mv.visitMethodInsn(INVOKESTATIC,
 209             Type.getInternalName(MethodHandles.class), "lookup",
 210             Type.getMethodDescriptor(lookupMethod), false);
 211 
 212         // ldc library-interface-class
 213         mv.visitLdcInsn(Type.getObjectType(headerClassName));
 214 
 215         // Libraries.bind(lookup, class);
 216         Method bindMethod = null;
 217         try {
 218             bindMethod = Libraries.class.getMethod("bind", Lookup.class, Class.class);
 219         } catch (NoSuchMethodException nsme) {
 220             throw new RuntimeException(nsme);
 221         }
 222         mv.visitMethodInsn(INVOKESTATIC,
 223             Type.getInternalName(Libraries.class), "bind",
 224             Type.getMethodDescriptor(bindMethod), false);
 225 
 226         // store it in library interface field
 227         mv.visitTypeInsn(CHECKCAST, headerClassName);
 228         mv.visitFieldInsn(PUTSTATIC, getClassName(),
 229             STATICS_LIBRARY_FIELD_NAME, headerClassNameDesc);
 230 
 231         mv.visitInsn(RETURN);
 232         mv.visitMaxs(0, 0);
 233         mv.visitEnd();
 234     }
 235 
 236     // emit static forwarder method for a specific library interface method
 237     private void emitStaticForwarder(String name, String desc, String signature) {
 238         MethodVisitor mv = cw.visitMethod(ACC_PUBLIC | ACC_STATIC,
 239             name, desc, signature, null);
 240         mv.visitCode();
 241 
 242         // load library interface (static) field
 243         mv.visitFieldInsn(GETSTATIC, getClassName(),
 244             STATICS_LIBRARY_FIELD_NAME, headerClassNameDesc);
 245 
 246         // forward the call to the interface
 247         Type[] argTypes = Type.getArgumentTypes(desc);
 248         Type retType = Type.getReturnType(desc);
 249 
 250         int loadIdx = 0;
 251         for (int i = 0; i < argTypes.length; i++) {
 252             mv.visitVarInsn(argTypes[i].getOpcode(ILOAD), loadIdx);
 253             loadIdx += argTypes[i].getSize();
 254         }
 255         mv.visitMethodInsn(INVOKEINTERFACE, headerClassName, name, desc, true);
 256         mv.visitInsn(retType.getOpcode(IRETURN));
 257 
 258         mv.visitMaxs(0, 0);
 259         mv.visitEnd();
 260     }
 261 }