1 /*
   2  * Copyright (c) 2015, 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.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package jdk.internal.module;
  26 
  27 import java.io.IOException;
  28 import java.io.OutputStream;
  29 import java.lang.module.ModuleDescriptor;
  30 import java.lang.module.ModuleDescriptor.Version;
  31 import java.nio.ByteBuffer;
  32 import java.util.Optional;
  33 
  34 import jdk.internal.org.objectweb.asm.ClassWriter;
  35 import jdk.internal.org.objectweb.asm.Opcodes;
  36 
  37 import static jdk.internal.module.ClassFileAttributes.*;
  38 import static jdk.internal.module.ClassFileConstants.ACC_MODULE;
  39 
  40 /**
  41  * Utility class to write a ModuleDescriptor as a module-info.class.
  42  */
  43 
  44 public final class ModuleInfoWriter {
  45 
  46     private ModuleInfoWriter() { }
  47 
  48     /**
  49      * Writes the given module descriptor to a module-info.class file,
  50      * returning it in a byte array.
  51      */
  52     private static byte[] toModuleInfo(ModuleDescriptor descriptor) {
  53 
  54         ClassWriter cw = new ClassWriter(0);
  55 
  56         String name = descriptor.name().replace('.', '/') + "/module-info";
  57         cw.visit(Opcodes.V1_8, ACC_MODULE, name, null, null, null);
  58 
  59         cw.visitAttribute(new ModuleAttribute(descriptor));
  60         cw.visitAttribute(new ConcealedPackagesAttribute(descriptor.conceals()));
  61 
  62         Optional<Version> oversion = descriptor.version();
  63         if (oversion.isPresent())
  64             cw.visitAttribute(new VersionAttribute(oversion.getWhenPresent()));
  65 
  66         Optional<String> omain = descriptor.mainClass();
  67         if (omain.isPresent())
  68             cw.visitAttribute(new MainClassAttribute(omain.getWhenPresent()));
  69 
  70         // write the TargetPlatform attribute if have any of OS name/arch/version
  71         String osName = descriptor.osName().orElse(null);
  72         String osArch = descriptor.osArch().orElse(null);
  73         String osVersion = descriptor.osVersion().orElse(null);
  74         if (osName != null || osArch != null || osVersion != null) {
  75             cw.visitAttribute(new TargetPlatformAttribute(osName,
  76                                                           osArch,
  77                                                           osVersion));
  78         }
  79 
  80         cw.visitEnd();
  81 
  82         return cw.toByteArray();
  83     }
  84 
  85     /**
  86      * Writes a module descriptor to the given output stream as a
  87      * module-info.class.
  88      */
  89     public static void write(ModuleDescriptor descriptor, OutputStream out)
  90         throws IOException
  91     {
  92         byte[] bytes = toModuleInfo(descriptor);
  93         out.write(bytes);
  94     }
  95 
  96     /**
  97      * Returns a {@code ByteBuffer} containing the given module descriptor
  98      * in module-info.class format.
  99      */
 100     public static ByteBuffer toByteBuffer(ModuleDescriptor descriptor) {
 101         byte[] bytes = toModuleInfo(descriptor);
 102         return ByteBuffer.wrap(bytes);
 103     }
 104 
 105 }