com.facebook.buck.jvm.java.abi.StubJar.java Source code

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Here is the source code for com.facebook.buck.jvm.java.abi.StubJar.java

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/*
 * Copyright 2014-present Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License. You may obtain
 * a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package com.facebook.buck.jvm.java.abi;

import static org.objectweb.asm.ClassReader.SKIP_CODE;
import static org.objectweb.asm.ClassReader.SKIP_DEBUG;
import static org.objectweb.asm.ClassReader.SKIP_FRAMES;

import com.facebook.buck.io.HashingDeterministicJarWriter;
import com.facebook.buck.io.MorePaths;
import com.facebook.buck.io.ProjectFilesystem;
import com.google.common.base.Preconditions;

import org.objectweb.asm.ClassReader;

import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Path;
import java.util.jar.JarOutputStream;

public class StubJar {

    private final Path toMirror;

    public StubJar(Path toMirror) {
        this.toMirror = Preconditions.checkNotNull(toMirror);
    }

    public void writeTo(ProjectFilesystem filesystem, Path path) throws IOException {
        Preconditions.checkState(!filesystem.exists(path), "Output file already exists: %s)", path);

        if (path.getParent() != null && !filesystem.exists(path.getParent())) {
            filesystem.createParentDirs(path);
        }

        Walker walker = Walkers.getWalkerFor(toMirror);
        try (HashingDeterministicJarWriter jar = new HashingDeterministicJarWriter(
                new JarOutputStream(filesystem.newFileOutputStream(path)))) {
            final CreateStubAction createStubAction = new CreateStubAction(jar);
            walker.walk(createStubAction);
        }
    }

    private static class CreateStubAction implements FileAction {
        private final HashingDeterministicJarWriter writer;

        public CreateStubAction(HashingDeterministicJarWriter writer) {
            this.writer = writer;
        }

        @Override
        public void visit(Path relativizedPath, InputStream stream) throws IOException {
            String fileName = MorePaths.pathWithUnixSeparators(relativizedPath);
            if (fileName.endsWith(".class")) {
                try (InputStream stubClassBytes = getStubClassBytes(stream, fileName)) {
                    writer.writeEntry(fileName, stubClassBytes);
                }
            } else if (!"META-INF/MANIFEST.MF".equals(fileName)) {
                writer.writeEntry(fileName, stream);
            }
        }

        private InputStream getStubClassBytes(InputStream stream, String fileName) throws IOException {
            ClassReader classReader = new ClassReader(stream);
            ClassMirror visitor = new ClassMirror(fileName);
            classReader.accept(visitor, SKIP_CODE | SKIP_DEBUG | SKIP_FRAMES);
            return visitor.getStubClassBytes().openStream();
        }
    }
}