1/*
2 * Copyright (c) 2015, 2016, 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
26package jdk.internal.jimage;
27
28import java.io.IOException;
29import java.io.UncheckedIOException;
30import java.nio.file.Path;
31import java.nio.file.Paths;
32import java.util.concurrent.ConcurrentHashMap;
33import java.util.Map;
34import java.util.Objects;
35import java.util.function.Function;
36
37/**
38 * Factory to get ImageReader
39 *
40 * @implNote This class needs to maintain JDK 8 source compatibility.
41 *
42 * It is used internally in the JDK to implement jimage/jrtfs access,
43 * but also compiled and delivered as part of the jrtfs.jar to support access
44 * to the jimage file provided by the shipped JDK by tools running on JDK 8.
45 */
46public class ImageReaderFactory {
47    private ImageReaderFactory() {}
48
49    private static final String JAVA_HOME = System.getProperty("java.home");
50    private static final Path BOOT_MODULES_JIMAGE =
51        Paths.get(JAVA_HOME, "lib", "modules");
52
53    private static final Map<Path, ImageReader> readers = new ConcurrentHashMap<>();
54
55    /**
56     * Returns an {@code ImageReader} to read from the given image file
57     */
58    public static ImageReader get(Path jimage) throws IOException {
59        Objects.requireNonNull(jimage);
60        try {
61            return readers.computeIfAbsent(jimage, OPENER);
62        } catch (UncheckedIOException io) {
63            throw io.getCause();
64        }
65    }
66
67    private static Function<Path, ImageReader> OPENER = new Function<Path, ImageReader>() {
68        public ImageReader apply(Path path) {
69            try {
70                return ImageReader.open(path);
71            } catch (IOException io) {
72                throw new UncheckedIOException(io);
73            }
74        }
75    };
76
77    /**
78     * Returns the {@code ImageReader} to read the image file in this
79     * run-time image.
80     *
81     * @throws UncheckedIOException if an I/O error occurs
82     */
83    public static ImageReader getImageReader() {
84        try {
85            return get(BOOT_MODULES_JIMAGE);
86        } catch (IOException ioe) {
87            throw new UncheckedIOException(ioe);
88        }
89    }
90}
91