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// Copyright 2017 The Bazel Authors. All rights reserved.
//
// 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.
import java.io.BufferedOutputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UncheckedIOException;
import java.lang.reflect.Method;
import java.net.URI;
import java.nio.file.DirectoryStream;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.GregorianCalendar;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;
import java.util.jar.JarEntry;
import java.util.jar.JarFile;
import java.util.jar.JarOutputStream;
import java.util.zip.CRC32;
import java.util.zip.ZipEntry;
/**
* Output a jar file containing all classes on the platform classpath of the given JDK release.
*
* <p>usage: {@code DumpPlatformClassPath <output jar> <path to target JDK>}
*/
public class DumpPlatformClassPath {
public static void main(String[] args) throws Exception {
if (args.length != 2) {
System.err.println("usage: DumpPlatformClassPath <output jar> <path to target JDK>");
System.exit(1);
}
Path output = Paths.get(args[0]);
Path targetJavabase = Paths.get(args[1]);
int hostMajorVersion = hostMajorVersion();
boolean ok;
if (hostMajorVersion == 8) {
ok = dumpJDK8BootClassPath(output, targetJavabase);
} else {
ok = dumpJDK9AndNewerBootClassPath(hostMajorVersion, output, targetJavabase);
}
System.exit(ok ? 0 : 1);
}
// JDK 8 bootclasspath handling.
// * JDK 8 represents a bootclasspath as a search path of jars (rt.jar, etc.).
// * It does not support --release or --system.
static boolean dumpJDK8BootClassPath(Path output, Path targetJavabase) throws IOException {
List<Path> bootClassPathJars = getBootClassPathJars(targetJavabase);
writeClassPathJars(output, bootClassPathJars);
return true;
}
// JDK > 8 --host_javabase bootclasspath handling.
// (The default --host_javabase is currently JDK 9.)
static boolean dumpJDK9AndNewerBootClassPath(
int hostMajorVersion, Path output, Path targetJavabase) throws IOException {
// JDK 9 and newer support cross-compiling to older platform versions using the --system
// and --release flags.
// * --system takes the path to a JDK root for JDK 9 and up, and causes the compilation
// to target the APIs from that JDK.
// * --release takes a language level (e.g. '9') and uses the API information baked in to
// the host JDK (in lib/ct.sym).
// Since --system only supports JDK >= 9, first check if the target JDK defines a JDK 8
// bootclasspath.
List<Path> bootClassPathJars = getBootClassPathJars(targetJavabase);
if (!bootClassPathJars.isEmpty()) {
writeClassPathJars(output, bootClassPathJars);
return true;
}
// Read the bootclasspath data using the JRT filesystem
Map<String, byte[]> entries = new TreeMap<>();
Map<String, String> env = new TreeMap<>();
env.put("java.home", String.valueOf(targetJavabase));
try (FileSystem fileSystem = FileSystems.newFileSystem(URI.create("jrt:/"), env)) {
Path modules = fileSystem.getPath("/modules");
try (DirectoryStream<Path> ms = Files.newDirectoryStream(modules)) {
for (Path m : ms) {
Files.walkFileTree(
m,
new SimpleFileVisitor<Path>() {
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
throws IOException {
if (file.getFileName().toString().endsWith(".class")) {
entries.put(m.relativize(file).toString(), Files.readAllBytes(file));
}
return super.visitFile(file, attrs);
}
});
}
}
writeEntries(output, entries);
}
return true;
}
/** Writes the given entry names and data to a jar archive at the given path. */
private static void writeEntries(Path output, Map<String, byte[]> entries) throws IOException {
if (!entries.containsKey("java/lang/Object.class")) {
throw new AssertionError(
"\nCould not find java.lang.Object on bootclasspath; something has gone terribly wrong.\n"
+ "Please file a bug: https://github.com/bazelbuild/bazel/issues");
}
try (OutputStream os = Files.newOutputStream(output);
BufferedOutputStream bos = new BufferedOutputStream(os, 65536);
JarOutputStream jos = new JarOutputStream(bos)) {
entries.entrySet().stream()
.forEachOrdered(
entry -> {
try {
addEntry(jos, entry.getKey(), entry.getValue());
} catch (IOException e) {
throw new UncheckedIOException(e);
}
});
}
}
/** Collects the entries of the given jar files into a map from jar entry names to their data. */
private static void writeClassPathJars(Path output, Collection<Path> paths) throws IOException {
List<JarFile> jars = new ArrayList<>();
for (Path path : paths) {
jars.add(new JarFile(path.toFile()));
}
SortedMap<String, byte[]> entries = new TreeMap<>();
for (JarFile jar : jars) {
jar.stream()
.filter(p -> p.getName().endsWith(".class"))
.forEachOrdered(
entry -> {
try {
entries.put(entry.getName(), toByteArray(jar.getInputStream(entry)));
} catch (IOException e) {
throw new UncheckedIOException(e);
}
});
}
writeEntries(output, entries);
for (JarFile jar : jars) {
jar.close();
}
}
/** Returns paths to the entries of a JDK 8-style bootclasspath. */
private static List<Path> getBootClassPathJars(Path javaHome) throws IOException {
List<Path> jars = new ArrayList<>();
Path extDir = javaHome.resolve("jre/lib/ext");
if (Files.exists(extDir)) {
for (Path extJar : Files.newDirectoryStream(extDir, "*.jar")) {
jars.add(extJar);
}
}
for (String jar :
Arrays.asList("rt.jar", "resources.jar", "jsse.jar", "jce.jar", "charsets.jar")) {
Path path = javaHome.resolve("jre/lib").resolve(jar);
if (Files.exists(path)) {
jars.add(path);
}
}
Path toolsJar = javaHome.resolve("lib/tools.jar");
if (Files.exists(toolsJar)) {
jars.add(toolsJar);
}
return jars;
}
// Use a fixed timestamp for deterministic jar output.
private static final long FIXED_TIMESTAMP =
new GregorianCalendar(2010, 0, 1, 0, 0, 0).getTimeInMillis();
/**
* Add a jar entry to the given {@link JarOutputStream}, normalizing the entry timestamps to
* ensure deterministic build output.
*/
private static void addEntry(JarOutputStream jos, String name, byte[] bytes) throws IOException {
JarEntry je = new JarEntry(name);
je.setTime(FIXED_TIMESTAMP);
je.setMethod(ZipEntry.STORED);
// When targeting JDK >= 10, patch the major version so it will be accepted by javac 9
// TODO(cushon): remove this after updating javac
if (bytes[7] > 53) {
bytes[7] = 53;
}
je.setSize(bytes.length);
CRC32 crc = new CRC32();
crc.update(bytes);
je.setCrc(crc.getValue());
jos.putNextEntry(je);
jos.write(bytes);
}
private static byte[] toByteArray(InputStream is) throws IOException {
byte[] buffer = new byte[8192];
ByteArrayOutputStream boas = new ByteArrayOutputStream();
while (true) {
int r = is.read(buffer);
if (r == -1) {
break;
}
boas.write(buffer, 0, r);
}
return boas.toByteArray();
}
/**
* Returns the major version of the host Java runtime (e.g. '8' for JDK 8), using {@link
* Runtime#version} if it is available, and otherwise falling back to the {@code
* java.class.version} system. property.
*/
static int hostMajorVersion() {
try {
Method versionMethod = Runtime.class.getMethod("version");
Object version = versionMethod.invoke(null);
return (int) version.getClass().getMethod("major").invoke(version);
} catch (ReflectiveOperationException e) {
// Runtime.version() isn't available on JDK 8; continue below
}
int version = (int) Double.parseDouble(System.getProperty("java.class.version"));
if (49 <= version && version <= 52) {
return version - (49 - 5);
}
throw new IllegalStateException(
"Unknown Java version: " + System.getProperty("java.specification.version"));
}
}