332 lines
12 KiB
Java
332 lines
12 KiB
Java
/*
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* Copyright (C) 2014 The Android Open Source Project
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* Copyright (c) 1995, 2010, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.lang;
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import java.io.BufferedInputStream;
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import java.io.BufferedOutputStream;
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import java.io.ByteArrayInputStream;
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import java.io.FileDescriptor;
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import java.io.FileInputStream;
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import java.io.FileOutputStream;
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import java.io.IOException;
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import java.io.InputStream;
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import java.io.OutputStream;
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import java.util.Arrays;
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import java.util.concurrent.Executors;
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import java.util.concurrent.Executor;
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import java.util.concurrent.ThreadFactory;
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import java.security.AccessController;
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import static java.security.AccessController.doPrivileged;
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import java.security.PrivilegedAction;
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import java.security.PrivilegedActionException;
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import java.security.PrivilegedExceptionAction;
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/**
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* java.lang.Process subclass in the UNIX environment.
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*
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* @author Mario Wolczko and Ross Knippel.
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* @author Konstantin Kladko (ported to Linux)
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* @author Martin Buchholz
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*/
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final class UNIXProcess extends Process {
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private final int pid;
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private int exitcode;
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private boolean hasExited;
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private /* final */ OutputStream stdin;
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private /* final */ InputStream stdout;
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private /* final */ InputStream stderr;
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/* this is for the reaping thread */
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private native int waitForProcessExit(int pid);
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/**
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* Create a process using fork(2) and exec(2).
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*
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* @param fds an array of three file descriptors.
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* Indexes 0, 1, and 2 correspond to standard input,
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* standard output and standard error, respectively. On
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* input, a value of -1 means to create a pipe to connect
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* child and parent processes. On output, a value which
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* is not -1 is the parent pipe fd corresponding to the
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* pipe which has been created. An element of this array
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* is -1 on input if and only if it is <em>not</em> -1 on
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* output.
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* @return the pid of the subprocess
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*/
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private native int forkAndExec(byte[] prog,
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byte[] argBlock, int argc,
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byte[] envBlock, int envc,
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byte[] dir,
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int[] fds,
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boolean redirectErrorStream)
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throws IOException;
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/**
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* The thread factory used to create "process reaper" daemon threads.
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*/
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private static class ProcessReaperThreadFactory implements ThreadFactory {
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private final static ThreadGroup group = getRootThreadGroup();
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private static ThreadGroup getRootThreadGroup() {
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return doPrivileged(new PrivilegedAction<ThreadGroup> () {
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public ThreadGroup run() {
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ThreadGroup root = Thread.currentThread().getThreadGroup();
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while (root.getParent() != null)
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root = root.getParent();
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return root;
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}});
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}
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public Thread newThread(Runnable grimReaper) {
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// Our thread stack requirement is quite modest.
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Thread t = new Thread(group, grimReaper, "process reaper", 32768);
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t.setDaemon(true);
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// A small attempt (probably futile) to avoid priority inversion
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t.setPriority(Thread.MAX_PRIORITY);
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return t;
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}
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}
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/**
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* The thread pool of "process reaper" daemon threads.
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*/
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private static final Executor processReaperExecutor =
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doPrivileged(new PrivilegedAction<Executor>() {
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public Executor run() {
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return Executors.newCachedThreadPool
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(new ProcessReaperThreadFactory());
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}});
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UNIXProcess(final byte[] prog,
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final byte[] argBlock, final int argc,
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final byte[] envBlock, final int envc,
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final byte[] dir,
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final int[] fds,
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final boolean redirectErrorStream)
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throws IOException {
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pid = forkAndExec(prog,
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argBlock, argc,
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envBlock, envc,
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dir,
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fds,
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redirectErrorStream);
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try {
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doPrivileged(new PrivilegedExceptionAction<Void>() {
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public Void run() throws IOException {
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initStreams(fds);
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return null;
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}});
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} catch (PrivilegedActionException ex) {
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throw (IOException) ex.getException();
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}
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}
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static FileDescriptor newFileDescriptor(int fd) {
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FileDescriptor fileDescriptor = new FileDescriptor();
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fileDescriptor.setInt$(fd);
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return fileDescriptor;
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}
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void initStreams(int[] fds) throws IOException {
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stdin = (fds[0] == -1) ?
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ProcessBuilder.NullOutputStream.INSTANCE :
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new ProcessPipeOutputStream(fds[0]);
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stdout = (fds[1] == -1) ?
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ProcessBuilder.NullInputStream.INSTANCE :
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new ProcessPipeInputStream(fds[1]);
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stderr = (fds[2] == -1) ?
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ProcessBuilder.NullInputStream.INSTANCE :
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new ProcessPipeInputStream(fds[2]);
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processReaperExecutor.execute(new Runnable() {
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public void run() {
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int exitcode = waitForProcessExit(pid);
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UNIXProcess.this.processExited(exitcode);
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}});
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}
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void processExited(int exitcode) {
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synchronized (this) {
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this.exitcode = exitcode;
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hasExited = true;
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notifyAll();
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}
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if (stdout instanceof ProcessPipeInputStream)
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((ProcessPipeInputStream) stdout).processExited();
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if (stderr instanceof ProcessPipeInputStream)
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((ProcessPipeInputStream) stderr).processExited();
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if (stdin instanceof ProcessPipeOutputStream)
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((ProcessPipeOutputStream) stdin).processExited();
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}
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public OutputStream getOutputStream() {
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return stdin;
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}
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public InputStream getInputStream() {
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return stdout;
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}
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public InputStream getErrorStream() {
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return stderr;
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}
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public synchronized int waitFor() throws InterruptedException {
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while (!hasExited) {
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wait();
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}
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return exitcode;
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}
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public synchronized int exitValue() {
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if (!hasExited) {
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throw new IllegalThreadStateException("process hasn't exited");
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}
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return exitcode;
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}
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private static native void destroyProcess(int pid);
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public void destroy() {
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// There is a risk that pid will be recycled, causing us to
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// kill the wrong process! So we only terminate processes
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// that appear to still be running. Even with this check,
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// there is an unavoidable race condition here, but the window
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// is very small, and OSes try hard to not recycle pids too
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// soon, so this is quite safe.
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synchronized (this) {
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if (!hasExited)
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destroyProcess(pid);
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}
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try { stdin.close(); } catch (IOException ignored) {}
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try { stdout.close(); } catch (IOException ignored) {}
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try { stderr.close(); } catch (IOException ignored) {}
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}
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@Override
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public String toString() {
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StringBuilder sb = new StringBuilder("Process[pid=");
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sb.append(pid);
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if (hasExited) {
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sb.append(" ,hasExited=true, exitcode=");
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sb.append(exitcode);
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sb.append("]");
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} else {
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sb.append(", hasExited=false]");
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}
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return sb.toString();
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}
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/* This routine initializes JNI field offsets for the class */
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private static native void initIDs();
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static {
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initIDs();
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}
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/**
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* A buffered input stream for a subprocess pipe file descriptor
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* that allows the underlying file descriptor to be reclaimed when
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* the process exits, via the processExited hook.
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*
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* This is tricky because we do not want the user-level InputStream to be
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* closed until the user invokes close(), and we need to continue to be
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* able to read any buffered data lingering in the OS pipe buffer.
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*/
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static class ProcessPipeInputStream extends BufferedInputStream {
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ProcessPipeInputStream(int fd) {
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super(new FileInputStream(newFileDescriptor(fd), true /* isFdOwner */));
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}
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private static byte[] drainInputStream(InputStream in)
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throws IOException {
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if (in == null) return null;
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int n = 0;
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int j;
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byte[] a = null;
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while ((j = in.available()) > 0) {
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a = (a == null) ? new byte[j] : Arrays.copyOf(a, n + j);
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n += in.read(a, n, j);
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}
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return (a == null || n == a.length) ? a : Arrays.copyOf(a, n);
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}
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/** Called by the process reaper thread when the process exits. */
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synchronized void processExited() {
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// Most BufferedInputStream methods are synchronized, but close()
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// is not, and so we have to handle concurrent racing close().
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try {
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InputStream in = this.in;
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if (in != null) {
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byte[] stragglers = drainInputStream(in);
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in.close();
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this.in = (stragglers == null) ?
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ProcessBuilder.NullInputStream.INSTANCE :
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new ByteArrayInputStream(stragglers);
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if (buf == null) // asynchronous close()?
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this.in = null;
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}
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} catch (IOException ignored) {
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// probably an asynchronous close().
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}
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}
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}
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/**
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* A buffered output stream for a subprocess pipe file descriptor
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* that allows the underlying file descriptor to be reclaimed when
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* the process exits, via the processExited hook.
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*/
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static class ProcessPipeOutputStream extends BufferedOutputStream {
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ProcessPipeOutputStream(int fd) {
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super(new FileOutputStream(newFileDescriptor(fd), true /* isFdOwner */));
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}
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/** Called by the process reaper thread when the process exits. */
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synchronized void processExited() {
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OutputStream out = this.out;
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if (out != null) {
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try {
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out.close();
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} catch (IOException ignored) {
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// We know of no reason to get an IOException, but if
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// we do, there's nothing else to do but carry on.
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}
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this.out = ProcessBuilder.NullOutputStream.INSTANCE;
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}
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}
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}
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}
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