ProcessImpl.java

/*
 * Copyright (c) 1995, 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package java.lang;

import java.io.IOException;
import java.io.File;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.FileDescriptor;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.lang.ProcessBuilder.Redirect;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.concurrent.TimeUnit;

/* This class is for the exclusive use of ProcessBuilder.start() to
 * create new processes.
 *
 * @author Martin Buchholz
 * @since   1.5
 */

final class ProcessImpl extends Process {
    private static final sun.misc.JavaIOFileDescriptorAccess fdAccess
        = sun.misc.SharedSecrets.getJavaIOFileDescriptorAccess();

    /**
     * Open a file for writing. If {@code append} is {@code true} then the file
     * is opened for atomic append directly and a FileOutputStream constructed
     * with the resulting handle. This is because a FileOutputStream created
     * to append to a file does not open the file in a manner that guarantees
     * that writes by the child process will be atomic.
     */
    private static FileOutputStream newFileOutputStream(File f, boolean append)
        throws IOException
    {
        if (append) {
            String path = f.getPath();
            SecurityManager sm = System.getSecurityManager();
            if (sm != null)
                sm.checkWrite(path);
            long handle = openForAtomicAppend(path);
            final FileDescriptor fd = new FileDescriptor();
            fdAccess.setHandle(fd, handle);
            return AccessController.doPrivileged(
                new PrivilegedAction<FileOutputStream>() {
                    public FileOutputStream run() {
                        return new FileOutputStream(fd);
                    }
                }
            );
        } else {
            return new FileOutputStream(f);
        }
    }

    // System-dependent portion of ProcessBuilder.start()
    static Process start(String cmdarray[],
                         java.util.Map<String,String> environment,
                         String dir,
                         ProcessBuilder.Redirect[] redirects,
                         boolean redirectErrorStream)
        throws IOException
    {
        String envblock = ProcessEnvironment.toEnvironmentBlock(environment);

        FileInputStream  f0 = null;
        FileOutputStream f1 = null;
        FileOutputStream f2 = null;

        try {
            long[] stdHandles;
            if (redirects == null) {
                stdHandles = new long[] { -1L, -1L, -1L };
            } else {
                stdHandles = new long[3];

                if (redirects[0] == Redirect.PIPE)
                    stdHandles[0] = -1L;
                else if (redirects[0] == Redirect.INHERIT)
                    stdHandles[0] = fdAccess.getHandle(FileDescriptor.in);
                else {
                    f0 = new FileInputStream(redirects[0].file());
                    stdHandles[0] = fdAccess.getHandle(f0.getFD());
                }

                if (redirects[1] == Redirect.PIPE)
                    stdHandles[1] = -1L;
                else if (redirects[1] == Redirect.INHERIT)
                    stdHandles[1] = fdAccess.getHandle(FileDescriptor.out);
                else {
                    f1 = newFileOutputStream(redirects[1].file(),
                                             redirects[1].append());
                    stdHandles[1] = fdAccess.getHandle(f1.getFD());
                }

                if (redirects[2] == Redirect.PIPE)
                    stdHandles[2] = -1L;
                else if (redirects[2] == Redirect.INHERIT)
                    stdHandles[2] = fdAccess.getHandle(FileDescriptor.err);
                else {
                    f2 = newFileOutputStream(redirects[2].file(),
                                             redirects[2].append());
                    stdHandles[2] = fdAccess.getHandle(f2.getFD());
                }
            }

            return new ProcessImpl(cmdarray, envblock, dir,
                                   stdHandles, redirectErrorStream);
        } finally {
            // In theory, close() can throw IOException
            // (although it is rather unlikely to happen here)
            try { if (f0 != null) f0.close(); }
            finally {
                try { if (f1 != null) f1.close(); }
                finally { if (f2 != null) f2.close(); }
            }
        }

    }

    private long handle = 0;
    private OutputStream stdin_stream;
    private InputStream stdout_stream;
    private InputStream stderr_stream;

    private ProcessImpl(final String cmd[],
                        final String envblock,
                        final String path,
                        final long[] stdHandles,
                        final boolean redirectErrorStream)
        throws IOException
    {
        // Win32 CreateProcess requires cmd[0] to be normalized
        cmd[0] = new File(cmd[0]).getPath();

        StringBuilder cmdbuf = new StringBuilder(80);
        for (int i = 0; i < cmd.length; i++) {
            if (i > 0) {
                cmdbuf.append(' ');
            }
            String s = cmd[i];
            if (s.indexOf(' ') >= 0 || s.indexOf('\t') >= 0) {
                if (s.charAt(0) != '"') {
                    cmdbuf.append('"');
                    cmdbuf.append(s);
                    if (s.endsWith("\\")) {
                        cmdbuf.append("\\");
                    }
                    cmdbuf.append('"');
                } else if (s.endsWith("\"")) {
                    /* The argument has already been quoted. */
                    cmdbuf.append(s);
                } else {
                    /* Unmatched quote for the argument. */
                    throw new IllegalArgumentException();
                }
            } else {
                cmdbuf.append(s);
            }
        }
        String cmdstr = cmdbuf.toString();

        handle = create(cmdstr, envblock, path,
                        stdHandles, redirectErrorStream);

        java.security.AccessController.doPrivileged(
        new java.security.PrivilegedAction<Void>() {
        public Void run() {
            if (stdHandles[0] == -1L)
                stdin_stream = ProcessBuilder.NullOutputStream.INSTANCE;
            else {
                FileDescriptor stdin_fd = new FileDescriptor();
                fdAccess.setHandle(stdin_fd, stdHandles[0]);
                stdin_stream = new BufferedOutputStream(
                    new FileOutputStream(stdin_fd));
            }

            if (stdHandles[1] == -1L)
                stdout_stream = ProcessBuilder.NullInputStream.INSTANCE;
            else {
                FileDescriptor stdout_fd = new FileDescriptor();
                fdAccess.setHandle(stdout_fd, stdHandles[1]);
                stdout_stream = new BufferedInputStream(
                    new FileInputStream(stdout_fd));
            }

            if (stdHandles[2] == -1L)
                stderr_stream = ProcessBuilder.NullInputStream.INSTANCE;
            else {
                FileDescriptor stderr_fd = new FileDescriptor();
                fdAccess.setHandle(stderr_fd, stdHandles[2]);
                stderr_stream = new FileInputStream(stderr_fd);
            }

            return null; }});
    }

    public OutputStream getOutputStream() {
        return stdin_stream;
    }

    public InputStream getInputStream() {
        return stdout_stream;
    }

    public InputStream getErrorStream() {
        return stderr_stream;
    }

    public void finalize() {
        closeHandle(handle);
    }

    private static final int STILL_ACTIVE = getStillActive();
    private static native int getStillActive();

    public int exitValue() {
        int exitCode = getExitCodeProcess(handle);
        if (exitCode == STILL_ACTIVE)
            throw new IllegalThreadStateException("process has not exited");
        return exitCode;
    }
    private static native int getExitCodeProcess(long handle);

    public int waitFor() throws InterruptedException {
        waitForInterruptibly(handle);
        if (Thread.interrupted())
            throw new InterruptedException();
        return exitValue();
    }

    private static native void waitForInterruptibly(long handle);

    @Override
    public boolean waitFor(long timeout, TimeUnit unit)
        throws InterruptedException
    {
        if (getExitCodeProcess(handle) != STILL_ACTIVE) return true;
        if (timeout <= 0) return false;

        long msTimeout = unit.toMillis(timeout);

        waitForTimeoutInterruptibly(handle, msTimeout);
        if (Thread.interrupted())
            throw new InterruptedException();
        return (getExitCodeProcess(handle) != STILL_ACTIVE);
    }

    private static native void waitForTimeoutInterruptibly(
        long handle, long timeout);

    public void destroy() { terminateProcess(handle); }

    @Override
    public Process destroyForcibly() {
        destroy();
        return this;
    }

    private static native void terminateProcess(long handle);

    @Override
    public boolean isAlive() {
        return isProcessAlive(handle);
    }

    private static native boolean isProcessAlive(long handle);

    /**
     * Create a process using the win32 function CreateProcess.
     *
     * @param cmdstr the Windows commandline
     * @param envblock NUL-separated, double-NUL-terminated list of
     *        environment strings in VAR=VALUE form
     * @param dir the working directory of the process, or null if
     *        inheriting the current directory from the parent process
     * @param stdHandles array of windows HANDLEs.  Indexes 0, 1, and
     *        2 correspond to standard input, standard output and
     *        standard error, respectively.  On input, a value of -1
     *        means to create a pipe to connect child and parent
     *        processes.  On output, a value which is not -1 is the
     *        parent pipe handle corresponding to the pipe which has
     *        been created.  An element of this array is -1 on input
     *        if and only if it is <em>not</em> -1 on output.
     * @param redirectErrorStream redirectErrorStream attribute
     * @return the native subprocess HANDLE returned by CreateProcess
     */
    private static native long create(String cmdstr,
                                      String envblock,
                                      String dir,
                                      long[] stdHandles,
                                      boolean redirectErrorStream)
        throws IOException;

    /**
     * Opens a file for atomic append. The file is created if it doesn't
     * already exist.
     *
     * @param file the file to open or create
     * @return the native HANDLE
     */
    private static native long openForAtomicAppend(String path)
        throws IOException;

    private static native boolean closeHandle(long handle);
}