Exec.java Source code

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Here is the source code for Exec.java

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/*
 * Copyright (c) 1998-2002 Carnegie Mellon University.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY CARNEGIE MELLON UNIVERSITY ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL CARNEGIE MELLON UNIVERSITY
 * NOR ITS EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

import java.io.*;

public abstract class Exec {

    public static Process exec(String[] cmdarray) throws IOException {
        return exec(cmdarray, null, null);
    }

    public static Process exec(String[] cmdarray, String[] envp) throws IOException {
        return exec(cmdarray, envp, null);
    }

    public static Process exec(String[] cmdarray, String[] envp, File directory) throws IOException {
        return isWindows() ? execWindows(cmdarray, envp, directory) : execUnix(cmdarray, envp, directory);
    }

    /*
     * Unix
     */

    static Process execUnix(String[] cmdarray, String[] envp, File directory) throws IOException {
        // instead of calling command directly, we'll call the shell to change
        // directory and set environment variables.

        // start constructing the sh command line.
        StringBuffer buf = new StringBuffer();

        if (directory != null) {
            // change to directory
            buf.append("cd '");
            buf.append(escapeQuote(directory.toString()));
            buf.append("'; ");
        }

        if (envp != null) {
            // set environment variables.  Quote the value (but not the name).
            for (int i = 0; i < envp.length; ++i) {
                String nameval = envp[i];
                int equals = nameval.indexOf('=');
                if (equals == -1)
                    throw new IOException("environment variable '" + nameval + "' should have form NAME=VALUE");
                buf.append(nameval.substring(0, equals + 1));
                buf.append('\'');
                buf.append(escapeQuote(nameval.substring(equals + 1)));
                buf.append("\' ");
            }
        }

        // now that we have the directory and environment, run "which" 
        // to test if the command name is found somewhere in the path.
        // If "which" fails, throw an IOException.
        String cmdname = escapeQuote(cmdarray[0]);
        Runtime rt = Runtime.getRuntime();
        String[] sharray = new String[] { "sh", "-c", buf.toString() + " which \'" + cmdname + "\'" };
        Process which = rt.exec(sharray);
        try {
            which.waitFor();
        } catch (InterruptedException e) {
            throw new IOException("interrupted");
        }

        if (which.exitValue() != 0)
            throw new IOException("can't execute " + cmdname + ": bad command or filename");

        // finish in 
        buf.append("exec \'");
        buf.append(cmdname);
        buf.append("\' ");

        // quote each argument in the command
        for (int i = 1; i < cmdarray.length; ++i) {
            buf.append('\'');
            buf.append(escapeQuote(cmdarray[i]));
            buf.append("\' ");
        }

        System.out.println("executing " + buf);
        sharray[2] = buf.toString();
        return rt.exec(sharray);
    }

    static String escapeQuote(String s) {
        // replace single quotes with a bit of magic (end-quote, escaped-quote, start-quote) 
        // that works in a single-quoted string in the Unix shell
        if (s.indexOf('\'') != -1) {
            System.out.println("replacing single-quotes in " + s);
            s = s.replace("'", "'\\''");
            System.out.println("to get " + s);
        }
        return s;
    }

    /*
     * Windows
     */

    static boolean isWindows() {
        String os = System.getProperty("os.name");
        return (os != null && os.startsWith("Windows"));
    }

    static boolean isJview() {
        String vendor = System.getProperty("java.vendor");
        return (vendor != null && vendor.startsWith("Microsoft"));
    }

    static Process execWindows(String[] cmdarray, String[] envp, File directory) throws IOException {
        if (envp != null || directory != null) {
            if (isJview())
                // jview doesn't support JNI, so can't call putenv/chdir
                throw new IOException("can't use Exec.exec() under Microsoft JVM");

            if (!linked) {
                try {
                    System.loadLibrary("win32exec");
                    linked = true;
                } catch (LinkageError e) {
                    throw new IOException("can't use Exec.exec(): " + e.getMessage());
                }
            }

            if (envp != null) {
                for (int i = 0; i < envp.length; ++i)
                    putenv(envp[i]);
            }

            if (directory != null)
                chdir(directory.toString());
        }

        return Runtime.getRuntime().exec(cmdarray);
    }

    static boolean linked = false; // true after System.loadLibrary() is called

    static native boolean putenv(String env);

    static native boolean chdir(String dir);
}