Ant example source code file (Execute.java)

This example Ant source code file (Execute.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Ant tags/keywords

buildexception, cannot, commandlauncher, commandlauncherproxy, execute, file, file, io, ioexception, ioexception, process, process, reflection, string, string, util, vector

The Execute.java source code

/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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.
 *
 */

package org.apache.tools.ant.taskdefs;

import java.io.BufferedReader;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.StringReader;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Vector;

import org.apache.tools.ant.BuildException;
import org.apache.tools.ant.MagicNames;
import org.apache.tools.ant.Project;
import org.apache.tools.ant.Task;
import org.apache.tools.ant.taskdefs.condition.Os;
import org.apache.tools.ant.types.Commandline;
import org.apache.tools.ant.util.FileUtils;
import org.apache.tools.ant.util.StringUtils;

/**
 * Runs an external program.
 *
 * @since Ant 1.2
 *
 */
public class Execute {

    /** Invalid exit code.
     * set to {@link Integer#MAX_VALUE}
     */
    public static final int INVALID = Integer.MAX_VALUE;

    private static final FileUtils FILE_UTILS = FileUtils.getFileUtils();

    private String[] cmdl = null;
    private String[] env = null;
    private int exitValue = INVALID;
    private ExecuteStreamHandler streamHandler;
    private ExecuteWatchdog watchdog;
    private File workingDirectory = null;
    private Project project = null;
    private boolean newEnvironment = false;
    //TODO: nothing appears to read this but is set using a public setter.
    private boolean spawn = false;


    /** Controls whether the VM is used to launch commands, where possible. */
    private boolean useVMLauncher = true;

    private static String antWorkingDirectory = System.getProperty("user.dir");
    private static CommandLauncher vmLauncher = null;
    private static CommandLauncher shellLauncher = null;
    private static Vector procEnvironment = null;

    /** Used to destroy processes when the VM exits. */
    private static ProcessDestroyer processDestroyer = new ProcessDestroyer();

    /** Used for replacing env variables */
    private static boolean environmentCaseInSensitive = false;

    /*
     * Builds a command launcher for the OS and JVM we are running under.
     */
    static {
        // Try using a JDK 1.3 launcher
        try {
            if (!Os.isFamily("os/2")) {
                vmLauncher = new Java13CommandLauncher();
            }
        } catch (NoSuchMethodException exc) {
            // Ignore and keep trying
        }
        if (Os.isFamily("mac") && !Os.isFamily("unix")) {
            // Mac
            shellLauncher = new MacCommandLauncher(new CommandLauncher());
        } else if (Os.isFamily("os/2")) {
            // OS/2
            shellLauncher = new OS2CommandLauncher(new CommandLauncher());
        } else if (Os.isFamily("windows")) {
            environmentCaseInSensitive = true;
            CommandLauncher baseLauncher = new CommandLauncher();

            if (!Os.isFamily("win9x")) {
                // Windows XP/2000/NT
                shellLauncher = new WinNTCommandLauncher(baseLauncher);
            } else {
                // Windows 98/95 - need to use an auxiliary script
                shellLauncher
                    = new ScriptCommandLauncher("bin/antRun.bat", baseLauncher);
            }
        } else if (Os.isFamily("netware")) {

            CommandLauncher baseLauncher = new CommandLauncher();

            shellLauncher
                = new PerlScriptCommandLauncher("bin/antRun.pl", baseLauncher);
        } else if (Os.isFamily("openvms")) {
            // OpenVMS
            try {
                shellLauncher = new VmsCommandLauncher();
            } catch (NoSuchMethodException exc) {
            // Ignore and keep trying
            }
        } else {
            // Generic
            shellLauncher = new ScriptCommandLauncher("bin/antRun",
                new CommandLauncher());
        }
    }

    /**
     * Set whether or not you want the process to be spawned.
     * Default is not spawned.
     *
     * @param spawn if true you do not want Ant
     *              to wait for the end of the process.
     *
     * @since Ant 1.6
     */
    public void setSpawn(boolean spawn) {
        this.spawn = spawn;
    }

    /**
     * Find the list of environment variables for this process.
     *
     * @return a vector containing the environment variables.
     * The vector elements are strings formatted like variable = value.
     */
    public static synchronized Vector getProcEnvironment() {
        if (procEnvironment != null) {
            return procEnvironment;
        }
        procEnvironment = new Vector();
        try {
            ByteArrayOutputStream out = new ByteArrayOutputStream();
            Execute exe = new Execute(new PumpStreamHandler(out));
            exe.setCommandline(getProcEnvCommand());
            // Make sure we do not recurse forever
            exe.setNewenvironment(true);
            int retval = exe.execute();
            if (retval != 0) {
                // Just try to use what we got
            }
            BufferedReader in =
                new BufferedReader(new StringReader(toString(out)));

            if (Os.isFamily("openvms")) {
                procEnvironment = addVMSLogicals(procEnvironment, in);
                return procEnvironment;
            }
            String var = null;
            String line, lineSep = StringUtils.LINE_SEP;
            while ((line = in.readLine()) != null) {
                if (line.indexOf('=') == -1) {
                    // Chunk part of previous env var (UNIX env vars can
                    // contain embedded new lines).
                    if (var == null) {
                        var = lineSep + line;
                    } else {
                        var += lineSep + line;
                    }
                } else {
                    // New env var...append the previous one if we have it.
                    if (var != null) {
                        procEnvironment.addElement(var);
                    }
                    var = line;
                }
            }
            // Since we "look ahead" before adding, there's one last env var.
            if (var != null) {
                procEnvironment.addElement(var);
            }
        } catch (java.io.IOException exc) {
            exc.printStackTrace();
            // Just try to see how much we got
        }
        return procEnvironment;
    }

    /**
     * This is the operation to get our environment.
     * It is a notorious troublespot pre-Java1.5, and should be approached
     * with extreme caution.
     * @return
     */
    private static String[] getProcEnvCommand() {
        if (Os.isFamily("os/2")) {
            // OS/2 - use same mechanism as Windows 2000
            return new String[] {"cmd", "/c", "set" };
        } else if (Os.isFamily("windows")) {
            // Determine if we're running under XP/2000/NT or 98/95
            if (Os.isFamily("win9x")) {
                // Windows 98/95
                return new String[] {"command.com", "/c", "set" };
            } else {
                // Windows XP/2000/NT/2003
                return new String[] {"cmd", "/c", "set" };
            }
        } else if (Os.isFamily("z/os") || Os.isFamily("unix")) {
            // On most systems one could use: /bin/sh -c env

            // Some systems have /bin/env, others /usr/bin/env, just try
            String[] cmd = new String[1];
            if (new File("/bin/env").canRead()) {
                cmd[0] = "/bin/env";
            } else if (new File("/usr/bin/env").canRead()) {
                cmd[0] = "/usr/bin/env";
            } else {
                // rely on PATH
                cmd[0] = "env";
            }
            return cmd;
        } else if (Os.isFamily("netware") || Os.isFamily("os/400")) {
            // rely on PATH
            return new String[] {"env"};
        } else if (Os.isFamily("openvms")) {
            return new String[] {"show", "logical"};
        } else {
            // MAC OS 9 and previous
            //TODO: I have no idea how to get it, someone must fix it
            return null;
        }
    }

    /**
     * ByteArrayOutputStream#toString doesn't seem to work reliably on
     * OS/390, at least not the way we use it in the execution
     * context.
     *
     * @param bos the output stream that one wants to read.
     * @return the output stream as a string, read with
     * special encodings in the case of z/os and os/400.
     *
     * @since Ant 1.5
     */
    public static String toString(ByteArrayOutputStream bos) {
        if (Os.isFamily("z/os")) {
            try {
                return bos.toString("Cp1047");
            } catch (java.io.UnsupportedEncodingException e) {
                //noop default encoding used
            }
        } else if (Os.isFamily("os/400")) {
            try {
                return bos.toString("Cp500");
            } catch (java.io.UnsupportedEncodingException e) {
                //noop default encoding used
            }
        }
        return bos.toString();
    }

    /**
     * Creates a new execute object using <code>PumpStreamHandler for
     * stream handling.
     */
    public Execute() {
        this(new PumpStreamHandler(), null);
    }

    /**
     * Creates a new execute object.
     *
     * @param streamHandler the stream handler used to handle the input and
     *        output streams of the subprocess.
     */
    public Execute(ExecuteStreamHandler streamHandler) {
        this(streamHandler, null);
    }

    /**
     * Creates a new execute object.
     *
     * @param streamHandler the stream handler used to handle the input and
     *        output streams of the subprocess.
     * @param watchdog a watchdog for the subprocess or <code>null to
     *        to disable a timeout for the subprocess.
     */
    public Execute(ExecuteStreamHandler streamHandler,
                   ExecuteWatchdog watchdog) {
        setStreamHandler(streamHandler);
        this.watchdog = watchdog;
        //By default, use the shell launcher for VMS
        //
        if (Os.isFamily("openvms")) {
            useVMLauncher = false;
        }
    }

    /**
     * Set the stream handler to use.
     * @param streamHandler ExecuteStreamHandler.
     * @since Ant 1.6
     */
    public void setStreamHandler(ExecuteStreamHandler streamHandler) {
        this.streamHandler = streamHandler;
    }

    /**
     * Returns the commandline used to create a subprocess.
     *
     * @return the commandline used to create a subprocess.
     */
    public String[] getCommandline() {
        return cmdl;
    }

    /**
     * Sets the commandline of the subprocess to launch.
     *
     * @param commandline the commandline of the subprocess to launch.
     */
    public void setCommandline(String[] commandline) {
        cmdl = commandline;
    }

    /**
     * Set whether to propagate the default environment or not.
     *
     * @param newenv whether to propagate the process environment.
     */
    public void setNewenvironment(boolean newenv) {
        newEnvironment = newenv;
    }

    /**
     * Returns the environment used to create a subprocess.
     *
     * @return the environment used to create a subprocess.
     */
    public String[] getEnvironment() {
        return (env == null || newEnvironment)
            ? env : patchEnvironment();
    }

    /**
     * Sets the environment variables for the subprocess to launch.
     *
     * @param env array of Strings, each element of which has
     * an environment variable settings in format <em>key=value.
     */
    public void setEnvironment(String[] env) {
        this.env = env;
    }

    /**
     * Sets the working directory of the process to execute.
     *
     * <p>This is emulated using the antRun scripts unless the OS is
     * Windows NT in which case a cmd.exe is spawned,
     * or MRJ and setting user.dir works, or JDK 1.3 and there is
     * official support in java.lang.Runtime.
     *
     * @param wd the working directory of the process.
     */
    public void setWorkingDirectory(File wd) {
        workingDirectory =
            (wd == null || wd.getAbsolutePath().equals(antWorkingDirectory))
            ? null : wd;
    }

    /**
     * Return the working directory.
     * @return the directory as a File.
     * @since Ant 1.7
     */
    public File getWorkingDirectory() {
        return workingDirectory == null ? new File(antWorkingDirectory)
                                        : workingDirectory;
    }

    /**
     * Set the name of the antRun script using the project's value.
     *
     * @param project the current project.
     *
     * @throws BuildException not clear when it is going to throw an exception, but
     * it is the method's signature.
     */
    public void setAntRun(Project project) throws BuildException {
        this.project = project;
    }

    /**
     * Launch this execution through the VM, where possible, rather than through
     * the OS's shell. In some cases and operating systems using the shell will
     * allow the shell to perform additional processing such as associating an
     * executable with a script, etc.
     *
     * @param useVMLauncher true if exec should launch through the VM,
     *                   false if the shell should be used to launch the
     *                   command.
     */
    public void setVMLauncher(boolean useVMLauncher) {
        this.useVMLauncher = useVMLauncher;
    }

    /**
     * Creates a process that runs a command.
     *
     * @param project the Project, only used for logging purposes, may be null.
     * @param command the command to run.
     * @param env the environment for the command.
     * @param dir the working directory for the command.
     * @param useVM use the built-in exec command for JDK 1.3 if available.
     * @return the process started.
     * @throws IOException forwarded from the particular launcher used.
     *
     * @since Ant 1.5
     */
    public static Process launch(Project project, String[] command,
                                 String[] env, File dir, boolean useVM)
        throws IOException {
        if (dir != null && !dir.exists()) {
            throw new BuildException(dir + " doesn't exist.");
        }
        CommandLauncher launcher
            = ((useVM && vmLauncher != null) ? vmLauncher : shellLauncher);
        return launcher.exec(project, command, env, dir);
    }

    /**
     * Runs a process defined by the command line and returns its exit status.
     *
     * @return the exit status of the subprocess or <code>INVALID.
     * @exception java.io.IOException The exception is thrown, if launching
     *            of the subprocess failed.
     */
    public int execute() throws IOException {
        if (workingDirectory != null && !workingDirectory.exists()) {
            throw new BuildException(workingDirectory + " doesn't exist.");
        }
        final Process process = launch(project, getCommandline(),
                                       getEnvironment(), workingDirectory,
                                       useVMLauncher);
        try {
            streamHandler.setProcessInputStream(process.getOutputStream());
            streamHandler.setProcessOutputStream(process.getInputStream());
            streamHandler.setProcessErrorStream(process.getErrorStream());
        } catch (IOException e) {
            process.destroy();
            throw e;
        }
        streamHandler.start();

        try {
            // add the process to the list of those to destroy if the VM exits
            //
            processDestroyer.add(process);

            if (watchdog != null) {
                watchdog.start(process);
            }
            waitFor(process);

            if (watchdog != null) {
                watchdog.stop();
            }
            streamHandler.stop();
            closeStreams(process);

            if (watchdog != null) {
                watchdog.checkException();
            }
            return getExitValue();
        } catch (ThreadDeath t) {
            // #31928: forcibly kill it before continuing.
            process.destroy();
            throw t;
        } finally {
            // remove the process to the list of those to destroy if
            // the VM exits
            //
            processDestroyer.remove(process);
        }
    }

    /**
     * Starts a process defined by the command line.
     * Ant will not wait for this process, nor log its output.
     *
     * @throws java.io.IOException The exception is thrown, if launching
     *            of the subprocess failed.
     * @since Ant 1.6
     */
    public void spawn() throws IOException {
        if (workingDirectory != null && !workingDirectory.exists()) {
            throw new BuildException(workingDirectory + " doesn't exist.");
        }
        final Process process = launch(project, getCommandline(),
                                       getEnvironment(), workingDirectory,
                                       useVMLauncher);
        if (Os.isFamily("windows")) {
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) {
                project.log("interruption in the sleep after having spawned a"
                            + " process", Project.MSG_VERBOSE);
            }
        }
        OutputStream dummyOut = new OutputStream() {
            public void write(int b) throws IOException {
            }
        };

        ExecuteStreamHandler handler = new PumpStreamHandler(dummyOut);
        handler.setProcessErrorStream(process.getErrorStream());
        handler.setProcessOutputStream(process.getInputStream());
        handler.start();
        process.getOutputStream().close();

        project.log("spawned process " + process.toString(),
                    Project.MSG_VERBOSE);
    }

    /**
     * Wait for a given process.
     *
     * @param process the process one wants to wait for.
     */
    protected void waitFor(Process process) {
        try {
            process.waitFor();
            setExitValue(process.exitValue());
        } catch (InterruptedException e) {
            process.destroy();
        }
    }

    /**
     * Set the exit value.
     *
     * @param value exit value of the process.
     */
    protected void setExitValue(int value) {
        exitValue = value;
    }

    /**
     * Query the exit value of the process.
     * @return the exit value or Execute.INVALID if no exit value has
     * been received.
     */
    public int getExitValue() {
        return exitValue;
    }

    /**
     * Checks whether <code>exitValue signals a failure on the current
     * system (OS specific).
     *
     * <p>Note that this method relies on the conventions of
     * the OS, it will return false results if the application you are
     * running doesn't follow these conventions.  One notable
     * exception is the Java VM provided by HP for OpenVMS - it will
     * return 0 if successful (like on any other platform), but this
     * signals a failure on OpenVMS.  So if you execute a new Java VM
     * on OpenVMS, you cannot trust this method.</p>
     *
     * @param exitValue the exit value (return code) to be checked.
     * @return <code>true if exitValue signals a failure.
     */
    public static boolean isFailure(int exitValue) {
        //on openvms even exit value signals failure;
        // for other platforms nonzero exit value signals failure
        return Os.isFamily("openvms")
            ? (exitValue % 2 == 0) : (exitValue != 0);
    }

    /**
     * Did this execute return in a failure.
     * @see #isFailure(int)
     * @return true if and only if the exit code is interpreted as a failure
     * @since Ant1.7
     */
    public boolean isFailure() {
        return isFailure(getExitValue());
    }

    /**
     * Test for an untimely death of the process.
     * @return true if a watchdog had to kill the process.
     * @since Ant 1.5
     */
    public boolean killedProcess() {
        return watchdog != null && watchdog.killedProcess();
    }

    /**
     * Patch the current environment with the new values from the user.
     * @return the patched environment.
     */
    private String[] patchEnvironment() {
        // On OpenVMS Runtime#exec() doesn't support the environment array,
        // so we only return the new values which then will be set in
        // the generated DCL script, inheriting the parent process environment
        if (Os.isFamily("openvms")) {
            return env;
        }
        Vector osEnv = (Vector) getProcEnvironment().clone();
        for (int i = 0; i < env.length; i++) {
            String keyValue = env[i];
            // Get key including "="
            String key = keyValue.substring(0, keyValue.indexOf('=') + 1);
            if (environmentCaseInSensitive) {
                // Nb: using default locale as key is a env name
                key = key.toLowerCase();
            }
            int size = osEnv.size();
            // Find the key in the current enviroment copy
            // and remove it.
            for (int j = 0; j < size; j++) {
                String osEnvItem = (String) osEnv.elementAt(j);
                String convertedItem = environmentCaseInSensitive
                    ? osEnvItem.toLowerCase() : osEnvItem;
                if (convertedItem.startsWith(key)) {
                    osEnv.removeElementAt(j);
                    if (environmentCaseInSensitive) {
                        // Use the original casiness of the key
                        keyValue = osEnvItem.substring(0, key.length())
                            + keyValue.substring(key.length());
                    }
                    break;
                }
            }
            // Add the key to the enviromnent copy
            osEnv.addElement(keyValue);
        }
        return (String[]) (osEnv.toArray(new String[osEnv.size()]));
    }

    /**
     * A utility method that runs an external command.  Writes the output and
     * error streams of the command to the project log.
     *
     * @param task      The task that the command is part of.  Used for logging
     * @param cmdline   The command to execute.
     *
     * @throws BuildException if the command does not exit successfully.
     */
    public static void runCommand(Task task, String[] cmdline)
        throws BuildException {
        try {
            task.log(Commandline.describeCommand(cmdline),
                     Project.MSG_VERBOSE);
            Execute exe = new Execute(
                new LogStreamHandler(task, Project.MSG_INFO, Project.MSG_ERR));
            exe.setAntRun(task.getProject());
            exe.setCommandline(cmdline);
            int retval = exe.execute();
            if (isFailure(retval)) {
                throw new BuildException(cmdline[0]
                    + " failed with return code " + retval, task.getLocation());
            }
        } catch (java.io.IOException exc) {
            throw new BuildException("Could not launch " + cmdline[0] + ": "
                + exc, task.getLocation());
        }
    }

    /**
     * Close the streams belonging to the given Process.
     * @param process   the <code>Process.
     */
    public static void closeStreams(Process process) {
        FileUtils.close(process.getInputStream());
        FileUtils.close(process.getOutputStream());
        FileUtils.close(process.getErrorStream());
    }

    /**
     * This method is VMS specific and used by getProcEnvironment().
     *
     * Parses VMS logicals from <code>in and adds them to
     * <code>environment.  in is expected to be the
     * output of "SHOW LOGICAL".  The method takes care of parsing the output
     * correctly as well as making sure that a logical defined in multiple
     * tables only gets added from the highest order table.  Logicals with
     * multiple equivalence names are mapped to a variable with multiple
     * values separated by a comma (,).
     */
    private static Vector addVMSLogicals(Vector environment, BufferedReader in)
        throws IOException {
        HashMap logicals = new HashMap();
        String logName = null, logValue = null, newLogName;
        String line = null;
        while ((line = in.readLine()) != null) {
            // parse the VMS logicals into required format ("VAR=VAL[,VAL2]")
            if (line.startsWith("\t=")) {
                // further equivalence name of previous logical
                if (logName != null) {
                    logValue += "," + line.substring(4, line.length() - 1);
                }
            } else if (line.startsWith("  \"")) {
                // new logical?
                if (logName != null) {
                    logicals.put(logName, logValue);
                }
                int eqIndex = line.indexOf('=');
                newLogName = line.substring(3, eqIndex - 2);
                if (logicals.containsKey(newLogName)) {
                    // already got this logical from a higher order table
                    logName = null;
                } else {
                    logName = newLogName;
                    logValue = line.substring(eqIndex + 3, line.length() - 1);
                }
            }
        }
        // Since we "look ahead" before adding, there's one last env var.
        if (logName != null) {
            logicals.put(logName, logValue);
        }
        for (Iterator i = logicals.keySet().iterator(); i.hasNext();) {
            String logical = (String) i.next();
            environment.add(logical + "=" + logicals.get(logical));
        }
        return environment;
    }

    /**
     * A command launcher for a particular JVM/OS platform.  This class is
     * a general purpose command launcher which can only launch commands in
     * the current working directory.
     */
    private static class CommandLauncher {
        /**
         * Launches the given command in a new process.
         *
         * @param project       The project that the command is part of.
         * @param cmd           The command to execute.
         * @param env           The environment for the new process.  If null,
         *                      the environment of the current process is used.
         * @return the created Process.
         * @throws IOException if attempting to run a command in a
         * specific directory.
         */
        public Process exec(Project project, String[] cmd, String[] env)
             throws IOException {
            if (project != null) {
                project.log("Execute:CommandLauncher: "
                    + Commandline.describeCommand(cmd), Project.MSG_DEBUG);
            }
            return Runtime.getRuntime().exec(cmd, env);
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         *
         * @param project       The project that the command is part of.
         * @param cmd           The command to execute.
         * @param env           The environment for the new process.  If null,
         *                      the environment of the current process is used.
         * @param workingDir    The directory to start the command in.  If null,
         *                      the current directory is used.
         * @return the created Process.
         * @throws IOException  if trying to change directory.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            if (workingDir == null) {
                return exec(project, cmd, env);
            }
            throw new IOException("Cannot execute a process in different "
                + "directory under this JVM");
        }
    }

    /**
     * A command launcher for JDK/JRE 1.3 (and higher).  Uses the built-in
     * Runtime.exec() command.
     */
    private static class Java13CommandLauncher extends CommandLauncher {
        private Method myExecWithCWD;

        public Java13CommandLauncher() throws NoSuchMethodException {
            // Locate method Runtime.exec(String[] cmdarray,
            //                            String[] envp, File dir)
            myExecWithCWD = Runtime.class.getMethod("exec",
                new Class[] {String[].class, String[].class, File.class});
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir the working directory where the command
         * should run.
         * @return the created Process.
         * @throws IOException probably forwarded from Runtime#exec.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            try {
                if (project != null) {
                    project.log("Execute:Java13CommandLauncher: "
                        + Commandline.describeCommand(cmd), Project.MSG_DEBUG);
                }
                return (Process) myExecWithCWD.invoke(Runtime.getRuntime(),
                   /* the arguments: */ new Object[] {cmd, env, workingDir});
            } catch (InvocationTargetException exc) {
                Throwable realexc = exc.getTargetException();
                if (realexc instanceof ThreadDeath) {
                    throw (ThreadDeath) realexc;
                } else if (realexc instanceof IOException) {
                    throw (IOException) realexc;
                } else {
                    throw new BuildException("Unable to execute command",
                                             realexc);
                }
            } catch (Exception exc) {
                // IllegalAccess, IllegalArgument, ClassCast
                throw new BuildException("Unable to execute command", exc);
            }
        }
    }

    /**
     * A command launcher that proxies another command launcher.
     *
     * Sub-classes override exec(args, env, workdir).
     */
    private static class CommandLauncherProxy extends CommandLauncher {
        private CommandLauncher myLauncher;

        CommandLauncherProxy(CommandLauncher launcher) {
            myLauncher = launcher;
        }

        /**
         * Launches the given command in a new process.  Delegates this
         * method to the proxied launcher.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env)
            throws IOException {
            return myLauncher.exec(project, cmd, env);
        }
    }

    /**
     * A command launcher for OS/2 that uses 'cmd.exe' when launching
     * commands in directories other than the current working
     * directory.
     *
     * <p>Unlike Windows NT and friends, OS/2's cd doesn't support the
     * /d switch to change drives and directories in one go.</p>
     */
    private static class OS2CommandLauncher extends CommandLauncherProxy {
        OS2CommandLauncher(CommandLauncher launcher) {
            super(launcher);
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir working directory where the command should run.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            File commandDir = workingDir;
            if (workingDir == null) {
                if (project != null) {
                    commandDir = project.getBaseDir();
                } else {
                    return exec(project, cmd, env);
                }
            }
            // Use cmd.exe to change to the specified drive and
            // directory before running the command
            final int preCmdLength = 7;
            final String cmdDir = commandDir.getAbsolutePath();
            String[] newcmd = new String[cmd.length + preCmdLength];
            newcmd[0] = "cmd";
            newcmd[1] = "/c";
            newcmd[2] = cmdDir.substring(0, 2);
            newcmd[3] = "&&";
            newcmd[4] = "cd";
            newcmd[5] = cmdDir.substring(2);
            newcmd[6] = "&&";
            System.arraycopy(cmd, 0, newcmd, preCmdLength, cmd.length);

            return exec(project, newcmd, env);
        }
    }

    /**
     * A command launcher for Windows XP/2000/NT that uses 'cmd.exe' when
     * launching commands in directories other than the current working
     * directory.
     */
    private static class WinNTCommandLauncher extends CommandLauncherProxy {
        WinNTCommandLauncher(CommandLauncher launcher) {
            super(launcher);
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir working directory where the command should run.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            File commandDir = workingDir;
            if (workingDir == null) {
                if (project != null) {
                    commandDir = project.getBaseDir();
                } else {
                    return exec(project, cmd, env);
                }
            }
            // Use cmd.exe to change to the specified directory before running
            // the command
            final int preCmdLength = 6;
            String[] newcmd = new String[cmd.length + preCmdLength];
            newcmd[0] = "cmd";
            newcmd[1] = "/c";
            newcmd[2] = "cd";
            newcmd[3] = "/d";
            newcmd[4] = commandDir.getAbsolutePath();
            newcmd[5] = "&&";
            System.arraycopy(cmd, 0, newcmd, preCmdLength, cmd.length);

            return exec(project, newcmd, env);
        }
    }

    /**
     * A command launcher for Mac that uses a dodgy mechanism to change
     * working directory before launching commands.
     */
    private static class MacCommandLauncher extends CommandLauncherProxy {
        MacCommandLauncher(CommandLauncher launcher) {
            super(launcher);
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir working directory where the command should run.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            if (workingDir == null) {
                return exec(project, cmd, env);
            }
            System.getProperties().put("user.dir", workingDir.getAbsolutePath());
            try {
                return exec(project, cmd, env);
            } finally {
                System.getProperties().put("user.dir", antWorkingDirectory);
            }
        }
    }

    /**
     * A command launcher that uses an auxiliary script to launch commands
     * in directories other than the current working directory.
     */
    private static class ScriptCommandLauncher extends CommandLauncherProxy {
        ScriptCommandLauncher(String script, CommandLauncher launcher) {
            super(launcher);
            myScript = script;
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir working directory where the command should run.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            if (project == null) {
                if (workingDir == null) {
                    return exec(project, cmd, env);
                }
                throw new IOException("Cannot locate antRun script: "
                    + "No project provided");
            }
            // Locate the auxiliary script
            String antHome = project.getProperty(MagicNames.ANT_HOME);
            if (antHome == null) {
                throw new IOException("Cannot locate antRun script: "
                    + "Property '" + MagicNames.ANT_HOME + "' not found");
            }
            String antRun =
                FILE_UTILS.resolveFile(project.getBaseDir(),
                        antHome + File.separator + myScript).toString();

            // Build the command
            File commandDir = workingDir;
            if (workingDir == null && project != null) {
                commandDir = project.getBaseDir();
            }
            String[] newcmd = new String[cmd.length + 2];
            newcmd[0] = antRun;
            newcmd[1] = commandDir.getAbsolutePath();
            System.arraycopy(cmd, 0, newcmd, 2, cmd.length);

            return exec(project, newcmd, env);
        }

        private String myScript;
    }

    /**
     * A command launcher that uses an auxiliary perl script to launch commands
     * in directories other than the current working directory.
     */
    private static class PerlScriptCommandLauncher
        extends CommandLauncherProxy {
        private String myScript;

        PerlScriptCommandLauncher(String script, CommandLauncher launcher) {
            super(launcher);
            myScript = script;
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir working directory where the command should run.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            if (project == null) {
                if (workingDir == null) {
                    return exec(project, cmd, env);
                }
                throw new IOException("Cannot locate antRun script: "
                    + "No project provided");
            }
            // Locate the auxiliary script
            String antHome = project.getProperty(MagicNames.ANT_HOME);
            if (antHome == null) {
                throw new IOException("Cannot locate antRun script: "
                    + "Property '" + MagicNames.ANT_HOME + "' not found");
            }
            String antRun =
                FILE_UTILS.resolveFile(project.getBaseDir(),
                        antHome + File.separator + myScript).toString();

            // Build the command
            File commandDir = workingDir;
            if (workingDir == null && project != null) {
                commandDir = project.getBaseDir();
            }
            String[] newcmd = new String[cmd.length + 3];
            newcmd[0] = "perl";
            newcmd[1] = antRun;
            newcmd[2] = commandDir.getAbsolutePath();
            System.arraycopy(cmd, 0, newcmd, 3, cmd.length);

            return exec(project, newcmd, env);
        }
    }

    /**
     * A command launcher for VMS that writes the command to a temporary DCL
     * script before launching commands.  This is due to limitations of both
     * the DCL interpreter and the Java VM implementation.
     */
    private static class VmsCommandLauncher extends Java13CommandLauncher {

        public VmsCommandLauncher() throws NoSuchMethodException {
            super();
        }

        /**
         * Launches the given command in a new process.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env)
            throws IOException {
            File cmdFile = createCommandFile(cmd, env);
            Process p
                = super.exec(project, new String[] {cmdFile.getPath()}, env);
            deleteAfter(cmdFile, p);
            return p;
        }

        /**
         * Launches the given command in a new process, in the given working
         * directory.  Note that under Java 1.3.1, 1.4.0 and 1.4.1 on VMS this
         * method only works if <code>workingDir is null or the logical
         * JAVA$FORK_SUPPORT_CHDIR needs to be set to TRUE.
         * @param project the Ant project.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @param workingDir working directory where the command should run.
         * @return the created Process.
         * @throws IOException forwarded from the exec method of the
         * command launcher.
         */
        public Process exec(Project project, String[] cmd, String[] env,
                            File workingDir) throws IOException {
            File cmdFile = createCommandFile(cmd, env);
            Process p = super.exec(project, new String[] {cmdFile.getPath()},
                                   env, workingDir);
            deleteAfter(cmdFile, p);
            return p;
        }

        /*
         * Writes the command into a temporary DCL script and returns the
         * corresponding File object.  The script will be deleted on exit.
         * @param cmd the command line to execute as an array of strings.
         * @param env the environment to set as an array of strings.
         * @return the command File.
         * @throws IOException if errors are encountered creating the file.
         */
        private File createCommandFile(String[] cmd, String[] env)
            throws IOException {
            File script = FILE_UTILS.createTempFile("ANT", ".COM", null);
            script.deleteOnExit();
            PrintWriter out = null;
            try {
                out = new PrintWriter(new FileWriter(script));

                // add the environment as logicals to the DCL script
                if (env != null) {
                    int eqIndex;
                    for (int i = 0; i < env.length; i++) {
                        eqIndex = env[i].indexOf('=');
                        if (eqIndex != -1) {
                            out.print("$ DEFINE/NOLOG ");
                            out.print(env[i].substring(0, eqIndex));
                            out.print(" \"");
                            out.print(env[i].substring(eqIndex + 1));
                            out.println('\"');
                        }
                    }
                }
                out.print("$ " + cmd[0]);
                for (int i = 1; i < cmd.length; i++) {
                    out.println(" -");
                    out.print(cmd[i]);
                }
            } finally {
                if (out != null) {
                    out.close();
                }
            }
            return script;
        }

        private void deleteAfter(final File f, final Process p) {
            new Thread() {
                public void run() {
                    try {
                        p.waitFor();
                    } catch (InterruptedException e) {
                        //ignore
                    }
                    FileUtils.delete(f);
                }
            }
            .start();
        }
    }
}