1 /*
   2  * Copyright (c) 2007, 2014, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 package test.java.awt.regtesthelpers.process;
  25 
  26 import java.io.*;
  27 
  28 /** 
  29  *  This class is created to solve interprocess communication problems.
  30  *  When you need to write a regression test which should verify inter jvm
  31  *  behavior such as DnD data transfer, Clipboard data transfer, focus
  32  *  transfer etc., you could use the next scenario:
  33  *
  34  *  1. Write an implementation for the parent JVM, using applet test.
  35  *  2. Write an implementation for the child JVM or native application, using
  36  *     main() function.
  37  *  3. Execute child process using  ProcessCommunicator.executeChildProcess()
  38  *     method.
  39  *  4. You can decide whether the test is passed on the basis of
  40  *     ProcessResults class data.
  41  *
  42  *  Note: The class is not thread safe. You should access its methods only from 
  43  *        the same thread.
  44  */
  45 
  46 public class ProcessCommunicator {
  47 
  48     private static final String javaHome = System.getProperty("java.home", "");
  49     private static final String javaPath = javaHome + File.separator + "bin" +
  50             File.separator + "java ";
  51     private static String command = "";
  52     private static volatile Process process;
  53     
  54     private ProcessCommunicator() {}
  55 
  56     /** 
  57      * The same as {#link #executeChildProcess(Class,String)} except
  58      * the {@code classPathArgument} parameter. The class path
  59      * parameter is for the debug purposes
  60      *
  61      * @param classToExecute is passed to the child JVM
  62      * @param classPathArguments class path for the child JVM
  63      * @param args arguments that will be passed to the executed class
  64      * @return results of the executed {@code Process}
  65      */
  66     public static ProcessResults executeChildProcess(final Class classToExecute,
  67                            final String classPathArguments, final String [] args)
  68     {
  69         try {
  70             String command = buildCommand(classToExecute, classPathArguments, args);
  71             process = Runtime.getRuntime().exec(command);
  72             return doWaitFor(process);
  73         } catch (IOException e) {
  74             throw new RuntimeException(e);
  75         }
  76     }
  77 
  78     /** 
  79      * Executes child {code Process}
  80      *
  81      * @param classToExecute class to be executed as a child java process
  82      * @param args args to be passed in to the child process
  83      * @return results of the executed {@code Process}
  84      */
  85     public static ProcessResults executeChildProcess(final Class classToExecute,
  86                            final String [] args)
  87     {
  88         return executeChildProcess(classToExecute, System.getProperty("java.class.path"), args);
  89     }
  90 
  91     /**
  92      * Waits for a process and return its results.
  93      * This is a workaround for {@code Process.waitFor()} never returning.
  94      *
  95      * @return results of the executed {@code Process}
  96      */
  97     public static ProcessResults doWaitFor(final Process p) {
  98         ProcessResults pres = new ProcessResults();
  99 
 100         final InputStream in;
 101         final InputStream err;
 102 
 103         try {
 104             in = p.getInputStream();
 105             err = p.getErrorStream();
 106 
 107             boolean finished = false;
 108 
 109             while (!finished) {
 110                 try {
 111                     while (in.available() > 0) {
 112                         pres.appendToStdOut((char)in.read());
 113                     }
 114                     while (err.available() > 0) {
 115                         pres.appendToStdErr((char)err.read());
 116                     }
 117                     // Ask the process for its exitValue. If the process
 118                     // is not finished, an IllegalThreadStateException
 119                     // is thrown. If it is finished, we fall through and
 120                     // the variable finished is set to true.
 121                     pres.setExitValue(p.exitValue());
 122                     finished  = true;
 123                 }
 124                 catch (IllegalThreadStateException e) {
 125                     // Process is not finished yet;
 126                     // Sleep a little to save on CPU cycles
 127                     Thread.currentThread().sleep(500);
 128                 }
 129             }
 130             if (in != null) in.close();
 131             if (err != null) err.close();
 132         }
 133         catch (Throwable e) {
 134             System.err.println("doWaitFor(): unexpected exception");
 135             e.printStackTrace();
 136         }
 137         return pres;
 138     }
 139 
 140     /** 
 141      * Builds command on the basis of the passed class name,
 142      * class path and arguments.
 143      *
 144      * @param classToExecute with class will be executed in the new JVM
 145      * @param classPathArguments java class path (only for test purposes)
 146      * @param args arguments for the new application. This could be used
 147      *             to pass some information from the parent to child JVM.
 148      * @return command to execute the {@code Process}
 149      */
 150     private static String buildCommand(final Class classToExecute,
 151                          final String classPathArguments, final String [] args)
 152     {
 153         StringBuilder commandBuilder = new StringBuilder();
 154         commandBuilder.append(javaPath).append(" ");
 155         commandBuilder.append("-cp ").append(System.getProperty("test.classes", ".")).append(File.pathSeparatorChar);
 156 
 157         if (classPathArguments.trim().length() > 0) {
 158             commandBuilder.append(classPathArguments).append(" ");
 159         }
 160 
 161         commandBuilder.append(" ");
 162         commandBuilder.append(classToExecute.getName());
 163         for (String argument:args) {
 164             commandBuilder.append(" ").append(argument);
 165         }
 166         command = commandBuilder.toString();
 167         return command;
 168     }
 169 
 170     /** 
 171      * Could be used for the debug purposes.
 172      *
 173      * @return command that was build to execute the child process
 174      */
 175     public static String getExecutionCommand () {
 176         return command;
 177     }
 178     
 179     /**
 180      * Terminates the process created by {@code executeChildProcess} methods.
 181      */
 182     public static void destroyProcess() {
 183         if (process != null) {
 184             if (process.isAlive()) {
 185                 process.destroy();
 186             }
 187             process = null;
 188         }
 189     }
 190 }