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Java > Open Source Codes > freemarker > template > utility > Execute


1 /*
2  * Copyright (c) 2003 The Visigoth Software Society. All rights
3  * reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *
9  * 1. Redistributions of source code must retain the above copyright
10  * notice, this list of conditions and the following disclaimer.
11  *
12  * 2. Redistributions in binary form must reproduce the above copyright
13  * notice, this list of conditions and the following disclaimer in
14  * the documentation and/or other materials provided with the
15  * distribution.
16  *
17  * 3. The end-user documentation included with the redistribution, if
18  * any, must include the following acknowledgement:
19  * "This product includes software developed by the
20  * Visigoth Software Society (http://www.visigoths.org/)."
21  * Alternately, this acknowledgement may appear in the software itself,
22  * if and wherever such third-party acknowledgements normally appear.
23  *
24  * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the
25  * project contributors may be used to endorse or promote products derived
26  * from this software without prior written permission. For written
27  * permission, please contact visigoths@visigoths.org.
28  *
29  * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth"
30  * nor may "FreeMarker" or "Visigoth" appear in their names
31  * without prior written permission of the Visigoth Software Society.
32  *
33  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
34  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
35  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
36  * DISCLAIMED. IN NO EVENT SHALL THE VISIGOTH SOFTWARE SOCIETY OR
37  * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
38  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
39  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
40  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
41  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
42  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
43  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
44  * SUCH DAMAGE.
45  * ====================================================================
46  *
47  * This software consists of voluntary contributions made by many
48  * individuals on behalf of the Visigoth Software Society. For more
49  * information on the Visigoth Software Society, please see
50  * http://www.visigoths.org/
51  */
52
53 package freemarker.template.utility;
54
55 import freemarker.template.*;
56 import java.io.*;
57 import java.util.*;
58
59 /**
60  * <p>Gives FreeMarker the the ability to execute external commands. Will fork
61  * a process, and inline anything that process sends to stdout in the template.
62  * Based on a patch submitted by Peter Molettiere.</p>
63  *
64  * <p>BE CAREFUL! this tag, depending on use, may allow you
65  * to set something up so that users of your web
66  * application could run arbitrary code on your server.
67  * This can only happen if you allow unchecked GET/POST
68  * submissions to be used as the command string in the
69  * exec tag.</p>
70  *
71  * <p>Usage:<br />
72  * From java:</p>
73  * <pre>
74  * SimpleHash root = new SimpleHash();
75  *
76  * root.put( "exec", new freemarker.template.utility.Execute() );
77  *
78  * ...
79  * </pre>
80  *
81  * <p>From your FreeMarker template:</p>
82  * <pre>
83  *
84  * The following is executed:
85  * ${exec( "/usr/bin/ls" )}
86  *
87  * ...
88  * </pre>
89  *
90  * @version $Id: Execute.java,v 1.14 2003/10/13 11:57:18 szegedia Exp $
91  */
92 public class Execute implements freemarker.template.TemplateMethodModel {
93
94     private final static int OUTPUT_BUFFER_SIZE = 1024;
95
96     /**
97      * Executes a method call.
98      *
99      * @param arguments a <tt>List</tt> of <tt>String</tt> objects containing the values
100      * of the arguments passed to the method.
101      * @return the <tt>TemplateModel</tt> produced by the method, or null.
102      */
103     public Object JavaDoc exec (List arguments) throws TemplateModelException {
104         String JavaDoc aExecute;
105         StringBuffer JavaDoc aOutputBuffer = new StringBuffer JavaDoc();
106
107         if( arguments.size() < 1 ) {
108             throw new TemplateModelException( "Need an argument to execute" );
109         }
110
111         aExecute = (String JavaDoc)(arguments.get(0));
112
113         try {
114             Process JavaDoc exec = Runtime.getRuntime().exec( aExecute );
115
116             // stdout from the process comes in here
117 InputStream execOut = exec.getInputStream();
118             Reader execReader = new InputStreamReader( execOut );
119
120             char[] buffer = new char[ OUTPUT_BUFFER_SIZE ];
121             int bytes_read = execReader.read( buffer );
122
123             while( bytes_read > 0 ) {
124                 aOutputBuffer.append( buffer, 0, bytes_read );
125                 bytes_read = execReader.read( buffer );
126             }
127         }
128         catch( IOException ioe ) {
129             throw new TemplateModelException( ioe.getMessage() );
130         }
131         return aOutputBuffer.toString();
132     }
133 }
134
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