1 /*
2  * Copyright (c) 1998, 2004, 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
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7  * published by the Free Software Foundation.  Oracle designates this
8  * particular file as subject to the "Classpath" exception as provided
9  * by Oracle in the LICENSE file that accompanied this code.
10  *
11  * This code is distributed in the hope that it will be useful, but WITHOUT
12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14  * version 2 for more details (a copy is included in the LICENSE file that
15  * accompanied this code).
16  *
17  * You should have received a copy of the GNU General Public License version
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19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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24  */
25 
26 package sun.security.util;
27 
28 import java.net.URI;
29 import java.net.URISyntaxException;
30 import java.security.GeneralSecurityException;
31 
32 /**
33  * A utility class to expand properties embedded in a string.
34  * Strings of the form ${some.property.name} are expanded to
35  * be the value of the property. Also, the special ${/} property
36  * is expanded to be the same as file.separator. If a property
37  * is not set, a GeneralSecurityException will be thrown.
38  *
39  * @author Roland Schemers
40  */
41 public class PropertyExpander {
42 
43 
44     public static class ExpandException extends GeneralSecurityException {
45 
46         private static final long serialVersionUID = -7941948581406161702L;
47 
ExpandException(String msg)48         public ExpandException(String msg) {
49             super(msg);
50         }
51     }
52 
expand(String value)53     public static String expand(String value)
54         throws ExpandException
55     {
56         return expand(value, false);
57     }
58 
expand(String value, boolean encodeURL)59      public static String expand(String value, boolean encodeURL)
60          throws ExpandException
61      {
62         if (value == null)
63             return null;
64 
65         int p = value.indexOf("${", 0);
66 
67         // no special characters
68         if (p == -1) return value;
69 
70         StringBuffer sb = new StringBuffer(value.length());
71         int max = value.length();
72         int i = 0;  // index of last character we copied
73 
74     scanner:
75         while (p < max) {
76             if (p > i) {
77                 // copy in anything before the special stuff
78                 sb.append(value.substring(i, p));
79                 i = p;
80             }
81             int pe = p+2;
82 
83             // do not expand ${{ ... }}
84             if (pe < max && value.charAt(pe) == '{') {
85                 pe = value.indexOf("}}", pe);
86                 if (pe == -1 || pe+2 == max) {
87                     // append remaining chars
88                     sb.append(value.substring(p));
89                     break scanner;
90                 } else {
91                     // append as normal text
92                     pe++;
93                     sb.append(value.substring(p, pe+1));
94                 }
95             } else {
96                 while ((pe < max) && (value.charAt(pe) != '}')) {
97                     pe++;
98                 }
99                 if (pe == max) {
100                     // no matching '}' found, just add in as normal text
101                     sb.append(value.substring(p, pe));
102                     break scanner;
103                 }
104                 String prop = value.substring(p+2, pe);
105                 if (prop.equals("/")) {
106                     sb.append(java.io.File.separatorChar);
107                 } else {
108                     String val = System.getProperty(prop);
109                     if (val != null) {
110                         if (encodeURL) {
111                             // encode 'val' unless it's an absolute URI
112                             // at the beginning of the string buffer
113                             try {
114                                 if (sb.length() > 0 ||
115                                     !(new URI(val)).isAbsolute()) {
116                                     val = sun.net.www.ParseUtil.encodePath(val);
117                                 }
118                             } catch (URISyntaxException use) {
119                                 val = sun.net.www.ParseUtil.encodePath(val);
120                             }
121                         }
122                         sb.append(val);
123                     } else {
124                         throw new ExpandException(
125                                              "unable to expand property " +
126                                              prop);
127                     }
128                 }
129             }
130             i = pe+1;
131             p = value.indexOf("${", i);
132             if (p == -1) {
133                 // no more to expand. copy in any extra
134                 if (i < max) {
135                     sb.append(value.substring(i, max));
136                 }
137                 // break out of loop
138                 break scanner;
139             }
140         }
141         return sb.toString();
142     }
143 }
144