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25 
26 package sun.security.action;
27 
28 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30 import java.util.Properties;
31 
32 /**
33  * A convenience class for retrieving the string value of a system
34  * property as a privileged action.
35  *
36  * <p>An instance of this class can be used as the argument of
37  * <code>AccessController.doPrivileged</code>.
38  *
39  * <p>The following code retrieves the value of the system
40  * property named <code>"prop"</code> as a privileged action:
41  *
42  * <pre>
43  * String s = java.security.AccessController.doPrivileged
44  *                      (new GetPropertyAction("prop"));
45  * </pre>
46  *
47  * @author Roland Schemers
48  * @see java.security.PrivilegedAction
49  * @see java.security.AccessController
50  * @since 1.2
51  */
52 
53 public class GetPropertyAction implements PrivilegedAction<String> {
54     private String theProp;
55     private String defaultVal;
56 
57     /**
58      * Constructor that takes the name of the system property whose
59      * string value needs to be determined.
60      *
61      * @param theProp the name of the system property.
62      */
GetPropertyAction(String theProp)63     public GetPropertyAction(String theProp) {
64         this.theProp = theProp;
65     }
66 
67     /**
68      * Constructor that takes the name of the system property and the default
69      * value of that property.
70      *
71      * @param theProp the name of the system property.
72      * @param defaultVal the default value.
73      */
GetPropertyAction(String theProp, String defaultVal)74     public GetPropertyAction(String theProp, String defaultVal) {
75         this.theProp = theProp;
76         this.defaultVal = defaultVal;
77     }
78 
79     /**
80      * Determines the string value of the system property whose
81      * name was specified in the constructor.
82      *
83      * @return the string value of the system property,
84      *         or the default value if there is no property with that key.
85      */
run()86     public String run() {
87         String value = System.getProperty(theProp);
88         return (value == null) ? defaultVal : value;
89     }
90 
91     /**
92      * Convenience method to get a property without going through doPrivileged
93      * if no security manager is present. This is unsafe for inclusion in a
94      * public API but allowable here since this class is now encapsulated.
95      *
96      * Note that this method performs a privileged action using caller-provided
97      * inputs. The caller of this method should take care to ensure that the
98      * inputs are not tainted and the returned property is not made accessible
99      * to untrusted code if it contains sensitive information.
100      *
101      * @param theProp the name of the system property.
102      */
privilegedGetProperty(String theProp)103     public static String privilegedGetProperty(String theProp) {
104         if (System.getSecurityManager() == null) {
105             return System.getProperty(theProp);
106         } else {
107             return AccessController.doPrivileged(
108                     new GetPropertyAction(theProp));
109         }
110     }
111 
112     /**
113      * Convenience method to get a property without going through doPrivileged
114      * if no security manager is present. This is unsafe for inclusion in a
115      * public API but allowable here since this class is now encapsulated.
116      *
117      * Note that this method performs a privileged action using caller-provided
118      * inputs. The caller of this method should take care to ensure that the
119      * inputs are not tainted and the returned property is not made accessible
120      * to untrusted code if it contains sensitive information.
121      *
122      * @param theProp the name of the system property.
123      * @param defaultVal the default value.
124      */
privilegedGetProperty(String theProp, String defaultVal)125     public static String privilegedGetProperty(String theProp,
126             String defaultVal) {
127         if (System.getSecurityManager() == null) {
128             return System.getProperty(theProp, defaultVal);
129         } else {
130             return AccessController.doPrivileged(
131                     new GetPropertyAction(theProp, defaultVal));
132         }
133     }
134 
135     /**
136      * Convenience method to call <code>System.getProperties</code> without
137      * having to go through doPrivileged if no security manager is present.
138      * This is unsafe for inclusion in a public API but allowable here since
139      * this class is now encapsulated.
140      *
141      * Note that this method performs a privileged action, and callers of
142      * this method should take care to ensure that the returned properties
143      * are not made accessible to untrusted code since it may contain
144      * sensitive information.
145      */
privilegedGetProperties()146     public static Properties privilegedGetProperties() {
147         if (System.getSecurityManager() == null) {
148             return System.getProperties();
149         } else {
150             return AccessController.doPrivileged(
151                     new PrivilegedAction<Properties>() {
152                         public Properties run() {
153                             return System.getProperties();
154                         }
155                     }
156             );
157         }
158     }
159 }
160