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25 
26 package sun.security.action;
27 
28 import java.security.AccessController;
29 import java.security.PrivilegedAction;
30 
31 /**
32  * A convenience class for retrieving the string value of a system
33  * property as a privileged action.
34  *
35  * <p>An instance of this class can be used as the argument of
36  * <code>AccessController.doPrivileged</code>.
37  *
38  * <p>The following code retrieves the value of the system
39  * property named <code>"prop"</code> as a privileged action: <p>
40  *
41  * <pre>
42  * String s = java.security.AccessController.doPrivileged
43  *                      (new GetPropertyAction("prop"));
44  * </pre>
45  *
46  * @author Roland Schemers
47  * @see java.security.PrivilegedAction
48  * @see java.security.AccessController
49  * @since 1.2
50  */
51 
52 public class GetPropertyAction implements PrivilegedAction<String> {
53     private String theProp;
54     private String defaultVal;
55 
56     /**
57      * Constructor that takes the name of the system property whose
58      * string value needs to be determined.
59      *
60      * @param theProp the name of the system property.
61      */
GetPropertyAction(String theProp)62     public GetPropertyAction(String theProp) {
63         this.theProp = theProp;
64     }
65 
66     /**
67      * Constructor that takes the name of the system property and the default
68      * value of that property.
69      *
70      * @param theProp the name of the system property.
71      * @param defaulVal the default value.
72      */
GetPropertyAction(String theProp, String defaultVal)73     public GetPropertyAction(String theProp, String defaultVal) {
74         this.theProp = theProp;
75         this.defaultVal = defaultVal;
76     }
77 
78     /**
79      * Determines the string value of the system property whose
80      * name was specified in the constructor.
81      *
82      * @return the string value of the system property,
83      *         or the default value if there is no property with that key.
84      */
run()85     public String run() {
86         String value = System.getProperty(theProp);
87         return (value == null) ? defaultVal : value;
88     }
89 
90     /**
91      * Convenience method to get a property without going through doPrivileged
92      * if no security manager is present. This is unsafe for inclusion in a
93      * public API but allowable here since this class is by default restricted
94      * by the package.access security property.
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