001    /* Provider.java -- Security provider information
002       Copyright (C) 1998, 1999, 2000, 2002, 2006 Free Software Foundation, Inc.
003    
004    This file is part of GNU Classpath.
005    
006    GNU Classpath is free software; you can redistribute it and/or modify
007    it under the terms of the GNU General Public License as published by
008    the Free Software Foundation; either version 2, or (at your option)
009    any later version.
010    
011    GNU Classpath is distributed in the hope that it will be useful, but
012    WITHOUT ANY WARRANTY; without even the implied warranty of
013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014    General Public License for more details.
015    
016    You should have received a copy of the GNU General Public License
017    along with GNU Classpath; see the file COPYING.  If not, write to the
018    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019    02110-1301 USA.
020    
021    Linking this library statically or dynamically with other modules is
022    making a combined work based on this library.  Thus, the terms and
023    conditions of the GNU General Public License cover the whole
024    combination.
025    
026    As a special exception, the copyright holders of this library give you
027    permission to link this library with independent modules to produce an
028    executable, regardless of the license terms of these independent
029    modules, and to copy and distribute the resulting executable under
030    terms of your choice, provided that you also meet, for each linked
031    independent module, the terms and conditions of the license of that
032    module.  An independent module is a module which is not derived from
033    or based on this library.  If you modify this library, you may extend
034    this exception to your version of the library, but you are not
035    obligated to do so.  If you do not wish to do so, delete this
036    exception statement from your version. */
037    
038    package java.security;
039    
040    import java.io.Serializable;
041    import java.util.Properties;
042    
043    /**
044     * This class represents a Java security architecture service provider. The
045     * services provided by a such a provider can range from security algorithms to
046     * key generation.
047     * <p>
048     * Providers are installed by name and version number. See the static
049     * initializer of the {@link java.security.Security} class for the default
050     * security providers installed by this class library.
051     * 
052     * @author Aaron M. Renn (arenn@urbanophile.com)
053     */
054    public abstract class Provider
055        extends Properties
056        implements Serializable
057    {
058      private static final long serialVersionUID = -4298000515446427739L;
059    
060      /**
061       * This is a textual description of the provider
062       */
063      private String info;
064    
065      /**
066       * This is the name of the provider
067       */
068      private String name;
069    
070      /**
071       * This is the version number of the provider
072       */
073      private double version;
074    
075      /**
076       * This method initializes a new instance of <code>Provider</code> to have
077       * the specified name, version, and description information.
078       *
079       * @param name The name to assign to this <code>Provider</code>.
080       * @param version The version number for this <code>Provider</code>.
081       * @param info A textual description of this provider.
082       */
083      protected Provider(String name, double version, String info)
084      {
085        this.name = name;
086        this.version = version;
087        this.info = info;
088      }
089    
090      /**
091       * This method returns the name assigned to this <code>Provider</code>.
092       *
093       * @return The <code>Provider</code>'s name.
094       */
095      public String getName()
096      {
097        return (name);
098      }
099    
100      /**
101       * This method retunrs the version number of this <code>Provider</code>.
102       * 
103       * @return The <code>Provider</code>'s version number.
104       */
105      public double getVersion()
106      {
107        return (version);
108      }
109    
110      /**
111       * This method returns a textual description of the <code>Provider</code>.
112       *
113       * @return A description of the <code>Provider</code>.
114       */
115      public String getInfo()
116      {
117        return (info);
118      }
119    
120      /**
121       * Maps a key property to a designated value.
122       * <p>
123       * If there is an installed {@link SecurityManager} object in the underlying
124       * VM, its {@link SecurityManager#checkSecurityAccess(String)} method is
125       * called with the string <code>"putProviderProperty." + name</code>, where
126       * <code>name</code> is this provider's name. For the default implementation
127       * this translates into a {@link SecurityManager#checkPermission(Permission)}
128       * for a <code>SecurityPermission("putProviderProperty." + name)</code>.
129       * 
130       * @param key The property key.
131       * @param value The property value.
132       * @return The previous value of the specified property (<code>key</code>),
133       *         or <code>null</code> if it did not have one.
134       * @throws SecurityException If a security manager is installed and its
135       *           {@link SecurityManager#checkSecurityAccess(String)} method
136       *           disallows adding properties at run-time.
137       * @since Classpath 0.4+cvs, JDK 1.2
138       * @see java.lang.Object#equals(Object)
139       * @see java.util.Hashtable#get(Object)
140       */
141      public Object put(Object key, Object value)
142      {
143        SecurityManager sm = System.getSecurityManager();
144        if (sm != null)
145          sm.checkSecurityAccess("putProviderProperty." + this.name);
146        return super.put(toCanonicalKey(key), value);
147      }
148    
149      // overrides same in java.util.Hashtable
150      public Object get(Object key)
151      {
152        return super.get(toCanonicalKey(key));
153      }
154    
155      /**
156       * This method removes the specified key entry (and its associated value)
157       * from the property mapping collection.
158       * <p>
159       * If there is an installed {@link SecurityManager} object in the underlying
160       * VM, its {@link SecurityManager#checkSecurityAccess(String)} method is
161       * called with the string <code>"removeProviderProperty." + name</code>, where
162       * <code>name</code> is this provider's name. For the default implementation
163       * this translates into a {@link SecurityManager#checkPermission(Permission)}
164       * for a <code>SecurityPermission("removeProviderProperty." + name)</code>.
165       * 
166       * @param key The key to remove
167       * @return The previous value for this key, or <code>null</code> if no
168       * previous value.
169       */
170      public Object remove(Object key)
171      {
172        SecurityManager sm = System.getSecurityManager();
173        if (sm != null)
174          sm.checkSecurityAccess("removeProviderProperty." + this.name);
175        return super.remove(toCanonicalKey(key));
176      }
177    
178      /**
179       * This method clears the entire property collection such that it no longer
180       * contains the properties used to look up the services provided by
181       * this <code>Provider</code>.
182       * <p>
183       * If there is an installed {@link SecurityManager} object in the underlying
184       * VM, its {@link SecurityManager#checkSecurityAccess(String)} method is
185       * called with the string <code>"clearProviderProperties." + name</code>,
186       * where <code>name</code> is this provider's name. For the default
187       * implementation this translates into a
188       * {@link SecurityManager#checkPermission(Permission)} for a
189       * <code>SecurityPermission("clearProviderProperties." + name)</code>.
190       */
191      public void clear()
192      {
193        SecurityManager sm = System.getSecurityManager();
194        if (sm != null)
195          sm.checkSecurityAccess("clearProviderProperties." + this.name);
196        super.clear();
197      }
198    
199      /**
200       * This method returns a <code>String</code> representation of this
201       * object.  This will include the <code>Provider</code> name and
202       * version number.
203       *
204       * @return A <code>String</code> representation of this object.
205       */
206      public String toString()
207      {
208        return (getClass().getName() + ": name=" + getName() + " version=" +
209                version);
210      }
211    
212      private Object toCanonicalKey(Object key)
213      {
214        if (key.getClass().isAssignableFrom(String.class)) // is it ours?
215          return ((String) key).toUpperCase(); // use default locale
216        return key;
217      }
218    }