Initial revision

From-SVN: r102074

libjava/classpath/java/security/AccessControlContext.java

@@ -0,0 +1,176 @@
+/* AccessControlContext.java --- Access Control Context Class
+   Copyright (C) 1999, 2004 Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+package java.security;
+
+import java.util.HashSet;
+
+/**
+ * AccessControlContext makes system resource access decsion 
+ * based on permission rights.  
+ *
+ * It is used for a specific context and has only one method
+ * checkPermission. It is similar to AccessController except
+ * that it makes decsions based on the current context instead
+ * of the the current thread.
+ *
+ * It is created by call AccessController.getContext method.
+ *
+ * @author Mark Benvenuto
+ * @since 1.2
+ */
+public final class AccessControlContext
+{
+  private final ProtectionDomain[] protectionDomains;
+  private final DomainCombiner combiner;
+
+  /**
+   * Construct a new AccessControlContext with the specified
+   * ProtectionDomains. <code>context</code> must not be 
+   * null and duplicates will be removed.
+   *
+   * @param context The ProtectionDomains to use
+   */
+  public AccessControlContext(ProtectionDomain[] context)
+  {
+    HashSet domains = new HashSet (context.length);
+    for (int i = 0; i < context.length; i++)
+      domains.add (context[i]);
+    protectionDomains = (ProtectionDomain[])
+      domains.toArray (new ProtectionDomain[domains.size()]);
+    combiner = null;
+  }
+
+  /**
+   * Construct a new AccessControlContext with the specified
+   * ProtectionDomains and DomainCombiner
+   *
+   * @since 1.3
+   */
+  public AccessControlContext(AccessControlContext acc,
+			      DomainCombiner combiner)
+  {
+    // XXX check permission to call this.
+    AccessControlContext acc2 = AccessController.getContext();
+    protectionDomains = combiner.combine (acc2.protectionDomains,
+                                          acc.protectionDomains);
+    this.combiner = combiner;
+  }
+
+  AccessControlContext (ProtectionDomain[] domains, AccessControlContext acc,
+                        DomainCombiner combiner)
+  {
+    protectionDomains = combiner.combine (domains, acc.protectionDomains);
+    this.combiner = combiner;
+  }
+
+  /**
+   * Returns the Domain Combiner associated with the AccessControlContext
+   *
+   * @return the DomainCombiner
+   */
+  public DomainCombiner getDomainCombiner()
+  {
+    return combiner;
+  }
+
+  /**
+   * Determines whether or not the specific permission is granted
+   * depending on the context it is within. 
+   *
+   * @param perm a permission to check
+   *
+   * @throws AccessControlException if the permssion is not permitted
+   */
+  public void checkPermission(Permission perm) throws AccessControlException
+  {
+    if (protectionDomains.length == 0)
+      throw new AccessControlException ("permission not granted");
+    for (int i = 0; i < protectionDomains.length; i++)
+      if (!protectionDomains[i].implies(perm))
+        throw new AccessControlException ("permission not granted");
+  }
+
+  /**
+   * Checks if two AccessControlContexts are equal.
+   *
+   * It first checks if obj is an AccessControlContext class, and
+   * then checks if each ProtectionDomain matches.
+   *
+   * @param obj The object to compare this class to
+   *
+   * @return true if equal, false otherwise
+   */
+  public boolean equals(Object obj)
+  {
+    if (obj instanceof AccessControlContext)
+      {
+	AccessControlContext acc = (AccessControlContext) obj;
+
+	if (acc.protectionDomains.length != protectionDomains.length)
+	  return false;
+
+        int i, j;
+        for (i = 0; i < protectionDomains.length; i++)
+          {
+            for (j = 0; j < acc.protectionDomains.length; j++)
+              {
+                if (acc.protectionDomains[j].equals (protectionDomains[i]))
+                  break;
+              }
+            if (j == acc.protectionDomains.length)
+              return false;
+          }
+        return true;
+      }
+    return false;
+  }
+
+  /**
+   * Computes a hash code of this class
+   *
+   * @return a hash code representing this class
+   */
+  public int hashCode()
+  {
+    int h = 0;
+    for (int i = 0; i < protectionDomains.length; i++)
+      h ^= protectionDomains[i].hashCode();
+
+    return h;
+  }
+}