Initial revision

From-SVN: r102074

libjava/classpath/java/security/BasicPermission.java

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+/* BasicPermission.java -- implements a simple named permission
+   Copyright (C) 1998, 1999, 2002, 2003, 2004, 2005  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.io.Serializable;
+import java.util.Enumeration;
+import java.util.Hashtable;
+
+/**
+ * This class implements a simple model for named permissions without an
+ * associated action list.  That is, either the named permission is granted
+ * or it is not.
+ *
+ * <p>It also supports trailing wildcards to allow the easy granting of
+ * permissions in a hierarchical fashion.  (For example, the name "org.gnu.*"
+ * might grant all permissions under the "org.gnu" permissions hierarchy).
+ * The only valid wildcard character is a '*' which matches anything. It
+ * must be the rightmost element in the permission name and must follow a
+ * '.' or else the Permission name must consist of only a '*'. Any other
+ * occurrence of a '*' is not valid.
+ *
+ * <p>This class ignores the action list.  Subclasses can choose to implement
+ * actions on top of this class if desired.
+ *
+ * @author Aaron M. Renn (arenn@urbanophile.com)
+ * @author Eric Blake (ebb9@email.byu.edu)
+ * @see Permission
+ * @see Permissions
+ * @see PermissionCollection
+ * @see RuntimePermission
+ * @see SecurityPermission
+ * @see PropertyPermission
+ * @see AWTPermission
+ * @see NetPermission
+ * @see SecurityManager
+ * @since 1.1
+ * @status updated to 1.4
+ */
+public abstract class BasicPermission extends java.security.Permission
+  implements Serializable
+  // FIXME extends with fully qualified classname as workaround for gcj 3.3.
+{
+  /**
+   * Compatible with JDK 1.1+.
+   */
+  private static final long serialVersionUID = 6279438298436773498L;
+
+  /**
+   * Create a new instance with the specified permission name. If the
+   * name is empty an exception is thrown.
+   *
+   * @param name the name of this permission
+   * @throws NullPointerException if name is null
+   * @throws IllegalArgumentException if name is invalid
+   */
+  public BasicPermission(String name)
+  {
+    super(name);
+
+    // This routine used to check for illegal wildcards, but no such
+    // requirement exists in the specification and Sun's runtime
+    // doesn't appear to do it.
+
+    if ("".equals(name))
+      throw new IllegalArgumentException("Empty name");
+  }
+
+  /**
+   * Create a new instance with the specified permission name. If the name
+   * is empty, or contains an illegal wildcard character, an exception is
+   * thrown. The actions parameter is ignored.
+   *
+   * @param name the name of this permission
+   * @param actions ignored
+   * @throws NullPointerException if name is null
+   * @throws IllegalArgumentException if name is invalid
+   */
+  public BasicPermission(String name, String actions)
+  {
+    this(name);
+  }
+
+  /**
+   * This method tests to see if the specified permission is implied by this
+   * permission.  This will be true if the following conditions are met:<ul>
+   * <li>The specified object is an instance of the same class as this
+   * object.</li>
+   * <li>The name of the specified permission is implied by this permission's
+   * name based on wildcard matching. For example, "a.*" implies "a.b".</li>
+   * </ul>
+   *
+   * @param perm the <code>Permission</code> object to test against
+   * @return true if the specified permission is implied
+   */
+  public boolean implies(Permission perm)
+  {
+    if (! getClass().isInstance(perm))
+      return false;
+
+    String otherName = perm.getName();
+    String name = getName();
+
+    if (name.equals(otherName))
+      return true;
+
+    int last = name.length() - 1;
+    return name.charAt(last) == '*'
+      && otherName.startsWith(name.substring(0, last));
+  }
+
+  /**
+   * This method tests to see if this object is equal to the specified
+   * <code>Object</code>.  This will be true if and only if the specified
+   * object meets the following conditions:<ul>
+   * <li>It is an instance of the same class as this.</li>
+   * <li>It has the same name as this permission.</li>
+   * </ul>
+   *
+   * @param obj the <code>Object</code> to test for equality
+   * @return true if obj is semantically equal to this
+   */
+  public boolean equals(Object obj)
+  {
+    return getClass().isInstance(obj)
+      && getName().equals(((BasicPermission) obj).getName());
+  }
+
+  /**
+   * This method returns a hash code for this permission object.  The hash
+   * code returned is the value returned by calling the <code>hashCode</code>
+   * method on the <code>String</code> that is the name of this permission.
+   *
+   * @return a hash value for this object
+   */
+  public int hashCode()
+  {
+    return getName().hashCode();
+  }
+
+  /**
+   * This method returns a list of the actions associated with this
+   * permission.  This method always returns the empty string ("") since
+   * this class ignores actions.
+   *
+   * @return the action list
+   */
+  public String getActions()
+  {
+    return "";
+  }
+
+  /**
+   * This method returns an instance of <code>PermissionCollection</code>
+   * suitable for storing <code>BasicPermission</code> objects.  The
+   * collection returned can only store objects of the same type as this.
+   * Subclasses which use actions must override this method; but a class with
+   * no actions will work fine with this.
+   *
+   * @return a new empty <code>PermissionCollection</code> object
+   */
+  public PermissionCollection newPermissionCollection()
+  {
+    return new BasicPermissionCollection(getClass());
+  }
+
+  /**
+   * Implements AllPermission.newPermissionCollection, and obeys serialization
+   * of JDK.
+   *
+   * @author Eric Blake (ebb9@email.byu.edu)
+   */
+  private static final class BasicPermissionCollection extends PermissionCollection
+  {
+    /**
+     * Compatible with JDK 1.1+.
+     */
+    private static final long serialVersionUID = 739301742472979399L;
+
+    /**
+     * The permissions in the collection.
+     *
+     * @serial a hash mapping name to permissions, all of type permClass
+     */
+    private final Hashtable permissions = new Hashtable();
+
+    /**
+     * If "*" is in the collection.
+     *
+     * @serial true if a permission named "*" is in the collection
+     */
+    private boolean all_allowed;
+
+    /**
+     * The runtime class which all entries in the table must belong to.
+     *
+     * @serial the limiting subclass of this collection
+     */
+    private final Class permClass;
+
+    /**
+     * Construct a collection over the given runtime class.
+     *
+     * @param c the class
+     */
+    BasicPermissionCollection(Class c)
+    {
+      permClass = c;
+    }
+
+    /**
+     * Add a Permission. It must be of the same type as the permission which
+     * created this collection.
+     *
+     * @param perm the permission to add
+     * @throws IllegalArgumentException if perm is not the correct type
+     * @throws SecurityException if the collection is read-only
+     */
+    public void add(Permission perm)
+    {
+      if (isReadOnly())
+        throw new SecurityException("readonly");
+      if (! permClass.isInstance(perm))
+        throw new IllegalArgumentException("Expecting instance of " + permClass);
+      BasicPermission bp = (BasicPermission) perm;
+      String name = bp.getName();
+      if (name.equals("*"))
+        all_allowed = true;
+      permissions.put(name, bp);
+    }
+
+    /**
+     * Returns true if this collection implies the given permission.
+     *
+     * @param permission the permission to check
+     * @return true if it is implied by this
+     */
+    public boolean implies(Permission permission)
+    {
+      if (! permClass.isInstance(permission))
+        return false;
+      if (all_allowed)
+        return true;
+      BasicPermission toImply = (BasicPermission) permission;
+      String name = toImply.getName();
+      if (name.equals("*"))
+        return false;
+      int prefixLength = name.length();
+      if (name.endsWith("*"))
+        prefixLength -= 2;
+
+      while (true)
+        {
+          if (permissions.get(name) != null)
+            return true;
+          prefixLength = name.lastIndexOf('.', prefixLength);
+          if (prefixLength < 0)
+            return false;
+          name = name.substring(0, prefixLength + 1) + '*';
+        }
+    }
+
+    /**
+     * Enumerate over the collection.
+     *
+     * @return an enumeration of the collection contents
+     */
+    public Enumeration elements()
+    {
+      return permissions.elements();
+    }
+  } // class BasicPermissionCollection
+} // class BasicPermission