Initial revision

From-SVN: r102074

libjava/classpath/java/security/SecureClassLoader.java

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+/* SecureClassLoader.java --- A Secure Class Loader
+   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;
+
+/**
+ * A Secure Class Loader for loading classes with additional 
+ * support for specifying code source and permissions when
+ * they are retrieved by the system policy handler.
+ *
+ * @since 1.2
+ *
+ * @author Mark Benvenuto
+ */
+public class SecureClassLoader extends ClassLoader
+{
+  java.util.WeakHashMap protectionDomainCache = new java.util.WeakHashMap();
+
+  protected SecureClassLoader(ClassLoader parent)
+  {
+    super(parent);
+    SecurityManager sm = System.getSecurityManager();
+    if(sm != null)
+      sm.checkCreateClassLoader();
+  }
+
+  protected SecureClassLoader()
+  {
+    SecurityManager sm = System.getSecurityManager();
+    if(sm != null)
+      sm.checkCreateClassLoader();
+  }
+
+  /** 
+   * Creates a class using an array of bytes and a 
+   * CodeSource.
+   *
+   * @param name the name to give the class.  null if unknown.
+   * @param b the data representing the classfile, in classfile format.
+   * @param off the offset into the data where the classfile starts.
+   * @param len the length of the classfile data in the array.
+   * @param cs the CodeSource for the class or null when unknown.
+   *
+   * @return the class that was defined and optional CodeSource.
+   *
+   * @exception ClassFormatError if the byte array is not in proper classfile format.
+   */
+  protected final Class defineClass(String name, byte[] b, int off, int len,
+				    CodeSource cs)
+  {
+    if (cs != null)
+      {
+	ProtectionDomain protectionDomain;
+	  
+	synchronized (protectionDomainCache)
+	  {
+	    protectionDomain = (ProtectionDomain)protectionDomainCache.get(cs);
+	  }
+
+	if (protectionDomain == null)
+	  {
+	    protectionDomain 
+	      = new ProtectionDomain(cs, getPermissions(cs), this, null);
+	    synchronized (protectionDomainCache)
+	      {
+		ProtectionDomain domain 
+		  = (ProtectionDomain)protectionDomainCache.get(cs);
+		if (domain == null)
+		  protectionDomainCache.put(cs, protectionDomain);
+		else
+		  protectionDomain = domain;
+	      }
+	  }
+	return super.defineClass(name, b, off, len, protectionDomain);
+      } 
+    else
+      return super.defineClass(name, b, off, len);
+  }
+
+  /**
+   * Returns a PermissionCollection for the specified CodeSource.
+   * The default implementation invokes 
+   * java.security.Policy.getPermissions.
+   *
+   * This method is called by defineClass that takes a CodeSource
+   * arguement to build a proper ProtectionDomain for the class
+   * being defined.
+   */
+  protected PermissionCollection getPermissions(CodeSource cs)
+  {
+    Policy policy = Policy.getCurrentPolicy();
+    return policy.getPermissions(cs);
+  }
+}