Initial revision

From-SVN: r102075
2026-06-30 07:15:51 +00:00 · 2005-07-16 00:31:27 +00:00
parent f911ba985a
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+/* VMStackWalker.java -- Reference implementation of VM hooks for stack access
+   Copyright (C) 2005 Free Software Foundation
+
+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 gnu.classpath;
+
+/**
+ * This class provides access to the classes on the Java stack
+ * for reflection and security purposes.
+ *
+ * <p>
+ * This class is only available to privileged code (i.e., code loaded
+ * by the bootstrap loader).
+ *
+ * @author John Keiser
+ * @author Eric Blake <ebb9@email.byu.edu>
+ * @author Archie Cobbs
+ */
+public final class VMStackWalker
+{
+  /**
+   * Get a list of all the classes currently executing methods on the
+   * Java stack. <code>getClassContext()[0]</code> is the class associated
+   * with the currently executing method, i.e., the method that called
+   * <code>VMStackWalker.getClassContext()</code> (possibly through
+   * reflection). So you may need to pop off these stack frames from
+   * the top of the stack:
+   * <ul>
+   * <li><code>VMStackWalker.getClassContext()</code>
+   * <li><code>Method.invoke()</code>
+   * </ul>
+   *
+   * @return an array of the declaring classes of each stack frame
+   */
+  public static native Class[] getClassContext();
+
+  /**
+   * Get the class associated with the method invoking the method
+   * invoking this method, or <code>null</code> if the stack is not
+   * that deep (e.g., invoked via JNI invocation API). This method
+   * is an optimization for the expression <code>getClassContext()[1]</code>
+   * and should return the same result.
+   *
+   * <p>
+   * VM implementers are encouraged to provide a more efficient
+   * version of this method.
+   */
+  public static Class getCallingClass()
+  {
+    Class[] ctx = getClassContext();
+    if (ctx.length < 3)
+      return null;
+    return ctx[2];
+  }
+
+  /**
+   * Get the class loader associated with the Class returned by
+   * <code>getCallingClass()</code>, or <code>null</code> if no
+   * such class exists or it is the boot loader. This method is an optimization
+   * for the expression <code>getClassContext()[1].getClassLoader()</code>
+   * and should return the same result.
+   *
+   * <p>
+   * VM implementers are encouraged to provide a more efficient
+   * version of this method.
+   */
+  public static ClassLoader getCallingClassLoader()
+  {
+    Class[] ctx = getClassContext();
+    if (ctx.length < 3)
+      return null;
+    return ctx[2].getClassLoader();
+  }
+}
+