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      1 /*
      2  * Copyright (C) 2007 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package dalvik.system;
     18 
     19 /**
     20  * Provides a limited interface to the Dalvik VM stack. This class is mostly
     21  * used for implementing security checks.
     22  *
     23  * @hide
     24  */
     25 public final class VMStack {
     26     /**
     27      * Returns the defining class loader of the caller's caller.
     28      *
     29      * @return the requested class loader, or {@code null} if this is the
     30      *         bootstrap class loader.
     31      */
     32     native public static ClassLoader getCallingClassLoader();
     33 
     34     /**
     35      * Returns the class of the caller's caller's caller.
     36      *
     37      * @return the requested class, or {@code null}.
     38      */
     39     native public static Class<?> getStackClass2();
     40 
     41     /**
     42      * Creates an array of classes from the methods at the top of the stack.
     43      * We continue until we reach the bottom of the stack or exceed the
     44      * specified maximum depth.
     45      * <p>
     46      * The topmost stack frame (this method) and the one above that (the
     47      * caller) are excluded from the array.  Frames with java.lang.reflect
     48      * classes are skipped over.
     49      * <p>
     50      * The classes in the array are the defining classes of the methods.
     51      * <p>
     52      * This is similar to Harmony's VMStack.getClasses, except that this
     53      * implementation doesn't have a concept of "privileged" frames.
     54      *
     55      * @param maxDepth
     56      *      maximum number of classes to return, or -1 for all
     57      * @return an array with classes for the most-recent methods on the stack
     58      */
     59     native public static Class<?>[] getClasses(int maxDepth);
     60 
     61     /**
     62      * Retrieves the stack trace from the specified thread.
     63      *
     64      * @param t
     65      *      thread of interest
     66      * @return an array of stack trace elements, or null if the thread
     67      *      doesn't have a stack trace (e.g. because it exited)
     68      */
     69     native public static StackTraceElement[] getThreadStackTrace(Thread t);
     70 
     71     /**
     72      * Retrieves a partial stack trace from the specified thread into
     73      * the provided array.
     74      *
     75      * @param t
     76      *      thread of interest
     77      * @param stackTraceElements
     78      *      preallocated array for use when only the top of stack is
     79      *      desired. Unused elements will be filled with null values.
     80      * @return the number of elements filled
     81      */
     82     native public static int fillStackTraceElements(Thread t,
     83         StackTraceElement[] stackTraceElements);
     84 }
     85