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
17package 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 */
25public 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