1 /*
2  * Copyright (C) 2017 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 android.os;
18 
19 import android.annotation.SystemApi;
20 
21 import java.util.Arrays;
22 import java.util.Collection;
23 import java.util.Iterator;
24 import java.util.List;
25 import java.util.Map;
26 import java.util.Objects;
27 import java.util.stream.IntStream;
28 
29 /** @hide */
30 @SystemApi
31 public class HidlSupport {
32     /**
33      * Similar to Objects.deepEquals, but also take care of lists.
34      * Two objects of HIDL types are considered equal if:
35      * 1. Both null
36      * 2. Both non-null, and of the same class, and:
37      * 2.1 Both are primitive arrays / enum arrays, elements are equal using == check
38      * 2.2 Both are object arrays, elements are checked recursively
39      * 2.3 Both are Lists, elements are checked recursively
40      * 2.4 (If both are collections other than lists or maps, throw an error)
41      * 2.5 lft.equals(rgt) returns true
42      * @hide
43      */
44     @SystemApi
deepEquals(Object lft, Object rgt)45     public static boolean deepEquals(Object lft, Object rgt) {
46         if (lft == rgt) {
47             return true;
48         }
49         if (lft == null || rgt == null) {
50             return false;
51         }
52 
53         Class<?> lftClazz = lft.getClass();
54         Class<?> rgtClazz = rgt.getClass();
55         if (lftClazz != rgtClazz) {
56             return false;
57         }
58 
59         if (lftClazz.isArray()) {
60             Class<?> lftElementType = lftClazz.getComponentType();
61             if (lftElementType != rgtClazz.getComponentType()) {
62                 return false;
63             }
64 
65             if (lftElementType.isPrimitive()) {
66                 return Objects.deepEquals(lft, rgt);
67             }
68 
69             Object[] lftArray = (Object[])lft;
70             Object[] rgtArray = (Object[])rgt;
71             return (lftArray.length == rgtArray.length) &&
72                    IntStream.range(0, lftArray.length).allMatch(
73                         i -> deepEquals(lftArray[i], rgtArray[i]));
74         }
75 
76         if (lft instanceof List<?>) {
77             List<Object> lftList = (List<Object>)lft;
78             List<Object> rgtList = (List<Object>)rgt;
79             if (lftList.size() != rgtList.size()) {
80                 return false;
81             }
82 
83             Iterator<Object> lftIter = lftList.iterator();
84             return rgtList.stream()
85                     .allMatch(rgtElement -> deepEquals(lftIter.next(), rgtElement));
86         }
87 
88         throwErrorIfUnsupportedType(lft);
89 
90         return lft.equals(rgt);
91     }
92 
93     /**
94      * Class which can be used to fetch an object out of a lambda. Fetching an object
95      * out of a local scope with HIDL is a common operation (although usually it can
96      * and should be avoided).
97      *
98      * @param <E> Inner object type.
99      * @hide
100      */
101     public static final class Mutable<E> {
102         public E value;
103 
Mutable()104         public Mutable() {
105             value = null;
106         }
107 
Mutable(E value)108         public Mutable(E value) {
109             this.value = value;
110         }
111     }
112 
113     /**
114      * Similar to Arrays.deepHashCode, but also take care of lists.
115      * @hide
116      */
117     @SystemApi
deepHashCode(Object o)118     public static int deepHashCode(Object o) {
119         if (o == null) {
120             return 0;
121         }
122         Class<?> clazz = o.getClass();
123         if (clazz.isArray()) {
124             Class<?> elementType = clazz.getComponentType();
125             if (elementType.isPrimitive()) {
126                 return primitiveArrayHashCode(o);
127             }
128             return Arrays.hashCode(Arrays.stream((Object[])o)
129                     .mapToInt(element -> deepHashCode(element))
130                     .toArray());
131         }
132 
133         if (o instanceof List<?>) {
134             return Arrays.hashCode(((List<Object>)o).stream()
135                     .mapToInt(element -> deepHashCode(element))
136                     .toArray());
137         }
138 
139         throwErrorIfUnsupportedType(o);
140 
141         return o.hashCode();
142     }
143 
144     /** @hide */
throwErrorIfUnsupportedType(Object o)145     private static void throwErrorIfUnsupportedType(Object o) {
146         if (o instanceof Collection<?> && !(o instanceof List<?>)) {
147             throw new UnsupportedOperationException(
148                     "Cannot check equality on collections other than lists: " +
149                     o.getClass().getName());
150         }
151 
152         if (o instanceof Map<?, ?>) {
153             throw new UnsupportedOperationException(
154                     "Cannot check equality on maps");
155         }
156     }
157 
158     /** @hide */
primitiveArrayHashCode(Object o)159     private static int primitiveArrayHashCode(Object o) {
160         Class<?> elementType = o.getClass().getComponentType();
161         if (elementType == boolean.class) {
162             return Arrays.hashCode(((boolean[])o));
163         }
164         if (elementType == byte.class) {
165             return Arrays.hashCode(((byte[])o));
166         }
167         if (elementType == char.class) {
168             return Arrays.hashCode(((char[])o));
169         }
170         if (elementType == double.class) {
171             return Arrays.hashCode(((double[])o));
172         }
173         if (elementType == float.class) {
174             return Arrays.hashCode(((float[])o));
175         }
176         if (elementType == int.class) {
177             return Arrays.hashCode(((int[])o));
178         }
179         if (elementType == long.class) {
180             return Arrays.hashCode(((long[])o));
181         }
182         if (elementType == short.class) {
183             return Arrays.hashCode(((short[])o));
184         }
185         // Should not reach here.
186         throw new UnsupportedOperationException();
187     }
188 
189     /**
190      * Test that two interfaces are equal. This is the Java equivalent to C++
191      * interfacesEqual function.
192      * This essentially calls .equals on the internal binder objects (via Binder()).
193      * - If both interfaces are proxies, asBinder() returns a {@link HwRemoteBinder}
194      *   object, and they are compared in {@link HwRemoteBinder#equals}.
195      * - If both interfaces are stubs, asBinder() returns the object itself. By default,
196      *   auto-generated IFoo.Stub does not override equals(), but an implementation can
197      *   optionally override it, and {@code interfacesEqual} will use it here.
198      * @hide
199      */
200     @SystemApi
interfacesEqual(IHwInterface lft, Object rgt)201     public static boolean interfacesEqual(IHwInterface lft, Object rgt) {
202         if (lft == rgt) {
203             return true;
204         }
205         if (lft == null || rgt == null) {
206             return false;
207         }
208         if (!(rgt instanceof IHwInterface)) {
209             return false;
210         }
211         return Objects.equals(lft.asBinder(), ((IHwInterface) rgt).asBinder());
212     }
213 
214     /**
215      * Return PID of process only if on a non-user build. For debugging purposes.
216      * @hide
217      */
218     @SystemApi
getPidIfSharable()219     public static native int getPidIfSharable();
220 
221     /** @hide */
HidlSupport()222     public HidlSupport() {}
223 }
224