1/*
2 * Copyright (C) 2015 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 android.security.keystore;
18
19import libcore.util.EmptyArray;
20
21/**
22 * @hide
23 */
24public abstract class ArrayUtils {
25    private ArrayUtils() {}
26
27    public static String[] nullToEmpty(String[] array) {
28        return (array != null) ? array : EmptyArray.STRING;
29    }
30
31    public static String[] cloneIfNotEmpty(String[] array) {
32        return ((array != null) && (array.length > 0)) ? array.clone() : array;
33    }
34
35    public static byte[] cloneIfNotEmpty(byte[] array) {
36        return ((array != null) && (array.length > 0)) ? array.clone() : array;
37    }
38
39    public static byte[] concat(byte[] arr1, byte[] arr2) {
40        return concat(arr1, 0, (arr1 != null) ? arr1.length : 0,
41                arr2, 0, (arr2 != null) ? arr2.length : 0);
42    }
43
44    public static byte[] concat(byte[] arr1, int offset1, int len1, byte[] arr2, int offset2,
45            int len2) {
46        if (len1 == 0) {
47            return subarray(arr2, offset2, len2);
48        } else if (len2 == 0) {
49            return subarray(arr1, offset1, len1);
50        } else {
51            byte[] result = new byte[len1 + len2];
52            System.arraycopy(arr1, offset1, result, 0, len1);
53            System.arraycopy(arr2, offset2, result, len1, len2);
54            return result;
55        }
56    }
57
58    public static byte[] subarray(byte[] arr, int offset, int len) {
59        if (len == 0) {
60            return EmptyArray.BYTE;
61        }
62        if ((offset == 0) && (len == arr.length)) {
63            return arr;
64        }
65        byte[] result = new byte[len];
66        System.arraycopy(arr, offset, result, 0, len);
67        return result;
68    }
69
70    public static int[] concat(int[] arr1, int[] arr2) {
71        if ((arr1 == null) || (arr1.length == 0)) {
72            return arr2;
73        } else if ((arr2 == null) || (arr2.length == 0)) {
74            return arr1;
75        } else {
76            int[] result = new int[arr1.length + arr2.length];
77            System.arraycopy(arr1, 0, result, 0, arr1.length);
78            System.arraycopy(arr2, 0, result, arr1.length, arr2.length);
79            return result;
80        }
81    }
82}
83