1/*
2 * Copyright (C) 2008 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.content.pm;
18
19import android.content.ComponentName;
20import android.os.Parcel;
21import android.os.Parcelable;
22
23import java.lang.ref.SoftReference;
24import java.util.Arrays;
25
26/**
27 * Opaque, immutable representation of a signature associated with an
28 * application package.
29 */
30public class Signature implements Parcelable {
31    private final byte[] mSignature;
32    private int mHashCode;
33    private boolean mHaveHashCode;
34    private SoftReference<String> mStringRef;
35
36    /**
37     * Create Signature from an existing raw byte array.
38     */
39    public Signature(byte[] signature) {
40        mSignature = signature.clone();
41    }
42
43    /**
44     * Create Signature from a text representation previously returned by
45     * {@link #toChars} or {@link #toCharsString()}.
46     */
47    public Signature(String text) {
48        final int N = text.length()/2;
49        byte[] sig = new byte[N];
50        for (int i=0; i<N; i++) {
51            char c = text.charAt(i*2);
52            byte b = (byte)(
53                    (c >= 'a' ? (c - 'a' + 10) : (c - '0'))<<4);
54            c = text.charAt(i*2 + 1);
55            b |= (byte)(c >= 'a' ? (c - 'a' + 10) : (c - '0'));
56            sig[i] = b;
57        }
58        mSignature = sig;
59    }
60
61    /**
62     * Encode the Signature as ASCII text.
63     */
64    public char[] toChars() {
65        return toChars(null, null);
66    }
67
68    /**
69     * Encode the Signature as ASCII text in to an existing array.
70     *
71     * @param existingArray Existing char array or null.
72     * @param outLen Output parameter for the number of characters written in
73     * to the array.
74     * @return Returns either <var>existingArray</var> if it was large enough
75     * to hold the ASCII representation, or a newly created char[] array if
76     * needed.
77     */
78    public char[] toChars(char[] existingArray, int[] outLen) {
79        byte[] sig = mSignature;
80        final int N = sig.length;
81        final int N2 = N*2;
82        char[] text = existingArray == null || N2 > existingArray.length
83                ? new char[N2] : existingArray;
84        for (int j=0; j<N; j++) {
85            byte v = sig[j];
86            int d = (v>>4)&0xf;
87            text[j*2] = (char)(d >= 10 ? ('a' + d - 10) : ('0' + d));
88            d = v&0xf;
89            text[j*2+1] = (char)(d >= 10 ? ('a' + d - 10) : ('0' + d));
90        }
91        if (outLen != null) outLen[0] = N;
92        return text;
93    }
94
95    /**
96     * Return the result of {@link #toChars()} as a String.  This result is
97     * cached so future calls will return the same String.
98     */
99    public String toCharsString() {
100        String str = mStringRef == null ? null : mStringRef.get();
101        if (str != null) {
102            return str;
103        }
104        str = new String(toChars());
105        mStringRef = new SoftReference<String>(str);
106        return str;
107    }
108
109    /**
110     * @return the contents of this signature as a byte array.
111     */
112    public byte[] toByteArray() {
113        byte[] bytes = new byte[mSignature.length];
114        System.arraycopy(mSignature, 0, bytes, 0, mSignature.length);
115        return bytes;
116    }
117
118    @Override
119    public boolean equals(Object obj) {
120        try {
121            if (obj != null) {
122                Signature other = (Signature)obj;
123                return Arrays.equals(mSignature, other.mSignature);
124            }
125        } catch (ClassCastException e) {
126        }
127        return false;
128    }
129
130    @Override
131    public int hashCode() {
132        if (mHaveHashCode) {
133            return mHashCode;
134        }
135        mHashCode = Arrays.hashCode(mSignature);
136        mHaveHashCode = true;
137        return mHashCode;
138    }
139
140    public int describeContents() {
141        return 0;
142    }
143
144    public void writeToParcel(Parcel dest, int parcelableFlags) {
145        dest.writeByteArray(mSignature);
146    }
147
148    public static final Parcelable.Creator<Signature> CREATOR
149            = new Parcelable.Creator<Signature>() {
150        public Signature createFromParcel(Parcel source) {
151            return new Signature(source);
152        }
153
154        public Signature[] newArray(int size) {
155            return new Signature[size];
156        }
157    };
158
159    private Signature(Parcel source) {
160        mSignature = source.createByteArray();
161    }
162}
163