1/*
2 * Copyright (C) 2012 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.annotation.SystemApi;
20import android.os.Parcel;
21import android.os.Parcelable;
22import android.util.Slog;
23
24import java.io.BufferedInputStream;
25import java.io.IOException;
26import java.io.InputStream;
27import java.security.DigestInputStream;
28import java.security.MessageDigest;
29import java.security.NoSuchAlgorithmException;
30import java.util.Arrays;
31
32import libcore.io.IoUtils;
33
34/**
35 * Represents the manifest digest for a package. This is suitable for comparison
36 * of two packages to know whether the manifests are identical.
37 *
38 * @hide
39 */
40@SystemApi
41public class ManifestDigest implements Parcelable {
42    private static final String TAG = "ManifestDigest";
43
44    /** The digest of the manifest in our preferred order. */
45    private final byte[] mDigest;
46
47    /** What we print out first when toString() is called. */
48    private static final String TO_STRING_PREFIX = "ManifestDigest {mDigest=";
49
50    /** Digest algorithm to use. */
51    private static final String DIGEST_ALGORITHM = "SHA-256";
52
53    ManifestDigest(byte[] digest) {
54        mDigest = digest;
55    }
56
57    private ManifestDigest(Parcel source) {
58        mDigest = source.createByteArray();
59    }
60
61    static ManifestDigest fromInputStream(InputStream fileIs) {
62        if (fileIs == null) {
63            return null;
64        }
65
66        final MessageDigest md;
67        try {
68            md = MessageDigest.getInstance(DIGEST_ALGORITHM);
69        } catch (NoSuchAlgorithmException e) {
70            throw new RuntimeException(DIGEST_ALGORITHM + " must be available", e);
71        }
72
73        final DigestInputStream dis = new DigestInputStream(new BufferedInputStream(fileIs), md);
74        try {
75            byte[] readBuffer = new byte[8192];
76            while (dis.read(readBuffer, 0, readBuffer.length) != -1) {
77                // not using
78            }
79        } catch (IOException e) {
80            Slog.w(TAG, "Could not read manifest");
81            return null;
82        } finally {
83            IoUtils.closeQuietly(dis);
84        }
85
86        final byte[] digest = md.digest();
87        return new ManifestDigest(digest);
88    }
89
90    @Override
91    public int describeContents() {
92        return 0;
93    }
94
95    @Override
96    public boolean equals(Object o) {
97        if (!(o instanceof ManifestDigest)) {
98            return false;
99        }
100
101        final ManifestDigest other = (ManifestDigest) o;
102
103        return this == other || Arrays.equals(mDigest, other.mDigest);
104    }
105
106    @Override
107    public int hashCode() {
108        return Arrays.hashCode(mDigest);
109    }
110
111    @Override
112    public String toString() {
113        final StringBuilder sb = new StringBuilder(TO_STRING_PREFIX.length()
114                + (mDigest.length * 3) + 1);
115
116        sb.append(TO_STRING_PREFIX);
117
118        final int N = mDigest.length;
119        for (int i = 0; i < N; i++) {
120            final byte b = mDigest[i];
121            IntegralToString.appendByteAsHex(sb, b, false);
122            sb.append(',');
123        }
124        sb.append('}');
125
126        return sb.toString();
127    }
128
129    @Override
130    public void writeToParcel(Parcel dest, int flags) {
131        dest.writeByteArray(mDigest);
132    }
133
134    public static final Parcelable.Creator<ManifestDigest> CREATOR
135            = new Parcelable.Creator<ManifestDigest>() {
136        public ManifestDigest createFromParcel(Parcel source) {
137            return new ManifestDigest(source);
138        }
139
140        public ManifestDigest[] newArray(int size) {
141            return new ManifestDigest[size];
142        }
143    };
144
145}