Licenses.java revision 95961816a768da387f0b5523cf4363ace2044089 
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
17package com.android.tv.license;
18
19import android.content.Context;
20import android.support.annotation.RawRes;
21import com.android.tv.R;
22import com.android.tv.common.SoftPreconditions;
23import java.io.ByteArrayOutputStream;
24import java.io.IOException;
25import java.io.InputStream;
26import java.io.UnsupportedEncodingException;
27import java.util.ArrayList;
28import java.util.Collections;
29
30/**
31 * A helper for extracting licenses embedded using
32 * third_party_licenses.build:third_party_licenses().
33 */
34public final class Licenses {
35
36    public static final String TAG = "Licenses";
37
38    public static boolean hasLicenses(Context context) {
39        return !getTextFromResource(
40                        context.getApplicationContext(), R.raw.third_party_license_metadata, 0, -1)
41                .isEmpty();
42    }
43
44    /** Return the licenses bundled into this app. */
45    public static ArrayList<License> getLicenses(Context context) {
46        return getLicenseListFromMetadata(
47                getTextFromResource(
48                        context.getApplicationContext(), R.raw.third_party_license_metadata, 0, -1),
49                "");
50    }
51
52    /**
53     * Returns a list of {@link License}s parsed from a license metadata file.
54     *
55     * @param metadata a {@code String} containing the contents of a license metadata file.
56     * @param filePath a path to a package archive with licenses or empty string for the app package
57     */
58    private static ArrayList<License> getLicenseListFromMetadata(String metadata, String filePath) {
59        String[] entries = metadata.split("\n");
60        ArrayList<License> licenses = new ArrayList<License>(entries.length);
61        for (String entry : entries) {
62            int delimiter = entry.indexOf(' ');
63            String[] licenseLocation = entry.substring(0, delimiter).split(":");
64            SoftPreconditions.checkState(
65                    licenseLocation.length == 2 && delimiter > 0,
66                    TAG,
67                    "Invalid license meta-data line:\n" + entry);
68            long licenseOffset = Long.parseLong(licenseLocation[0]);
69            int licenseLength = Integer.parseInt(licenseLocation[1]);
70            licenses.add(
71                    License.create(
72                            entry.substring(delimiter + 1),
73                            licenseOffset,
74                            licenseLength,
75                            filePath));
76        }
77        Collections.sort(licenses);
78        return licenses;
79    }
80
81    /** Return the text of a bundled license file. */
82    public static String getLicenseText(Context context, License license) {
83        long offset = license.getLicenseOffset();
84        int length = license.getLicenseLength();
85        return getTextFromResource(context, R.raw.third_party_licenses, offset, length);
86    }
87
88    private static String getTextFromResource(
89            Context context, @RawRes int resourcesIdentifier, long offset, int length) {
90        InputStream stream =
91                context.getApplicationContext().getResources().openRawResource(resourcesIdentifier);
92        return getTextFromInputStream(stream, offset, length);
93    }
94
95    private static String getTextFromInputStream(InputStream stream, long offset, int length) {
96        byte[] buffer = new byte[1024];
97        ByteArrayOutputStream textArray = new ByteArrayOutputStream();
98
99        try {
100            stream.skip(offset);
101            int bytesRemaining = length > 0 ? length : Integer.MAX_VALUE;
102            int bytes = 0;
103
104            while (bytesRemaining > 0
105                    && (bytes = stream.read(buffer, 0, Math.min(bytesRemaining, buffer.length)))
106                            != -1) {
107                textArray.write(buffer, 0, bytes);
108                bytesRemaining -= bytes;
109            }
110            stream.close();
111        } catch (IOException e) {
112            throw new RuntimeException("Failed to read license or metadata text.", e);
113        }
114        try {
115            return textArray.toString("UTF-8");
116        } catch (UnsupportedEncodingException e) {
117            throw new RuntimeException(
118                    "Unsupported encoding UTF8. This should always be supported.", e);
119        }
120    }
121}
122