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 package com.android.car.pm;
17 
18 import android.content.Context;
19 import android.content.pm.ApplicationInfo;
20 import android.content.pm.PackageManager;
21 import android.content.pm.PackageManager.NameNotFoundException;
22 import android.content.res.Resources;
23 import android.content.res.XmlResourceParser;
24 import android.util.Log;
25 
26 import com.android.car.CarLog;
27 
28 import java.io.IOException;
29 import java.util.LinkedList;
30 
31 import org.xmlpull.v1.XmlPullParser;
32 import org.xmlpull.v1.XmlPullParserException;
33 
34 /**
35  * Read meta data containing car application info.
36  */
37 public class CarAppMetadataReader {
38     /** Name of the meta-data attribute for the automotive application XML resource */
39     private static final String METADATA_ATTRIBUTE = "android.car.application";
40     /** Name of the tag to declare automotive usage */
41     private static final String USES_TAG = "uses";
42     /** Name of the attribute to name the usage type */
43     private static final String NAME_ATTRIBUTE = "name";
44 
45     private static final String NAME_ATTR_TYPE_SERVICE = "service";
46     private static final String NAME_ATTR_TYPE_ACTIVITY = "activity";
47 
48     private static final String CLASS_ATTRIBUTE = "class";
49 
parseMetadata(Context context, String packageName)50     public static CarAppMetadataInfo parseMetadata(Context context, String packageName) {
51         int metadataId = 0;
52         Resources resources = null;
53         try {
54             metadataId = getMetadataId(context, packageName);
55             if (metadataId == 0) {
56                 return null;
57             }
58             PackageManager pm = context.getPackageManager();
59             resources = pm.getResourcesForApplication(packageName);
60         } catch (NameNotFoundException e) {
61             Log.w(CarLog.TAG_PACKAGE, "Cannot read mta data, package:" + packageName, e);
62             return null;
63         }
64 
65         // Try to open the XML resource
66         XmlResourceParser parser = null;
67         try {
68             parser = resources.getXml(metadataId);
69         } catch (Resources.NotFoundException e) {
70             Log.w(CarLog.TAG_PACKAGE, "Resource not found [" + packageName + "]");
71             return null;
72         }
73 
74         boolean useService = false;
75         boolean useAllActivities = false;
76         LinkedList<String> activities = null;
77         // Now, read the XML and pull out the appropriate "uses" attribute
78         int eventType;
79         try {
80             eventType = parser.next();
81             while (eventType != XmlPullParser.END_DOCUMENT) {
82                 if (eventType == XmlPullParser.START_TAG && USES_TAG.equals(parser.getName())) {
83                     String nameAttribute =
84                             parser.getAttributeValue(null /*namespace*/, NAME_ATTRIBUTE);
85                     if (nameAttribute == null) {
86                         Log.w(CarLog.TAG_PACKAGE, "Bad metadata," + METADATA_ATTRIBUTE +
87                                 " for pavkage:" + packageName);
88                         return null;
89                     }
90                     switch (nameAttribute) {
91                         case NAME_ATTR_TYPE_SERVICE:
92                             useService = true;
93                             break;
94                         case NAME_ATTR_TYPE_ACTIVITY: {
95                             String classAttribute = parser.getAttributeValue(null /*namespace*/,
96                                     CLASS_ATTRIBUTE);
97                             if (classAttribute == null) { // all activities
98                                 useAllActivities = true;
99                             } else {
100                                 if (activities == null) {
101                                     activities = new LinkedList<>();
102                                 }
103                                 activities.add(classAttribute);
104                             }
105                         } break;
106                     }
107                 }
108                 eventType = parser.next();
109             }
110         } catch (XmlPullParserException | IOException e) {
111             Log.w(CarLog.TAG_PACKAGE, "Resource not parsable [" + packageName + "]");
112             return null;
113         }
114         String[] activityStrings = null;
115         if (activities != null) {
116             activityStrings = activities.toArray(new String[activities.size()]);
117         }
118         return new CarAppMetadataInfo(useService, useAllActivities, activityStrings);
119     }
120 
121     /**
122      * Returns the resource ID of the automotive application XML
123      * @throws NameNotFoundException
124      */
getMetadataId(Context context, String packageName)125     private static int getMetadataId(Context context, String packageName)
126             throws NameNotFoundException {
127         final PackageManager pm = context.getPackageManager();
128         ApplicationInfo appInfo;
129         appInfo = pm.getApplicationInfo(packageName, PackageManager.GET_META_DATA /*flags*/);
130         if (appInfo.metaData == null) {
131             return 0;
132         }
133         return appInfo.metaData.getInt(METADATA_ATTRIBUTE, 0);
134     }
135 
136     /**
137      * App's metada for car application
138      */
139     public static class CarAppMetadataInfo {
140         /** has "service" use */
141         public final boolean useService;
142         /** has "activity" use with no specific class */
143         public final boolean useAllActivities;
144         /** has "activity" uses with specific classes */
145         public String[] activities;
146 
CarAppMetadataInfo(boolean useService, boolean useAllActivities, String[] activities)147         private CarAppMetadataInfo(boolean useService, boolean useAllActivities,
148                 String[] activities) {
149             this.useService = useService;
150             this.useAllActivities = useAllActivities;
151             this.activities = activities;
152         }
153     }
154 }
155