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 package android.content.res; 17 18 import android.annotation.NonNull; 19 20 import com.android.internal.annotations.GuardedBy; 21 import com.android.internal.util.Preconditions; 22 23 import java.io.FileDescriptor; 24 import java.io.IOException; 25 26 /** 27 * The loaded, immutable, in-memory representation of an APK. 28 * 29 * The main implementation is native C++ and there is very little API surface exposed here. The APK 30 * is mainly accessed via {@link AssetManager}. 31 * 32 * Since the ApkAssets instance is immutable, it can be reused and shared across AssetManagers, 33 * making the creation of AssetManagers very cheap. 34 * @hide 35 */ 36 public final class ApkAssets { 37 @GuardedBy("this") private final long mNativePtr; 38 @GuardedBy("this") private StringBlock mStringBlock; 39 40 /** 41 * Creates a new ApkAssets instance from the given path on disk. 42 * 43 * @param path The path to an APK on disk. 44 * @return a new instance of ApkAssets. 45 * @throws IOException if a disk I/O error or parsing error occurred. 46 */ 47 public static @NonNull ApkAssets loadFromPath(@NonNull String path) throws IOException { 48 return new ApkAssets(path, false /*system*/, false /*forceSharedLib*/, false /*overlay*/); 49 } 50 51 /** 52 * Creates a new ApkAssets instance from the given path on disk. 53 * 54 * @param path The path to an APK on disk. 55 * @param system When true, the APK is loaded as a system APK (framework). 56 * @return a new instance of ApkAssets. 57 * @throws IOException if a disk I/O error or parsing error occurred. 58 */ 59 public static @NonNull ApkAssets loadFromPath(@NonNull String path, boolean system) 60 throws IOException { 61 return new ApkAssets(path, system, false /*forceSharedLib*/, false /*overlay*/); 62 } 63 64 /** 65 * Creates a new ApkAssets instance from the given path on disk. 66 * 67 * @param path The path to an APK on disk. 68 * @param system When true, the APK is loaded as a system APK (framework). 69 * @param forceSharedLibrary When true, any packages within the APK with package ID 0x7f are 70 * loaded as a shared library. 71 * @return a new instance of ApkAssets. 72 * @throws IOException if a disk I/O error or parsing error occurred. 73 */ 74 public static @NonNull ApkAssets loadFromPath(@NonNull String path, boolean system, 75 boolean forceSharedLibrary) throws IOException { 76 return new ApkAssets(path, system, forceSharedLibrary, false /*overlay*/); 77 } 78 79 /** 80 * Creates a new ApkAssets instance from the given file descriptor. Not for use by applications. 81 * 82 * Performs a dup of the underlying fd, so you must take care of still closing 83 * the FileDescriptor yourself (and can do that whenever you want). 84 * 85 * @param fd The FileDescriptor of an open, readable APK. 86 * @param friendlyName The friendly name used to identify this ApkAssets when logging. 87 * @param system When true, the APK is loaded as a system APK (framework). 88 * @param forceSharedLibrary When true, any packages within the APK with package ID 0x7f are 89 * loaded as a shared library. 90 * @return a new instance of ApkAssets. 91 * @throws IOException if a disk I/O error or parsing error occurred. 92 */ 93 public static @NonNull ApkAssets loadFromFd(@NonNull FileDescriptor fd, 94 @NonNull String friendlyName, boolean system, boolean forceSharedLibrary) 95 throws IOException { 96 return new ApkAssets(fd, friendlyName, system, forceSharedLibrary); 97 } 98 99 /** 100 * Creates a new ApkAssets instance from the IDMAP at idmapPath. The overlay APK path 101 * is encoded within the IDMAP. 102 * 103 * @param idmapPath Path to the IDMAP of an overlay APK. 104 * @param system When true, the APK is loaded as a system APK (framework). 105 * @return a new instance of ApkAssets. 106 * @throws IOException if a disk I/O error or parsing error occurred. 107 */ 108 public static @NonNull ApkAssets loadOverlayFromPath(@NonNull String idmapPath, boolean system) 109 throws IOException { 110 return new ApkAssets(idmapPath, system, false /*forceSharedLibrary*/, true /*overlay*/); 111 } 112 113 private ApkAssets(@NonNull String path, boolean system, boolean forceSharedLib, boolean overlay) 114 throws IOException { 115 Preconditions.checkNotNull(path, "path"); 116 mNativePtr = nativeLoad(path, system, forceSharedLib, overlay); 117 mStringBlock = new StringBlock(nativeGetStringBlock(mNativePtr), true /*useSparse*/); 118 } 119 120 private ApkAssets(@NonNull FileDescriptor fd, @NonNull String friendlyName, boolean system, 121 boolean forceSharedLib) throws IOException { 122 Preconditions.checkNotNull(fd, "fd"); 123 Preconditions.checkNotNull(friendlyName, "friendlyName"); 124 mNativePtr = nativeLoadFromFd(fd, friendlyName, system, forceSharedLib); 125 mStringBlock = new StringBlock(nativeGetStringBlock(mNativePtr), true /*useSparse*/); 126 } 127 128 public @NonNull String getAssetPath() { 129 synchronized (this) { 130 return nativeGetAssetPath(mNativePtr); 131 } 132 } 133 134 CharSequence getStringFromPool(int idx) { 135 synchronized (this) { 136 return mStringBlock.get(idx); 137 } 138 } 139 140 /** 141 * Retrieve a parser for a compiled XML file. This is associated with a single APK and 142 * <em>NOT</em> a full AssetManager. This means that shared-library references will not be 143 * dynamically assigned runtime package IDs. 144 * 145 * @param fileName The path to the file within the APK. 146 * @return An XmlResourceParser. 147 * @throws IOException if the file was not found or an error occurred retrieving it. 148 */ 149 public @NonNull XmlResourceParser openXml(@NonNull String fileName) throws IOException { 150 Preconditions.checkNotNull(fileName, "fileName"); 151 synchronized (this) { 152 long nativeXmlPtr = nativeOpenXml(mNativePtr, fileName); 153 try (XmlBlock block = new XmlBlock(null, nativeXmlPtr)) { 154 XmlResourceParser parser = block.newParser(); 155 // If nativeOpenXml doesn't throw, it will always return a valid native pointer, 156 // which makes newParser always return non-null. But let's be paranoid. 157 if (parser == null) { 158 throw new AssertionError("block.newParser() returned a null parser"); 159 } 160 return parser; 161 } 162 } 163 } 164 165 /** 166 * Returns false if the underlying APK was changed since this ApkAssets was loaded. 167 */ 168 public boolean isUpToDate() { 169 synchronized (this) { 170 return nativeIsUpToDate(mNativePtr); 171 } 172 } 173 174 @Override 175 public String toString() { 176 return "ApkAssets{path=" + getAssetPath() + "}"; 177 } 178 179 @Override 180 protected void finalize() throws Throwable { 181 nativeDestroy(mNativePtr); 182 } 183 184 private static native long nativeLoad( 185 @NonNull String path, boolean system, boolean forceSharedLib, boolean overlay) 186 throws IOException; 187 private static native long nativeLoadFromFd(@NonNull FileDescriptor fd, 188 @NonNull String friendlyName, boolean system, boolean forceSharedLib) 189 throws IOException; 190 private static native void nativeDestroy(long ptr); 191 private static native @NonNull String nativeGetAssetPath(long ptr); 192 private static native long nativeGetStringBlock(long ptr); 193 private static native boolean nativeIsUpToDate(long ptr); 194 private static native long nativeOpenXml(long ptr, @NonNull String fileName) throws IOException; 195 } 196
