WebViewFactory.java revision 6c778cebc73e7eb76510f6e2183d804b8c07082b 
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.webkit;
18
19import android.app.AppGlobals;
20import android.content.Context;
21import android.content.pm.PackageManager;
22import android.os.Build;
23import android.os.Process;
24import android.os.RemoteException;
25import android.os.ServiceManager;
26import android.os.StrictMode;
27import android.util.AndroidRuntimeException;
28import android.util.Log;
29import dalvik.system.VMRuntime;
30
31import java.io.File;
32
33import com.android.internal.os.Zygote;
34
35/**
36 * Top level factory, used creating all the main WebView implementation classes.
37 *
38 * @hide
39 */
40public final class WebViewFactory {
41
42    private static final String CHROMIUM_WEBVIEW_FACTORY =
43            "com.android.webview.chromium.WebViewChromiumFactoryProvider";
44
45    private static final String NULL_WEBVIEW_FACTORY =
46            "com.android.webview.nullwebview.NullWebViewFactoryProvider";
47
48    // TODO(torne): we need to use a system property instead of hardcoding the library paths to
49    // enable it to be changed when a webview update apk is installed.
50    private static final String CHROMIUM_WEBVIEW_NATIVE_LIB_32 =
51            "/system/lib/libwebviewchromium.so";
52    private static final String CHROMIUM_WEBVIEW_NATIVE_LIB_64 =
53            "/system/lib64/libwebviewchromium.so";
54    private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_32 =
55            "/data/misc/shared_relro/libwebviewchromium32.relro";
56    private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_64 =
57            "/data/misc/shared_relro/libwebviewchromium64.relro";
58
59    private static final String LOGTAG = "WebViewFactory";
60
61    private static final boolean DEBUG = false;
62
63    // Cache the factory both for efficiency, and ensure any one process gets all webviews from the
64    // same provider.
65    private static WebViewFactoryProvider sProviderInstance;
66    private static final Object sProviderLock = new Object();
67    private static boolean sAddressSpaceReserved = false;
68
69    public static String getWebViewPackageName() {
70        // TODO: Make this dynamic based on resource configuration.
71        return "com.android.webview";
72    }
73
74    static WebViewFactoryProvider getProvider() {
75        synchronized (sProviderLock) {
76            // For now the main purpose of this function (and the factory abstraction) is to keep
77            // us honest and minimize usage of WebView internals when binding the proxy.
78            if (sProviderInstance != null) return sProviderInstance;
79
80            loadNativeLibrary();
81
82            Class<WebViewFactoryProvider> providerClass;
83            try {
84                providerClass = getFactoryClass();
85            } catch (ClassNotFoundException e) {
86                Log.e(LOGTAG, "error loading provider", e);
87                throw new AndroidRuntimeException(e);
88            }
89
90            StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
91            try {
92                sProviderInstance = providerClass.newInstance();
93                if (DEBUG) Log.v(LOGTAG, "Loaded provider: " + sProviderInstance);
94                return sProviderInstance;
95            } catch (Exception e) {
96                Log.e(LOGTAG, "error instantiating provider", e);
97                throw new AndroidRuntimeException(e);
98            } finally {
99                StrictMode.setThreadPolicy(oldPolicy);
100            }
101        }
102    }
103
104    private static Class<WebViewFactoryProvider> getFactoryClass() throws ClassNotFoundException {
105        try {
106            Context webViewContext = AppGlobals.getInitialApplication().createPackageContext(
107                    getWebViewPackageName(),
108                    Context.CONTEXT_INCLUDE_CODE | Context.CONTEXT_IGNORE_SECURITY);
109            ClassLoader clazzLoader = webViewContext.getClassLoader();
110            return (Class<WebViewFactoryProvider>) Class.forName(CHROMIUM_WEBVIEW_FACTORY, true,
111                                                                 clazzLoader);
112        } catch (PackageManager.NameNotFoundException e) {
113            Log.e(LOGTAG, "Chromium WebView package does not exist");
114            return (Class<WebViewFactoryProvider>) Class.forName(NULL_WEBVIEW_FACTORY);
115        }
116    }
117
118    /**
119     * Perform any WebView loading preparations that must happen in the zygote.
120     * Currently, this means allocating address space to load the real JNI library later.
121     */
122    public static void prepareWebViewInZygote() {
123        try {
124            System.loadLibrary("webviewchromium_loader");
125            sAddressSpaceReserved = nativeReserveAddressSpace(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
126                                                              CHROMIUM_WEBVIEW_NATIVE_LIB_64);
127            if (sAddressSpaceReserved) {
128                if (DEBUG) Log.v(LOGTAG, "address space reserved");
129            } else {
130                Log.e(LOGTAG, "reserving address space failed");
131            }
132        } catch (Throwable e) {
133            // Log and discard errors at this stage as we must not crash the zygote.
134            Log.e(LOGTAG, "error preparing native loader", e);
135        }
136    }
137
138    /**
139     * Perform any WebView loading preparations that must happen at boot from the system server,
140     * after the package manager has started.
141     * This must be called in the system server.
142     * Currently, this means spawning the child processes which will create the relro files.
143     */
144    public static void prepareWebViewInSystemServer() {
145        if (DEBUG) Log.v(LOGTAG, "creating relro files");
146        if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_64).exists()) {
147            createRelroFile(Build.SUPPORTED_64_BIT_ABIS[0]);
148        }
149        if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_32).exists()) {
150            createRelroFile(Build.SUPPORTED_32_BIT_ABIS[0]);
151        }
152    }
153
154    private static void createRelroFile(String abi) {
155        try {
156            Process.start("android.webkit.WebViewFactory$RelroFileCreator",
157                          "WebViewLoader-" + abi,
158                          Process.SHARED_RELRO_UID,
159                          Process.SHARED_RELRO_UID,
160                          null,
161                          0,                 // TODO(torne): do we need to set debug flags?
162                          Zygote.MOUNT_EXTERNAL_NONE,
163                          Build.VERSION.SDK_INT,
164                          null,
165                          abi,
166                          null);
167        } catch (Throwable e) {
168            // Log and discard errors as we must not crash the system server.
169            Log.e(LOGTAG, "error starting relro file creator for abi " + abi, e);
170        }
171    }
172
173    private static class RelroFileCreator {
174        // Called in an unprivileged child process to create the relro file.
175        public static void main(String[] args) {
176            if (!sAddressSpaceReserved) {
177                Log.e(LOGTAG, "can't create relro file; address space not reserved");
178                return;
179            }
180            boolean result = nativeCreateRelroFile(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
181                                                   CHROMIUM_WEBVIEW_NATIVE_LIB_64,
182                                                   CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
183                                                   CHROMIUM_WEBVIEW_NATIVE_RELRO_64);
184            if (!result) {
185                Log.e(LOGTAG, "failed to create relro file");
186            } else if (DEBUG) {
187                Log.v(LOGTAG, "created relro file");
188            }
189            try {
190                getUpdateService().notifyRelroCreationCompleted(VMRuntime.getRuntime().is64Bit(),
191                                                                result);
192            } catch (RemoteException e) {
193                Log.e(LOGTAG, "error notifying update service", e);
194            }
195
196            // Must explicitly exit or else this process will just sit around after we return.
197            System.exit(0);
198        }
199    }
200
201    private static void loadNativeLibrary() {
202        if (!sAddressSpaceReserved) {
203            Log.e(LOGTAG, "can't load with relro file; address space not reserved");
204            return;
205        }
206
207        try {
208            getUpdateService().waitForRelroCreationCompleted(VMRuntime.getRuntime().is64Bit());
209        } catch (RemoteException e) {
210            Log.e(LOGTAG, "error waiting for relro creation, proceeding without", e);
211            return;
212        }
213
214        boolean result = nativeLoadWithRelroFile(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
215                                                 CHROMIUM_WEBVIEW_NATIVE_LIB_64,
216                                                 CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
217                                                 CHROMIUM_WEBVIEW_NATIVE_RELRO_64);
218        if (!result) {
219            Log.w(LOGTAG, "failed to load with relro file, proceeding without");
220        } else if (DEBUG) {
221            Log.v(LOGTAG, "loaded with relro file");
222        }
223    }
224
225    private static IWebViewUpdateService getUpdateService() {
226        return IWebViewUpdateService.Stub.asInterface(ServiceManager.getService("webviewupdate"));
227    }
228
229    private static native boolean nativeReserveAddressSpace(String lib32, String lib64);
230    private static native boolean nativeCreateRelroFile(String lib32, String lib64,
231                                                        String relro32, String relro64);
232    private static native boolean nativeLoadWithRelroFile(String lib32, String lib64,
233                                                          String relro32, String relro64);
234}
235