WebViewFactory.java revision 08cfaf672604422dd355d6703aec78f3aa5ee74e 
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.os.Build;
20import android.os.Process;
21import android.os.RemoteException;
22import android.os.ServiceManager;
23import android.os.StrictMode;
24import android.util.AndroidRuntimeException;
25import android.util.Log;
26import dalvik.system.VMRuntime;
27
28import java.io.File;
29
30import com.android.internal.os.Zygote;
31
32/**
33 * Top level factory, used creating all the main WebView implementation classes.
34 *
35 * @hide
36 */
37public final class WebViewFactory {
38
39    private static final String CHROMIUM_WEBVIEW_FACTORY =
40            "com.android.webview.chromium.WebViewChromiumFactoryProvider";
41
42    private static final String NULL_WEBVIEW_FACTORY =
43            "com.android.webview.nullwebview.NullWebViewFactoryProvider";
44
45    // TODO(torne): we need to use a system property instead of hardcoding the library paths to
46    // enable it to be changed when a webview update apk is installed.
47    private static final String CHROMIUM_WEBVIEW_NATIVE_LIB_32 =
48            "/system/lib/libwebviewchromium.so";
49    private static final String CHROMIUM_WEBVIEW_NATIVE_LIB_64 =
50            "/system/lib64/libwebviewchromium.so";
51    private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_32 =
52            "/data/misc/shared_relro/libwebviewchromium32.relro";
53    private static final String CHROMIUM_WEBVIEW_NATIVE_RELRO_64 =
54            "/data/misc/shared_relro/libwebviewchromium64.relro";
55
56    private static final String LOGTAG = "WebViewFactory";
57
58    private static final boolean DEBUG = false;
59
60    // Cache the factory both for efficiency, and ensure any one process gets all webviews from the
61    // same provider.
62    private static WebViewFactoryProvider sProviderInstance;
63    private static final Object sProviderLock = new Object();
64    private static boolean sAddressSpaceReserved = false;
65
66    static WebViewFactoryProvider getProvider() {
67        synchronized (sProviderLock) {
68            // For now the main purpose of this function (and the factory abstraction) is to keep
69            // us honest and minimize usage of WebView internals when binding the proxy.
70            if (sProviderInstance != null) return sProviderInstance;
71
72            loadNativeLibrary();
73
74            Class<WebViewFactoryProvider> providerClass;
75            try {
76                providerClass = getFactoryClass();
77            } catch (ClassNotFoundException e) {
78                Log.e(LOGTAG, "error loading provider", e);
79                throw new AndroidRuntimeException(e);
80            }
81
82            StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
83            try {
84                sProviderInstance = providerClass.newInstance();
85                if (DEBUG) Log.v(LOGTAG, "Loaded provider: " + sProviderInstance);
86                return sProviderInstance;
87            } catch (Exception e) {
88                Log.e(LOGTAG, "error instantiating provider", e);
89                throw new AndroidRuntimeException(e);
90            } finally {
91                StrictMode.setThreadPolicy(oldPolicy);
92            }
93        }
94    }
95
96    private static Class<WebViewFactoryProvider> getFactoryClass() throws ClassNotFoundException {
97        try {
98            return (Class<WebViewFactoryProvider>) Class.forName(CHROMIUM_WEBVIEW_FACTORY);
99        } catch (ClassNotFoundException e) {
100            Log.e(LOGTAG, "Chromium WebView does not exist");
101            return (Class<WebViewFactoryProvider>) Class.forName(NULL_WEBVIEW_FACTORY);
102        }
103    }
104
105    /**
106     * Perform any WebView loading preparations that must happen in the zygote.
107     * Currently, this means allocating address space to load the real JNI library later.
108     */
109    public static void prepareWebViewInZygote() {
110        try {
111            System.loadLibrary("webviewchromium_loader");
112            sAddressSpaceReserved = nativeReserveAddressSpace(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
113                                                              CHROMIUM_WEBVIEW_NATIVE_LIB_64);
114            if (sAddressSpaceReserved) {
115                if (DEBUG) Log.v(LOGTAG, "address space reserved");
116            } else {
117                Log.e(LOGTAG, "reserving address space failed");
118            }
119        } catch (Throwable e) {
120            // Log and discard errors at this stage as we must not crash the zygote.
121            Log.e(LOGTAG, "error preparing native loader", e);
122        }
123    }
124
125    /**
126     * Perform any WebView loading preparations that must happen at boot from the system server,
127     * after the package manager has started.
128     * This must be called in the system server.
129     * Currently, this means spawning the child processes which will create the relro files.
130     */
131    public static void prepareWebViewInSystemServer() {
132        if (DEBUG) Log.v(LOGTAG, "creating relro files");
133        if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_64).exists()) {
134            createRelroFile(Build.SUPPORTED_64_BIT_ABIS[0]);
135        }
136        if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_32).exists()) {
137            createRelroFile(Build.SUPPORTED_32_BIT_ABIS[0]);
138        }
139    }
140
141    private static void createRelroFile(String abi) {
142        try {
143            Process.start("android.webkit.WebViewFactory$RelroFileCreator",
144                          "WebViewLoader-" + abi,
145                          Process.SHARED_RELRO_UID,
146                          Process.SHARED_RELRO_UID,
147                          null,
148                          0,                 // TODO(torne): do we need to set debug flags?
149                          Zygote.MOUNT_EXTERNAL_NONE,
150                          Build.VERSION.SDK_INT,
151                          null,
152                          abi,
153                          null);
154        } catch (Throwable e) {
155            // Log and discard errors as we must not crash the system server.
156            Log.e(LOGTAG, "error starting relro file creator for abi " + abi, e);
157        }
158    }
159
160    private static class RelroFileCreator {
161        // Called in an unprivileged child process to create the relro file.
162        public static void main(String[] args) {
163            if (!sAddressSpaceReserved) {
164                Log.e(LOGTAG, "can't create relro file; address space not reserved");
165                return;
166            }
167            boolean result = nativeCreateRelroFile(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
168                                                   CHROMIUM_WEBVIEW_NATIVE_LIB_64,
169                                                   CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
170                                                   CHROMIUM_WEBVIEW_NATIVE_RELRO_64);
171            if (!result) {
172                Log.e(LOGTAG, "failed to create relro file");
173            } else if (DEBUG) {
174                Log.v(LOGTAG, "created relro file");
175            }
176            try {
177                getUpdateService().notifyRelroCreationCompleted(VMRuntime.getRuntime().is64Bit(),
178                                                                result);
179            } catch (RemoteException e) {
180                Log.e(LOGTAG, "error notifying update service", e);
181            }
182
183            // Must explicitly exit or else this process will just sit around after we return.
184            System.exit(0);
185        }
186    }
187
188    private static void loadNativeLibrary() {
189        if (!sAddressSpaceReserved) {
190            Log.e(LOGTAG, "can't load with relro file; address space not reserved");
191            return;
192        }
193
194        try {
195            getUpdateService().waitForRelroCreationCompleted(VMRuntime.getRuntime().is64Bit());
196        } catch (RemoteException e) {
197            Log.e(LOGTAG, "error waiting for relro creation, proceeding without", e);
198            return;
199        }
200
201        boolean result = nativeLoadWithRelroFile(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
202                                                 CHROMIUM_WEBVIEW_NATIVE_LIB_64,
203                                                 CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
204                                                 CHROMIUM_WEBVIEW_NATIVE_RELRO_64);
205        if (!result) {
206            Log.w(LOGTAG, "failed to load with relro file, proceeding without");
207        } else if (DEBUG) {
208            Log.v(LOGTAG, "loaded with relro file");
209        }
210    }
211
212    private static IWebViewUpdateService getUpdateService() {
213        return IWebViewUpdateService.Stub.asInterface(ServiceManager.getService("webviewupdate"));
214    }
215
216    private static native boolean nativeReserveAddressSpace(String lib32, String lib64);
217    private static native boolean nativeCreateRelroFile(String lib32, String lib64,
218                                                        String relro32, String relro64);
219    private static native boolean nativeLoadWithRelroFile(String lib32, String lib64,
220                                                          String relro32, String relro64);
221}
222