WebViewFactory.java revision dc00a84af15ff3594a6dfa512be21095bf9fee82 
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    public static String getWebViewPackageName() {
67        // TODO: Make this dynamic based on resource configuration.
68        return "com.android.webview";
69    }
70
71    static WebViewFactoryProvider getProvider() {
72        synchronized (sProviderLock) {
73            // For now the main purpose of this function (and the factory abstraction) is to keep
74            // us honest and minimize usage of WebView internals when binding the proxy.
75            if (sProviderInstance != null) return sProviderInstance;
76
77            loadNativeLibrary();
78
79            Class<WebViewFactoryProvider> providerClass;
80            try {
81                providerClass = getFactoryClass();
82            } catch (ClassNotFoundException e) {
83                Log.e(LOGTAG, "error loading provider", e);
84                throw new AndroidRuntimeException(e);
85            }
86
87            StrictMode.ThreadPolicy oldPolicy = StrictMode.allowThreadDiskReads();
88            try {
89                sProviderInstance = providerClass.newInstance();
90                if (DEBUG) Log.v(LOGTAG, "Loaded provider: " + sProviderInstance);
91                return sProviderInstance;
92            } catch (Exception e) {
93                Log.e(LOGTAG, "error instantiating provider", e);
94                throw new AndroidRuntimeException(e);
95            } finally {
96                StrictMode.setThreadPolicy(oldPolicy);
97            }
98        }
99    }
100
101    private static Class<WebViewFactoryProvider> getFactoryClass() throws ClassNotFoundException {
102        try {
103            return (Class<WebViewFactoryProvider>) Class.forName(CHROMIUM_WEBVIEW_FACTORY);
104        } catch (ClassNotFoundException e) {
105            Log.e(LOGTAG, "Chromium WebView does not exist");
106            return (Class<WebViewFactoryProvider>) Class.forName(NULL_WEBVIEW_FACTORY);
107        }
108    }
109
110    /**
111     * Perform any WebView loading preparations that must happen in the zygote.
112     * Currently, this means allocating address space to load the real JNI library later.
113     */
114    public static void prepareWebViewInZygote() {
115        try {
116            System.loadLibrary("webviewchromium_loader");
117            sAddressSpaceReserved = nativeReserveAddressSpace(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
118                                                              CHROMIUM_WEBVIEW_NATIVE_LIB_64);
119            if (sAddressSpaceReserved) {
120                if (DEBUG) Log.v(LOGTAG, "address space reserved");
121            } else {
122                Log.e(LOGTAG, "reserving address space failed");
123            }
124        } catch (Throwable e) {
125            // Log and discard errors at this stage as we must not crash the zygote.
126            Log.e(LOGTAG, "error preparing native loader", e);
127        }
128    }
129
130    /**
131     * Perform any WebView loading preparations that must happen at boot from the system server,
132     * after the package manager has started.
133     * This must be called in the system server.
134     * Currently, this means spawning the child processes which will create the relro files.
135     */
136    public static void prepareWebViewInSystemServer() {
137        if (DEBUG) Log.v(LOGTAG, "creating relro files");
138        if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_64).exists()) {
139            createRelroFile(Build.SUPPORTED_64_BIT_ABIS[0]);
140        }
141        if (new File(CHROMIUM_WEBVIEW_NATIVE_LIB_32).exists()) {
142            createRelroFile(Build.SUPPORTED_32_BIT_ABIS[0]);
143        }
144    }
145
146    private static void createRelroFile(String abi) {
147        try {
148            Process.start("android.webkit.WebViewFactory$RelroFileCreator",
149                          "WebViewLoader-" + abi,
150                          Process.SHARED_RELRO_UID,
151                          Process.SHARED_RELRO_UID,
152                          null,
153                          0,                 // TODO(torne): do we need to set debug flags?
154                          Zygote.MOUNT_EXTERNAL_NONE,
155                          Build.VERSION.SDK_INT,
156                          null,
157                          abi,
158                          null);
159        } catch (Throwable e) {
160            // Log and discard errors as we must not crash the system server.
161            Log.e(LOGTAG, "error starting relro file creator for abi " + abi, e);
162        }
163    }
164
165    private static class RelroFileCreator {
166        // Called in an unprivileged child process to create the relro file.
167        public static void main(String[] args) {
168            if (!sAddressSpaceReserved) {
169                Log.e(LOGTAG, "can't create relro file; address space not reserved");
170                return;
171            }
172            boolean result = nativeCreateRelroFile(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
173                                                   CHROMIUM_WEBVIEW_NATIVE_LIB_64,
174                                                   CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
175                                                   CHROMIUM_WEBVIEW_NATIVE_RELRO_64);
176            if (!result) {
177                Log.e(LOGTAG, "failed to create relro file");
178            } else if (DEBUG) {
179                Log.v(LOGTAG, "created relro file");
180            }
181            try {
182                getUpdateService().notifyRelroCreationCompleted(VMRuntime.getRuntime().is64Bit(),
183                                                                result);
184            } catch (RemoteException e) {
185                Log.e(LOGTAG, "error notifying update service", e);
186            }
187
188            // Must explicitly exit or else this process will just sit around after we return.
189            System.exit(0);
190        }
191    }
192
193    private static void loadNativeLibrary() {
194        if (!sAddressSpaceReserved) {
195            Log.e(LOGTAG, "can't load with relro file; address space not reserved");
196            return;
197        }
198
199        try {
200            getUpdateService().waitForRelroCreationCompleted(VMRuntime.getRuntime().is64Bit());
201        } catch (RemoteException e) {
202            Log.e(LOGTAG, "error waiting for relro creation, proceeding without", e);
203            return;
204        }
205
206        boolean result = nativeLoadWithRelroFile(CHROMIUM_WEBVIEW_NATIVE_LIB_32,
207                                                 CHROMIUM_WEBVIEW_NATIVE_LIB_64,
208                                                 CHROMIUM_WEBVIEW_NATIVE_RELRO_32,
209                                                 CHROMIUM_WEBVIEW_NATIVE_RELRO_64);
210        if (!result) {
211            Log.w(LOGTAG, "failed to load with relro file, proceeding without");
212        } else if (DEBUG) {
213            Log.v(LOGTAG, "loaded with relro file");
214        }
215    }
216
217    private static IWebViewUpdateService getUpdateService() {
218        return IWebViewUpdateService.Stub.asInterface(ServiceManager.getService("webviewupdate"));
219    }
220
221    private static native boolean nativeReserveAddressSpace(String lib32, String lib64);
222    private static native boolean nativeCreateRelroFile(String lib32, String lib64,
223                                                        String relro32, String relro64);
224    private static native boolean nativeLoadWithRelroFile(String lib32, String lib64,
225                                                          String relro32, String relro64);
226}
227