[WebLayer] Use crazy linker for M- and "/." trick for N+

Instead of copying libraries on M-, this changes to using the crazy
linker, which loads the library without any knowledge of what libraries
have been loaded by the system linker. This requires manual JNI
registration. To make sure we only register WebLayer JNI when needed,
a minimal set of JNI methods is registered, and the full set is
registered later if we require WebView compatibility.

In N+, we switch to prepending "/." to library paths instead of using
symlinks, which allows us to avoid writing any files to the apps data
directory. This simplifies the interface quite a bit, allowing
initializeWebViewCompatibilityMode() to be sync instead of async. I will
follow up with the Android team to make sure we have a better solution
for future versions of Android.

The API has not been used in the client app yet, so it should be safe
to remove M- support for the copy library approach in the
implementation. The old version of initializeWebViewCompatibilityMode()
was kept so the WebLayer API version compat tests would still pass.

TBR=agrieve@chromium.org

Bug: 1051358
Change-Id: I2cd5ae0e025feaeb5c41cf9ddfafc91cd09fbad7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2090024
Commit-Queue: Clark DuVall <cduvall@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#749973}

android_webview/lib/BUILD.gn

@@ -63,6 +63,6 @@ source_set("webview_entry_point") {
 
   if (webview_includes_weblayer) {
     defines = [ "WEBVIEW_INCLUDES_WEBLAYER" ]
-    deps += [ "//weblayer:weblayer_lib" ]
+    deps += [ "//weblayer:weblayer_lib_webview" ]
   }
 }

android_webview/lib/webview_entry_point.cc

@@ -32,6 +32,10 @@ bool NativeInit(base::android::LibraryProcessType library_process_type) {
 // Most of the initialization is done in LibraryLoadedOnMainThread(), not here.
 JNI_EXPORT jint JNI_OnLoad(JavaVM* vm, void* reserved) {
   base::android::InitVM(vm);
+#if defined(WEBVIEW_INCLUDES_WEBLAYER)
+  if (!weblayer::RegisterMinimalNatives())
+    return -1;
+#endif
   base::android::SetNativeInitializationHook(&NativeInit);
   return JNI_VERSION_1_4;
 }

android_webview/system_webview_apk_tmpl.gni

@@ -132,6 +132,11 @@ template("system_webview_apk_or_module_tmpl") {
         "//third_party/crashpad/crashpad/handler:crashpad_handler_trampoline",
       ]
       loadable_modules = [ "$root_out_dir/libcrashpad_handler_trampoline.so" ]
+      if (webview_includes_weblayer) {
+        deps += [ "//base/android/linker:chromium_android_linker" ]
+        loadable_modules +=
+            [ "$root_out_dir/libchromium_android_linker$shlib_extension" ]
+      }
     }
     if (_include_secondary_support) {
       _trampoline = "//third_party/crashpad/crashpad/handler:crashpad_handler_trampoline($android_secondary_abi_toolchain)"
@@ -142,6 +147,11 @@ template("system_webview_apk_or_module_tmpl") {
       _secondary_out_dir = get_label_info(_trampoline, "root_out_dir")
       secondary_abi_loadable_modules =
           [ "$_secondary_out_dir/libcrashpad_handler_trampoline.so" ]
+      if (webview_includes_weblayer) {
+        deps += [ "//base/android/linker:chromium_android_linker($android_secondary_abi_toolchain)" ]
+        secondary_abi_loadable_modules +=
+            [ "$_secondary_out_dir/libchromium_android_linker$shlib_extension" ]
+      }
     }
 
     if (!_use_trichrome_library || android_64bit_target_cpu) {

base/android/java/src/org/chromium/base/library_loader/LibraryLoader.java

@@ -124,6 +124,9 @@ public class LibraryLoader {
     // Whether the configuration has been set.
     private boolean mConfigurationSet;
 
+    // Runs after all native libraries have been loaded.
+    private Runnable mPostLoadHook;
+
     @IntDef({LoadState.NOT_LOADED, LoadState.MAIN_DEX_LOADED, LoadState.LOADED})
     @Retention(RetentionPolicy.SOURCE)
     private @interface LoadState {
@@ -147,10 +150,6 @@ public class LibraryLoader {
     // will be reported via UMA. Set once when the libraries are done loading.
     private long mLibraryLoadTimeMs;
 
-    // The suffix to add when loading the library. This is useful if a library with the same name is
-    // loaded in the same process, as can be the case with WebView/WebLayer.
-    private String mLibrarySuffix = "";
-
     /**
      * Call this method to determine if the chromium project must load the library
      * directly from a zip file.
@@ -186,13 +185,10 @@ public class LibraryLoader {
         mLibraryProcessType = type;
     }
 
-    /**
-     * Sets a suffix to use when loading the library. This will be appended to the library names
-     * for calls to System.loadLibrary().
-     */
-    public void setLibrarySuffix(String suffix) {
+    /** Sets a function to run after all native libraries have been loaded. */
+    public void setPostLoadHook(Runnable postLoadHook) {
         assert mLoadState == LoadState.NOT_LOADED;
-        mLibrarySuffix = suffix;
+        mPostLoadHook = postLoadHook;
     }
 
     /**
@@ -492,7 +488,7 @@ public class LibraryLoader {
         // Load libraries using the system linker.
         for (String library : NativeLibraries.LIBRARIES) {
             if (!isInZipFile()) {
-                System.loadLibrary(library + mLibrarySuffix);
+                System.loadLibrary(library);
             } else {
                 // Load directly from the APK.
                 boolean is64Bit = ApiHelperForM.isProcess64Bit();
@@ -540,6 +536,10 @@ public class LibraryLoader {
         } catch (UnsatisfiedLinkError e) {
             throw new ProcessInitException(LoaderErrors.NATIVE_LIBRARY_LOAD_FAILED, e);
         }
+
+        if (mPostLoadHook != null) {
+            mPostLoadHook.run();
+        }
     }
 
     @VisibleForTesting

base/android/library_loader/library_loader_hooks.cc

@@ -61,6 +61,7 @@ void SetNativeInitializationHook(
 
 void SetNonMainDexJniRegistrationHook(
     NonMainDexJniRegistrationHook jni_registration_hook) {
+  DCHECK(!g_jni_registration_hook);
   g_jni_registration_hook = jni_registration_hook;
 }
 

chrome/android/monochrome/scripts/monochrome_apk_checker.py

@@ -40,6 +40,7 @@ CHROME_SPECIFIC = BuildFileMatchRegex(
 # WebView specific files which are not in Monochrome.apk
 WEBVIEW_SPECIFIC = BuildFileMatchRegex(
     r'lib/.*/libwebviewchromium\.so',
+    r'lib/.*/libchromium_android_linker\.so',
     r'assets/webview_licenses.notice',
     r'res/.*/icon_webview(.webp)?',
     r'META-INF/.*',

weblayer/BUILD.gn

@@ -86,7 +86,7 @@ if (is_android) {
   }
 }
 
-static_library("weblayer_lib") {
+source_set("weblayer_lib_base") {
   sources = [
     "app/content_main_delegate_impl.cc",
     "app/content_main_delegate_impl.h",
@@ -303,6 +303,7 @@ static_library("weblayer_lib") {
 
   if (is_android) {
     sources += [
+      "$target_gen_dir/browser/java/weblayer_minimal_jni_registration.h",
       "app/jni_onload.cc",
       "app/jni_onload.h",
       "browser/android/exception_filter.cc",
@@ -344,13 +345,16 @@ static_library("weblayer_lib") {
       "//android_webview:generate_aw_strings",
       "//components/android_system_error_page",
       "//components/autofill/android:provider",
+      "//components/crash/android:crash_android",
       "//components/crash/android:crashpad_main",
       "//components/embedder_support/android:context_menu",
+      "//components/embedder_support/android:util",
       "//components/embedder_support/android:web_contents_delegate",
       "//components/embedder_support/android/metrics",
       "//components/javascript_dialogs",
       "//components/metrics",
       "//components/minidump_uploader",
+      "//components/permissions/android:native",
       "//components/safe_browsing/content/common:interfaces",
       "//components/safe_browsing/content/renderer:throttles",
       "//components/safe_browsing/core/common",
@@ -358,6 +362,7 @@ static_library("weblayer_lib") {
       "//services/resource_coordinator/public/cpp/memory_instrumentation:browser",
       "//ui/android",
       "//weblayer/browser/java:jni",
+      "//weblayer/browser/java:weblayer_minimal_jni_registration",
       "//weblayer/browser/safe_browsing:safe_browsing",
     ]
   } else {
@@ -399,6 +404,45 @@ static_library("weblayer_lib") {
   }
 }
 
+if (is_android) {
+  # Lib used in standalone WebView which allows manual JNI registration.
+  static_library("weblayer_lib_webview") {
+    public_deps = [ ":weblayer_lib_base" ]
+    deps = [
+      "//base",
+      "//weblayer/browser/java:jni",
+      "//weblayer/browser/java:weblayer_jni_registration",
+    ]
+    sources = [
+      "$target_gen_dir/browser/java/weblayer_jni_registration.h",
+      "browser/web_view_compatibility_helper_impl.cc",
+    ]
+    defines = [ "WEBLAYER_MANUAL_JNI_REGISTRATION" ]
+
+    # Explicit dependency required for JNI registration to be able to
+    # find the native side functions.
+    if (is_component_build) {
+      deps += [
+        "//device/gamepad",
+        "//media/midi",
+        "//ui/events/devices",
+      ]
+    }
+  }
+
+  # Lib used in Monochrome which does not support manual JNI registration.
+  # Separate from the standalone WebView version to reduce APK size.
+  static_library("weblayer_lib") {
+    public_deps = [ ":weblayer_lib_base" ]
+    deps = [ "//weblayer/browser/java:jni" ]
+    sources = [ "browser/web_view_compatibility_helper_impl.cc" ]
+  }
+} else {
+  static_library("weblayer_lib") {
+    public_deps = [ ":weblayer_lib_base" ]
+  }
+}
+
 grit("resources") {
   source = "weblayer_resources.grd"
 
@@ -420,7 +464,7 @@ if (is_android) {
   shared_library("libweblayer") {
     sources = [ "app/entry_point.cc" ]
     deps = [
-      ":weblayer_lib",
+      ":weblayer_lib_webview",
       "//base",
       "//content/public/app:both",
     ]

weblayer/app/jni_onload.cc

@@ -9,6 +9,7 @@
 #include "content/public/app/content_jni_onload.h"
 #include "content/public/app/content_main.h"
 #include "weblayer/app/content_main_delegate_impl.h"
+#include "weblayer/browser/java/weblayer_minimal_jni_registration.h"
 
 namespace weblayer {
 
@@ -34,4 +35,9 @@ bool OnJNIOnLoadInit() {
   return true;
 }
 
+bool RegisterMinimalNatives() {
+  return weblayer_minimal::RegisterMainDexNatives(
+      base::android::AttachCurrentThread());
+}
+
 }  // namespace weblayer

weblayer/app/jni_onload.h

@@ -11,6 +11,10 @@ namespace weblayer {
 
 bool OnJNIOnLoadInit();
 
+// Registers the minimal set of natives needed to later register the full set of
+// natives if WebView compatibility is needed.
+bool RegisterMinimalNatives();
+
 }  // namespace weblayer
 
 #endif  // WEBLAYER_APP_JNI_ONLOAD_H_

weblayer/browser/android/javatests/src/org/chromium/weblayer/test/WebViewCompatibilityTest.java

@@ -32,8 +32,7 @@ public class WebViewCompatibilityTest {
     public void testBothLoadPage() throws Exception {
         TestThreadUtils.runOnUiThreadBlocking(() -> {
             WebLayer.initializeWebViewCompatibilityMode(
-                    InstrumentationRegistry.getTargetContext().getApplicationContext(),
-                    InstrumentationRegistry.getTargetContext().getCacheDir(), null);
+                    InstrumentationRegistry.getTargetContext().getApplicationContext());
         });
         mActivityTestRule.launchShellWithUrl(mActivityTestRule.getTestDataURL("simple_page.html"));
         WebView webView = TestThreadUtils.runOnUiThreadBlocking(

weblayer/browser/java/BUILD.gn

@@ -32,6 +32,18 @@ java_cpp_enum("generated_enums") {
   ]
 }
 
+_webview_compat_sources =
+    [ "org/chromium/weblayer_private/WebViewCompatibilityHelperImpl.java" ]
+
+android_library("webview_compat_java") {
+  sources = _webview_compat_sources
+  deps = [
+    "//base:base_java",
+    "//base:jni_java",
+  ]
+  annotation_processor_deps = [ "//base/android/jni_generator:jni_processor" ]
+}
+
 android_library("java") {
   sources = [
     "org/chromium/weblayer_private/ActionModeCallback.java",
@@ -75,6 +87,7 @@ android_library("java") {
     ":gms_bridge_java",
     ":interfaces_java",
     ":weblayer_resources",
+    ":webview_compat_java",
     "//base:base_java",
     "//base:jni_java",
     "//components/autofill/android:provider_java",
@@ -117,6 +130,20 @@ android_library("java") {
       "//third_party/android_sdk:public_framework_system_java"
 }
 
+generate_jni_registration("weblayer_jni_registration") {
+  targets = [ ":java" ]
+  header_output = "$target_gen_dir/$target_name.h"
+  sources_blacklist = _webview_compat_sources
+  namespace = "weblayer"
+}
+
+generate_jni_registration("weblayer_minimal_jni_registration") {
+  targets = [ ":webview_compat_java" ]
+  header_output = "$target_gen_dir/$target_name.h"
+  namespace = "weblayer_minimal"
+  no_transitive_deps = true
+}
+
 android_resources("weblayer_test_resources") {
   resource_dirs = [ "res_test" ]
   custom_package = "org.chromium.weblayer_private.test"
@@ -153,6 +180,7 @@ generate_jni("jni") {
     "org/chromium/weblayer_private/UrlBarControllerImpl.java",
     "org/chromium/weblayer_private/WebLayerExceptionFilter.java",
     "org/chromium/weblayer_private/WebLayerImpl.java",
+    "org/chromium/weblayer_private/WebViewCompatibilityHelperImpl.java",
     "org/chromium/weblayer_private/metrics/MetricsServiceClient.java",
     "org/chromium/weblayer_private/metrics/UmaUtils.java",
     "org/chromium/weblayer_private/resources/ResourceMapper.java",

weblayer/browser/java/org/chromium/weblayer_private/WebLayerImpl.java

@@ -190,9 +190,10 @@ public final class WebLayerImpl extends IWebLayer.Stub {
         mIsWebViewCompatMode = remoteContext != null
                 && !remoteContext.getClassLoader().equals(WebLayerImpl.class.getClassLoader());
         if (mIsWebViewCompatMode && Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
-            // We need to change the library name for Android M and below, otherwise the system will
-            // load the version loaded for WebView.
-            LibraryLoader.getInstance().setLibrarySuffix("-weblayer");
+            // Load the library with the crazy linker.
+            LibraryLoader.getInstance().setLinkerImplementation(true, false);
+            LibraryLoader.getInstance().setPostLoadHook(
+                    WebViewCompatibilityHelperImpl::registerJni);
         }
 
         Context appContext = minimalInitForContext(appContextWrapper, remoteContextWrapper);

weblayer/browser/java/org/chromium/weblayer_private/WebViewCompatibilityHelperImpl.java

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.weblayer_private;
+
+import org.chromium.base.annotations.JNINamespace;
+import org.chromium.base.annotations.MainDex;
+import org.chromium.base.annotations.NativeMethods;
+
+/**
+ * Minimal native interface to allow registering all natives if WebView compatibility is needed.
+ */
+@MainDex
+@JNINamespace("weblayer")
+public final class WebViewCompatibilityHelperImpl {
+    public static void registerJni() {
+        WebViewCompatibilityHelperImplJni.get().registerJni();
+    }
+
+    @NativeMethods
+    interface Natives {
+        void registerJni();
+    }
+}

weblayer/browser/web_view_compatibility_helper_impl.cc

+// Copyright 2020 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "weblayer/browser/java/jni/WebViewCompatibilityHelperImpl_jni.h"
+
+#if defined(WEBLAYER_MANUAL_JNI_REGISTRATION)
+#include "base/android/library_loader/library_loader_hooks.h"  // nogncheck
+#include "weblayer/browser/java/weblayer_jni_registration.h"   // nogncheck
+#endif
+
+namespace weblayer {
+namespace {
+#if defined(WEBLAYER_MANUAL_JNI_REGISTRATION)
+void RegisterNonMainDexNativesHook() {
+  RegisterNonMainDexNatives(base::android::AttachCurrentThread());
+}
+#endif
+}  // namespace
+
+void JNI_WebViewCompatibilityHelperImpl_RegisterJni(JNIEnv* env) {
+#if defined(WEBLAYER_MANUAL_JNI_REGISTRATION)
+  RegisterMainDexNatives(base::android::AttachCurrentThread());
+  base::android::SetNonMainDexJniRegistrationHook(
+      RegisterNonMainDexNativesHook);
+#endif
+}
+
+}  // namespace weblayer

weblayer/browser/weblayer_variations_service_client.cc

@@ -7,9 +7,12 @@
 #include "base/bind.h"
 #include "base/threading/scoped_blocking_call.h"
 #include "build/build_config.h"
-#include "components/version_info/android/channel_getter.h"
 #include "services/network/public/cpp/shared_url_loader_factory.h"
 
+#if defined(OS_ANDROID)
+#include "components/version_info/android/channel_getter.h"
+#endif
+
 using version_info::Channel;
 
 namespace weblayer {
@@ -47,7 +50,11 @@ WebLayerVariationsServiceClient::GetNetworkTimeTracker() {
 }
 
 Channel WebLayerVariationsServiceClient::GetChannel() {
+#if defined(OS_ANDROID)
   return version_info::android::GetChannel();
+#else
+  return version_info::Channel::UNKNOWN;
+#endif
 }
 
 bool WebLayerVariationsServiceClient::OverridesRestrictParameter(

weblayer/public/java/org/chromium/weblayer/WebLayer.java

@@ -14,6 +14,7 @@ import android.os.RemoteException;
 import android.support.v4.app.Fragment;
 import android.util.AndroidRuntimeException;
 import android.util.Log;
+import android.util.Pair;
 import android.webkit.ValueCallback;
 
 import androidx.annotation.NonNull;
@@ -33,7 +34,6 @@ import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.ExecutionException;
 
 /**
  * WebLayer is responsible for initializing state necessary to use any of the classes in web layer.
@@ -59,18 +59,12 @@ public class WebLayer {
     @NonNull
     private final IWebLayer mImpl;
 
-    private static WebViewCompatibilityHelper sWebViewCompatHelper;
+    private static ClassLoader sWebViewCompatClassLoader;
 
     /** The result of calling {@link #initializeWebViewCompatibilityMode}. */
     public enum WebViewCompatibilityResult {
-        /** Native libs were copied to data directory. */
-        SUCCESS_COPIED,
-
-        /** Correct libs have already been copied, or symlinks were used. */
-        SUCCESS_CACHED,
-
-        /** IOException was thrown, could mean there is not enough disk space. */
-        FAILURE_IO_ERROR,
+        /** Compatibility mode has been successfully set up. */
+        SUCCESS,
 
         /** This version of the WebLayer implementation does not support WebView compatibility. */
         FAILURE_UNSUPPORTED_VERSION,
@@ -100,18 +94,24 @@ public class WebLayer {
         }
     }
 
+    /** Deprecated. Use initializeWebViewCompatibilityMode(Context) instead. */
+    public static void initializeWebViewCompatibilityMode(@NonNull Context appContext,
+            @NonNull File baseDir, @NonNull Callback<WebViewCompatibilityResult> callback) {
+        WebViewCompatibilityResult result = initializeWebViewCompatibilityMode(appContext);
+        if (callback != null) {
+            callback.onResult(result);
+        }
+    }
+
     /**
-     * Performs initialization needed to run WebView and WebLayer in the same process. This should
-     * be called as early as possible if this functionality is needed.
+     * Performs initialization needed to run WebView and WebLayer in the same process.
      *
      * @param appContext The hosting application's Context.
-     * @param baseDir The directory to copy any necessary files into.
-     * @param callback Callback called on success or failure.
      */
-    public static void initializeWebViewCompatibilityMode(@NonNull Context appContext,
-            @NonNull File baseDir, @NonNull Callback<WebViewCompatibilityResult> callback) {
+    public static WebViewCompatibilityResult initializeWebViewCompatibilityMode(
+            @NonNull Context appContext) {
         ThreadCheck.ensureOnUiThread();
-        if (sWebViewCompatHelper != null) {
+        if (sWebViewCompatClassLoader != null) {
             throw new AndroidRuntimeException(
                     "initializeWebViewCompatibilityMode() has already been called.");
         }
@@ -121,13 +121,14 @@ public class WebLayer {
                     + "loaded.");
         }
         try {
-            sWebViewCompatHelper = WebViewCompatibilityHelper.initialize(
-                    appContext, getOrCreateRemoteContext(appContext), baseDir, callback);
+            Pair<ClassLoader, WebLayer.WebViewCompatibilityResult> result =
+                    WebViewCompatibilityHelper.initialize(
+                            appContext, getOrCreateRemoteContext(appContext));
+            sWebViewCompatClassLoader = result.first;
+            return result.second;
         } catch (Exception e) {
-            if (callback != null) {
-                callback.onResult(WebViewCompatibilityResult.FAILURE_OTHER);
-            }
             Log.e(TAG, "Unable to initialize WebView compatibility", e);
+            return WebViewCompatibilityResult.FAILURE_OTHER;
         }
     }
 
@@ -265,8 +266,8 @@ public class WebLayer {
             int majorVersion = -1;
             String version = "<unavailable>";
             try {
-                if (sWebViewCompatHelper != null) {
-                    remoteClassLoader = sWebViewCompatHelper.getWebLayerClassLoader();
+                if (sWebViewCompatClassLoader != null) {
+                    remoteClassLoader = sWebViewCompatClassLoader;
                 }
                 if (remoteClassLoader == null) {
                     remoteClassLoader = getOrCreateRemoteContext(appContext).getClassLoader();
@@ -285,7 +286,7 @@ public class WebLayer {
                 majorVersion = mFactory.getImplementationMajorVersion();
                 version = mFactory.getImplementationVersion();
             } catch (PackageManager.NameNotFoundException | ReflectiveOperationException
-                    | RemoteException | ExecutionException | InterruptedException e) {
+                    | RemoteException e) {
                 Log.e(TAG, "Unable to create WebLayerFactory", e);
             }
             mAvailable = available;

weblayer/public/java/org/chromium/weblayer/WebViewCompatibilityHelper.java

@@ -9,51 +9,41 @@ import android.content.pm.ApplicationInfo;
 import android.content.pm.PackageInfo;
 import android.content.pm.PackageManager;
 import android.os.Build;
-import android.system.ErrnoException;
-import android.system.Os;
 import android.text.TextUtils;
+import android.util.Pair;
 
 import dalvik.system.BaseDexClassLoader;
-import dalvik.system.DexClassLoader;
+import dalvik.system.PathClassLoader;
 
 import java.io.File;
-import java.io.FileInputStream;
-import java.io.FileOutputStream;
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.ExecutionException;
 
 /** Helper class which performs initialization needed for WebView compatibility. */
-@SuppressWarnings("NoAndroidAsyncTaskCheck")
 final class WebViewCompatibilityHelper {
-    private final PackageInfo mPackageInfo;
-    private final GetClassLoaderPathsTask mClassLoaderPathsTask;
-
-    WebViewCompatibilityHelper(String[] libraryPaths, PackageInfo packageInfo, File baseDir,
-            Callback<WebLayer.WebViewCompatibilityResult> callback) {
-        mPackageInfo = packageInfo;
-        mClassLoaderPathsTask =
-                new GetClassLoaderPathsTask(libraryPaths, mPackageInfo, baseDir, callback);
-        mClassLoaderPathsTask.executeOnExecutor(android.os.AsyncTask.THREAD_POOL_EXECUTOR);
-    }
-
-    /** Creates a WebViewCompatibilityHelper and begins initialization. */
-    static WebViewCompatibilityHelper initialize(Context appContext, Context remoteContext,
-            File baseDir, Callback<WebLayer.WebViewCompatibilityResult> callback)
+    /** Creates a the ClassLoader to use for WebView compatibility. */
+    static Pair<ClassLoader, WebLayer.WebViewCompatibilityResult> initialize(
+            Context appContext, Context remoteContext)
             throws PackageManager.NameNotFoundException, ReflectiveOperationException {
         PackageInfo info =
                 appContext.getPackageManager().getPackageInfo(remoteContext.getPackageName(),
                         PackageManager.GET_SHARED_LIBRARY_FILES
                                 | PackageManager.MATCH_UNINSTALLED_PACKAGES);
         if (!isSupportedVersion(info.versionName)) {
-            if (callback != null) {
-                callback.onResult(WebLayer.WebViewCompatibilityResult.FAILURE_UNSUPPORTED_VERSION);
-            }
-            return null;
+            return Pair.create(
+                    null, WebLayer.WebViewCompatibilityResult.FAILURE_UNSUPPORTED_VERSION);
         }
-        return new WebViewCompatibilityHelper(
-                getLibraryPaths(remoteContext.getClassLoader()), info, baseDir, callback);
+        // Prepend "/." to all library paths. This changes the library path while still pointing to
+        // the same directory, allowing us to get around a check in the JVM.
+        String[] libraryPaths = getLibraryPaths(remoteContext.getClassLoader());
+        for (int i = 0; i < libraryPaths.length; i++) {
+            assert libraryPaths[i].startsWith("/");
+            libraryPaths[i] = "/." + libraryPaths[i];
+        }
+        ClassLoader classLoader = new PathClassLoader(getAllApkPaths(info.applicationInfo),
+                TextUtils.join(File.pathSeparator, libraryPaths),
+                ClassLoader.getSystemClassLoader());
+        return Pair.create(classLoader, WebLayer.WebViewCompatibilityResult.SUCCESS);
     }
 
     /**
@@ -75,22 +65,11 @@ final class WebViewCompatibilityHelper {
         } catch (NumberFormatException e) {
             return false;
         }
-        return majorVersion >= 81;
-    }
-
-    /**
-     * Returns the class loader to be used for WebView compatibility. This class loader will not
-     * interfere with any WebViews that are created.
-     */
-    ClassLoader getWebLayerClassLoader() throws ExecutionException, InterruptedException {
-        ClassLoaderPaths paths = mClassLoaderPathsTask.get();
-        if (paths.mResult != WebLayer.WebViewCompatibilityResult.SUCCESS_CACHED
-                && paths.mResult != WebLayer.WebViewCompatibilityResult.SUCCESS_COPIED) {
-            return null;
+        // M- only supports WebView compat via copying the libraries on 81, so only support 82+.
+        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
+            return majorVersion >= 82;
         }
-        return new DexClassLoader(getAllApkPaths(mPackageInfo.applicationInfo),
-                paths.mOptimizedDirectory, paths.mLibrarySearchPath,
-                ClassLoader.getSystemClassLoader());
+        return majorVersion >= 81;
     }
 
     /** Returns the library paths the given class loader will search. */
@@ -103,7 +82,7 @@ final class WebViewCompatibilityHelper {
     }
 
     /** This is mostly taken from ApplicationInfo.getAllApkPaths(). */
-    private String getAllApkPaths(ApplicationInfo info) {
+    private static String getAllApkPaths(ApplicationInfo info) {
         // The OS version of this method also includes resourceDirs, but this is not available in
         // the SDK.
         final String[][] inputLists = {info.sharedLibraryFiles, info.splitSourceDirs};
@@ -121,158 +100,5 @@ final class WebViewCompatibilityHelper {
         return TextUtils.join(File.pathSeparator, output);
     }
 
-    private class ClassLoaderPaths {
-        String mLibrarySearchPath;
-        String mOptimizedDirectory;
-        WebLayer.WebViewCompatibilityResult mResult =
-                WebLayer.WebViewCompatibilityResult.SUCCESS_CACHED;
-    }
-
-    /**
-     * Task to retrieve file paths which should be used when creating a class loader compatible
-     * with WebView.
-     */
-    private class GetClassLoaderPathsTask
-            extends android.os.AsyncTask<Void, Void, ClassLoaderPaths> {
-        private static final String PRIVATE_DIR = "weblayer_private";
-
-        private final String[] mOriginalLibraryPaths;
-        private final PackageInfo mPackageInfo;
-        private final File mBaseDir;
-        private final Callback<WebLayer.WebViewCompatibilityResult> mCallback;
-
-        public GetClassLoaderPathsTask(String[] libraryPaths, PackageInfo packageInfo, File baseDir,
-                Callback<WebLayer.WebViewCompatibilityResult> callback) {
-            mOriginalLibraryPaths = libraryPaths;
-            mPackageInfo = packageInfo;
-            mBaseDir = baseDir;
-            mCallback = callback;
-        }
-
-        @Override
-        protected ClassLoaderPaths doInBackground(Void... params) {
-            File webLayerDir = getWebLayerDir();
-            ClassLoaderPaths paths = new ClassLoaderPaths();
-            try {
-                addLibrarySearchPath(webLayerDir, paths);
-            } catch (ErrnoException | IOException e) {
-                // Make sure to clean up anything left over after an IOException.
-                recursivelyDeleteFile(new File(mBaseDir, PRIVATE_DIR));
-
-                paths.mResult = WebLayer.WebViewCompatibilityResult.FAILURE_IO_ERROR;
-                return paths;
-            }
-            File codeCacheDir = new File(webLayerDir, "codecache");
-            codeCacheDir.mkdirs();
-            paths.mOptimizedDirectory = codeCacheDir.toString();
-            return paths;
-        }
-
-        @Override
-        protected void onPostExecute(ClassLoaderPaths paths) {
-            if (mCallback != null) {
-                mCallback.onResult(paths.mResult);
-            }
-        }
-
-        /**
-         * Creates the directory to copy/symlink WebView libraries. This will be a directory
-         * structure like files/weblayer_private/374100010/.
-         */
-        private File getWebLayerDir() {
-            File webLayerDir = new File(mBaseDir, PRIVATE_DIR);
-            webLayerDir.mkdirs();
-            // Clean up previous versions before we copy any files.
-            String[] names = webLayerDir.list();
-            String versionCodeString = String.valueOf(mPackageInfo.versionCode);
-            if (names != null) {
-                for (String name : names) {
-                    if (!name.equals(versionCodeString)) {
-                        recursivelyDeleteFile(new File(webLayerDir, name));
-                    }
-                }
-            }
-
-            File finalDir = new File(webLayerDir, versionCodeString);
-            finalDir.mkdirs();
-            return finalDir;
-        }
-
-        private void addLibrarySearchPath(File webLayerDir, ClassLoaderPaths paths)
-                throws ErrnoException, IOException {
-            ArrayList<String> finalPaths = new ArrayList<>();
-            for (int i = 0; i < mOriginalLibraryPaths.length; i++) {
-                File path = new File(mOriginalLibraryPaths[i]);
-                // Skip libs from other directories like /vendor.
-                if (!path.toString().startsWith("/data")) {
-                    continue;
-                }
-                File newPath = new File(webLayerDir, "lib" + i);
-                String suffix = "";
-                if (path.toString().contains("!")) {
-                    String[] splitPath = path.toString().split("!");
-                    path = new File(splitPath[0]);
-                    suffix = "!" + splitPath[1];
-                }
-                if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
-                    // If this path isn't a directory, it's probably pointing to the APK. We don't
-                    // want to try to copy the APK, and libraries are only stored in the APK in
-                    // Monochrome/Trichrome which is only used for N+.
-                    if (!path.isDirectory()) {
-                        continue;
-                    }
-                    for (String libName : path.list()) {
-                        // Make sure we only copy the necessary lib.
-                        if (!libName.equals("libwebviewchromium.so")) {
-                            continue;
-                        }
-                        File oldFile = new File(path, libName);
-                        File newFile = new File(newPath, libName.replace(".so", "-weblayer.so"));
-                        if (!newFile.exists()) {
-                            newPath.mkdirs();
-                            copyFile(oldFile, newFile);
-                            paths.mResult = WebLayer.WebViewCompatibilityResult.SUCCESS_COPIED;
-                        }
-                    }
-                } else {
-                    newPath.mkdirs();
-                    // Make sure to re-create the symlink in case the WebView APK moved.
-                    newPath.delete();
-                    Os.symlink(path.toString(), newPath.toString());
-                }
-                finalPaths.add(newPath.toString() + suffix);
-            }
-            paths.mLibrarySearchPath = TextUtils.join(File.pathSeparator, finalPaths);
-        }
-
-        private void copyFile(File src, File dst) throws IOException {
-            try (FileInputStream inputStream = new FileInputStream(src);
-                    FileOutputStream outputStream = new FileOutputStream(dst)) {
-                byte[] bytes = new byte[8192];
-                int length;
-                while ((length = inputStream.read(bytes)) > 0) {
-                    outputStream.write(bytes, 0, length);
-                }
-            }
-        }
-
-        private void recursivelyDeleteFile(File currentFile) {
-            if (!currentFile.exists()) {
-                // This file could be a broken symlink, so try to delete. If we don't delete a
-                // broken symlink, the directory containing it cannot be deleted.
-                currentFile.delete();
-                return;
-            }
-            if (currentFile.isDirectory()) {
-                File[] files = currentFile.listFiles();
-                if (files != null) {
-                    for (File file : files) {
-                        recursivelyDeleteFile(file);
-                    }
-                }
-            }
-
-            currentFile.delete();
-        }
-    }
+    private WebViewCompatibilityHelper() {}
 }

weblayer/public/javatests/org/chromium/weblayer/WebViewCompatibilityHelperTest.java

@@ -4,265 +4,49 @@
 
 package org.chromium.weblayer;
 
-import android.content.pm.ApplicationInfo;
-import android.content.pm.PackageInfo;
+import android.content.Context;
 import android.os.Build;
 import android.support.test.InstrumentationRegistry;
 import android.support.test.filters.SmallTest;
-
-import dalvik.system.DexClassLoader;
+import android.util.Pair;
 
 import org.junit.Assert;
-import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
-import org.chromium.base.FileUtils;
 import org.chromium.base.test.BaseJUnit4ClassRunner;
-import org.chromium.base.test.util.CallbackHelper;
-import org.chromium.base.test.util.MinAndroidSdkLevel;
-import org.chromium.base.test.util.TestFileUtil;
-
-import java.io.ByteArrayInputStream;
-import java.io.File;
-import java.io.IOException;
-import java.util.concurrent.TimeoutException;
 
 /**
  * Tests for (@link WebViewCompatibilityHelper}.
  */
 @RunWith(BaseJUnit4ClassRunner.class)
 public class WebViewCompatibilityHelperTest {
-    private File mTmpDir;
-    private File mOriginalLibDir;
-    private File mNewLibDir;
-    private PackageInfo mPackageInfo;
-
-    private static class ResultHelper implements Callback<WebLayer.WebViewCompatibilityResult> {
-        private WebLayer.WebViewCompatibilityResult mResult;
-        private CallbackHelper mCallbackHelper = new CallbackHelper();
-
-        @Override
-        public void onResult(WebLayer.WebViewCompatibilityResult result) {
-            mResult = result;
-            mCallbackHelper.notifyCalled();
-        }
-
-        public WebLayer.WebViewCompatibilityResult getResult() throws TimeoutException {
-            mCallbackHelper.waitForFirst();
-            return mResult;
-        }
-    }
-
-    @Before
-    public void setUp() {
-        mTmpDir = InstrumentationRegistry.getTargetContext().getCacheDir();
-        mOriginalLibDir = new File(mTmpDir, "original");
-        mOriginalLibDir.mkdirs();
-
-        mNewLibDir = new File(mTmpDir, "new");
-
-        mPackageInfo = new PackageInfo();
-        mPackageInfo.versionCode = 1;
-        ApplicationInfo applicationInfo = new ApplicationInfo();
-        applicationInfo.publicSourceDir = new File(mTmpDir, "fake.apk").toString();
-        mPackageInfo.applicationInfo = applicationInfo;
-    }
-
     @Test
     @SmallTest
-    public void testLibsCopied() throws Exception {
-        writeFile(new File(mOriginalLibDir, "libwebviewchromium.so"), "foo");
-        writeFile(new File(mOriginalLibDir, "libbar.so"), "bar");
-        String[] libraryPaths = new String[] {mOriginalLibDir.toString()};
-        ResultHelper helper = new ResultHelper();
-        DexClassLoader classLoader = (DexClassLoader) new WebViewCompatibilityHelper(
-                libraryPaths, mPackageInfo, mNewLibDir, helper)
-                                             .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), getExpectedCopyResult());
-
-        File libDir = new File(mNewLibDir, "weblayer_private/1/lib0");
-        File foo = new File(libDir, getExpectedLibFileName());
-        Assert.assertEquals(readFile(foo), "foo");
-        Assert.assertEquals(classLoader.findLibrary(getExpectedLibName()), foo.toString());
-        // M- will only copy libwebviewchromium.so.
-        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.M) {
-            File bar = new File(libDir, "libbar.so");
-            Assert.assertEquals(readFile(bar), "bar");
-            Assert.assertEquals(classLoader.findLibrary("bar"), bar.toString());
-        }
-
-        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
-            Assert.assertFalse(isSymlink(libDir));
-        } else {
-            Assert.assertTrue(isSymlink(libDir));
+    public void testLibraryPaths() throws Exception {
+        Context appContext = InstrumentationRegistry.getTargetContext();
+        Context remoteContext = WebLayer.getOrCreateRemoteContext(appContext);
+        Pair<ClassLoader, WebLayer.WebViewCompatibilityResult> result =
+                WebViewCompatibilityHelper.initialize(appContext, remoteContext);
+        Assert.assertEquals(result.second, WebLayer.WebViewCompatibilityResult.SUCCESS);
+        String[] libraryPaths = WebViewCompatibilityHelper.getLibraryPaths(result.first);
+        for (String path : libraryPaths) {
+            Assert.assertTrue(path.startsWith("/./"));
         }
     }
 
     @Test
     @SmallTest
-    public void testIoError() throws Exception {
-        writeFile(new File(mOriginalLibDir, "libwebviewchromium.so"), "foo");
-        String[] libraryPaths = new String[] {mOriginalLibDir.toString()};
-        ResultHelper helper = new ResultHelper();
-        DexClassLoader classLoader = (DexClassLoader) new WebViewCompatibilityHelper(
-                libraryPaths, mPackageInfo, new File("/bad_dir"), helper)
-                                             .getWebLayerClassLoader();
-        Assert.assertNull(classLoader);
-        Assert.assertEquals(
-                helper.getResult(), WebLayer.WebViewCompatibilityResult.FAILURE_IO_ERROR);
-    }
-
-    @Test
-    @SmallTest
-    public void testMultipleLibDirs() throws Exception {
-        writeFile(new File(mOriginalLibDir, "foo/foo"), "foo");
-        writeFile(new File(mOriginalLibDir, "bar/libwebviewchromium.so"), "bar");
-        String[] libraryPaths = new String[] {new File(mOriginalLibDir, "foo").toString(),
-                new File(mOriginalLibDir, "bar").toString()};
-        ResultHelper helper = new ResultHelper();
-        new WebViewCompatibilityHelper(libraryPaths, mPackageInfo, mNewLibDir, helper)
-                .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), getExpectedCopyResult());
-
-        // M- will only copy libwebviewchromium.so.
+    public void testSupportedVersion() throws Exception {
         if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
-            Assert.assertFalse(new File(mNewLibDir, "weblayer_private/1/lib0/").exists());
-            Assert.assertTrue(
-                    new File(mNewLibDir, "weblayer_private/1/lib1/" + getExpectedLibFileName())
-                            .exists());
+            Assert.assertFalse(WebViewCompatibilityHelper.isSupportedVersion("81.0.2.5"));
         } else {
-            Assert.assertTrue(new File(mNewLibDir, "weblayer_private/1/lib0/foo").exists());
-            Assert.assertTrue(
-                    new File(mNewLibDir, "weblayer_private/1/lib1/" + getExpectedLibFileName())
-                            .exists());
-        }
-    }
-
-    @Test
-    @SmallTest
-    public void testLibsNotCopiedAgain() throws Exception {
-        writeFile(new File(mOriginalLibDir, "libwebviewchromium.so"), "foo");
-        String[] libraryPaths = new String[] {mOriginalLibDir.toString()};
-        ResultHelper helper = new ResultHelper();
-        new WebViewCompatibilityHelper(libraryPaths, mPackageInfo, mNewLibDir, helper)
-                .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), getExpectedCopyResult());
-
-        File foo = new File(mNewLibDir, "weblayer_private/1/lib0/" + getExpectedLibFileName());
-        Assert.assertTrue(foo.exists());
-        long lastModified = foo.lastModified();
-
-        // Sleep for 1 sec to guarantee last modified would have changed.
-        Thread.sleep(1000);
-
-        helper = new ResultHelper();
-        new WebViewCompatibilityHelper(libraryPaths, mPackageInfo, mNewLibDir, helper)
-                .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), WebLayer.WebViewCompatibilityResult.SUCCESS_CACHED);
-        Assert.assertTrue(foo.exists());
-        Assert.assertEquals(foo.lastModified(), lastModified);
-    }
-
-    @Test
-    @SmallTest
-    public void testOldLibsDeleted() throws Exception {
-        writeFile(new File(mOriginalLibDir, "libwebviewchromium.so"), "foo");
-        String[] libraryPaths = new String[] {mOriginalLibDir.toString()};
-        ResultHelper helper = new ResultHelper();
-        new WebViewCompatibilityHelper(libraryPaths, mPackageInfo, mNewLibDir, helper)
-                .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), getExpectedCopyResult());
-
-        File oldFile = new File(mNewLibDir, "weblayer_private/1/lib0/" + getExpectedLibFileName());
-        Assert.assertTrue(oldFile.exists());
-
-        FileUtils.recursivelyDeleteFile(mOriginalLibDir, FileUtils.DELETE_ALL);
-
-        File originalLibDir2 = new File(mTmpDir, "original2");
-        originalLibDir2.mkdirs();
-        writeFile(new File(originalLibDir2, "libwebviewchromium.so"), "foo2");
-        mPackageInfo.versionCode = 2;
-        libraryPaths = new String[] {originalLibDir2.toString()};
-        helper = new ResultHelper();
-        new WebViewCompatibilityHelper(libraryPaths, mPackageInfo, mNewLibDir, helper)
-                .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), getExpectedCopyResult());
-        Assert.assertFalse(oldFile.exists());
-        Assert.assertFalse(new File(mNewLibDir, "weblayer_private/1").exists());
-
-        Assert.assertEquals(readFile(new File(mNewLibDir,
-                                    "weblayer_private/2/lib0/" + getExpectedLibFileName())),
-                "foo2");
-    }
-
-    @Test
-    @SmallTest
-    @MinAndroidSdkLevel(Build.VERSION_CODES.N)
-    public void testZipPath() throws Exception {
-        File originalZip = new File(mOriginalLibDir, "foo.apk");
-        writeFile(originalZip, "zip stuff");
-        String[] libraryPaths = new String[] {originalZip.toString() + "!/libs"};
-        ResultHelper helper = new ResultHelper();
-        ClassLoader classLoader =
-                new WebViewCompatibilityHelper(libraryPaths, mPackageInfo, mNewLibDir, helper)
-                        .getWebLayerClassLoader();
-        Assert.assertEquals(helper.getResult(), getExpectedCopyResult());
-
-        File newZip = new File(mNewLibDir, "weblayer_private/1/lib0");
-        Assert.assertArrayEquals(WebViewCompatibilityHelper.getLibraryPaths(classLoader),
-                new String[] {newZip.toString() + "!/libs"});
-        Assert.assertTrue(newZip.exists());
-        Assert.assertTrue(isSymlink(newZip));
-    }
-
-    @Test
-    @SmallTest
-    public void testSupportedVersion() throws Exception {
         Assert.assertTrue(WebViewCompatibilityHelper.isSupportedVersion("81.0.2.5"));
+        }
         Assert.assertTrue(WebViewCompatibilityHelper.isSupportedVersion("82.0.2.5"));
         Assert.assertFalse(WebViewCompatibilityHelper.isSupportedVersion("80.0.2.5"));
         Assert.assertFalse(WebViewCompatibilityHelper.isSupportedVersion(""));
         Assert.assertFalse(WebViewCompatibilityHelper.isSupportedVersion("82.0"));
         Assert.assertFalse(WebViewCompatibilityHelper.isSupportedVersion(null));
     }
-
-    private void writeFile(File file, String contents) throws Exception {
-        file.getParentFile().mkdirs();
-        FileUtils.copyStreamToFile(new ByteArrayInputStream(contents.getBytes()), file);
-    }
-
-    private String readFile(File file) throws Exception {
-        // Assert.assertTrue(file.exists());
-        return new String(TestFileUtil.readUtf8File(file.toString(), 1024 /* sizeLimit */));
-    }
-
-    private boolean isSymlink(File file) throws IOException {
-        File canonical;
-        if (file.getParent() == null) {
-            canonical = file;
-        } else {
-            File canonicalDir = file.getParentFile().getCanonicalFile();
-            canonical = new File(canonicalDir, file.getName());
-        }
-        return !canonical.getCanonicalFile().equals(canonical.getAbsoluteFile());
-    }
-
-    private static String getExpectedLibName() {
-        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
-            return "webviewchromium-weblayer";
-        }
-        return "webviewchromium";
-    }
-
-    private static String getExpectedLibFileName() {
-        return "lib" + getExpectedLibName() + ".so";
-    }
-
-    private static WebLayer.WebViewCompatibilityResult getExpectedCopyResult() {
-        if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
-            return WebLayer.WebViewCompatibilityResult.SUCCESS_COPIED;
-        }
-        return WebLayer.WebViewCompatibilityResult.SUCCESS_CACHED;
-    }
 }