Tinker源码分析(三):加载dex补丁流程

俞其荣

发布于 2019-03-15 15:57:21

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发布于 2019-03-15 15:57:21

文章被收录于专栏：俞其荣的博客俞其荣的博客

本系列 Tinker 源码解析基于 Tinker v1.9.12

加载dex补丁流程

TinkerDexLoader.loadTinkerJars

判断一下 dexList 和 classLoader

    if (loadDexList.isEmpty() && classNDexInfo.isEmpty()) {
        Log.w(TAG, "there is no dex to load");
        return true;
    }
    
    PathClassLoader classLoader = (PathClassLoader) TinkerDexLoader.class.getClassLoader();
    if (classLoader != null) {
        Log.i(TAG, "classloader: " + classLoader.toString());
    } else {
        Log.e(TAG, "classloader is null");
        ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_DEX_CLASSLOADER_NULL);
        return false;
    }

如果 TinkerLoadVerifyFlag 为 true 的话，会对每个 dex 进行 md5 校验

    String dexPath = directory + "/" + DEX_PATH + "/";
    
    ArrayList<File> legalFiles = new ArrayList<>();
    
    for (ShareDexDiffPatchInfo info : loadDexList) {
        //for dalvik, ignore art support dex
        // 对于 dalvik 虚拟机，忽略 art support dex
        if (isJustArtSupportDex(info)) {
            continue;
        }
    
        String path = dexPath + info.realName;
        File file = new File(path);
    
        if (application.isTinkerLoadVerifyFlag()) {
            long start = System.currentTimeMillis();
            String checkMd5 = getInfoMd5(info);
            // 校验dex文件的 md5 值
            if (!SharePatchFileUtil.verifyDexFileMd5(file, checkMd5)) {
                //it is good to delete the mismatch file
                ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_DEX_MD5_MISMATCH);
                intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_MISMATCH_DEX_PATH,
                    file.getAbsolutePath());
                return false;
            }
            Log.i(TAG, "verify dex file:" + file.getPath() + " md5, use time: " + (System.currentTimeMillis() - start));
        }
        // dex文件都通过的话，加入到 legalFiles 集合中 
        legalFiles.add(file);
    }

如果是 art 虚拟机并且是 Android N 及以上的环境，会另外加上 tinker_classN.apk

    // verify merge classN.apk
    if (isVmArt && !classNDexInfo.isEmpty()) {
        File classNFile = new File(dexPath + ShareConstants.CLASS_N_APK_NAME);
        long start = System.currentTimeMillis();
    
        if (application.isTinkerLoadVerifyFlag()) {
            for (ShareDexDiffPatchInfo info : classNDexInfo) {
                if (!SharePatchFileUtil.verifyDexFileMd5(classNFile, info.rawName, info.destMd5InArt)) {
                    ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_DEX_MD5_MISMATCH);
                    intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_MISMATCH_DEX_PATH,
                        classNFile.getAbsolutePath());
                    return false;
                }
            }
        }
        Log.i(TAG, "verify dex file:" + classNFile.getPath() + " md5, use time: " + (System.currentTimeMillis() - start));
    
        legalFiles.add(classNFile);
    }

如果用户是ART虚拟机并且做了OTA升级，那么在加载dex补丁的时候就会先把最近一次的补丁全部DexFile.loadDex一遍.这么做的原因是有些场景做了OTA后,oat的规则可能发生变化,在这种情况下去加载上个系统版本oat过的dex就会出现问题.

    File optimizeDir = new File(directory + "/" + oatDir);
    
            if (isSystemOTA) {
                final boolean[] parallelOTAResult = {true};
                final Throwable[] parallelOTAThrowable = new Throwable[1];
                String targetISA;
                try {
                    targetISA = ShareTinkerInternals.getCurrentInstructionSet();
                } catch (Throwable throwable) {
                    Log.i(TAG, "getCurrentInstructionSet fail:" + throwable);
    //                try {
    //                    targetISA = ShareOatUtil.getOatFileInstructionSet(testOptDexFile);
    //                } catch (Throwable throwable) {
                    // don't ota on the front
                    deleteOutOfDateOATFile(directory);
    
                    intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_INTERPRET_EXCEPTION, throwable);
                    ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_GET_OTA_INSTRUCTION_SET_EXCEPTION);
                    return false;
    //                }
                }
    
                deleteOutOfDateOATFile(directory);
    
                Log.w(TAG, "systemOTA, try parallel oat dexes, targetISA:" + targetISA);
                // change dir
                optimizeDir = new File(directory + "/" + INTERPRET_DEX_OPTIMIZE_PATH);
    
                // 对 dex 文件作 odex 处理
                TinkerDexOptimizer.optimizeAll(
                    legalFiles, optimizeDir, true, targetISA,
                    new TinkerDexOptimizer.ResultCallback() {
                        long start;
    
                        @Override
                        public void onStart(File dexFile, File optimizedDir) {
                            start = System.currentTimeMillis();
                            Log.i(TAG, "start to optimize dex:" + dexFile.getPath());
                        }
    
                        @Override
                        public void onSuccess(File dexFile, File optimizedDir, File optimizedFile) {
                            // Do nothing.
                            Log.i(TAG, "success to optimize dex " + dexFile.getPath() + ", use time " + (System.currentTimeMillis() - start));
                        }
    
                        @Override
                        public void onFailed(File dexFile, File optimizedDir, Throwable thr) {
                            parallelOTAResult[0] = false;
                            parallelOTAThrowable[0] = thr;
                            Log.i(TAG, "fail to optimize dex " + dexFile.getPath() + ", use time " + (System.currentTimeMillis() - start));
                        }
                    }
                );
    
    
                if (!parallelOTAResult[0]) {
                    Log.e(TAG, "parallel oat dexes failed");
                    intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_INTERPRET_EXCEPTION, parallelOTAThrowable[0]);
                    ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_OTA_INTERPRET_ONLY_EXCEPTION);
                    return false;
                }
            }

加载dex

    try {
           SystemClassLoaderAdder.installDexes(application, classLoader, optimizeDir, legalFiles);
       } catch (Throwable e) {
           Log.e(TAG, "install dexes failed");
    //            e.printStackTrace();
           intentResult.putExtra(ShareIntentUtil.INTENT_PATCH_EXCEPTION, e);
           ShareIntentUtil.setIntentReturnCode(intentResult, ShareConstants.ERROR_LOAD_PATCH_VERSION_DEX_LOAD_EXCEPTION);
           return false;
       }
        
       return true;

SystemClassLoaderAdder.installDexes

    public static void installDexes(Application application, PathClassLoader loader, File dexOptDir, List<File> files)
        throws Throwable {
        Log.i(TAG, "installDexes dexOptDir: " + dexOptDir.getAbsolutePath() + ", dex size:" + files.size());
    
        if (!files.isEmpty()) {
            files = createSortedAdditionalPathEntries(files);
            ClassLoader classLoader = loader;
            if (Build.VERSION.SDK_INT >= 24 && !checkIsProtectedApp(files)) {
                classLoader = AndroidNClassLoader.inject(loader, application);
            }
            //because in dalvik, if inner class is not the same classloader with it wrapper class.
            //it won't fail at dex2opt
            if (Build.VERSION.SDK_INT >= 23) {
                V23.install(classLoader, files, dexOptDir);
            } else if (Build.VERSION.SDK_INT >= 19) {
                V19.install(classLoader, files, dexOptDir);
            } else if (Build.VERSION.SDK_INT >= 14) {
                V14.install(classLoader, files, dexOptDir);
            } else {
                V4.install(classLoader, files, dexOptDir);
            }
            //install done
            sPatchDexCount = files.size();
            Log.i(TAG, "after loaded classloader: " + classLoader + ", dex size:" + sPatchDexCount);
    
            if (!checkDexInstall(classLoader)) {
                //reset patch dex
                SystemClassLoaderAdder.uninstallPatchDex(classLoader);
                throw new TinkerRuntimeException(ShareConstants.CHECK_DEX_INSTALL_FAIL);
            }
        }
    }

可以看到，在加载 dex 的时候，分别分成了四个版本：

其中如果是 SDK 24 及以上，需要改造一下 classloder

针对每个版本不同的源码，进行 dex 插入

我们就来看其中一个版本 v19

    private static final class V19 {
    
        private static void install(ClassLoader loader, List<File> additionalClassPathEntries,
                                    File optimizedDirectory)
            throws IllegalArgumentException, IllegalAccessException,
            NoSuchFieldException, InvocationTargetException, NoSuchMethodException, IOException {
            /* The patched class loader is expected to be a descendant of
             * dalvik.system.BaseDexClassLoader. We modify its
             * dalvik.system.DexPathList pathList field to append additional DEX
             * file entries.
             */
            Field pathListField = ShareReflectUtil.findField(loader, "pathList");
            Object dexPathList = pathListField.get(loader);
            ArrayList<IOException> suppressedExceptions = new ArrayList<IOException>();
            ShareReflectUtil.expandFieldArray(dexPathList, "dexElements", makeDexElements(dexPathList,
                new ArrayList<File>(additionalClassPathEntries), optimizedDirectory,
                suppressedExceptions));
            if (suppressedExceptions.size() > 0) {
                for (IOException e : suppressedExceptions) {
                    Log.w(TAG, "Exception in makeDexElement", e);
                    throw e;
                }
            }
        }
    
        /**
         * A wrapper around
         * {@code private static final dalvik.system.DexPathList#makeDexElements}.
         */
        private static Object[] makeDexElements(
            Object dexPathList, ArrayList<File> files, File optimizedDirectory,
            ArrayList<IOException> suppressedExceptions)
            throws IllegalAccessException, InvocationTargetException, NoSuchMethodException {
    
            Method makeDexElements = null;
            try {
                makeDexElements = ShareReflectUtil.findMethod(dexPathList, "makeDexElements", ArrayList.class, File.class,
                    ArrayList.class);
            } catch (NoSuchMethodException e) {
                Log.e(TAG, "NoSuchMethodException: makeDexElements(ArrayList,File,ArrayList) failure");
                // 对不同的 rom 做兼容，有的 rom 的 makeDexElements 方法参数类型是 List
                try {
                    makeDexElements = ShareReflectUtil.findMethod(dexPathList, "makeDexElements", List.class, File.class, List.class);
                } catch (NoSuchMethodException e1) {
                    Log.e(TAG, "NoSuchMethodException: makeDexElements(List,File,List) failure");
                    throw e1;
                }
            }
    
            return (Object[]) makeDexElements.invoke(dexPathList, files, optimizedDirectory, suppressedExceptions);
        }
    }

首先反射拿到反射得到 PathClassLoader 中的 pathList 对象,再将补丁文件通过反射调用makeDexElements 得到补丁文件的 Element[] ,再将补丁包的 Element[] 数组插入到 dexElements 中

另外，需要对 Android 7.0 及以上单独处理一下，具体看 Android N混合编译与对热补丁影响解析

加载补丁操作做好之后，最后还要检查一下，如果没加载成功就会执行卸载：

    if (!checkDexInstall(classLoader)) {
        //reset patch dex
        SystemClassLoaderAdder.uninstallPatchDex(classLoader);
        throw new TinkerRuntimeException(ShareConstants.CHECK_DEX_INSTALL_FAIL);
    }

具体验证补丁是否加载成功的方法就是判断 TinkerTestDexLoad.isPatch 的值。

在没有补丁加载的情况下都是返回 false 的, 在补丁中修改 isPatch 属性为 true 。所以只要反射拿到isPatch 的属性为 true 就说明补丁已经成功加载进来了。否则就调用 SystemClassLoaderAdder.uninstallPatchDex 执行卸载

    public static void uninstallPatchDex(ClassLoader classLoader) throws Throwable {
        if (sPatchDexCount <= 0) {
            return;
        }
        if (Build.VERSION.SDK_INT >= 14) {
            Field pathListField = ShareReflectUtil.findField(classLoader, "pathList");
            Object dexPathList = pathListField.get(classLoader);
            ShareReflectUtil.reduceFieldArray(dexPathList, "dexElements", sPatchDexCount);
        } else {
            ShareReflectUtil.reduceFieldArray(classLoader, "mPaths", sPatchDexCount);
            ShareReflectUtil.reduceFieldArray(classLoader, "mFiles", sPatchDexCount);
            ShareReflectUtil.reduceFieldArray(classLoader, "mZips", sPatchDexCount);
            try {
                ShareReflectUtil.reduceFieldArray(classLoader, "mDexs", sPatchDexCount);
            } catch (Exception e) {
            }
        }
    }

卸载补丁可以说是加载补丁的逆向操作，具体操作可以分成 v4 和 v14 两个版本

具体的内容就是把 dexElements 中的头部 element 去除了。

到这，dex 补丁加载的流程结束了。

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原始发表：2019.03.11 ，如有侵权请联系 cloudcommunity@tencent.com 删除

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