Tinker 资源修复

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Tinker 资源修复

资源修复的原理参考了 Instant Run warm swap 的技术方案:

构建一个新的AssertManager，通过反射调用它的addAssetPath方法把新push到设备上的改动资源的路径加进去，然后还是通过反射把当前所有使用中的AssertManager替换成这个新的，再重启就能找到修改后的资源

资源的diff

资源的 diff 在 ResDiffDecoder.java 中完成：

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public boolean patch(File oldFile, File newFile) throws IOException, TinkerPatchException {
    String name = getRelativePathStringToNewFile(newFile);
		//处理删除的资源文件，将文件路径记录在 deletedSet 集合中
    //actually, it won't go below
    if (newFile == null || !newFile.exists()) {
        String relativeStringByOldDir = getRelativePathStringToOldFile(oldFile);
        if (Utils.checkFileInPattern(config.mResIgnoreChangePattern, relativeStringByOldDir)) {
            Logger.e("found delete resource: " + relativeStringByOldDir + " ,but it match ignore change pattern, just ignore!");
            return false;
        }
        deletedSet.add(relativeStringByOldDir);
        writeResLog(newFile, oldFile, TypedValue.DEL);
        return true;
    }
		//处理新增的资源文件，将新文件路径记录在 addedSet 集合中
    File outputFile = getOutputPath(newFile).toFile();
    if (oldFile == null || !oldFile.exists()) {
        if (Utils.checkFileInPattern(config.mResIgnoreChangePattern, name)) {
            Logger.e("found add resource: " + name + " ,but it match ignore change pattern, just ignore!");
            return false;
        }
        FileOperation.copyFileUsingStream(newFile, outputFile);
        addedSet.add(name);
        writeResLog(newFile, oldFile, TypedValue.ADD);
        return true;
    }
    //both file length is 0
    if (oldFile.length() == 0 && newFile.length() == 0) {
        return false;
    }
    //new add file
    String newMd5 = MD5.getMD5(newFile);
    String oldMd5 = MD5.getMD5(oldFile);
    //oldFile or newFile may be 0b length
    if (oldMd5 != null && oldMd5.equals(newMd5)) {
        return false;
    }
    if (Utils.checkFileInPattern(config.mResIgnoreChangePattern, name)) {
        Logger.d("found modify resource: " + name + ", but it match ignore change pattern, just ignore!");
        return false;
    }
    if (name.equals(TypedValue.RES_MANIFEST)) {
        Logger.d("found modify resource: " + name + ", but it is AndroidManifest.xml, just ignore!");
        return false;
    }
    if (name.equals(TypedValue.RES_ARSC)) {
        if (AndroidParser.resourceTableLogicalChange(config)) {
            Logger.d("found modify resource: " + name + ", but it is logically the same as original new resources.arsc, just ignore!");
            return false;
        }
    }
    //处理修改的资源文件
    dealWithModifyFile(name, newMd5, oldFile, newFile, outputFile);
    return true;
}
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private boolean dealWithModifyFile(String name, String newMd5, File oldFile, File newFile, File outputFile) throws IOException {
		//如果新文件的大小超过了阈值，则尝试采用二进制差分BSDiff
    if (checkLargeModFile(newFile)) {
        if (!outputFile.getParentFile().exists()) {
            outputFile.getParentFile().mkdirs();
        }
        BSDiff.bsdiff(oldFile, newFile, outputFile);
        //treat it as normal modify
        //如果二进制差分后的patch包大小不超过一定阈值
        if (Utils.checkBsDiffFileSize(outputFile, newFile)) {
            LargeModeInfo largeModeInfo = new LargeModeInfo();
            largeModeInfo.path = newFile;
            largeModeInfo.crc = FileOperation.getFileCrc32(newFile);
            largeModeInfo.md5 = newMd5;
            largeModifiedSet.add(name);
            largeModifiedMap.put(name, largeModeInfo);
            writeResLog(newFile, oldFile, TypedValue.LARGE_MOD);
            return true;
        }
    }
    modifiedSet.add(name);
    FileOperation.copyFileUsingStream(newFile, outputFile);
    writeResLog(newFile, oldFile, TypedValue.MOD);
    return false;
}

总结一下上面的 diff 过程，遍历新包和老包中的资源文件列表，将新增文件、删除文件、修改的文件分别保存到对应集合中，并且将信息写入日志文件。

资源的合并

差分包的合成是在 UpgradePatch.java 的 tryPatch 方法中完成的。该方法中调用了 tryRecoverResourceFiles 方法来完成资源的合并 ：

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if (!ResDiffPatchInternal.tryRecoverResourceFiles(manager, signatureCheck, context, patchVersionDirectory, destPatchFile)) {
    ShareTinkerLog.e(TAG, "UpgradePatch tryPatch:new patch recover, try patch resource failed");
    return false;
}

tryRecoverResourceFiles -> patchResourceExtractViaResourceDiff -> extractResourceDiffInternals:

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private static boolean extractResourceDiffInternals(Context context, String dir, String meta, File patchFile, int type) {
    ShareResPatchInfo resPatchInfo = new ShareResPatchInfo();
    ShareResPatchInfo.parseAllResPatchInfo(meta, resPatchInfo);
    ShareTinkerLog.i(TAG, "res dir: %s, meta: %s", dir, resPatchInfo.toString());
    Tinker manager = Tinker.with(context);
    File directory = new File(dir);
    File tempResFileDirectory = new File(directory, "res_temp");
		//合成的资源文件会存储在 resources.apk 中
    File resOutput = new File(directory, ShareConstants.RES_NAME);
    try {
        ApplicationInfo applicationInfo = context.getApplicationInfo();
        if (applicationInfo == null) {
            //Looks like running on a test Context, so just return without patching.
            ShareTinkerLog.w(TAG, "applicationInfo == null!!!!");
            return false;
        }
        String apkPath = applicationInfo.sourceDir;
        TinkerZipOutputStream out = null;
        TinkerZipFile oldApk = null;
        TinkerZipFile newApk = null;
        int totalEntryCount = 0;
        try {
            out = new TinkerZipOutputStream(new BufferedOutputStream(new FileOutputStream(resOutput)));
            oldApk = new TinkerZipFile(apkPath);
            newApk = new TinkerZipFile(patchFile);
            final Enumeration<? extends TinkerZipEntry> entries = oldApk.entries();
            while (entries.hasMoreElements()) {
                TinkerZipEntry zipEntry = entries.nextElement();
                if (zipEntry == null) {
                    throw new TinkerRuntimeException("zipEntry is null when get from oldApk");
                }
                String name = zipEntry.getName();
                if (name.contains("../")) {
                    continue;
                }
                //遍历老apk中的资源，如果资源文件既没有被删除、修改，也不是MANIFEST文件，则把资源拷贝到resources.apk 中
                if (ShareResPatchInfo.checkFileInPattern(resPatchInfo.patterns, name)) {
                    //won't contain in add set.
                    if (!resPatchInfo.deleteRes.contains(name)
                        && !resPatchInfo.modRes.contains(name)
                        && !resPatchInfo.largeModRes.contains(name)
                        && !name.equals(ShareConstants.RES_MANIFEST)) {
                        TinkerZipUtil.extractTinkerEntry(oldApk, zipEntry, out);
                        totalEntryCount++;
                    }
                }
            }
            //process manifest
            TinkerZipEntry manifestZipEntry = oldApk.getEntry(ShareConstants.RES_MANIFEST);
            if (manifestZipEntry == null) {
                ShareTinkerLog.w(TAG, "manifest patch entry is null. path:" + ShareConstants.RES_MANIFEST);
                manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, ShareConstants.RES_MANIFEST, type);
                return false;
            }
            TinkerZipUtil.extractTinkerEntry(oldApk, manifestZipEntry, out);
            totalEntryCount++;
            for (String name : resPatchInfo.largeModRes) {
                TinkerZipEntry largeZipEntry = oldApk.getEntry(name);
                if (largeZipEntry == null) {
                    ShareTinkerLog.w(TAG, "large patch entry is null. path:" + name);
                    manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, name, type);
                    return false;
                }
                ShareResPatchInfo.LargeModeInfo largeModeInfo = resPatchInfo.largeModMap.get(name);
                TinkerZipUtil.extractLargeModifyFile(largeZipEntry, largeModeInfo.file, largeModeInfo.crc, out);
                totalEntryCount++;
            }
						//对差分包新增资源文件的处理
            for (String name : resPatchInfo.addRes) {
                TinkerZipEntry addZipEntry = newApk.getEntry(name);
                if (addZipEntry == null) {
                    ShareTinkerLog.w(TAG, "add patch entry is null. path:" + name);
                    manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, name, type);
                    return false;
                }
                if (resPatchInfo.storeRes.containsKey(name)) {
                    File storeFile = resPatchInfo.storeRes.get(name);
                    TinkerZipUtil.extractLargeModifyFile(addZipEntry, storeFile, addZipEntry.getCrc(), out);
                } else {
                    TinkerZipUtil.extractTinkerEntry(newApk, addZipEntry, out);
                }
                totalEntryCount++;
            }
						//对差分包被修改的资源文件的处理
            for (String name : resPatchInfo.modRes) {
                TinkerZipEntry modZipEntry = newApk.getEntry(name);
                if (modZipEntry == null) {
                    ShareTinkerLog.w(TAG, "mod patch entry is null. path:" + name);
                    manager.getPatchReporter().onPatchTypeExtractFail(patchFile, resOutput, name, type);
                    return false;
                }
                if (resPatchInfo.storeRes.containsKey(name)) {
                    File storeFile = resPatchInfo.storeRes.get(name);
                    TinkerZipUtil.extractLargeModifyFile(modZipEntry, storeFile, modZipEntry.getCrc(), out);
                } else {
                    TinkerZipUtil.extractTinkerEntry(newApk, modZipEntry, out);
                }
                totalEntryCount++;
            }
            // set comment back
            out.setComment(oldApk.getComment());
        } finally {
     				....
            //delete temp files
            SharePatchFileUtil.deleteDir(tempResFileDirectory);
        }
        boolean result = SharePatchFileUtil.checkResourceArscMd5(resOutput, resPatchInfo.resArscMd5);
   ...
    return true;
}

资源的加载

Tinker 加载资源是在 TinkerResourceLoader 类的 loadTinkerResources 方法：

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public static boolean loadTinkerResources(TinkerApplication application, String directory, Intent intentResult) {
    if (resPatchInfo == null || resPatchInfo.resArscMd5 == null) {
        return true;
    }
    String resourceString = directory + "/" + RESOURCE_PATH +  "/" + RESOURCE_FILE;
    File resourceFile = new File(resourceString);
    long start = System.currentTimeMillis();
    if (application.isTinkerLoadVerifyFlag()) {
    ......
    }
    try {
        TinkerResourcePatcher.monkeyPatchExistingResources(application, resourceString);
        ShareTinkerLog.i(TAG, "monkeyPatchExistingResources resource file:" + resourceString + ", use time: " + (System.currentTimeMillis() - start));
    } catch (Throwable e) {
       .....
        return false;
    }
    return true;
}

接着看 monkeyPatchExistingResources 方法：

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public static void monkeyPatchExistingResources(Context context, String externalResourceFile) throws Throwable {
    if (externalResourceFile == null) {
        return;
    }
    final ApplicationInfo appInfo = context.getApplicationInfo();
    final Field[] packagesFields;
    if (Build.VERSION.SDK_INT < 27) {
        packagesFields = new Field[]{packagesFiled, resourcePackagesFiled};
    } else {
        packagesFields = new Field[]{packagesFiled};
    }
    for (Field field : packagesFields) {
        final Object value = field.get(currentActivityThread);
        for (Map.Entry<String, WeakReference<?>> entry
                : ((Map<String, WeakReference<?>>) value).entrySet()) {
            final Object loadedApk = entry.getValue().get();
            if (loadedApk == null) {
                continue;
            }
            final String resDirPath = (String) resDir.get(loadedApk);
            if (appInfo.sourceDir.equals(resDirPath)) {
            		//替换应用进程对应 LoadedApk 类的成员变量mResDir
                resDir.set(loadedApk, externalResourceFile);
            }
        }
    }
    // Create a new AssetManager instance and point it to the resources installed under
    //创建新的 AssetManager，调用 addAssetPath 方法为该 AssetManager 添加资源路径
    if (((Integer) addAssetPathMethod.invoke(newAssetManager, externalResourceFile)) == 0) {
        throw new IllegalStateException("Could not create new AssetManager");
    }
    // Add SharedLibraries to AssetManager for resolve system resources not found issue
    // This influence SharedLibrary Package ID
    if (shouldAddSharedLibraryAssets(appInfo)) {
        for (String sharedLibrary : appInfo.sharedLibraryFiles) {
            if (!sharedLibrary.endsWith(".apk")) {
                continue;
            }
            if (((Integer) addAssetPathAsSharedLibraryMethod.invoke(newAssetManager, sharedLibrary)) == 0) {
                throw new IllegalStateException("AssetManager add SharedLibrary Fail");
            }
            Log.i(TAG, "addAssetPathAsSharedLibrary " + sharedLibrary);
        }
    }
    // Kitkat needs this method call, Lollipop doesn't. However, it doesn't seem to cause any harm
    // in L, so we do it unconditionally.
    if (stringBlocksField != null && ensureStringBlocksMethod != null) {
        stringBlocksField.set(newAssetManager, null);
        ensureStringBlocksMethod.invoke(newAssetManager);
    }
    for (WeakReference<Resources> wr : references) {
        final Resources resources = wr.get();
        if (resources == null) {
            continue;
        }
        // Set the AssetManager of the Resources instance to our brand new one
        try {
            //pre-N
            // 重新设置 resources 对象的 mAsset 成员变量
            assetsFiled.set(resources, newAssetManager);
        } catch (Throwable ignore) {
            // N
            final Object resourceImpl = resourcesImplFiled.get(resources);
            // for Huawei HwResourcesImpl
            final Field implAssets = findField(resourceImpl, "mAssets");
            implAssets.set(resourceImpl, newAssetManager);
        }
        clearPreloadTypedArrayIssue(resources);
        resources.updateConfiguration(resources.getConfiguration(), resources.getDisplayMetrics());
    }
    // Handle issues caused by WebView on Android N.
    // Issue: On Android N, if an activity contains a webview, when screen rotates
    // our resource patch may lost effects.
    // for 5.x/6.x, we found Couldn't expand RemoteView for StatusBarNotification Exception
    if (Build.VERSION.SDK_INT >= 24) {
        try {
            if (publicSourceDirField != null) {
                publicSourceDirField.set(context.getApplicationInfo(), externalResourceFile);
            }
        } catch (Throwable ignore) {
            // Ignored.
        }
    }
    if (!checkResUpdate(context)) {
        throw new TinkerRuntimeException(ShareConstants.CHECK_RES_INSTALL_FAIL);
    }
}

Tinker的方案虽然采用全量的替换，但是在下发patch中依然采用差量资源的方式获取差分包，下发到手机后再合成全量的资源文件，有效的控制了补丁文件的大小。

参考链接: 深入理解Instant Run——原理篇