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 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 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：
- v4
- v14
- v19
- v23
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 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 suppressedExceptions = new ArrayList();
ShareReflectUtil.expandFieldArray(dexPathList, "dexElements", makeDexElements(dexPathList,
new ArrayList(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 files, File optimizedDirectory,
ArrayList 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。