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Android——APK 在32bit/64bit平台动态库问题

發布時間：2025/4/16 Android 22 豆豆

生活随笔收集整理的這篇文章主要介紹了 Android——APK 在32bit/64bit平台动态库问题小編覺得挺不錯的,現在分享給大家,幫大家做個參考.

目前64bit android系統也慢慢的多了，看到也有apk聲稱支持64bit system，然后就往里面打包搞了個arm64-v8a 目錄，放了個64bit的so，但是apk代碼里面卻不按規范去load so ，導致一系列 file not found 異常~
撰寫不易,轉載需注明出處：http://blog.csdn.net/jscese/article/details/47101815本文來自?【jscese】的博客！

apk lib目錄:

先看下apk中的lib打包的目錄：?
?
依次代表不同類型的cpu

PMS安裝路徑：

pms install 流程比較繁雜，只關注so相關的scanPackageDirtyLI函數中：

private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg, int parseFlags,int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {...//invoke installer to do the actual installation //作為外部apk 創建data目錄相關項//\frameworks\native\cmds\installd\commands.c install()中創建int ret = **createDataDirsLI**(pkgName, pkg.applicationInfo.uid,pkg.applicationInfo.seinfo);...if (isSystemApp(pkg) && !isUpdatedSystemApp(pkg)) {...setBundledAppAbisAndRoots(pkg, pkgSetting);...setNativeLibraryPaths(pkg); }else{setNativeLibraryPaths(pkg);...if (isAsec) {copyRet = NativeLibraryHelper.findSupportedAbi(handle, abiList);} else {copyRet = NativeLibraryHelper.copyNativeBinariesForSupportedAbi(handle,nativeLibraryRoot, abiList, useIsaSpecificSubdirs);}setNativeLibraryPaths(pkg);if (DEBUG_INSTALL) Slog.i(TAG, "Linking native library dir for " + path);final int[] userIds = sUserManager.getUserIds();synchronized (mInstallLock) {// Create a native library symlink only if we have native libraries// and if the native libraries are 32 bit libraries. We do not provide// this symlink for 64 bit libraries.if (pkg.applicationInfo.primaryCpuAbi != null &&**!VMRuntime.is64BitAbi(pkg.applicationInfo.primaryCpuAbi)**) {final String nativeLibPath = pkg.applicationInfo.nativeLibraryDir;for (int userId : userIds) { if (mInstaller.linkNativeLibraryDirectory(pkg.packageName, nativeLibPath, userId) < 0) {throw new PackageManagerException(INSTALL_FAILED_INTERNAL_ERROR,"Failed linking native library dir (user=" + userId + ")");}}}}} }

看下system app 的安裝配置函數?setBundledAppAbisAndRoots：

/*** Calculate the abis and roots for a bundled app. These can uniquely* be determined from the contents of the system partition, i.e whether* it contains 64 or 32 bit shared libraries etc. We do not validate any* of this information, and instead assume that the system was built* sensibly.*/private void setBundledAppAbisAndRoots(PackageParser.Package pkg,PackageSetting pkgSetting) {final String apkName = deriveCodePathName(pkg.applicationInfo.getCodePath());// If "/system/lib64/apkname" exists, assume that is the per-package// native library directory to use; otherwise use "/system/lib/apkname".final String apkRoot = calculateBundledApkRoot(pkg.applicationInfo.sourceDir);setBundledAppAbi(pkg, apkRoot, apkName);// pkgSetting might be null during rescan following uninstall of updates// to a bundled app, so accommodate that possibility. The settings in// that case will be established later from the parsed package.//// If the settings aren't null, sync them up with what we've just derived.// note that apkRoot isn't stored in the package settings.if (pkgSetting != null) {pkgSetting.primaryCpuAbiString = pkg.applicationInfo.primaryCpuAbi;pkgSetting.secondaryCpuAbiString = pkg.applicationInfo.secondaryCpuAbi;}}

主要是在setBundledAppAbi中：

/*** Deduces the ABI of a bundled app and sets the relevant fields on the* parsed pkg object.** @param apkRoot the root of the installed apk, something like {@code /system} or {@code /oem}* under which system libraries are installed.* @param apkName the name of the installed package.*/private static void setBundledAppAbi(PackageParser.Package pkg, String apkRoot, String apkName) {final File codeFile = new File(pkg.codePath); ...if (has64BitLibs && !has32BitLibs) {// The package has 64 bit libs, but not 32 bit libs. Its primary// ABI should be 64 bit. We can safely assume here that the bundled// native libraries correspond to the most preferred ABI in the list.pkg.applicationInfo.primaryCpuAbi = Build.SUPPORTED_64_BIT_ABIS[0];pkg.applicationInfo.secondaryCpuAbi = null;} else if (has32BitLibs && !has64BitLibs) {// The package has 32 bit libs but not 64 bit libs. Its primary// ABI should be 32 bit.pkg.applicationInfo.primaryCpuAbi = Build.SUPPORTED_32_BIT_ABIS[0];pkg.applicationInfo.secondaryCpuAbi = null;} else if (has32BitLibs && has64BitLibs) {// The application has both 64 and 32 bit bundled libraries. We check// here that the app declares multiArch support, and warn if it doesn't.//// We will be lenient here and record both ABIs. The primary will be the// ABI that's higher on the list, i.e, a device that's configured to prefer// 64 bit apps will see a 64 bit primary ABI,if ((pkg.applicationInfo.flags & ApplicationInfo.FLAG_MULTIARCH) == 0) {Slog.e(TAG, "Package: " + pkg + " has multiple bundled libs, but is not multiarch.");}if (VMRuntime.is64BitInstructionSet(getPreferredInstructionSet())) {pkg.applicationInfo.primaryCpuAbi = Build.SUPPORTED_64_BIT_ABIS[0];pkg.applicationInfo.secondaryCpuAbi = Build.SUPPORTED_32_BIT_ABIS[0];} else {pkg.applicationInfo.primaryCpuAbi = Build.SUPPORTED_32_BIT_ABIS[0];pkg.applicationInfo.secondaryCpuAbi = Build.SUPPORTED_64_BIT_ABIS[0];}} else {pkg.applicationInfo.primaryCpuAbi = null;pkg.applicationInfo.secondaryCpuAbi = null;}}

根據file 查找確定primaryCpuAbi secondaryCpuAbi 變量值，這個也就決定了這個 apk 由64bit 還是32bit 的zygote去fork 還有nativelibrary 查找的path

其中nativelibrary的幾個主要函數?setNativeLibraryPaths：

/*** Derive and set the location of native libraries for the given package,* which varies depending on where and how the package was installed.*/private void setNativeLibraryPaths(PackageParser.Package pkg) {final ApplicationInfo info = pkg.applicationInfo;final String codePath = pkg.codePath;final File codeFile = new File(codePath);final boolean bundledApp = isSystemApp(info) && !isUpdatedSystemApp(info);final boolean asecApp = isForwardLocked(info) || isExternal(info);info.nativeLibraryRootDir = null;info.nativeLibraryRootRequiresIsa = false;info.nativeLibraryDir = null;info.secondaryNativeLibraryDir = null;if (isApkFile(codeFile)) {// Monolithic installif (bundledApp) {// If "/system/lib64/apkname" exists, assume that is the per-package// native library directory to use; otherwise use "/system/lib/apkname".final String apkRoot = calculateBundledApkRoot(info.sourceDir);final boolean is64Bit = VMRuntime.is64BitInstructionSet(getPrimaryInstructionSet(info));// This is a bundled system app so choose the path based on the ABI.// if it's a 64 bit abi, use lib64 otherwise use lib32. Note that this// is just the default path.final String apkName = deriveCodePathName(codePath);final String libDir = is64Bit ? LIB64_DIR_NAME : LIB_DIR_NAME;info.nativeLibraryRootDir = Environment.buildPath(new File(apkRoot), libDir,apkName).getAbsolutePath();if (info.secondaryCpuAbi != null) {final String secondaryLibDir = is64Bit ? LIB_DIR_NAME : LIB64_DIR_NAME;info.secondaryNativeLibraryDir = Environment.buildPath(new File(apkRoot),secondaryLibDir, apkName).getAbsolutePath();}} else if (asecApp) {info.nativeLibraryRootDir = new File(codeFile.getParentFile(), LIB_DIR_NAME).getAbsolutePath();} else {final String apkName = deriveCodePathName(codePath);info.nativeLibraryRootDir = new File(mAppLib32InstallDir, apkName).getAbsolutePath();}info.nativeLibraryRootRequiresIsa = false;info.nativeLibraryDir = info.nativeLibraryRootDir;} else {// Cluster installinfo.nativeLibraryRootDir = new File(codeFile, LIB_DIR_NAME).getAbsolutePath();info.nativeLibraryRootRequiresIsa = true;info.nativeLibraryDir = new File(info.nativeLibraryRootDir,getPrimaryInstructionSet(info)).getAbsolutePath();if (info.secondaryCpuAbi != null) {info.secondaryNativeLibraryDir = new File(info.nativeLibraryRootDir,VMRuntime.getInstructionSet(info.secondaryCpuAbi)).getAbsolutePath();}}}

根據pkg application info 來確定nativelibrarydir 依賴info中的?info.primaryCpuAbi

private static String getPrimaryInstructionSet(ApplicationInfo info) {if (info.primaryCpuAbi == null) {return getPreferredInstructionSet();}return VMRuntime.getInstructionSet(info.primaryCpuAbi);}

非system apk 會調用?NativeLibraryHelper?的?findSupportedAbi?去解析 .apk 文件，根據系統suportabilist 去查找 lib目錄下的打包子目錄找到匹配的abi

向文章開頭的那個 lib目錄，在64bit 機器上suportabilist為：

public static final String[] SUPPORTED_ABIS = getStringList("ro.product.cpu.abilist", ",");

root@:/ # getprop ro.product.cpu.abilist arm64-v8a,armeabi-v7a,armeabi

會匹配arm64-v8a?賦值給?info.primaryCpuAbi

copyNativeBinariesForSupportedAbi?會去copy 前面匹配的lib 目錄到本地

最后設置NativeLibraryPaths ，?
如果匹配的是64bit的，也就是arm64-v8a?那么就不為/data/data/../lib 建立軟鏈接，這是與32bit 不同的地方

system.loadlibrary

作為動態庫加載的標準接口，直接看實現：

public static void loadLibrary(String libName) {Runtime.getRuntime().loadLibrary(libName, VMStack.getCallingClassLoader());}

到Runtime.java中：

/** Searches for and loads the given shared library using the given ClassLoader.*/void loadLibrary(String libraryName, ClassLoader loader) {if (loader != null) {String filename = loader.findLibrary(libraryName);if (filename == null) {// It's not necessarily true that the ClassLoader used// System.mapLibraryName, but the default setup does, and it's// misleading to say we didn't find "libMyLibrary.so" when we// actually searched for "liblibMyLibrary.so.so".throw new UnsatisfiedLinkError(loader + " couldn't find \"" +System.mapLibraryName(libraryName) + "\"");}String error = doLoad(filename, loader);if (error != null) {throw new UnsatisfiedLinkError(error);}return;}String filename = System.mapLibraryName(libraryName);List<String> candidates = new ArrayList<String>();String lastError = null;for (String directory : mLibPaths) {String candidate = directory + filename;candidates.add(candidate);if (IoUtils.canOpenReadOnly(candidate)) {String error = doLoad(candidate, loader);if (error == null) {return; // We successfully loaded the library. Job done.}lastError = error;}}if (lastError != null) {throw new UnsatisfiedLinkError(lastError);}throw new UnsatisfiedLinkError("Library " + libraryName + " not found; tried " + candidates);}

這里的?ClassLoader loader?實際上會在 apk啟動的時候初始化好一些相關的子類父類還有參數

大體記錄一下啟動時初始流程：

ActivityThread.java - handleBindApplication final ContextImpl appContext = ContextImpl.createAppContext(this, data.info);LoadedApk pi = getPackageInfo(instrApp, data.compatInfo,appContext.getClassLoader(), false, true, false);ContextImpl.java -getClassLoader() LoadedApk.java -getClassLoader() ： mLibDir = aInfo.nativeLibraryDir; mClassLoader = ApplicationLoaders.getDefault().getClassLoader(zip, lib,mBaseClassLoader); ApplicationLoaders.java -getClassLoader(...)PathClassLoader pathClassloader = new PathClassLoader(zip, libPath, parent); //這里的libPath 就是上面傳下來的aInfo.nativeLibraryDirpublic class PathClassLoader extends BaseDexClassLoader public class BaseDexClassLoader extends ClassLoader

loader.findLibrary(libraryName);

/*** Finds the named native code library on any of the library* directories pointed at by this instance. This will find the* one in the earliest listed directory, ignoring any that are not* readable regular files.** @return the complete path to the library or {@code null} if no* library was found*/public String findLibrary(String libraryName) {String fileName = System.mapLibraryName(libraryName);for (File directory : nativeLibraryDirectories) {String path = new File(directory, fileName).getPath();if (IoUtils.canOpenReadOnly(path)) { return path;}} return null;}

這里的nativeLibraryDirectories?即為前面一系列構造時設置了值其中就有?aInfo.nativeLibraryDir

后面的邏輯就不去敘述了，根據名字在這個目錄下去找，然后調用到本地JNI 最終調用?dlopen?加載打開so，必須是相同位數，而這個關乎當前進程是屬于64bit 還是 32bit，這個會在zygote fork時區分，同樣也是由PMS解析時得到的 info.primaryCpuAbi

AMS 請求zygote fork app process選擇

只關心相關代碼?startProcessLocked函數：

private final void startProcessLocked(ProcessRecord app, String hostingType,String hostingNameStr, String abiOverride, String entryPoint, String[] entryPointArgs) { ...String requiredAbi = (abiOverride != null) ? abiOverride : app.info.primaryCpuAbi;if (requiredAbi == null) {requiredAbi = Build.SUPPORTED_ABIS[0];}String instructionSet = null;if (app.info.primaryCpuAbi != null) {instructionSet = VMRuntime.getInstructionSet(app.info.primaryCpuAbi);}app.gids = gids;app.requiredAbi = requiredAbi;app.instructionSet = instructionSet;// Start the process. It will either succeed and return a result containing// the PID of the new process, or else throw a RuntimeException.boolean isActivityProcess = (entryPoint == null);if (entryPoint == null) entryPoint = "android.app.ActivityThread";checkTime(startTime, "startProcess: asking zygote to start proc");Process.ProcessStartResult startResult = Process.start(entryPoint,app.processName, uid, uid, gids, debugFlags, mountExternal,app.info.targetSdkVersion, app.info.seinfo, requiredAbi, instructionSet,app.info.dataDir, entryPointArgs);checkTime(startTime, "startProcess: returned from zygote!");... }

Process中真正的socket 請求實現：

return zygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi), argsForZygote);

openZygoteSocketIfNeeded?會根據傳下來的abi 去選擇通信的socket

而在64bit 機器上，啟動時會啟動兩個 zygote service ，用于接收 64 32 的apk 請求：

service zygote /system/bin/app_process64 -Xzygote /system/bin --zygote --start-system-server --socket-name=zygoteclass mainsocket zygote stream 660 root systemonrestart write /sys/android_power/request_state wakeonrestart write /sys/power/state ononrestart restart mediaonrestart restart netdservice zygote_secondary /system/bin/app_process32 -Xzygote /system/bin --zygote --socket-name=zygote_secondaryclass mainsocket zygote_secondary stream 660 root systemonrestart restart zygote

可以看到兩個 zygote 進程，基本一致，區別在于 64bit 32bit ，注冊socket不同?
關于這兩個 zygote 進程啟動時的socket 注冊就不多說了

暫時先記錄這么多吧~

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