Android APK 在32bit 和64bit 的区别问题

private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg, int parseFlags,
            int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {
            ...
             //invoke installer to do the actual installation  //作为外部apk 创建data目录相关项
             //frameworksnativecmdsinstalldcommands.c  install()中创建
                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 + ")");
                        }
                    }
                }
            }

    }
}

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setBundledAppAbisAndRoots： 
 //blog.csdn.net/sergeycao
  
    /**     * 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;
        }
    }

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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;
        }
 }

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 根据file 查找 确定primaryCpuAbi secondaryCpuAbi 变量值，这个也就决定了 这个 apk 由64bit 还是32bit 的zygote去fork 还有nativelibrary 查找的path
setNativeLibraryPaths：
 //blog.csdn.net/sergeycao
  
/**     * 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 install
            if (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 install
            info.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();
            }
        }
    }

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

        return VMRuntime.getInstructionSet(info.primaryCpuAbi);
    }

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NativeLibraryHelper 的 findSupportedAbi
 向文章开头的那个 lib目录 ，在64bit 机器上suportabilist为：  
 public static final String[] SUPPORTED_ABIS = getStringList("ro.product.cpu.abilist", ",");
1
 
root@:/ # getprop ro.product.cpu.abilist                                 arm64-v8a,armeabi-v7a,armeabi

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arm64-v8a 赋值给 info.primaryCpuAbi
copyNativeBinariesForSupportedAbi
 最后设置NativeLibraryPaths ， 
 如果匹配的是64bit的，也就是arm64-v8a 那么就不为/data/data/../lib 建立软链接，这是与32bit 不同的地方system.loadlibrary
 作为动态库加载的标准接口，直接看实现：
  
    public static void loadLibrary(String libName) {        Runtime.getRuntime().loadLibrary(libName, VMStack.getCallingClassLoader());
    }

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 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);
        ListString> candidates = new ArrayListString>();
        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);
    }

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ClassLoader loader
 大体记录一下 启动时 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);   //这里的libPath 就是上面传下来的aInfo.nativeLibraryDir

public class PathClassLoader extends BaseDexClassLoader
public class BaseDexClassLoader extends ClassLoader

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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;
    }

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nativeLibraryDirectories 即为前面一系列 构造时 设置了值 其中就有 aInfo.nativeLibraryDir
dlopen
AMS 请求zygote fork app process选择
startProcessLocked函数：
  
    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!");

...
}

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 Process中真正的socket 请求实现：
  
return zygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi), argsForZygote);
1
  
openZygoteSocketIfNeeded 会根据传下来的abi 去选择 通信的socket
 而在64bit 机器上，启动时会 启动 两个 zygote service ，用于接收 64 32 的apk 请求：
  
service zygote /system/bin/app_process64 -Xzygote /system/bin --zygote --start-system-server --socket-name=zygote    class main
    socket zygote stream 660 root system
    onrestart write /sys/android_power/request_state wake
    onrestart write /sys/power/state on
    onrestart restart media
    onrestart restart netd

service zygote_secondary /system/bin/app_process32 -Xzygote /system/bin --zygote --socket-name=zygote_secondary
    class main
    socket zygote_secondary stream 660 root system
    onrestart restart zygote
 
 
scanpackageDirtyLI函数中：
 private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg, int parseFlags, int scanFlags, long currentTime, UserHandle user) throws PackageManagerException { ... //invoke installer to do the actual installation //作为外部apk 创建data目录相关项 //frameworksnativecmdsinstalldcommands.c install()中创建 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) 

/** * 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 install if (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 install info.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

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

public static final String[] SUPPORTED_ABIS = getStringList("ro.product.cpu.abilist", ",");
 root@:/ # getprop ro.product.cpu.abilist arm64-v8a,armeabi-v7a,armeabi

作为动态库加载的标准接口，直接看实现：
 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 candidates = new ArrayList(); 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 "
ClassLoader loader
 大体记录一下 启动时 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); //这里的libPath 就是上面传下来的aInfo.nativeLibraryDir public 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

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!"); ...

return zygoteSendArgsAndGetResult(openZygoteSocketIfNeeded(abi), argsForZygote);

service zygote /system/bin/app_process64 -Xzygote /system/bin --zygote --start-system-server --socket-name=zygote class main socket zygote stream 660 root system onrestart write /sys/android_power/request_state wake onrestart write /sys/power/state on onrestart restart media onrestart restart netd service zygote_secondary /system/bin/app_process32 -Xzygote /system/bin --zygote --socket-name=zygote_secondary class main socket zygote_secondary stream 660 root system