Android 源码 installPackage 流程分析_ipackagemanager.stub.asinterface

installPackage 安装流程最终会调用 PackageManagerService 对应方法，当然是使用 binder 机制得以实现跨进程通信。

先来看看 installPackage 流程具体和各种进程如何关联调用，有个整体印象以后我们再来分析其流程。

起点是 ApplicationPackageManager 类 installPackage 方法。

frameworks/base/core/java/android/app/ApplicationPackageManager.java

/*package*/
final class ApplicationPackageManager extends PackageManager {
    ......
    @Override
    public void installPackage(Uri packageURI, PackageInstallObserver observer,
            int flags, String installerPackageName) {
        final VerificationParams verificationParams = new VerificationParams(null, null,
                null, VerificationParams.NO_UID, null);
        installCommon(packageURI, observer, flags, installerPackageName, verificationParams, null);
    }
    ......
}
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1. 参数检查
2. 调用 android.content.pm.IPackageManager.Stub.Proxy 类 installPackage 方法

frameworks/base/core/java/android/app/ApplicationPackageManager.java

/*package*/
final class ApplicationPackageManager extends PackageManager {
    ......
    private void installCommon(Uri packageURI,
            PackageInstallObserver observer, int flags, String installerPackageName,
            VerificationParams verificationParams, ContainerEncryptionParams encryptionParams) {
        if (!"file".equals(packageURI.getScheme())) {
            throw new UnsupportedOperationException("Only file:// URIs are supported");
        }
        if (encryptionParams != null) {
            throw new UnsupportedOperationException("ContainerEncryptionParams not supported");
        }

        final String originPath = packageURI.getPath();
        try {
            mPM.installPackage(originPath, observer.getBinder(), flags, installerPackageName,
                    verificationParams, null);
        } catch (RemoteException ignored) {
        }
    }
    ......
}
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IPackageManager.Stub.Proxy 代理类是在 ActivityThread 类方法 getPackageManager() 中获取的。

1. 从 ServiceManager 服务关键处获取包管理 IBinder
2. 调用 IPackageManager.Stub.asInterface() 方法返回代理对象 IPackageManager.Stub.Proxy

frameworks/base/core/java/android/app/ActivityThread.java

public final class ActivityThread {
    ......
    public static IPackageManager getPackageManager() {
        if (sPackageManager != null) {
            //Slog.v("PackageManager", "returning cur default = " + sPackageManager);
            return sPackageManager;
        }
        IBinder b = ServiceManager.getService("package");
        //Slog.v("PackageManager", "default service binder = " + b);
        sPackageManager = IPackageManager.Stub.asInterface(b);
        //Slog.v("PackageManager", "default service = " + sPackageManager);
        return sPackageManager;
    }
    ......
}
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下面是编译 aidl 生成的 IPackageManager Java 文件，其中揭示了如何返回 IPackageManager.Stub.Proxy 代理类的逻辑。

public interface IPackageManager extends android.os.IInterface {
    /**
     * Local-side IPC implementation stub class.
     */
    public static abstract class Stub extends android.os.Binder implements android.content.pm.IPackageManager {
        private static final java.lang.String DESCRIPTOR = "android.content.pm.IPackageManager";

        /**
         * Construct the stub at attach it to the interface.
         */
        public Stub() {
            this.attachInterface(this, DESCRIPTOR);
        }

        /**
         * Cast an IBinder object into an android.content.pm.IPackageManager interface,
         * generating a proxy if needed.
         */
        public static android.content.pm.IPackageManager asInterface(android.os.IBinder obj) {
            if ((obj == null)) {
                return null;
            }
            android.os.IInterface iin = obj.queryLocalInterface(DESCRIPTOR);
            if (((iin != null) && (iin instanceof android.content.pm.IPackageManager))) {
                return ((android.content.pm.IPackageManager) iin);
            }
            return new android.content.pm.IPackageManager.Stub.Proxy(obj);
        }

        @Override
        public android.os.IBinder asBinder() {
            return this;
        }
        ......
        private static class Proxy implements android.content.pm.IPackageManager {
            private android.os.IBinder mRemote;

            Proxy(android.os.IBinder remote) {
                mRemote = remote;
            }

            @Override
            public android.os.IBinder asBinder() {
                return mRemote;
            }

            public java.lang.String getInterfaceDescriptor() {
                return DESCRIPTOR;
            }
            ......
        }
        ......
    }
    ......
}
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下面来追一下 mPM，赋值是在 ApplicationPackageManager 构造函数内。

frameworks/base/core/java/android/app/ApplicationPackageManager.java

final class ApplicationPackageManager extends PackageManager {
    ......
    ApplicationPackageManager(ContextImpl context,
                              IPackageManager pm) {
        mContext = context;
        mPM = pm;
    }
    ......
}
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ApplicationPackageManager 对象创建又是在 ContextImpl（上下文实现类） 类 getPackageManager() 方法中。

frameworks/base/core/java/android/app/ContextImpl.java

class ContextImpl extends Context {
    ......
    @Override
    public PackageManager getPackageManager() 方法中。 {
        if (mPackageManager != null) {
            return mPackageManager;
        }

        IPackageManager pm = ActivityThread.getPackageManager();
        if (pm != null) {
            // Doesn't matter if we make more than one instance.
            return (mPackageManager = new ApplicationPackageManager(this, pm));
        }

        return null;
    }
    ......
}
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现在继续回到 ApplicationPackageManager 类 installCommon 方法，最后会调用远程 PackageManagerService 类 installPackage 方法。

1. 权限检查，系统级或 root 用户才能安装
2. 发送消息，消息的 obj 赋值为 InstallParams 对象（包含了安装包的必要信息）

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    @Override
    public void installPackage(String originPath, IPackageInstallObserver2 observer,
            int installFlags, String installerPackageName, VerificationParams verificationParams,
            String packageAbiOverride) {
        installPackageAsUser(originPath, observer, installFlags, installerPackageName,
                verificationParams, packageAbiOverride, UserHandle.getCallingUserId());
    }

    @Override
    public void installPackageAsUser(String originPath, IPackageInstallObserver2 observer,
            int installFlags, String installerPackageName, VerificationParams verificationParams,
            String packageAbiOverride, int userId) {
        mContext.enforceCallingOrSelfPermission(android.Manifest.permission.INSTALL_PACKAGES, null);

        final int callingUid = Binder.getCallingUid();
        enforceCrossUserPermission(callingUid, userId, true, true, "installPackageAsUser");

        if (isUserRestricted(userId, UserManager.DISALLOW_INSTALL_APPS)) {
            try {
                if (observer != null) {
                    observer.onPackageInstalled("", INSTALL_FAILED_USER_RESTRICTED, null, null);
                }
            } catch (RemoteException re) {
            }
            return;
        }

        if ((callingUid == Process.SHELL_UID) || (callingUid == Process.ROOT_UID)) {
            installFlags |= PackageManager.INSTALL_FROM_ADB;

        } else {
            // 调用方拥有 INSTALL_PACKAGES 权限，因此我们对 installerPackageName 的要求不严格。
            installFlags &= ~PackageManager.INSTALL_FROM_ADB;
            installFlags &= ~PackageManager.INSTALL_ALL_USERS;
        }

        UserHandle user;
        if ((installFlags & PackageManager.INSTALL_ALL_USERS) != 0) {
            user = UserHandle.ALL;
        } else {
            user = new UserHandle(userId);
        }

        // 在安装时，只有系统组件可以绕过运行时权限。
        if ((installFlags & PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS) != 0
                && mContext.checkCallingOrSelfPermission(Manifest.permission
                .INSTALL_GRANT_RUNTIME_PERMISSIONS) == PackageManager.PERMISSION_DENIED) {
            throw new SecurityException("You need the "
                    + "android.permission.INSTALL_GRANT_RUNTIME_PERMISSIONS permission "
                    + "to use the PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS flag");
        }

        verificationParams.setInstallerUid(callingUid);

        final File originFile = new File(originPath);
        final OriginInfo origin = OriginInfo.fromUntrustedFile(originFile);

        final Message msg = mHandler.obtainMessage(INIT_COPY);
        msg.obj = new InstallParams(origin, null, observer, installFlags, installerPackageName,
                null, verificationParams, user, packageAbiOverride, null);
        mHandler.sendMessage(msg);
    }
    ......
}
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Handler 收到消息之后在 doHandleMessage 函数中进行处理。

1. 如果已经绑定到了 DefaultContainerService，只需将 HandlerParams 添加到 mPendingInstalls 待处理的安装列表，并且 idx = 0，马上发送消息 MCS_BOUND 进一步处理
2. 如果没有绑定到 DefaultContainerService，首先调用 connectToService() 进行绑定，绑定成功以后 mBound 置为 true，connectToService() 函数返回 true，然后将 HandlerParams 添加到 mPendingInstalls 列表

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class PackageHandler extends Handler {
        private boolean mBound = false;
        final ArrayList<HandlerParams> mPendingInstalls =
            new ArrayList<HandlerParams>();

        private boolean connectToService() {
            if (DEBUG_SD_INSTALL) Log.i(TAG, "Trying to bind to" +
                    " DefaultContainerService");
            Intent service = new Intent().setComponent(DEFAULT_CONTAINER_COMPONENT);
            Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
            if (mContext.bindServiceAsUser(service, mDefContainerConn,
                    Context.BIND_AUTO_CREATE, UserHandle.OWNER)) {
                Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
                mBound = true;
                return true;
            }
            Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
            return false;
        }

        private void disconnectService() {
            mContainerService = null;
            mBound = false;
            Process.setThreadPriority(Process.THREAD_PRIORITY_DEFAULT);
            mContext.unbindService(mDefContainerConn);
            Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
        }

        PackageHandler(Looper looper) {
            super(looper);
        }
        
        public void handleMessage(Message msg) {
            try {
                doHandleMessage(msg);
            } finally {
                Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
            }
        }
        
         void doHandleMessage(Message msg) {
            switch (msg.what) {
                case INIT_COPY: {
                    HandlerParams params = (HandlerParams) msg.obj;
                    int idx = mPendingInstalls.size();
                    if (DEBUG_INSTALL) Slog.i(TAG, "init_copy idx=" + idx + ": " + params);
                    // 如果一个 bind 已经启动，我们实际上不需要做任何事情。稍后将处理待决的安装。
                    if (!mBound) {
                        // 如果只有这一个待决的安装，我们可能不得不再次绑定服务。
                        if (!connectToService()) {
                            Slog.e(TAG, "Failed to bind to media container service");
                            params.serviceError();
                            return;
                        } else {
                            // 一旦我们绑定到服务，第一个待决的安装请求将被处理。
                            mPendingInstalls.add(idx, params);
                        }
                    } else {
                        mPendingInstalls.add(idx, params);
                        // 已经绑定到服务。只要确保我们启动了处理第一个请求。
                        if (idx == 0) {
                            mHandler.sendEmptyMessage(MCS_BOUND);
                        }
                    }
                    break;
                }
                ......
            }
        }
    }
    ......
}
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DefaultContainerService 提供检查和复制可能驻留在可移动存储器上的文件的服务。这是为了防止系统进程持有打开的文件，这些文件会导致内核在删除底层设备时杀死它。

connectToService() 进行 DefaultContainerService 服务绑定，当服务绑定成功会回调 DefaultContainerConnection 类 onServiceConnected 方法。

1. 调用 IMediaContainerService.Stub.asInterface 获取 IMediaContainerService.Stub.Proxy 代理类
2. 将代理类封装到 MCS_BOUND 消息发送

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    final private DefaultContainerConnection mDefContainerConn =
            new DefaultContainerConnection();
    class DefaultContainerConnection implements ServiceConnection {
        public void onServiceConnected(ComponentName name, IBinder service) {
            if (DEBUG_SD_INSTALL) Log.i(TAG, "onServiceConnected");
            IMediaContainerService imcs =
                IMediaContainerService.Stub.asInterface(service);
            mHandler.sendMessage(mHandler.obtainMessage(MCS_BOUND, imcs));
        }

        public void onServiceDisconnected(ComponentName name) {
            if (DEBUG_SD_INSTALL) Log.i(TAG, "onServiceDisconnected");
        }
    }
    ......
}
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1. 从消息中获取 IMediaContainerService.Stub.Proxy 代理对象
2. 从 mPendingInstalls 待决安装队列中逐个取出 HandlerParams 对象，调用其 startCopy() 方法完成拷贝
3. mPendingInstalls 待决安装队列清空之后发送 MCS_UNBIND 消息对 DefaultContainerService 进行解绑定

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class PackageHandler extends Handler {
        ......
         void doHandleMessage(Message msg) {
            switch (msg.what) {
                ......
                case MCS_BOUND: {
                    if (DEBUG_INSTALL) Slog.i(TAG, "mcs_bound");
                    if (msg.obj != null) {
                        mContainerService = (IMediaContainerService) msg.obj;
                    }
                    if (mContainerService == null) {
                        ......
                    } else if (mPendingInstalls.size() > 0) {
                        HandlerParams params = mPendingInstalls.get(0);
                        if (params != null) {
                            if (params.startCopy()) {
                                // 我们完成了...寻找更多工作或开始 idle
                                if (DEBUG_SD_INSTALL) Log.i(TAG,
                                        "Checking for more work or unbind...");
                                // 从列表中删除待决安装
                                if (mPendingInstalls.size() > 0) {
                                    mPendingInstalls.remove(0);
                                }
                                if (mPendingInstalls.size() == 0) {
                                    if (mBound) {
                                        if (DEBUG_SD_INSTALL) Log.i(TAG,
                                                "Posting delayed MCS_UNBIND");
                                        removeMessages(MCS_UNBIND);
                                        Message ubmsg = obtainMessage(MCS_UNBIND);
                                        // 稍微延迟后解除绑定，以避免不断地颠簸。
                                        sendMessageDelayed(ubmsg, 10000);
                                    }
                                } else {
                                    // 队列中有更多的待决安装请求。
                                    // 只需发布 MCS_BOUND 消息来触发对下一个待决安装的处理。
                                    if (DEBUG_SD_INSTALL) Log.i(TAG,
                                            "Posting MCS_BOUND for next work");
                                    mHandler.sendEmptyMessage(MCS_BOUND);
                                }
                            }
                        }
                    } else {
                        ......
                    }
                    break;
                }
                ......
            }
        }
    }
    ......
}
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startCopy() 完成的工作：

1. 超出最大重试次数，发送 MCS_GIVE_UP 消息放弃
2. 实际调用 handleStartCopy() 开始处理拷贝
3. 远程调用抛出异常，发出 MCS_RECONNECT 消息重连
4. 最后调用 handleReturnCode() 处理返回值

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    private abstract class HandlerParams {
        private static final int MAX_RETRIES = 4;

        /**
         * 尝试 startCopy() 并发生非致命错误的次数。
         */
        private int mRetries = 0;

        /** 用户请求信息或安装的用户句柄。 */
        private final UserHandle mUser;

        HandlerParams(UserHandle user) {
            mUser = user;
        }

        UserHandle getUser() {
            return mUser;
        }

        final boolean startCopy() {
            boolean res;
            try {
                if (DEBUG_INSTALL) Slog.i(TAG, "startCopy " + mUser + ": " + this);
                // 超出最大次数，发送 MCS_GIVE_UP 放弃消息
                if (++mRetries > MAX_RETRIES) {
                    Slog.w(TAG, "Failed to invoke remote methods on default container service. Giving up");
                    mHandler.sendEmptyMessage(MCS_GIVE_UP);
                    handleServiceError();
                    return false;
                } else {
                    handleStartCopy();
                    res = true;
                }
            } catch (RemoteException e) {
                if (DEBUG_INSTALL) Slog.i(TAG, "Posting install MCS_RECONNECT");
                // 远程调用抛出异常，发出 MCS_RECONNECT 重连消息
                mHandler.sendEmptyMessage(MCS_RECONNECT);
                res = false;
            }
            handleReturnCode();
            return res;
        }

        final void serviceError() {
            if (DEBUG_INSTALL) Slog.i(TAG, "serviceError");
            handleServiceError();
            handleReturnCode();
        }

        abstract void handleStartCopy() throws RemoteException;
        abstract void handleServiceError();
        abstract void handleReturnCode();
    }
    ......
}
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HandlerParams 实际为 InstallParams 类型，因此会调用其 handleStartCopy() 真正开始处理拷贝。

调用远程方法以获取软件包信息并处理安装位置。如果需要，根据默认策略覆盖安装位置，然后根据安装位置创建安装参数。接下来做一些相关的包验证工作。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class InstallParams extends HandlerParams {
        ......
        public void handleStartCopy() throws RemoteException {
            int ret = PackageManager.INSTALL_SUCCEEDED;

            // 设置 installFlags 安装位置对应位
            if (origin.staged) {
                if (origin.file != null) {
                    installFlags |= PackageManager.INSTALL_INTERNAL;
                    installFlags &= ~PackageManager.INSTALL_EXTERNAL;
                } else if (origin.cid != null) {
                    installFlags |= PackageManager.INSTALL_EXTERNAL;
                    installFlags &= ~PackageManager.INSTALL_INTERNAL;
                } else {
                    throw new IllegalStateException("Invalid stage location");
                }
            }

            final boolean onSd = (installFlags & PackageManager.INSTALL_EXTERNAL) != 0;
            final boolean onInt = (installFlags & PackageManager.INSTALL_INTERNAL) != 0;

            PackageInfoLite pkgLite = null;

            if (onInt && onSd) {
                // 无效的安装位置
                Slog.w(TAG, "Conflicting flags specified for installing on both internal and external");
                ret = PackageManager.INSTALL_FAILED_INVALID_INSTALL_LOCATION;
            } else {
                // 解析给定的包并返回最小的细节，
                // 这是通过 binder 机制调用远程 IMediaContainerService.Stub 类 getMinimalPackageInfo 方法完成的
                pkgLite = mContainerService.getMinimalPackageInfo(origin.resolvedPath, installFlags,
                        packageAbiOverride);

                /*
                 * 如果我们的可用空间太少，请在放弃之前尝试释放缓存。
                 */
                if (!origin.staged && pkgLite.recommendedInstallLocation
                        == PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE) {
                    // TODO: focus freeing disk space on the target device
                    final StorageManager storage = StorageManager.from(mContext);
                    final long lowThreshold = storage.getStorageLowBytes(
                            Environment.getDataDirectory());

                    final long sizeBytes = mContainerService.calculateInstalledSize(
                            origin.resolvedPath, isForwardLocked(), packageAbiOverride);

                    if (mInstaller.freeCache(null, sizeBytes + lowThreshold) >= 0) {
                        pkgLite = mContainerService.getMinimalPackageInfo(origin.resolvedPath,
                                installFlags, packageAbiOverride);
                    }

                    /*
                     * The cache free must have deleted the file we
                     * downloaded to install.
                     *
                     * TODO: fix the "freeCache" call to not delete
                     *       the file we care about.
                     */
                    if (pkgLite.recommendedInstallLocation
                            == PackageHelper.RECOMMEND_FAILED_INVALID_URI) {
                        pkgLite.recommendedInstallLocation
                            = PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE;
                    }
                }
            }

            if (ret == PackageManager.INSTALL_SUCCEEDED) {
                int loc = pkgLite.recommendedInstallLocation;
                if (loc == PackageHelper.RECOMMEND_FAILED_INVALID_LOCATION) {
                    ret = PackageManager.INSTALL_FAILED_INVALID_INSTALL_LOCATION;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_ALREADY_EXISTS) {
                    ret = PackageManager.INSTALL_FAILED_ALREADY_EXISTS;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_INSUFFICIENT_STORAGE) {
                    ret = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_INVALID_APK) {
                    ret = PackageManager.INSTALL_FAILED_INVALID_APK;
                } else if (loc == PackageHelper.RECOMMEND_FAILED_INVALID_URI) {
                    ret = PackageManager.INSTALL_FAILED_INVALID_URI;
                } else if (loc == PackageHelper.RECOMMEND_MEDIA_UNAVAILABLE) {
                    ret = PackageManager.INSTALL_FAILED_MEDIA_UNAVAILABLE;
                } else {
                    // 获取建议安装位置
                    loc = installLocationPolicy(pkgLite);
                    if (loc == PackageHelper.RECOMMEND_FAILED_VERSION_DOWNGRADE) {
                        ret = PackageManager.INSTALL_FAILED_VERSION_DOWNGRADE;
                    } else if (!onSd && !onInt) {
                        // Override install location with flags
                        if (loc == PackageHelper.RECOMMEND_INSTALL_EXTERNAL) {
                            // 将标志设置为安装在外部媒体上
                            installFlags |= PackageManager.INSTALL_EXTERNAL;
                            installFlags &= ~PackageManager.INSTALL_INTERNAL;
                        } else {
                            // 确保在外部媒体上安装的标志未设置
                            installFlags |= PackageManager.INSTALL_INTERNAL;
                            installFlags &= ~PackageManager.INSTALL_EXTERNAL;
                        }
                    }
                }
            }
            // 创建安装参数
            final InstallArgs args = createInstallArgs(this);
            mArgs = args;

            if (ret == PackageManager.INSTALL_SUCCEEDED) {
                 /*
                 * ADB 安装呈现为 UserHandle.USER_ALL，
                 * 并且只能由 UserHandle.USER_OWNER 执行，
                 * 因此请使用 UserHandle.USER_OWNER 的包验证程序。
                 */
                int userIdentifier = getUser().getIdentifier();
                if (userIdentifier == UserHandle.USER_ALL
                        && ((installFlags & PackageManager.INSTALL_FROM_ADB) != 0)) {
                    userIdentifier = UserHandle.USER_OWNER;
                }

                /*
                 * 确定我们是否已安装任何包验证程序。使用它们对包进行验证。
                 */
                final int requiredUid = mRequiredVerifierPackage == null ? -1
                        : getPackageUid(mRequiredVerifierPackage, userIdentifier);
                if (!origin.existing && requiredUid != -1
                        && isVerificationEnabled(userIdentifier, installFlags)) {
                    final Intent verification = new Intent(
                            Intent.ACTION_PACKAGE_NEEDS_VERIFICATION);
                    verification.addFlags(Intent.FLAG_RECEIVER_FOREGROUND);
                    verification.setDataAndType(Uri.fromFile(new File(origin.resolvedPath)),
                            PACKAGE_MIME_TYPE);
                    verification.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);

                    final List<ResolveInfo> receivers = queryIntentReceivers(verification,
                            PACKAGE_MIME_TYPE, PackageManager.GET_DISABLED_COMPONENTS,
                            0 /* TODO: Which userId? */);

                    if (DEBUG_VERIFY) {
                        Slog.d(TAG, "Found " + receivers.size() + " verifiers for intent "
                                + verification.toString() + " with " + pkgLite.verifiers.length
                                + " optional verifiers");
                    }

                    final int verificationId = mPendingVerificationToken++;

                    verification.putExtra(PackageManager.EXTRA_VERIFICATION_ID, verificationId);

                    verification.putExtra(PackageManager.EXTRA_VERIFICATION_INSTALLER_PACKAGE,
                            installerPackageName);

                    verification.putExtra(PackageManager.EXTRA_VERIFICATION_INSTALL_FLAGS,
                            installFlags);

                    verification.putExtra(PackageManager.EXTRA_VERIFICATION_PACKAGE_NAME,
                            pkgLite.packageName);

                    verification.putExtra(PackageManager.EXTRA_VERIFICATION_VERSION_CODE,
                            pkgLite.versionCode);

                    if (verificationParams != null) {
                        if (verificationParams.getVerificationURI() != null) {
                           verification.putExtra(PackageManager.EXTRA_VERIFICATION_URI,
                                 verificationParams.getVerificationURI());
                        }
                        if (verificationParams.getOriginatingURI() != null) {
                            verification.putExtra(Intent.EXTRA_ORIGINATING_URI,
                                  verificationParams.getOriginatingURI());
                        }
                        if (verificationParams.getReferrer() != null) {
                            verification.putExtra(Intent.EXTRA_REFERRER,
                                  verificationParams.getReferrer());
                        }
                        if (verificationParams.getOriginatingUid() >= 0) {
                            verification.putExtra(Intent.EXTRA_ORIGINATING_UID,
                                  verificationParams.getOriginatingUid());
                        }
                        if (verificationParams.getInstallerUid() >= 0) {
                            verification.putExtra(PackageManager.EXTRA_VERIFICATION_INSTALLER_UID,
                                  verificationParams.getInstallerUid());
                        }
                    }

                    final PackageVerificationState verificationState = new PackageVerificationState(
                            requiredUid, args);

                    mPendingVerification.append(verificationId, verificationState);

                    final List<ComponentName> sufficientVerifiers = matchVerifiers(pkgLite,
                            receivers, verificationState);

                    // 为“所有”用户安装的应用程序使用设备所有者来验证应用程序
                    UserHandle verifierUser = getUser();
                    if (verifierUser == UserHandle.ALL) {
                        verifierUser = UserHandle.OWNER;
                    }

                    /*
                     * 如果软件包清单中列出了足够的验证者，请尝试询问它们。
                     */
                    if (sufficientVerifiers != null) {
                        final int N = sufficientVerifiers.size();
                        if (N == 0) {
                            Slog.i(TAG, "Additional verifiers required, but none installed.");
                            ret = PackageManager.INSTALL_FAILED_VERIFICATION_FAILURE;
                        } else {
                            for (int i = 0; i < N; i++) {
                                final ComponentName verifierComponent = sufficientVerifiers.get(i);

                                final Intent sufficientIntent = new Intent(verification);
                                sufficientIntent.setComponent(verifierComponent);
                                mContext.sendBroadcastAsUser(sufficientIntent, verifierUser);
                            }
                        }
                    }

                    final ComponentName requiredVerifierComponent = matchComponentForVerifier(
                            mRequiredVerifierPackage, receivers);
                    if (ret == PackageManager.INSTALL_SUCCEEDED
                            && mRequiredVerifierPackage != null) {
                        /*
                         * 将意图发送到所需的验证代理，
                         * 但仅在目标 BroadcastReceivers 运行之后才开始验证超时。
                         */
                        verification.setComponent(requiredVerifierComponent);
                        mContext.sendOrderedBroadcastAsUser(verification, verifierUser,
                                android.Manifest.permission.PACKAGE_VERIFICATION_AGENT,
                                new BroadcastReceiver() {
                                    @Override
                                    public void onReceive(Context context, Intent intent) {
                                        final Message msg = mHandler
                                                .obtainMessage(CHECK_PENDING_VERIFICATION);
                                        msg.arg1 = verificationId;
                                        mHandler.sendMessageDelayed(msg, getVerificationTimeout());
                                    }
                                }, null, 0, null, null);

                        /*
                         * 在验证成功之前，我们不希望继续进行复制，因此将该字段设为空。
                         */
                        mArgs = null;
                    }
                } else {
                    /*
                     * 没有启用包验证，因此立即启动远程调用以使用临时文件启动复制。
                     */
                    ret = args.copyApk(mContainerService, true);
                }
            }

            mRet = ret;
        }
        ......
    }
    ......
}
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再继续分析之前需要把 Log 搬出来。（新安装 com.cgollner.systemmonitor 这个包）

06-04 15:09:26.796   473   497 D PackageManager: args=com.android.server.pm.PackageManagerService$FileInstallArgs@d438816
06-04 15:09:26.796   473   497 D PackageManager: -----copyApk----
06-04 15:09:26.797   473   497 D PackageManager: tempDir path=/data/app/vmdl1872124892.tmp
06-04 15:09:26.843  1303  1317 D DefContainer: Copying /storage/emulated/0/TestUpdate.apk to base.apk
06-04 15:09:26.850   473   497 D PackageManager: IParcelFileDescriptorFactory file=/data/app/vmdl1872124892.tmp/base.apk
06-04 15:09:27.043   473   497 D PackageManager: libraryRoot=/data/app/vmdl1872124892.tmp/lib
06-04 15:09:28.758   473   497 I PackageManager.DexOptimizer: Running dexopt (dex2oat) on: /data/app/vmdl1872124892.tmp/base.apk pkg=com.cgollner.systemmonitor isa=arm vmSafeMode=false debuggable=false oatDir = /data/app/vmdl1872124892.tmp/oat bootComplete=true
06-04 15:09:28.811  1526  1526 I dex2oat : Starting dex2oat.
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1. mArgs 指向了 PackageManagerService 类内部类 FileInstallArgs
2. 没走到包验证分支，直接走到了 FileInstallArgs 类 copyApk 方法，对 Apk 进行了拷贝动作
3. 最后的 Log 表明 apk 还进行了 dex2oat 转化（dex 转为 oat）

现在可以继续分析 copyApk 方法了。

tempDir 文件夹路径为 /data/app/vmdl1872124892.tmp

apk 拷贝路径从 /storage/emulated/0/xxx.apk （TestUpdate.apk）到 /data/app/vmdl1872124892.tmp/base.apk

libraryRoot 文件夹路径为 /data/app/vmdl1872124892.tmp/lib

1. 创建临时 temp 路径 /data/app/vmdl1872124892.tmp -> /data/app/com.cgollner.systemmonitor-1
2. 拷贝 apk
3. 拷贝 native lib

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class FileInstallArgs extends InstallArgs {
        ......
        // Example topology:
        // /data/app/com.example/base.apk
        // /data/app/com.example/split_foo.apk
        // /data/app/com.example/lib/arm/libfoo.so
        // /data/app/com.example/lib/arm64/libfoo.so
        // /data/app/com.example/dalvik/arm/base.apk@classes.dex
        ......
        int copyApk(IMediaContainerService imcs, boolean temp) throws RemoteException {
            ......
            try {
                // 创建临时 temp 路径 
                final File tempDir = mInstallerService.allocateStageDirLegacy(volumeUuid);
                codeFile = tempDir;
                resourceFile = tempDir;
            } catch (IOException e) {
                Slog.w(TAG, "Failed to create copy file: " + e);
                return PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
            }

            final IParcelFileDescriptorFactory target = new IParcelFileDescriptorFactory.Stub() {
                @Override
                public ParcelFileDescriptor open(String name, int mode) throws RemoteException {
                    if (!FileUtils.isValidExtFilename(name)) {
                        throw new IllegalArgumentException("Invalid filename: " + name);
                    }
                    try {
                        final File file = new File(codeFile, name);
                        final FileDescriptor fd = Os.open(file.getAbsolutePath(),
                                O_RDWR | O_CREAT, 0644);
                        Os.chmod(file.getAbsolutePath(), 0644);
                        return new ParcelFileDescriptor(fd);
                    } catch (ErrnoException e) {
                        throw new RemoteException("Failed to open: " + e.getMessage());
                    }
                }
            };

            int ret = PackageManager.INSTALL_SUCCEEDED;
            // apk 拷贝
            ret = imcs.copyPackage(origin.file.getAbsolutePath(), target);
            if (ret != PackageManager.INSTALL_SUCCEEDED) {
                Slog.e(TAG, "Failed to copy package");
                return ret;
            }

            final File libraryRoot = new File(codeFile, LIB_DIR_NAME);
            NativeLibraryHelper.Handle handle = null;
            try {
                handle = NativeLibraryHelper.Handle.create(codeFile);
                // native lib 拷贝
                ret = NativeLibraryHelper.copyNativeBinariesWithOverride(handle, libraryRoot,
                        abiOverride);
            } catch (IOException e) {
                Slog.e(TAG, "Copying native libraries failed", e);
                ret = PackageManager.INSTALL_FAILED_INTERNAL_ERROR;
            } finally {
                IoUtils.closeQuietly(handle);
            }

            return ret;
        }
        ......
    }
    ......
}
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拷贝 apk 是通过调用（binder远程调用） IMediaContainerService.Stub 类 copyPackage 方法实现的，传入两个参数，第一个为 apk 的原始路径，第二个参数是一个 IParcelFileDescriptorFactory.Stub 对象，传输到 IMediaContainerService.Stub 类它会拿到对应的代理类。

调用链如下：

copyPackage -> copyPackageInner -> copyFile

frameworks/base/packages/DefaultContainerService/src/com/android/defcontainer/DefaultContainerService.java

public class DefaultContainerService extends IntentService {
    private static final String TAG = "DefContainer";

    private IMediaContainerService.Stub mBinder = new IMediaContainerService.Stub() {
        ......
        @Override
        public int copyPackage(String packagePath, IParcelFileDescriptorFactory target) {
            if (packagePath == null || target == null) {
                return PackageManager.INSTALL_FAILED_INVALID_URI;
            }

            PackageLite pkg = null;
            try {
                final File packageFile = new File(packagePath);
                // 解析安装包获取包信息 PackageLite
                pkg = PackageParser.parsePackageLite(packageFile, 0);
                return copyPackageInner(pkg, target);
            } catch (PackageParserException | IOException | RemoteException e) {
                Slog.w(TAG, "Failed to copy package at " + packagePath + ": " + e);
                return PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
            }
        }
        ......
    }
    ......
    private int copyPackageInner(PackageLite pkg, IParcelFileDescriptorFactory target)
            throws IOException, RemoteException {
        copyFile(pkg.baseCodePath, target, "base.apk");
        ......
        return PackageManager.INSTALL_SUCCEEDED;
    }

    private void copyFile(String sourcePath, IParcelFileDescriptorFactory target, String targetName)
            throws IOException, RemoteException {
        Slog.d(TAG, "Copying " + sourcePath + " to " + targetName);
        InputStream in = null;
        OutputStream out = null;
        try {
            in = new FileInputStream(sourcePath);
            // 这里调用了 IParcelFileDescriptorFactory.Stub 类 open 方法
            out = new ParcelFileDescriptor.AutoCloseOutputStream(
                    target.open(targetName, ParcelFileDescriptor.MODE_READ_WRITE));
            // 发生实际拷贝动作
            Streams.copy(in, out);
        } finally {
            IoUtils.closeQuietly(out);
            IoUtils.closeQuietly(in);
        }
    }    
    ......
}
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startCopy() 最后调用了 InstallParams 类 handleReturnCode() 方法，它又实际调用了 processPendingInstall。此时 mRet = PackageManager.INSTALL_SUCCEEDED。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class InstallParams extends HandlerParams {
        ......
        @Override
        void handleReturnCode() {
            if (mArgs != null) {
                processPendingInstall(mArgs, mRet);
            }
        }
        ......
    }
    ......
}
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分析前继续看一段后续 Log：

06-04 13:52:41.691  1588  1588 W dex2oat : Before Android 4.1, method int android.support.v7.internal.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
06-04 13:52:47.537  1588  1588 I dex2oat : dex2oat took 6.235s (threads: 2) arena alloc=1471KB java alloc=3MB native alloc=11MB free=2MB
06-04 13:52:47.636   446   471 W PackageManager: Unknown permission android.permission.ACCESS_SUPERUSER in package com.cgollner.systemmonitor
06-04 13:52:47.636   446   471 W PackageManager: Unknown permission com.android.vending.CHECK_LICENSE in package com.cgollner.systemmonitor
06-04 13:52:47.712   446   471 V BackupManagerService: restoreAtInstall pkg=com.cgollner.systemmonitor token=5 restoreSet=0
06-04 13:52:47.712   446   471 V BackupManagerService: Finishing install immediately
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1. 调用 FileInstallArgs 类 doPreInstall 方法执行安装前动作
2. 调用 installPackageLI 执行实际的安装动作
3. 调用 FileInstallArgs 类 doPostInstall 方法执行安装后动作
4. 如果 (a) 安装成功，(b) 操作不是更新，以及 © 新包没有选择不参与备份，此时应该执行 restore。Log 指明 BackupManagerService 执行了 restore 动作。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
        private void processPendingInstall(final InstallArgs args, final int currentStatus) {
        // 异步操作排队，因为包的安装可能需要一段时间。
        mHandler.post(new Runnable() {
            public void run() {
                mHandler.removeCallbacks(this);
                 // 要返回的结果对象
                PackageInstalledInfo res = new PackageInstalledInfo();
                res.returnCode = currentStatus;
                res.uid = -1;
                res.pkg = null;
                res.removedInfo = new PackageRemovedInfo();
                if (res.returnCode == PackageManager.INSTALL_SUCCEEDED) {
                    args.doPreInstall(res.returnCode);
                    synchronized (mInstallLock) {
                        installPackageLI(args, res);
                    }
                    args.doPostInstall(res.returnCode, res.uid);
                }

                // 如果(a)安装成功，(b)操作不是更新，以及(c)新包没有选择不参与备份，
                // 此时应该执行 restore 。
                final boolean update = res.removedInfo.removedPackage != null;
                final int flags = (res.pkg == null) ? 0 : res.pkg.applicationInfo.flags;
                boolean doRestore = !update
                        && ((flags & ApplicationInfo.FLAG_ALLOW_BACKUP) != 0);

                // 设置安装后工作请求簿记。安装后事件处理将使用并清理此事件，
                // 而不管是否执行了 restore 过程。令牌值 >= 1。
                int token;
                if (mNextInstallToken < 0) mNextInstallToken = 1;
                token = mNextInstallToken++;

                PostInstallData data = new PostInstallData(args, res);
                mRunningInstalls.put(token, data);
                if (DEBUG_INSTALL) Log.v(TAG, "+ starting restore round-trip " + token);

                if (res.returnCode == PackageManager.INSTALL_SUCCEEDED && doRestore) {
                    // 将责任移交给备份管理器。 
                    // 它将在适当时执行 restore，
                    // 然后将责任传递回包管理器以运行安装后的观察者回调和广播。
                    IBackupManager bm = IBackupManager.Stub.asInterface(
                            ServiceManager.getService(Context.BACKUP_SERVICE));
                    if (bm != null) {
                        if (DEBUG_INSTALL) Log.v(TAG, "token " + token
                                + " to BM for possible restore");
                        try {
                            if (bm.isBackupServiceActive(UserHandle.USER_OWNER)) {
                                bm.restoreAtInstall(res.pkg.applicationInfo.packageName, token);
                            } else {
                                doRestore = false;
                            }
                        } catch (RemoteException e) {
                            // can't happen; the backup manager is local
                        } catch (Exception e) {
                            Slog.e(TAG, "Exception trying to enqueue restore", e);
                            doRestore = false;
                        }
                    } else {
                        Slog.e(TAG, "Backup Manager not found!");
                        doRestore = false;
                    }
                }

                if (!doRestore) {
                    // 无法 restore，或者备份管理器不可用———直接发出安装后工作请求即可。
                    if (DEBUG_INSTALL) Log.v(TAG, "No restore - queue post-install for " + token);
                    Message msg = mHandler.obtainMessage(POST_INSTALL, token, 0);
                    mHandler.sendMessage(msg);
                }
            }
        });
    }
    ......
}
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doPreInstall() 安装前动作很简单，如果 status != PackageManager.INSTALL_SUCCEEDED，说明前面拷贝安装包出现了问题，直接调用 cleanUp() 删除临时创建的文件夹。doPostInstall() 在安装包之后进行善后工作，和 doPreInstall() 实现一致，删除临时创建的文件夹。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class FileInstallArgs extends InstallArgs {
        ......
        int doPreInstall(int status) {
            if (status != PackageManager.INSTALL_SUCCEEDED) {
                cleanUp();
            }
            return status;
        }
        ......
        int doPostInstall(int status, int uid) {
            if (status != PackageManager.INSTALL_SUCCEEDED) {
                cleanUp();
            }
            return status;
        }
        ......
        private boolean cleanUp() {
            if (codeFile == null || !codeFile.exists()) {
                return false;
            }

            if (codeFile.isDirectory()) {
                mInstaller.rmPackageDir(codeFile.getAbsolutePath());
            } else {
                codeFile.delete();
            }

            if (resourceFile != null && !FileUtils.contains(codeFile, resourceFile)) {
                resourceFile.delete();
            }

            return true;
        }        
        ......
    }
    ......
}
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installPackageLI 函数非常复杂，涉及解析安装包、验证签名、检查权限、dex2oat、重命名、应用替换（含升级）和新应用安装几个方面。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    private void installPackageLI(InstallArgs args, PackageInstalledInfo res) {
        final int installFlags = args.installFlags;
        final String installerPackageName = args.installerPackageName;
        final String volumeUuid = args.volumeUuid;
        final File tmpPackageFile = new File(args.getCodePath());
        final boolean forwardLocked = ((installFlags & PackageManager.INSTALL_FORWARD_LOCK) != 0);
        final boolean onExternal = (((installFlags & PackageManager.INSTALL_EXTERNAL) != 0)
                || (args.volumeUuid != null));
        boolean replace = false;
        int scanFlags = SCAN_NEW_INSTALL | SCAN_UPDATE_SIGNATURE;
        if (args.move != null) {
            // 移动完整的应用程序；在新的安装位置执行初始扫描
            scanFlags |= SCAN_INITIAL;
        }
        // 要返回的结果对象
        res.returnCode = PackageManager.INSTALL_SUCCEEDED;

        if (DEBUG_INSTALL) Slog.d(TAG, "installPackageLI: path=" + tmpPackageFile);
        // 检索 PackageSettings 和解析包
        final int parseFlags = mDefParseFlags | PackageParser.PARSE_CHATTY
                | (forwardLocked ? PackageParser.PARSE_FORWARD_LOCK : 0)
                | (onExternal ? PackageParser.PARSE_EXTERNAL_STORAGE : 0);
        PackageParser pp = new PackageParser();
        pp.setSeparateProcesses(mSeparateProcesses);
        pp.setDisplayMetrics(mMetrics);

        final PackageParser.Package pkg;
        try {
            // 解析安装包
            pkg = pp.parsePackage(tmpPackageFile, parseFlags);
        } catch (PackageParserException e) {
            res.setError("Failed parse during installPackageLI", e);
            return;
        }

        // 标记我们有一个安装时 CPU ABI 覆盖。
        pkg.cpuAbiOverride = args.abiOverride;

        String pkgName = res.name = pkg.packageName;
        if ((pkg.applicationInfo.flags&ApplicationInfo.FLAG_TEST_ONLY) != 0) {
            if ((installFlags & PackageManager.INSTALL_ALLOW_TEST) == 0) {
                res.setError(INSTALL_FAILED_TEST_ONLY, "installPackageLI");
                return;
            }
        }

        try {
            pp.collectCertificates(pkg, parseFlags);
            pp.collectManifestDigest(pkg);
        } catch (PackageParserException e) {
            res.setError("Failed collect during installPackageLI", e);
            return;
        }

        /* 签名验证相关：如果安装程序传递了清单摘要，请立即进行比较。 */
        if (args.manifestDigest != null) {
            if (DEBUG_INSTALL) {
                final String parsedManifest = pkg.manifestDigest == null ? "null"
                        : pkg.manifestDigest.toString();
                Slog.d(TAG, "Comparing manifests: " + args.manifestDigest.toString() + " vs. "
                        + parsedManifest);
            }

            if (!args.manifestDigest.equals(pkg.manifestDigest)) {
                res.setError(INSTALL_FAILED_PACKAGE_CHANGED, "Manifest digest changed");
                return;
            }
        } else if (DEBUG_INSTALL) {
            final String parsedManifest = pkg.manifestDigest == null
                    ? "null" : pkg.manifestDigest.toString();
            Slog.d(TAG, "manifestDigest was not present, but parser got: " + parsedManifest);
        }

        // Get rid of all references to package scan path via parser.
        pp = null;
        String oldCodePath = null;
        boolean systemApp = false;
        synchronized (mPackages) {
            // 检查是否安装已经存在的包
            if ((installFlags & PackageManager.INSTALL_REPLACE_EXISTING) != 0) {
                String oldName = mSettings.mRenamedPackages.get(pkgName);
                if (pkg.mOriginalPackages != null
                        && pkg.mOriginalPackages.contains(oldName)
                        && mPackages.containsKey(oldName)) {
                    // 该软件包派生自原始软件包，并且该设备已从该原始名称进行更新。
                    // 我们必须继续使用原始名称，因此在此处重命名新软件包。
                    pkg.setPackageName(oldName);
                    pkgName = pkg.packageName;
                    replace = true;
                    if (DEBUG_INSTALL) Slog.d(TAG, "Replacing existing renamed package: oldName="
                            + oldName + " pkgName=" + pkgName);
                } else if (mPackages.containsKey(pkgName)) {
                    // 该软件包以其正式名称在设备上已经存在；我们应该替换它。
                    replace = true;
                    if (DEBUG_INSTALL) Slog.d(TAG, "Replace existing pacakge: " + pkgName);
                }

                // 阻止应用选择运行时权限
                if (replace) {
                    PackageParser.Package oldPackage = mPackages.get(pkgName);
                    final int oldTargetSdk = oldPackage.applicationInfo.targetSdkVersion;
                    final int newTargetSdk = pkg.applicationInfo.targetSdkVersion;
                    if (oldTargetSdk > Build.VERSION_CODES.LOLLIPOP_MR1
                            && newTargetSdk <= Build.VERSION_CODES.LOLLIPOP_MR1) {
                        res.setError(PackageManager.INSTALL_FAILED_PERMISSION_MODEL_DOWNGRADE,
                                "Package " + pkg.packageName + " new target SDK " + newTargetSdk
                                        + " doesn't support runtime permissions but the old"
                                        + " target SDK " + oldTargetSdk + " does.");
                        return;
                    }
                }
            }

            PackageSetting ps = mSettings.mPackages.get(pkgName);
            if (ps != null) {
                if (DEBUG_INSTALL) Slog.d(TAG, "Existing package: " + ps);

                // 快速检查是否更新时签名正确；
                // 稍后我们将在扫描时再次检查这一点，
                // 但我们希望在切换到重新定义的权限之前尽早退出。
                if (shouldCheckUpgradeKeySetLP(ps, scanFlags)) {
                    if (!checkUpgradeKeySetLP(ps, pkg)) {
                        res.setError(INSTALL_FAILED_UPDATE_INCOMPATIBLE, "Package "
                                + pkg.packageName + " upgrade keys do not match the "
                                + "previously installed version");
                        return;
                    }
                } else {
                    try {
                        verifySignaturesLP(ps, pkg);
                    } catch (PackageManagerException e) {
                        res.setError(e.error, e.getMessage());
                        return;
                    }
                }

                oldCodePath = mSettings.mPackages.get(pkgName).codePathString;
                if (ps.pkg != null && ps.pkg.applicationInfo != null) {
                    systemApp = (ps.pkg.applicationInfo.flags &
                            ApplicationInfo.FLAG_SYSTEM) != 0;
                }
                res.origUsers = ps.queryInstalledUsers(sUserManager.getUserIds(), true);
            }

            // 检查新扫描的包是否要定义一个已经定义的权限
            int N = pkg.permissions.size();
            for (int i = N-1; i >= 0; i--) {
                PackageParser.Permission perm = pkg.permissions.get(i);
                BasePermission bp = mSettings.mPermissions.get(perm.info.name);
                if (bp != null) {
                    // 如果定义包使用匹配的证书进行了签名，则没有问题。
                    // 当然，这也包括“更新相同的包”的情况。
                    final boolean sigsOk;
                    if (bp.sourcePackage.equals(pkg.packageName)
                            && (bp.packageSetting instanceof PackageSetting)
                            && (shouldCheckUpgradeKeySetLP((PackageSetting) bp.packageSetting,
                                    scanFlags))) {
                        sigsOk = checkUpgradeKeySetLP((PackageSetting) bp.packageSetting, pkg);
                    } else {
                        sigsOk = compareSignatures(bp.packageSetting.signatures.mSignatures,
                                pkg.mSignatures) == PackageManager.SIGNATURE_MATCH;
                    }
                    if (!sigsOk) {
                        // 如果是系统本身拥有的软件包，我们将记录下来，但允许进行安装；
                        // 我们在所有其他权限重新定义上均使安装失败。
                        if (!bp.sourcePackage.equals("android")) {
                            res.setError(INSTALL_FAILED_DUPLICATE_PERMISSION, "Package "
                                    + pkg.packageName + " attempting to redeclare permission "
                                    + perm.info.name + " already owned by " + bp.sourcePackage);
                            res.origPermission = perm.info.name;
                            res.origPackage = bp.sourcePackage;
                            return;
                        } else {
                            Slog.w(TAG, "Package " + pkg.packageName
                                    + " attempting to redeclare system permission "
                                    + perm.info.name + "; ignoring new declaration");
                            pkg.permissions.remove(i);
                        }
                    } else if (!"android".equals(pkg.packageName)) {
                        // 阻止应用程序将保护级别从任何其他类型更改为危险，因为这将允许特权升级，
                        // 其中一个应用程序在其他应用程序的组中添加普通/签名权限，
                        // 然后将其重新定义为危险级别，从而导致该组自动授予权限。
                        if ((perm.info.protectionLevel & PermissionInfo.PROTECTION_MASK_BASE)
                                == PermissionInfo.PROTECTION_DANGEROUS) {
                            if (bp != null && !bp.isRuntime()) {
                                Slog.w(TAG, "Package " + pkg.packageName + " trying to change a "
                                        + "non-runtime permission " + perm.info.name
                                        + " to runtime; keeping old protection level");
                                perm.info.protectionLevel = bp.protectionLevel;
                            }
                        }
                    }
                }
            }

        }

        if (systemApp && onExternal) {
            // 禁用SD卡上系统应用程序的更新
            res.setError(INSTALL_FAILED_INVALID_INSTALL_LOCATION,
                    "Cannot install updates to system apps on sdcard");
            return;
        }

        if (args.move != null) {
            // 我们做了原地移动，因此dex准备就绪
            scanFlags |= SCAN_NO_DEX;
            scanFlags |= SCAN_MOVE;

            synchronized (mPackages) {
                final PackageSetting ps = mSettings.mPackages.get(pkgName);
                if (ps == null) {
                    res.setError(INSTALL_FAILED_INTERNAL_ERROR,
                            "Missing settings for moved package " + pkgName);
                }

                // 我们按原样移动了整个应用程序，因此引入了以前派生的 ABI 信息。
                pkg.applicationInfo.primaryCpuAbi = ps.primaryCpuAbiString;
                pkg.applicationInfo.secondaryCpuAbi = ps.secondaryCpuAbiString;
            }

        } else if (!forwardLocked && !pkg.applicationInfo.isExternalAsec()) {
            // 启用 SCAN_NO_DEX 标志以在以后跳过 dexopt
            scanFlags |= SCAN_NO_DEX;

            try {
                derivePackageAbi(pkg, new File(pkg.codePath), args.abiOverride,
                        true /* extract libs */);
            } catch (PackageManagerException pme) {
                Slog.e(TAG, "Error deriving application ABI", pme);
                res.setError(INSTALL_FAILED_INTERNAL_ERROR, "Error deriving application ABI");
                return;
            }

            // 在删除旧软件包之前运行dexopt，以最大程度地减少应用程序不可用时的时间
            int result = mPackageDexOptimizer
                    .performDexOpt(pkg, null /* instruction sets */, false /* forceDex */,
                            false /* defer */, false /* inclDependencies */,
                            true /* boot complete */);
            if (result == PackageDexOptimizer.DEX_OPT_FAILED) {
                res.setError(INSTALL_FAILED_DEXOPT, "Dexopt failed for " + pkg.codePath);
                return;
            }
        }
        // 重命名（将临时路径命名为最终路径）
        if (!args.doRename(res.returnCode, pkg, oldCodePath)) {
            res.setError(INSTALL_FAILED_INSUFFICIENT_STORAGE, "Failed rename");
            return;
        }

        startIntentFilterVerifications(args.user.getIdentifier(), replace, pkg);

        if (replace) {
            // 替换应用
            replacePackageLI(pkg, parseFlags, scanFlags | SCAN_REPLACING, args.user,
                    installerPackageName, volumeUuid, res);
        } else {
            // 安装新应用
            installNewPackageLI(pkg, parseFlags, scanFlags | SCAN_DELETE_DATA_ON_FAILURES,
                    args.user, installerPackageName, volumeUuid, res);
        }
        synchronized (mPackages) {
            final PackageSetting ps = mSettings.mPackages.get(pkgName);
            if (ps != null) {
                res.newUsers = ps.queryInstalledUsers(sUserManager.getUserIds(), true);
            }
        }
    }
    ......
}
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重命名非常简单，把临时路径命名为了最终路径：/data/app/vmdl1872124892.tmp -> /data/app/com.cgollner.systemmonitor-1

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class FileInstallArgs extends InstallArgs {
        ......
        boolean doRename(int status, PackageParser.Package pkg, String oldCodePath) {
            if (status != PackageManager.INSTALL_SUCCEEDED) {
                cleanUp();
                return false;
            }

            final File targetDir = codeFile.getParentFile();
            final File beforeCodeFile = codeFile;
            final File afterCodeFile = getNextCodePath(targetDir, pkg.packageName);

            if (DEBUG_INSTALL) Slog.d(TAG, "Renaming " + beforeCodeFile + " to " + afterCodeFile);
            try {
                Os.rename(beforeCodeFile.getAbsolutePath(), afterCodeFile.getAbsolutePath());
            } catch (ErrnoException e) {
                Slog.w(TAG, "Failed to rename", e);
                return false;
            }

            if (!SELinux.restoreconRecursive(afterCodeFile)) {
                Slog.w(TAG, "Failed to restorecon");
                return false;
            }

            // 在内部反映重命名
            codeFile = afterCodeFile;
            resourceFile = afterCodeFile;

            // 在扫描的细节中反映重命名
            pkg.codePath = afterCodeFile.getAbsolutePath();
            pkg.baseCodePath = FileUtils.rewriteAfterRename(beforeCodeFile, afterCodeFile,
                    pkg.baseCodePath);
            pkg.splitCodePaths = FileUtils.rewriteAfterRename(beforeCodeFile, afterCodeFile,
                    pkg.splitCodePaths);

            // 在应用信息中反映重命名
            pkg.applicationInfo.volumeUuid = pkg.volumeUuid;
            pkg.applicationInfo.setCodePath(pkg.codePath);
            pkg.applicationInfo.setBaseCodePath(pkg.baseCodePath);
            pkg.applicationInfo.setSplitCodePaths(pkg.splitCodePaths);
            pkg.applicationInfo.setResourcePath(pkg.codePath);
            pkg.applicationInfo.setBaseResourcePath(pkg.baseCodePath);
            pkg.applicationInfo.setSplitResourcePaths(pkg.splitCodePaths);

            return true;
        }        
        ......
    }
    ......
}
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再来分析 installNewPackageLI。

1. 处理系统中已经安装同名包的情况
2. 调用 scanPackageLI 扫描安装包
3. 更新 Settings（包含有关动态设置的信息）
4. 删除部分安装的应用程序。如果数据目录已经存在，则必须将其还原

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    private void installNewPackageLI(PackageParser.Package pkg, int parseFlags, int scanFlags,
            UserHandle user, String installerPackageName, String volumeUuid,
            PackageInstalledInfo res) {
        // 记住这一点，以防我们需要回滚此安装
        String pkgName = pkg.packageName;

        if (DEBUG_INSTALL) Slog.d(TAG, "installNewPackageLI: " + pkg);
        final boolean dataDirExists = Environment
                .getDataUserPackageDirectory(volumeUuid, UserHandle.USER_OWNER, pkgName).exists();
        synchronized(mPackages) {
            if (mSettings.mRenamedPackages.containsKey(pkgName)) {
                // 已经安装了同名的包，尽管它已被重命名为较旧的名称。
                // 我们试图安装的软件包应该作为现有软件包的更新来安装，但没有被要求
                res.setError(INSTALL_FAILED_ALREADY_EXISTS, "Attempt to re-install " + pkgName
                        + " without first uninstalling package running as "
                        + mSettings.mRenamedPackages.get(pkgName));
                return;
            }
            if (mPackages.containsKey(pkgName)) {
                // 不允许通过相同名称的现有软件包进行安装。
                res.setError(INSTALL_FAILED_ALREADY_EXISTS, "Attempt to re-install " + pkgName
                        + " without first uninstalling.");
                return;
            }
        }

        try {
            // 扫描安装包
            PackageParser.Package newPackage = scanPackageLI(pkg, parseFlags, scanFlags,
                    System.currentTimeMillis(), user);
            // 更新 Settings（包含有关动态设置的信息）
            updateSettingsLI(newPackage, installerPackageName, volumeUuid, null, null, res, user);
            // 删除部分安装的应用程序。如果数据目录已经存在，则必须将其还原
            if (res.returnCode != PackageManager.INSTALL_SUCCEEDED) {
                // 从内部结构中移除包。
                // 请注意，我们希望 deletePackageX 删除在 scanPackageLocked 中创建的程序包数据和缓存目录，
                // 除非这些目录在我们尝试安装之前就已经存在。
                deletePackageLI(pkgName, UserHandle.ALL, false, null, null,
                        dataDirExists ? PackageManager.DELETE_KEEP_DATA : 0,
                                res.removedInfo, true);
            }

        } catch (PackageManagerException e) {
            res.setError("Package couldn't be installed in " + pkg.codePath, e);
        }
    }
    ......
}
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扫描安装包是调用 scanPackageLI 实现的。scanPackageLI 主要工作是调用 scanPackageDirtyLI 方法完成的。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    private PackageParser.Package scanPackageLI(PackageParser.Package pkg, int parseFlags,
            int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {
        boolean success = false;
        try {
            final PackageParser.Package res = scanPackageDirtyLI(pkg, parseFlags, scanFlags,
                    currentTime, user);
            success = true;
            return res;
        } finally {
            ......
        }
    }
    ......
}
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scanPackageDirtyLI 这个方法的代码太长了，不得不吐槽一下 google 开发这个函数的工程师，这个函数为何不能细分一下呢？委屈脸~这个函数完成了一系列艰难的任务，涵盖初始化包源目录和资源目录、验证签名、创建数据目录、设置 native 库路径等等。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg, int parseFlags,
            int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {
        final File scanFile = new File(pkg.codePath);
        if (pkg.applicationInfo.getCodePath() == null ||
                pkg.applicationInfo.getResourcePath() == null) {
            // 抛出异常，资源和代码路径还没有设置。
            throw new PackageManagerException(INSTALL_FAILED_INVALID_APK,
                    "Code and resource paths haven't been set correctly");
        }
        // 设置 FLAG_SYSTEM，表示系统应用
        if ((parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_SYSTEM;
        } else {
            // 只允许系统应用被标记为核心应用。
            pkg.coreApp = false;
        }
        // 设置 PRIVATE_FLAG_PRIVILEGED，表示特权系统应用
        if ((parseFlags&PackageParser.PARSE_IS_PRIVILEGED) != 0) {
            pkg.applicationInfo.privateFlags |= ApplicationInfo.PRIVATE_FLAG_PRIVILEGED;
        }

        if (mCustomResolverComponentName != null &&
                mCustomResolverComponentName.getPackageName().equals(pkg.packageName)) {
            setUpCustomResolverActivity(pkg);
        }

        if (pkg.packageName.equals("android")) {
            synchronized (mPackages) {
                if (mAndroidApplication != null) {
                    Slog.w(TAG, "*************************************************");
                    Slog.w(TAG, "Core android package being redefined.  Skipping.");
                    Slog.w(TAG, " file=" + scanFile);
                    Slog.w(TAG, "*************************************************");
                    throw new PackageManagerException(INSTALL_FAILED_DUPLICATE_PACKAGE,
                            "Core android package being redefined.  Skipping.");
                }

                // Set up information for our fall-back user intent resolution activity.
                mPlatformPackage = pkg;
                pkg.mVersionCode = mSdkVersion;
                mAndroidApplication = pkg.applicationInfo;

                if (!mResolverReplaced) {
                    mResolveActivity.applicationInfo = mAndroidApplication;
                    mResolveActivity.name = ResolverActivity.class.getName();
                    mResolveActivity.packageName = mAndroidApplication.packageName;
                    mResolveActivity.processName = "system:ui";
                    mResolveActivity.launchMode = ActivityInfo.LAUNCH_MULTIPLE;
                    mResolveActivity.documentLaunchMode = ActivityInfo.DOCUMENT_LAUNCH_NEVER;
                    mResolveActivity.flags = ActivityInfo.FLAG_EXCLUDE_FROM_RECENTS;
                    mResolveActivity.theme = R.style.Theme_Holo_Dialog_Alert;
                    mResolveActivity.exported = true;
                    mResolveActivity.enabled = true;
                    mResolveInfo.activityInfo = mResolveActivity;
                    mResolveInfo.priority = 0;
                    mResolveInfo.preferredOrder = 0;
                    mResolveInfo.match = 0;
                    mResolveComponentName = new ComponentName(
                            mAndroidApplication.packageName, mResolveActivity.name);
                }
            }
        }

        if (DEBUG_PACKAGE_SCANNING) {
            if ((parseFlags & PackageParser.PARSE_CHATTY) != 0)
                Log.d(TAG, "Scanning package " + pkg.packageName);
        }
        // 应用程序软件包已安装，跳过重复项。
        if (mPackages.containsKey(pkg.packageName)
                || mSharedLibraries.containsKey(pkg.packageName)) {
            throw new PackageManagerException(INSTALL_FAILED_DUPLICATE_PACKAGE,
                    "Application package " + pkg.packageName
                    + " already installed.  Skipping duplicate.");
        }

        // 如果只安装预存在的包，则要求扫描的APK是已知的，
        // 并且位于先前为其建立的路径上。我们通常会选择以前不知道的包，
        // 但是如果我们对这个包的安装状态有一个先验的预期，就强制执行它。
        // 对于新系统包，只有一个例外。当OTA包含一个新的系统包时，
        // 我们允许代码路径从系统位置更改为用户安装的位置。如果我们不允许此更改，
        // 则应用程序的任何更新的、用户安装的版本将被忽略。
        if ((scanFlags & SCAN_REQUIRE_KNOWN) != 0) {
            if (mExpectingBetter.containsKey(pkg.packageName)) {
                logCriticalInfo(Log.WARN,
                        "Relax SCAN_REQUIRE_KNOWN requirement for package " + pkg.packageName);
            } else {
                PackageSetting known = mSettings.peekPackageLPr(pkg.packageName);
                if (known != null) {
                    if (DEBUG_PACKAGE_SCANNING) {
                        Log.d(TAG, "Examining " + pkg.codePath
                                + " and requiring known paths " + known.codePathString
                                + " & " + known.resourcePathString);
                    }
                    if (!pkg.applicationInfo.getCodePath().equals(known.codePathString)
                            || !pkg.applicationInfo.getResourcePath().equals(known.resourcePathString)) {
                        throw new PackageManagerException(INSTALL_FAILED_PACKAGE_CHANGED,
                                "Application package " + pkg.packageName
                                + " found at " + pkg.applicationInfo.getCodePath()
                                + " but expected at " + known.codePathString + "; ignoring.");
                    }
                }
            }
        }

        // 初始化包源目录和资源目录
        File destCodeFile = new File(pkg.applicationInfo.getCodePath());
        File destResourceFile = new File(pkg.applicationInfo.getResourcePath());

        SharedUserSetting suid = null;
        PackageSetting pkgSetting = null;

        if (!isSystemApp(pkg)) {
            // 只有系统应用程序才能使用这些功能。
            pkg.mOriginalPackages = null;
            pkg.mRealPackage = null;
            pkg.mAdoptPermissions = null;
        }

        // writer
        synchronized (mPackages) {
            if (pkg.mSharedUserId != null) {
                suid = mSettings.getSharedUserLPw(pkg.mSharedUserId, 0, 0, true);
                if (suid == null) {
                    throw new PackageManagerException(INSTALL_FAILED_INSUFFICIENT_STORAGE,
                            "Creating application package " + pkg.packageName
                            + " for shared user failed");
                }
                if (DEBUG_PACKAGE_SCANNING) {
                    if ((parseFlags & PackageParser.PARSE_CHATTY) != 0)
                        Log.d(TAG, "Shared UserID " + pkg.mSharedUserId + " (uid=" + suid.userId
                                + "): packages=" + suid.packages);
                }
            }

            // 检查是否从原来的包名重命名。
            PackageSetting origPackage = null;
            String realName = null;
            if (pkg.mOriginalPackages != null) {
                // 这个包可能需要重命名为以前安装的名称。让我们检查一下……
                final String renamed = mSettings.mRenamedPackages.get(pkg.mRealPackage);
                if (pkg.mOriginalPackages.contains(renamed)) {
                    // 这个包最初是作为原始名称安装的，我们已经完成了向新名称的转换。只需更新新名称以继续使用旧名称。
                    realName = pkg.mRealPackage;
                    if (!pkg.packageName.equals(renamed)) {
                        // 这个函数的调用者可能已经负责了包的重命名；如果还没做，就在这里做。
                        pkg.setPackageName(renamed);
                    }

                } else {
                    for (int i=pkg.mOriginalPackages.size()-1; i>=0; i--) {
                        if ((origPackage = mSettings.peekPackageLPr(
                                pkg.mOriginalPackages.get(i))) != null) {
                            // 我们确实已经用原来的名字安装了这个包…
                            if (!verifyPackageUpdateLPr(origPackage, pkg)) {
                                // 新包与原包不兼容。
                                origPackage = null;
                                continue;
                            } else if (origPackage.sharedUser != null) {
                                // 确保uid在包之间是兼容的。
                                if (!origPackage.sharedUser.name.equals(pkg.mSharedUserId)) {
                                    Slog.w(TAG, "Unable to migrate data from " + origPackage.name
                                            + " to " + pkg.packageName + ": old uid "
                                            + origPackage.sharedUser.name
                                            + " differs from " + pkg.mSharedUserId);
                                    origPackage = null;
                                    continue;
                                }
                            } else {
                                if (DEBUG_UPGRADE) Log.v(TAG, "Renaming new package "
                                        + pkg.packageName + " to old name " + origPackage.name);
                            }
                            break;
                        }
                    }
                }
            }

            if (mTransferedPackages.contains(pkg.packageName)) {
                Slog.w(TAG, "Package " + pkg.packageName
                        + " was transferred to another, but its .apk remains");
            }

            // 只需创建设置，不添加即可。对于已经存在的软件包，PkgSetting 已经存在，因此不必创建。
            pkgSetting = mSettings.getPackageLPw(pkg, origPackage, realName, suid, destCodeFile,
                    destResourceFile, pkg.applicationInfo.nativeLibraryRootDir,
                    pkg.applicationInfo.primaryCpuAbi,
                    pkg.applicationInfo.secondaryCpuAbi,
                    pkg.applicationInfo.flags, pkg.applicationInfo.privateFlags,
                    user, false);
            if (pkgSetting == null) {
                throw new PackageManagerException(INSTALL_FAILED_INSUFFICIENT_STORAGE,
                        "Creating application package " + pkg.packageName + " failed");
            }

            if (pkgSetting.origPackage != null) {
                // 如果我们是第一次从原始程序包过渡，请立即确定新程序包的名称。
                // 我们需要在使用新名称查找软件包之后执行此操作，
                // 因此 getPackageLP 可以正确处理问题。
                pkg.setPackageName(origPackage.name);

                // 提交关于此的报告。
                String msg = "New package " + pkgSetting.realName
                        + " renamed to replace old package " + pkgSetting.name;
                reportSettingsProblem(Log.WARN, msg);

                // 把它记下来。
                mTransferedPackages.add(origPackage.name);

                // 不再需要保留这些。
                pkgSetting.origPackage = null;
            }

            if (realName != null) {
                // 把它记下来
                mTransferedPackages.add(pkg.packageName);
            }

            if (mSettings.isDisabledSystemPackageLPr(pkg.packageName)) {
                pkg.applicationInfo.flags |= ApplicationInfo.FLAG_UPDATED_SYSTEM_APP;
            }

            if ((parseFlags&PackageParser.PARSE_IS_SYSTEM_DIR) == 0) {
                // 检查所有共享库并映射到它们的实际文件路径。
                // 我们在这里只对不在系统目录上的应用程序执行此操作，
                // 因为它们是唯一会因此导致安装失败的应用程序。
                // 扫描完成后，我们将更新系统应用程序的所有库路径。
                updateSharedLibrariesLPw(pkg, null);
            }

            if (mFoundPolicyFile) {
                SELinuxMMAC.assignSeinfoValue(pkg);
            }

            pkg.applicationInfo.uid = pkgSetting.appId;
            pkg.mExtras = pkgSetting;
            if (shouldCheckUpgradeKeySetLP(pkgSetting, scanFlags)) {
                if (checkUpgradeKeySetLP(pkgSetting, pkg)) {
                    // 我们刚刚确定了应用程序的签名是正确的，提交最新解析的证书。
                    pkgSetting.signatures.mSignatures = pkg.mSignatures;
                } else {
                    if ((parseFlags & PackageParser.PARSE_IS_SYSTEM_DIR) == 0) {
                        throw new PackageManagerException(INSTALL_FAILED_UPDATE_INCOMPATIBLE,
                                "Package " + pkg.packageName + " upgrade keys do not match the "
                                + "previously installed version");
                    } else {
                        pkgSetting.signatures.mSignatures = pkg.mSignatures;
                        String msg = "System package " + pkg.packageName
                            + " signature changed; retaining data.";
                        reportSettingsProblem(Log.WARN, msg);
                    }
                }
            } else {
                try {
                    verifySignaturesLP(pkgSetting, pkg);
                    // 我们刚刚确定了应用程序的签名是正确的，提交最新解析的证书。
                    pkgSetting.signatures.mSignatures = pkg.mSignatures;
                } catch (PackageManagerException e) {
                    if ((parseFlags & PackageParser.PARSE_IS_SYSTEM_DIR) == 0) {
                        throw e;
                    }
                    // 签名已经更改，但是这个包在系统映像中…让我们恢复!
                    pkgSetting.signatures.mSignatures = pkg.mSignatures;
                    // 然而……如果这个包是共享用户的一部分，但是它与共享用户的签名不匹配，那么我们失败。
                    // 这意味着你不能更改与整个共享用户相关联的签名，这看起来并没有那么不合理。
                    if (pkgSetting.sharedUser != null) {
                        if (compareSignatures(pkgSetting.sharedUser.signatures.mSignatures,
                                              pkg.mSignatures) != PackageManager.SIGNATURE_MATCH) {
                            throw new PackageManagerException(
                                    INSTALL_PARSE_FAILED_INCONSISTENT_CERTIFICATES,
                                            "Signature mismatch for shared user : "
                                            + pkgSetting.sharedUser);
                        }
                    }
                    // 提交关于此的报告。
                    String msg = "System package " + pkg.packageName
                        + " signature changed; retaining data.";
                    reportSettingsProblem(Log.WARN, msg);
                }
            }
            // 确认此新程序包没有与现有程序包冲突的任何内容提供程序。
            // 仅在尚未安装软件包的情况下才这样做，因为我们不想破坏已安装的东西。
            if ((scanFlags & SCAN_NEW_INSTALL) != 0) {
                final int N = pkg.providers.size();
                int i;
                for (i=0; i<N; i++) {
                    PackageParser.Provider p = pkg.providers.get(i);
                    if (p.info.authority != null) {
                        String names[] = p.info.authority.split(";");
                        for (int j = 0; j < names.length; j++) {
                            if (mProvidersByAuthority.containsKey(names[j])) {
                                PackageParser.Provider other = mProvidersByAuthority.get(names[j]);
                                final String otherPackageName =
                                        ((other != null && other.getComponentName() != null) ?
                                                other.getComponentName().getPackageName() : "?");
                                throw new PackageManagerException(
                                        INSTALL_FAILED_CONFLICTING_PROVIDER,
                                                "Can't install because provider name " + names[j]
                                                + " (in package " + pkg.applicationInfo.packageName
                                                + ") is already used by " + otherPackageName);
                            }
                        }
                    }
                }
            }

            if (pkg.mAdoptPermissions != null) {
                // 该软件包希望采用另一个软件包的权限所有权。
                for (int i = pkg.mAdoptPermissions.size() - 1; i >= 0; i--) {
                    final String origName = pkg.mAdoptPermissions.get(i);
                    final PackageSetting orig = mSettings.peekPackageLPr(origName);
                    if (orig != null) {
                        if (verifyPackageUpdateLPr(orig, pkg)) {
                            Slog.i(TAG, "Adopting permissions from " + origName + " to "
                                    + pkg.packageName);
                            mSettings.transferPermissionsLPw(origName, pkg.packageName);
                        }
                    }
                }
            }
        }

        final String pkgName = pkg.packageName;

        final long scanFileTime = scanFile.lastModified();
        final boolean forceDex = (scanFlags & SCAN_FORCE_DEX) != 0;
        pkg.applicationInfo.processName = fixProcessName(
                pkg.applicationInfo.packageName,
                pkg.applicationInfo.processName,
                pkg.applicationInfo.uid);

        File dataPath;
        if (mPlatformPackage == pkg) {
            // 系统软件包是特殊的。
            dataPath = new File(Environment.getDataDirectory(), "system");

            pkg.applicationInfo.dataDir = dataPath.getPath();

        } else {
            // 这是一个普通的程序包，需要创建数据目录。
            dataPath = Environment.getDataUserPackageDirectory(pkg.volumeUuid,
                    UserHandle.USER_OWNER, pkg.packageName);

            boolean uidError = false;
            if (dataPath.exists()) {
                int currentUid = 0;
                try {
                    StructStat stat = Os.stat(dataPath.getPath());
                    currentUid = stat.st_uid;
                } catch (ErrnoException e) {
                    Slog.e(TAG, "Couldn't stat path " + dataPath.getPath(), e);
                }

                // 如果数据路径的所有者不匹配，就会出现问题。
                if (currentUid != pkg.applicationInfo.uid) {
                    boolean recovered = false;
                    if (currentUid == 0) {
                        // 目录以某种方式归根用户所有。
                        // 请求 installd 来解决这个问题。
                        int ret = mInstaller.fixUid(pkg.volumeUuid, pkgName,
                                pkg.applicationInfo.uid, pkg.applicationInfo.uid);
                        if (ret >= 0) {
                            recovered = true;
                            String msg = "Package " + pkg.packageName
                                    + " unexpectedly changed to uid 0; recovered to " +
                                    + pkg.applicationInfo.uid;
                            reportSettingsProblem(Log.WARN, msg);
                        }
                    }
                    if (!recovered && ((parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0
                            || (scanFlags&SCAN_BOOTING) != 0)) {
                        // 如果这是系统应用程序，我们至少可以删除其当前数据，以便该应用程序仍然可以运行。
                        int ret = removeDataDirsLI(pkg.volumeUuid, pkgName);
                        if (ret >= 0) {
                            // TODO: Kill the processes first
                            // Old data gone!
                            String prefix = (parseFlags&PackageParser.PARSE_IS_SYSTEM) != 0
                                    ? "System package " : "Third party package ";
                            String msg = prefix + pkg.packageName
                                    + " has changed from uid: "
                                    + currentUid + " to "
                                    + pkg.applicationInfo.uid + "; old data erased";
                            reportSettingsProblem(Log.WARN, msg);
                            recovered = true;

                            // 现在重新安装应用程序。
                            ret = createDataDirsLI(pkg.volumeUuid, pkgName, pkg.applicationInfo.uid,
                                    pkg.applicationInfo.seinfo);
                            if (ret == -1) {
                                // Ack should not happen!
                                msg = prefix + pkg.packageName
                                        + " could not have data directory re-created after delete.";
                                reportSettingsProblem(Log.WARN, msg);
                                throw new PackageManagerException(
                                        INSTALL_FAILED_INSUFFICIENT_STORAGE, msg);
                            }
                        }
                        if (!recovered) {
                            mHasSystemUidErrors = true;
                        }
                    } else if (!recovered) {
                        // If we allow this install to proceed, we will be broken.
                        // Abort, abort!
                        throw new PackageManagerException(INSTALL_FAILED_UID_CHANGED,
                                "scanPackageLI");
                    }
                    if (!recovered) {
                        pkg.applicationInfo.dataDir = "/mismatched_uid/settings_"
                            + pkg.applicationInfo.uid + "/fs_"
                            + currentUid;
                        pkg.applicationInfo.nativeLibraryDir = pkg.applicationInfo.dataDir;
                        pkg.applicationInfo.nativeLibraryRootDir = pkg.applicationInfo.dataDir;
                        String msg = "Package " + pkg.packageName
                                + " has mismatched uid: "
                                + currentUid + " on disk, "
                                + pkg.applicationInfo.uid + " in settings";
                        // writer
                        synchronized (mPackages) {
                            mSettings.mReadMessages.append(msg);
                            mSettings.mReadMessages.append('\n');
                            uidError = true;
                            if (!pkgSetting.uidError) {
                                reportSettingsProblem(Log.ERROR, msg);
                            }
                        }
                    }
                }
                pkg.applicationInfo.dataDir = dataPath.getPath();
                if (mShouldRestoreconData) {
                    Slog.i(TAG, "SELinux relabeling of " + pkg.packageName + " issued.");
                    mInstaller.restoreconData(pkg.volumeUuid, pkg.packageName,
                            pkg.applicationInfo.seinfo, pkg.applicationInfo.uid);
                }
            } else {
                if (DEBUG_PACKAGE_SCANNING) {
                    if ((parseFlags & PackageParser.PARSE_CHATTY) != 0)
                        Log.v(TAG, "Want this data dir: " + dataPath);
                }
                // 调用安装程序来执行实际安装
                int ret = createDataDirsLI(pkg.volumeUuid, pkgName, pkg.applicationInfo.uid,
                        pkg.applicationInfo.seinfo);
                if (ret < 0) {
                    // Error from installer
                    throw new PackageManagerException(INSTALL_FAILED_INSUFFICIENT_STORAGE,
                            "Unable to create data dirs [errorCode=" + ret + "]");
                }

                if (dataPath.exists()) {
                    pkg.applicationInfo.dataDir = dataPath.getPath();
                } else {
                    Slog.w(TAG, "Unable to create data directory: " + dataPath);
                    pkg.applicationInfo.dataDir = null;
                }
            }

            pkgSetting.uidError = uidError;
        }

        final String path = scanFile.getPath();
        final String cpuAbiOverride = deriveAbiOverride(pkg.cpuAbiOverride, pkgSetting);

        if ((scanFlags & SCAN_NEW_INSTALL) == 0) {
            derivePackageAbi(pkg, scanFile, cpuAbiOverride, true /* extract libs */);

            // 一些系统应用程序仍对本地库使用目录结构，
            // 在这种情况下，我们可能最终无法仅基于apk结构来检测abi。 
            // 尝试根据目录结构检测abi。
            if (isSystemApp(pkg) && !pkg.isUpdatedSystemApp() &&
                    pkg.applicationInfo.primaryCpuAbi == null) {
                setBundledAppAbisAndRoots(pkg, pkgSetting);
                setNativeLibraryPaths(pkg);
            }

        } else {
            if ((scanFlags & SCAN_MOVE) != 0) {
                // 我们没有为此操作运行dex-opt（因为我们也移动了编译后的输出），
                // 但是我们已经在 PackageSetting 中包含了该软件包的软件包信息。 
                // 我们只使用它并基于新的代码路径派生 native 库路径。
                pkg.applicationInfo.primaryCpuAbi = pkgSetting.primaryCpuAbiString;
                pkg.applicationInfo.secondaryCpuAbi = pkgSetting.secondaryCpuAbiString;
            }

            // 再次设置 native 库路径。对于移动，路径将根据我们上面确定的ABI进行更新。
            // 对于非移动，路径将根据我们在编译期间确定的ABI进行更新，但该路径将取决于最终的包路径。
            setNativeLibraryPaths(pkg);
        }

        if (DEBUG_INSTALL) Slog.i(TAG, "Linking native library dir for " + path);
        final int[] userIds = sUserManager.getUserIds();
        synchronized (mInstallLock) {
            // 确保所有用户数据目录已准备就绪
            if (!TextUtils.isEmpty(pkg.volumeUuid)) {
                for (int userId : userIds) {
                    if (userId != 0) {
                        mInstaller.createUserData(pkg.volumeUuid, pkg.packageName,
                                UserHandle.getUid(userId, pkg.applicationInfo.uid), userId,
                                pkg.applicationInfo.seinfo);
                    }
                }
            }

            // 仅当我们有 native 库并且 native 库是32位库时，才创建本机库符号链接。
            // 我们不为64位库提供此符号链接。
            if (pkg.applicationInfo.primaryCpuAbi != null &&
                    !VMRuntime.is64BitAbi(pkg.applicationInfo.primaryCpuAbi)) {
                final String nativeLibPath = pkg.applicationInfo.nativeLibraryDir;
                for (int userId : userIds) {
                    if (mInstaller.linkNativeLibraryDirectory(pkg.volumeUuid, pkg.packageName,
                            nativeLibPath, userId) < 0) {
                        throw new PackageManagerException(INSTALL_FAILED_INTERNAL_ERROR,
                                "Failed linking native library dir (user=" + userId + ")");
                    }
                }
            }
        }

        // 这是“system”程序包的特例，其中的ABI由zygote配置（和init.rc）决定。
        // 我们应该跟踪此ABI，以便我们可以处理在相同UID下正确运行的“正常”应用程序。
        if (mPlatformPackage == pkg) {
            pkg.applicationInfo.primaryCpuAbi = VMRuntime.getRuntime().is64Bit() ?
                    Build.SUPPORTED_64_BIT_ABIS[0] : Build.SUPPORTED_32_BIT_ABIS[0];
        }

        // 如果软件包设置中的abi-override与为安装指定的abiOverride之间不匹配。
        // 对此发出警告，因为我们已经在不考虑软件包设置的情况下编译了该应用程序。
        if ((scanFlags & SCAN_NO_DEX) == 0 && (scanFlags & SCAN_NEW_INSTALL) != 0) {
            if (cpuAbiOverride == null && pkgSetting.cpuAbiOverrideString != null) {
                Slog.w(TAG, "Ignoring persisted ABI override " + cpuAbiOverride +
                        " for package: " + pkg.packageName);
            }
        }

        pkgSetting.primaryCpuAbiString = pkg.applicationInfo.primaryCpuAbi;
        pkgSetting.secondaryCpuAbiString = pkg.applicationInfo.secondaryCpuAbi;
        pkgSetting.cpuAbiOverrideString = cpuAbiOverride;

        // 将派生的覆盖复制回已解析的包，以便我们可以相应地更新包设置。
        pkg.cpuAbiOverride = cpuAbiOverride;

        if (DEBUG_ABI_SELECTION) {
            Slog.d(TAG, "Resolved nativeLibraryRoot for " + pkg.applicationInfo.packageName
                    + " to root=" + pkg.applicationInfo.nativeLibraryRootDir + ", isa="
                    + pkg.applicationInfo.nativeLibraryRootRequiresIsa);
        }

        // 将派生路径写入 PackageSettings，以便我们知道在卸载时清理什么。
        pkgSetting.legacyNativeLibraryPathString = pkg.applicationInfo.nativeLibraryRootDir;

        if (DEBUG_ABI_SELECTION) {
            Log.d(TAG, "Abis for package[" + pkg.packageName + "] are" +
                    " primary=" + pkg.applicationInfo.primaryCpuAbi +
                    " secondary=" + pkg.applicationInfo.secondaryCpuAbi);
        }

        if ((scanFlags&SCAN_BOOTING) == 0 && pkgSetting.sharedUser != null) {
            // We don't do this here during boot because we can do it all
            // at once after scanning all existing packages.
            //
            // We also do this *before* we perform dexopt on this package, so that
            // we can avoid redundant dexopts, and also to make sure we've got the
            // code and package path correct.
            adjustCpuAbisForSharedUserLPw(pkgSetting.sharedUser.packages,
                    pkg, forceDex, (scanFlags & SCAN_DEFER_DEX) != 0, true /* boot complete */);
        }

        if ((scanFlags & SCAN_NO_DEX) == 0) {
            int result = mPackageDexOptimizer.performDexOpt(pkg, null /* instruction sets */,
                    forceDex, (scanFlags & SCAN_DEFER_DEX) != 0, false /* inclDependencies */,
                    (scanFlags & SCAN_BOOTING) == 0);
            if (result == PackageDexOptimizer.DEX_OPT_FAILED) {
                throw new PackageManagerException(INSTALL_FAILED_DEXOPT, "scanPackageLI");
            }
        }
        if (mFactoryTest && pkg.requestedPermissions.contains(
                android.Manifest.permission.FACTORY_TEST)) {
            pkg.applicationInfo.flags |= ApplicationInfo.FLAG_FACTORY_TEST;
        }

        ArrayList<PackageParser.Package> clientLibPkgs = null;

        // writer
        synchronized (mPackages) {
            if ((pkg.applicationInfo.flags&ApplicationInfo.FLAG_SYSTEM) != 0) {
                // 只有系统应用程序可以添加新的共享库。
                if (pkg.libraryNames != null) {
                    for (int i=0; i<pkg.libraryNames.size(); i++) {
                        String name = pkg.libraryNames.get(i);
                        boolean allowed = false;
                        if (pkg.isUpdatedSystemApp()) {
                            // 新的库条目只能通过系统映像添加。
                            final PackageSetting sysPs = mSettings
                                    .getDisabledSystemPkgLPr(pkg.packageName);
                            if (sysPs.pkg != null && sysPs.pkg.libraryNames != null) {
                                for (int j=0; j<sysPs.pkg.libraryNames.size(); j++) {
                                    if (name.equals(sysPs.pkg.libraryNames.get(j))) {
                                        allowed = true;
                                        allowed = true;
                                        break;
                                    }
                                }
                            }
                        } else {
                            allowed = true;
                        }
                        if (allowed) {
                            if (!mSharedLibraries.containsKey(name)) {
                                mSharedLibraries.put(name, new SharedLibraryEntry(null, pkg.packageName));
                            } else if (!name.equals(pkg.packageName)) {
                                Slog.w(TAG, "Package " + pkg.packageName + " library "
                                        + name + " already exists; skipping");
                            }
                        } else {
                            Slog.w(TAG, "Package " + pkg.packageName + " declares lib "
                                    + name + " that is not declared on system image; skipping");
                        }
                    }
                    if ((scanFlags&SCAN_BOOTING) == 0) {
                        // 需要更新作为共享库客户端的所有应用程序。
                        clientLibPkgs = updateAllSharedLibrariesLPw(pkg);
                    }
                }
            }
        }

        // 我们还需要 dexopt 任何依赖于这个库的应用程序。
        // 注意，如果这些失败，我们应该中止安装，因为安装库将导致一些应用程序被破坏。
        if (clientLibPkgs != null) {
            if ((scanFlags & SCAN_NO_DEX) == 0) {
                for (int i = 0; i < clientLibPkgs.size(); i++) {
                    PackageParser.Package clientPkg = clientLibPkgs.get(i);
                    int result = mPackageDexOptimizer.performDexOpt(clientPkg,
                            null /* instruction sets */, forceDex,
                            (scanFlags & SCAN_DEFER_DEX) != 0, false,
                            (scanFlags & SCAN_BOOTING) == 0);
                    if (result == PackageDexOptimizer.DEX_OPT_FAILED) {
                        throw new PackageManagerException(INSTALL_FAILED_DEXOPT,
                                "scanPackageLI failed to dexopt clientLibPkgs");
                    }
                }
            }
        }

        // 请求 ActivityManager 终止进程（仅适用于现有软件包）
        if ((scanFlags & SCAN_REPLACING) != 0) {
            killApplication(pkg.applicationInfo.packageName,
                        pkg.applicationInfo.uid, "replace pkg");
        }

        // 还需要杀死所有依赖该库的应用程序。
        if (clientLibPkgs != null) {
            for (int i=0; i<clientLibPkgs.size(); i++) {
                PackageParser.Package clientPkg = clientLibPkgs.get(i);
                killApplication(clientPkg.applicationInfo.packageName,
                        clientPkg.applicationInfo.uid, "update lib");
            }
        }

        // 确保我们没有添加任何虚假的键集信息
        KeySetManagerService ksms = mSettings.mKeySetManagerService;
        ksms.assertScannedPackageValid(pkg);

        // writer
        synchronized (mPackages) {
            // 将新设置添加到 mSettings
            mSettings.insertPackageSettingLPw(pkgSetting, pkg);
            // 将新设置添加到 mPackages
            mPackages.put(pkg.applicationInfo.packageName, pkg);
            // 确保我们不会意外删除其数据。
            final Iterator<PackageCleanItem> iter = mSettings.mPackagesToBeCleaned.iterator();
            while (iter.hasNext()) {
                PackageCleanItem item = iter.next();
                if (pkgName.equals(item.packageName)) {
                    iter.remove();
                }
            }

            // 请注意首次安装/最后更新时间。
            if (currentTime != 0) {
                if (pkgSetting.firstInstallTime == 0) {
                    pkgSetting.firstInstallTime = pkgSetting.lastUpdateTime = currentTime;
                } else if ((scanFlags&SCAN_UPDATE_TIME) != 0) {
                    pkgSetting.lastUpdateTime = currentTime;
                }
            } else if (pkgSetting.firstInstallTime == 0) {
                // 使用文件的时间戳。
                pkgSetting.firstInstallTime = pkgSetting.lastUpdateTime = scanFileTime;
            } else if ((parseFlags&PackageParser.PARSE_IS_SYSTEM_DIR) != 0) {
                if (scanFileTime != pkgSetting.timeStamp) {
                    // 系统映像上的包已更改；可以将此看作是一次更新。
                    pkgSetting.lastUpdateTime = scanFileTime;
                }
            }

            // 将程序包的 KeySets 添加到全局 KeySetManagerService
            ksms.addScannedPackageLPw(pkg);
            // 处理内容提供者 Provider
            int N = pkg.providers.size();
            StringBuilder r = null;
            int i;
            for (i=0; i<N; i++) {
                PackageParser.Provider p = pkg.providers.get(i);
                p.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        p.info.processName, pkg.applicationInfo.uid);
                mProviders.addProvider(p);
                p.syncable = p.info.isSyncable;
                if (p.info.authority != null) {
                    String names[] = p.info.authority.split(";");
                    p.info.authority = null;
                    for (int j = 0; j < names.length; j++) {
                        if (j == 1 && p.syncable) {
                            // We only want the first authority for a provider to possibly be
                            // syncable, so if we already added this provider using a different
                            // authority clear the syncable flag. We copy the provider before
                            // changing it because the mProviders object contains a reference
                            // to a provider that we don't want to change.
                            // Only do this for the second authority since the resulting provider
                            // object can be the same for all future authorities for this provider.
                            p = new PackageParser.Provider(p);
                            p.syncable = false;
                        }
                        if (!mProvidersByAuthority.containsKey(names[j])) {
                            mProvidersByAuthority.put(names[j], p);
                            if (p.info.authority == null) {
                                p.info.authority = names[j];
                            } else {
                                p.info.authority = p.info.authority + ";" + names[j];
                            }
                            if (DEBUG_PACKAGE_SCANNING) {
                                if ((parseFlags & PackageParser.PARSE_CHATTY) != 0)
                                    Log.d(TAG, "Registered content provider: " + names[j]
                                            + ", className = " + p.info.name + ", isSyncable = "
                                            + p.info.isSyncable);
                            }
                        } else {
                            PackageParser.Provider other = mProvidersByAuthority.get(names[j]);
                            Slog.w(TAG, "Skipping provider name " + names[j] +
                                    " (in package " + pkg.applicationInfo.packageName +
                                    "): name already used by "
                                    + ((other != null && other.getComponentName() != null)
                                            ? other.getComponentName().getPackageName() : "?"));
                        }
                    }
                }
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(p.info.name);
                }
            }
            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Providers: " + r);
            }
            // 处理 Service
            N = pkg.services.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Service s = pkg.services.get(i);
                s.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        s.info.processName, pkg.applicationInfo.uid);
                mServices.addService(s);
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(s.info.name);
                }
            }
            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Services: " + r);
            }

            N = pkg.receivers.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.receivers.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        a.info.processName, pkg.applicationInfo.uid);
                mReceivers.addActivity(a, "receiver");
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(a.info.name);
                }
            }
            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Receivers: " + r);
            }
            // 处理 Activity
            N = pkg.activities.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Activity a = pkg.activities.get(i);
                a.info.processName = fixProcessName(pkg.applicationInfo.processName,
                        a.info.processName, pkg.applicationInfo.uid);
                mActivities.addActivity(a, "activity");
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(a.info.name);
                }
            }
            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Activities: " + r);
            }
            // 处理 PermissionGroup
            N = pkg.permissionGroups.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.PermissionGroup pg = pkg.permissionGroups.get(i);
                PackageParser.PermissionGroup cur = mPermissionGroups.get(pg.info.name);
                if (cur == null) {
                    mPermissionGroups.put(pg.info.name, pg);
                    if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                        if (r == null) {
                            r = new StringBuilder(256);
                        } else {
                            r.append(' ');
                        }
                        r.append(pg.info.name);
                    }
                } else {
                    Slog.w(TAG, "Permission group " + pg.info.name + " from package "
                            + pg.info.packageName + " ignored: original from "
                            + cur.info.packageName);
                    if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                        if (r == null) {
                            r = new StringBuilder(256);
                        } else {
                            r.append(' ');
                        }
                        r.append("DUP:");
                        r.append(pg.info.name);
                    }
                }
            }
            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Permission Groups: " + r);
            }
            // 处理 Permission
            N = pkg.permissions.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Permission p = pkg.permissions.get(i);

                // Assume by default that we did not install this permission into the system.
                p.info.flags &= ~PermissionInfo.FLAG_INSTALLED;

                // Now that permission groups have a special meaning, we ignore permission
                // groups for legacy apps to prevent unexpected behavior. In particular,
                // permissions for one app being granted to someone just becuase they happen
                // to be in a group defined by another app (before this had no implications).
                if (pkg.applicationInfo.targetSdkVersion > Build.VERSION_CODES.LOLLIPOP_MR1) {
                    p.group = mPermissionGroups.get(p.info.group);
                    // Warn for a permission in an unknown group.
                    if (p.info.group != null && p.group == null) {
                        Slog.w(TAG, "Permission " + p.info.name + " from package "
                                + p.info.packageName + " in an unknown group " + p.info.group);
                    }
                }

                ArrayMap<String, BasePermission> permissionMap =
                        p.tree ? mSettings.mPermissionTrees
                                : mSettings.mPermissions;
                BasePermission bp = permissionMap.get(p.info.name);

                // Allow system apps to redefine non-system permissions
                if (bp != null && !Objects.equals(bp.sourcePackage, p.info.packageName)) {
                    final boolean currentOwnerIsSystem = (bp.perm != null
                            && isSystemApp(bp.perm.owner));
                    if (isSystemApp(p.owner)) {
                        if (bp.type == BasePermission.TYPE_BUILTIN && bp.perm == null) {
                            // It's a built-in permission and no owner, take ownership now
                            bp.packageSetting = pkgSetting;
                            bp.perm = p;
                            bp.uid = pkg.applicationInfo.uid;
                            bp.sourcePackage = p.info.packageName;
                            p.info.flags |= PermissionInfo.FLAG_INSTALLED;
                        } else if (!currentOwnerIsSystem) {
                            String msg = "New decl " + p.owner + " of permission  "
                                    + p.info.name + " is system; overriding " + bp.sourcePackage;
                            reportSettingsProblem(Log.WARN, msg);
                            bp = null;
                        }
                    }
                }

                if (bp == null) {
                    bp = new BasePermission(p.info.name, p.info.packageName,
                            BasePermission.TYPE_NORMAL);
                    permissionMap.put(p.info.name, bp);
                }

                if (bp.perm == null) {
                    if (bp.sourcePackage == null
                            || bp.sourcePackage.equals(p.info.packageName)) {
                        BasePermission tree = findPermissionTreeLP(p.info.name);
                        if (tree == null
                                || tree.sourcePackage.equals(p.info.packageName)) {
                            bp.packageSetting = pkgSetting;
                            bp.perm = p;
                            bp.uid = pkg.applicationInfo.uid;
                            bp.sourcePackage = p.info.packageName;
                            p.info.flags |= PermissionInfo.FLAG_INSTALLED;
                            if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                                if (r == null) {
                                    r = new StringBuilder(256);
                                } else {
                                    r.append(' ');
                                }
                                r.append(p.info.name);
                            }
                        } else {
                            Slog.w(TAG, "Permission " + p.info.name + " from package "
                                    + p.info.packageName + " ignored: base tree "
                                    + tree.name + " is from package "
                                    + tree.sourcePackage);
                        }
                    } else {
                        Slog.w(TAG, "Permission " + p.info.name + " from package "
                                + p.info.packageName + " ignored: original from "
                                + bp.sourcePackage);
                    }
                } else if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append("DUP:");
                    r.append(p.info.name);
                }
                if (bp.perm == p) {
                    bp.protectionLevel = p.info.protectionLevel;
                }
            }

            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Permissions: " + r);
            }
            // 处理 Instrumentation
            N = pkg.instrumentation.size();
            r = null;
            for (i=0; i<N; i++) {
                PackageParser.Instrumentation a = pkg.instrumentation.get(i);
                a.info.packageName = pkg.applicationInfo.packageName;
                a.info.sourceDir = pkg.applicationInfo.sourceDir;
                a.info.publicSourceDir = pkg.applicationInfo.publicSourceDir;
                a.info.splitSourceDirs = pkg.applicationInfo.splitSourceDirs;
                a.info.splitPublicSourceDirs = pkg.applicationInfo.splitPublicSourceDirs;
                a.info.dataDir = pkg.applicationInfo.dataDir;

                // TODO: Update instrumentation.nativeLibraryDir as well ? Does it
                // need other information about the application, like the ABI and what not ?
                a.info.nativeLibraryDir = pkg.applicationInfo.nativeLibraryDir;
                mInstrumentation.put(a.getComponentName(), a);
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) {
                    if (r == null) {
                        r = new StringBuilder(256);
                    } else {
                        r.append(' ');
                    }
                    r.append(a.info.name);
                }
            }
            if (r != null) {
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Instrumentation: " + r);
            }

            if (pkg.protectedBroadcasts != null) {
                N = pkg.protectedBroadcasts.size();
                for (i=0; i<N; i++) {
                    mProtectedBroadcasts.add(pkg.protectedBroadcasts.get(i));
                }
            }

            pkgSetting.setTimeStamp(scanFileTime);

            // Create idmap files for pairs of (packages, overlay packages).
            // Note: "android", ie framework-res.apk, is handled by native layers.
            if (pkg.mOverlayTarget != null) {
                // This is an overlay package.
                if (pkg.mOverlayTarget != null && !pkg.mOverlayTarget.equals("android")) {
                    if (!mOverlays.containsKey(pkg.mOverlayTarget)) {
                        mOverlays.put(pkg.mOverlayTarget,
                                new ArrayMap<String, PackageParser.Package>());
                    }
                    ArrayMap<String, PackageParser.Package> map = mOverlays.get(pkg.mOverlayTarget);
                    map.put(pkg.packageName, pkg);
                    PackageParser.Package orig = mPackages.get(pkg.mOverlayTarget);
                    if (orig != null && !createIdmapForPackagePairLI(orig, pkg)) {
                        throw new PackageManagerException(INSTALL_FAILED_UPDATE_INCOMPATIBLE,
                                "scanPackageLI failed to createIdmap");
                    }
                }
            } else if (mOverlays.containsKey(pkg.packageName) &&
                    !pkg.packageName.equals("android")) {
                // This is a regular package, with one or more known overlay packages.
                createIdmapsForPackageLI(pkg);
            }
        }

        return pkg;
    }
    ......
}
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安装成功以后在系统中的路径如下图：

/data/app/xxx-x

回到 PackageManagerService 类 processPendingInstall 方法，最后会调用 BackupManagerService 类 restoreAtInstall 方法。此方法的作用：为正在安装的应用程序将需要一个恢复通道，然后需要在恢复完成时通知包管理器。

BackupManagerService 是负责备份和恢复服务功能的。

frameworks/base/services/backup/java/com/android/server/backup/BackupManagerService.java

    public void restoreAtInstall(String packageName, int token) {
        ......
        boolean skip = false;

        long restoreSet = getAvailableRestoreToken(packageName);
        if (DEBUG) Slog.v(TAG, "restoreAtInstall pkg=" + packageName
                + " token=" + Integer.toHexString(token)
                + " restoreSet=" + Long.toHexString(restoreSet));
        if (restoreSet == 0) {
            if (MORE_DEBUG) Slog.i(TAG, "No restore set");
            skip = true;
        }

        // Do we have a transport to fetch data for us?
        IBackupTransport transport = getTransport(mCurrentTransport);
        if (transport == null) {
            if (DEBUG) Slog.w(TAG, "No transport");
            skip = true;
        }

        if (!mAutoRestore) {
            if (DEBUG) {
                Slog.w(TAG, "Non-restorable state: auto=" + mAutoRestore);
            }
            skip = true;
        }

        if (!skip) {
            ......
        }

        if (skip) {
            // Auto-restore disabled or no way to attempt a restore; just tell the Package
            // Manager to proceed with the post-install handling for this package.
            if (DEBUG) Slog.v(TAG, "Finishing install immediately");
            try {
                mPackageManagerBinder.finishPackageInstall(token);
            } catch (RemoteException e) { /* can't happen */ }
        }
    }
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重点关注发送 POST_INSTALL 消息。

frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    @Override
    public void finishPackageInstall(int token) {
        enforceSystemOrRoot("Only the system is allowed to finish installs");

        if (DEBUG_INSTALL) {
            Slog.v(TAG, "BM finishing package install for " + token);
        }

        final Message msg = mHandler.obtainMessage(POST_INSTALL, token, 0);
        mHandler.sendMessage(msg);
    }
    ......
}
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frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java

public class PackageManagerService extends IPackageManager.Stub {
    ......
    class PackageHandler extends Handler {
        ......
         void doHandleMessage(Message msg) {
            switch (msg.what) {
                ......
                case POST_INSTALL: {
                    if (DEBUG_INSTALL) Log.v(TAG, "Handling post-install for " + msg.arg1);
                    PostInstallData data = mRunningInstalls.get(msg.arg1);
                    mRunningInstalls.delete(msg.arg1);
                    boolean deleteOld = false;

                    if (data != null) {
                        InstallArgs args = data.args;
                        PackageInstalledInfo res = data.res;

                        if (res.returnCode == PackageManager.INSTALL_SUCCEEDED) {
                            final String packageName = res.pkg.applicationInfo.packageName;
                            res.removedInfo.sendBroadcast(false, true, false);
                            Bundle extras = new Bundle(1);
                            extras.putInt(Intent.EXTRA_UID, res.uid);

                            // 既然我们已经成功安装了包，那么在发布安装之前，如果需要，就授予运行时权限。
                            if ((args.installFlags
                                    & PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS) != 0) {
                                grantRequestedRuntimePermissions(res.pkg, args.user.getIdentifier(),
                                        args.installGrantPermissions);
                            }

                            // 确定第一次添加此包的用户和看到更新的用户。
                            int[] firstUsers;
                            int[] updateUsers = new int[0];
                            if (res.origUsers == null || res.origUsers.length == 0) {
                                firstUsers = res.newUsers;
                            } else {
                                firstUsers = new int[0];
                                for (int i=0; i<res.newUsers.length; i++) {
                                    int user = res.newUsers[i];
                                    boolean isNew = true;
                                    for (int j=0; j<res.origUsers.length; j++) {
                                        if (res.origUsers[j] == user) {
                                            isNew = false;
                                            break;
                                        }
                                    }
                                    if (isNew) {
                                        int[] newFirst = new int[firstUsers.length+1];
                                        System.arraycopy(firstUsers, 0, newFirst, 0,
                                                firstUsers.length);
                                        newFirst[firstUsers.length] = user;
                                        firstUsers = newFirst;
                                    } else {
                                        int[] newUpdate = new int[updateUsers.length+1];
                                        System.arraycopy(updateUsers, 0, newUpdate, 0,
                                                updateUsers.length);
                                        newUpdate[updateUsers.length] = user;
                                        updateUsers = newUpdate;
                                    }
                                }
                            }
                            // 发送包安装成功广播，感兴趣的接受者可以接收，比如 Launcher 应用
                            sendPackageBroadcast(Intent.ACTION_PACKAGE_ADDED,
                                    packageName, extras, null, null, firstUsers);
                            final boolean update = res.removedInfo.removedPackage != null;
                            if (update) {
                                extras.putBoolean(Intent.EXTRA_REPLACING, true);
                            }
                            sendPackageBroadcast(Intent.ACTION_PACKAGE_ADDED,
                                    packageName, extras, null, null, updateUsers);
                            if (update) {
                                // 发送包替换成功广播
                                sendPackageBroadcast(Intent.ACTION_PACKAGE_REPLACED,
                                        packageName, extras, null, null, updateUsers);
                                sendPackageBroadcast(Intent.ACTION_MY_PACKAGE_REPLACED,
                                        null, null, packageName, null, updateUsers);

                                // 在升级时，将 asec 承载的包视为可移动媒体
                                if (res.pkg.isForwardLocked() || isExternal(res.pkg)) {
                                    if (DEBUG_INSTALL) {
                                        Slog.i(TAG, "upgrading pkg " + res.pkg
                                                + " is ASEC-hosted -> AVAILABLE");
                                    }
                                    int[] uidArray = new int[] { res.pkg.applicationInfo.uid };
                                    ArrayList<String> pkgList = new ArrayList<String>(1);
                                    pkgList.add(packageName);
                                    sendResourcesChangedBroadcast(true, true,
                                            pkgList,uidArray, null);
                                }
                            }
                            if (res.removedInfo.args != null) {
                                // 现在安全地删除被替换包的旧资源
                                deleteOld = true;
                            }

                            // 如果这个应用程序是浏览器，并且是新安装的，清除这些用户的默认浏览器状态
                            if (firstUsers.length > 0) {
                                // 该应用程序的性质并不取决于用户，因此我们可以在任何用户中检查其浏览器性质并进行概括。
                                if (packageIsBrowser(packageName, firstUsers[0])) {
                                    synchronized (mPackages) {
                                        for (int userId : firstUsers) {
                                            mSettings.setDefaultBrowserPackageNameLPw(null, userId);
                                        }
                                    }
                                }
                            }
                            // Log current value of "unknown sources" setting
                            EventLog.writeEvent(EventLogTags.UNKNOWN_SOURCES_ENABLED,
                                getUnknownSourcesSettings());
                        }
                        // 强制 gc 清理
                        Runtime.getRuntime().gc();
                        // 我们在一次gc后删除sdcard上的应用程序。
                        if (deleteOld) {
                            synchronized (mInstallLock) {
                                res.removedInfo.args.doPostDeleteLI(true);
                            }
                        }
                        if (args.observer != null) {
                            try {
                                Bundle extras = extrasForInstallResult(res);
                                // 安装成功回调。
                                // 这会调用到 installPackage 方法中传入的参数 PackageInstallObserver 对象
                                args.observer.onPackageInstalled(res.name, res.returnCode,
                                        res.returnMsg, extras);
                            } catch (RemoteException e) {
                                Slog.i(TAG, "Observer no longer exists.");
                            }
                        }
                    } else {
                        Slog.e(TAG, "Bogus post-install token " + msg.arg1);
                    }
                } break;
                ......
            }
        }
    }
    ......
}
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