Android应用程序安装过程浅析（2）

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作者：孙有军  

 这里会重试多次，如果超过最大次数则发送一个what为MCS_GIVE_UP的message表示安装失败，否则调用handleStartCopy，我们来看看handleStartCopy，这里调用的是InstallParams的handleStartCopy函数：

/*
 * Invoke remote method to get package information and install
 * location values. Override install location based on default
 * policy if needed and then create install arguments based
 * on the install location.
 */
public void handleStartCopy() throws RemoteException {
    int ret = PackageManager.INSTALL_SUCCEEDED;

    // If we're already staged, we've firmly committed to an install location
    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) {
        // Check if both bits are set.
        Slog.w(TAG, "Conflicting flags specified for installing on both internal and external");
        ret = PackageManager.INSTALL_FAILED_INVALID_INSTALL_LOCATION;
    } else {
        pkgLite = mContainerService.getMinimalPackageInfo(origin.resolvedPath, installFlags,
                packageAbiOverride);

        /*
         * If we have too little free space, try to free cache
         * before giving up.
         */
        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;
            }
        }
    }

    // 设置ret
    final InstallArgs args = createInstallArgs(this);
    mArgs = args;

    if (ret == PackageManager.INSTALL_SUCCEEDED) {
         /*
         * ADB installs appear as UserHandle.USER_ALL, and can only be performed by
         * UserHandle.USER_OWNER, so use the package verifier for UserHandle.USER_OWNER.
         */
        int userIdentifier = getUser().getIdentifier();
        if (userIdentifier == UserHandle.USER_ALL
                && ((installFlags & PackageManager.INSTALL_FROM_ADB) != 0)) {
            userIdentifier = UserHandle.USER_OWNER;
        }

        /*
         * Determine if we have any installed package verifiers. If we
         * do, then we'll defer to them to verify the packages.
         */
        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);、
            .......
            设置verification的参数

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

            mPendingVerification.append(verificationId, verificationState);

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

            // Apps installed for "all" users use the device owner to verify the app
            UserHandle verifierUser = getUser();
            if (verifierUser == UserHandle.ALL) {
                verifierUser = UserHandle.OWNER;
            }

            /*
             * If any sufficient verifiers were listed in the package
             * manifest, attempt to ask them.
             */
            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) {
                /*
                 * Send the intent to the required verification agent,
                 * but only start the verification timeout after the
                 * target BroadcastReceivers have run.
                 */
                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);

                /*
                 * We don't want the copy to proceed until verification
                 * succeeds, so null out this field.
                 */
                mArgs = null;
            }
        } else {
            /*
             * No package verification is enabled, so immediately start
             * the remote call to initiate copy using temporary file.
             */
            ret = args.copyApk(mContainerService, true);
        }
    }

    mRet = ret;
}

@Override
void handleReturnCode() {
    // If mArgs is null, then MCS couldn't be reached. When it
    // reconnects, it will try again to install. At that point, this
    // will succeed.
    if (mArgs != null) {
        processPendingInstall(mArgs, mRet);
    }
}

 首先设置installFlags参数，之后设置ret参数与verification参数，之后根据参数创建了InstallArgs参数，根据参数这里实际返回的是AsecInstallArgs类型，如果该包需要被验证，则发送一个广播进行包验证，否则直接拷贝apk，广播的onReceive中发送了一个what为CHECK_PENDING_VERIFICATION的message，参数为verificationId，handleReturnCode中直接调用了processPendingInstall来进行安装处理，我们先来看看CHECK_PENDING_VERIFICATION的处理，这里最终也会调用到processPendingInstall。

case CHECK_PENDING_VERIFICATION: {
    final int verificationId = msg.arg1;
    final PackageVerificationState state = mPendingVerification.get(verificationId);

    if ((state != null) && !state.timeoutExtended()) {
        final InstallArgs args = state.getInstallArgs();
        final Uri originUri = Uri.fromFile(args.origin.resolvedFile);

        Slog.i(TAG, "Verification timed out for " + originUri);
        mPendingVerification.remove(verificationId);

        int ret = PackageManager.INSTALL_FAILED_VERIFICATION_FAILURE;

        if (getDefaultVerificationResponse() == PackageManager.VERIFICATION_ALLOW) {
            Slog.i(TAG, "Continuing with installation of " + originUri);
            state.setVerifierResponse(Binder.getCallingUid(),
                    PackageManager.VERIFICATION_ALLOW_WITHOUT_SUFFICIENT);
            broadcastPackageVerified(verificationId, originUri,
                    PackageManager.VERIFICATION_ALLOW,
                    state.getInstallArgs().getUser());
            try {
                ret = args.copyApk(mContainerService, true);
            } catch (RemoteException e) {
                Slog.e(TAG, "Could not contact the ContainerService");
            }
        } else {
            broadcastPackageVerified(verificationId, originUri,
                    PackageManager.VERIFICATION_REJECT,
                    state.getInstallArgs().getUser());
        }

        processPendingInstall(args, ret);
        mHandler.sendEmptyMessage(MCS_UNBIND);
    }
    break;
}

       验证完成后发送一个验证完成的广播，之后调用InstallArgs的copyApk函数拷贝包，这里的InstallArgs是什么类型呐？就是前面创建的AsecInstallArgs类型，因此执行的是AsecInstallArgs的copyApk函数，执行完成后调用processPendingInstall。copyApk主要是拷贝包到指定的目录下。这里就不详述了。接着看看processPendingInstall函数：

private void processPendingInstall(final InstallArgs args, final int currentStatus) {
    // Queue up an async operation since the package installation may take a little while.
    mHandler.post(new Runnable() {
        public void run() {
            mHandler.removeCallbacks(this);
             // Result object to be returned
            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);
            }

            // A restore should be performed at this point if (a) the install
            // succeeded, (b) the operation is not an update, and (c) the new
            // package has not opted out of backup participation.
            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);

            // Set up the post-install work request bookkeeping.  This will be used
            // and cleaned up by the post-install event handling regardless of whether
            // there's a restore pass performed.  Token values are >= 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) {
                // Pass responsibility to the Backup Manager.  It will perform a
                // restore if appropriate, then pass responsibility back to the
                // Package Manager to run the post-install observer callbacks
                // and broadcasts.
                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) {
                // No restore possible, or the Backup Manager was mysteriously not
                // available -- just fire the post-install work request directly.
                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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