Is it possible to merge/install split APK files (AKA "app bundle"), on Android device itself, without root?

Question

Background

In the past, I've asked about sharing or backup of app-bundle / split apk files, here .

This seems like an almost impossible task, which I could only figure out how to install the split APK files, and even then it's only via adb:

adb install-multiple apk1 apk2 ... 

The problem

I was told that it should be actually possible to merge multiple split APK files into one that I could install (here), but wasn't given of how to do it.

This could be useful for saving it for later (backup), and because currently there is no way to install split-apk files within the device.

In fact, this is such a major issue, that I don't know of any backup app that can handle split APK files (app bundle), and this include Titanium app.

What I've found

I took a sample app that uses app-bundles, called "AirBnb".

Looking at the files it has, those are what the Play Store decided to download:

So I tried to enter each. The "base" is the main one, so I skipped it to look at the others. To me it seems that all have these files within:

• "META-INF"
• "resources.arsc"
• "AndroidManifest.xml"
• in the case of the one with the "xxxhdpi", I also get "res" folder.

Thing is, since those all exist in multiple places, I don't get how could I merge them.

The questions

1. What is the way to merge those all into one APK file?

2. Is it possible to install split APK files without root and without PC ? This was possible in the past on backup apps such as Titanium, but only on normal APK files, and not app bundle (split apk).

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EDIT: I've set a bounty. Please, if you know of a solution, show it. Show something that you've tested to work. Either of merging split APK files, or installing them , all without root and right on the device.

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EDIT: Sadly all solutions here didn't work, with or without root, and that's even though I've found an app that succeeded doing it (with and without root), called "SAI (Split APKs Installer)" (I think its repository is here, found after I've put a bounty).

I'm putting a new bounty. Please, whoever publishes a new answer, show that it works with and without root. Show on Github if needed (and here just the important stuff). I know this app is open sourced anyway, but it's important for me how to do it here, and share with others, as currently what's shown here isn't working, and requires root, even though it's not really needed.

This time I won't grant the bounty till I see something that indeed works (previously I was short on time and granted it to the answer I thought should work).

Answer 1

Please check this. when we send

adb install-multiple apk1 apk2 ... 

it calls this code install-multiple

 std::string install_cmd;     if (_use_legacy_install()) {         install_cmd = "exec:pm";     } else {         install_cmd = "exec:cmd package";     }      std::string cmd = android::base::StringPrintf("%s install-create -S %" PRIu64, install_cmd.c_str(), total_size);     for (i = 1; i < first_apk; i++) {         cmd += " " + escape_arg(argv[i]);     } 

which in turn calls Pm.java or a new way of executing PackageManagerService code, both are similar

I tried to integrate that code in my app, The problem which I faced, apk installation was not able to complete, it is due to the reason that the app needs.

<uses-permission android:name="android.permission.INSTALL_PACKAGES"/> 

But it is only given to system-priv apps. When I executed these steps from adb shell apk installation was successful and when I created my app a system priv-app apk install was successfull.

code to call new apis of PackageManager, mostly copied from Pm.java Steps in installing split apks

1. Create a session with argument -S , return session id.

   (install-create, -S, 52488426) 52488426 -- total size of apks.

2. Write split apks in that session with size , name and path

   (install-write, -S, 44334187, 824704264, 1_base.apk, -)

   (install-write, -S, 1262034, 824704264, 2_split_config.en.apk, -)

   (install-write, -S, 266117, 824704264, 3_split_config.hdpi.apk, -)

   (install-write, -S, 6626088, 824704264, 4_split_config.x86.apk, -)

3. commit the session with session id

   (install-commit, 824704264)

I have placed airbnb apk in my sdcard.

OnePlus5:/sdcard/com.airbnb.android-1 $ ll total 51264 -rw-rw---- 1 root sdcard_rw 44334187 2019-04-01 14:20 base.apk -rw-rw---- 1 root sdcard_rw  1262034 2019-04-01 14:20 split_config.en.apk -rw-rw---- 1 root sdcard_rw   266117 2019-04-01 14:20 split_config.hdpi.apk -rw-rw---- 1 root sdcard_rw  6626088 2019-04-01 14:20 split_config.x86.apk 

and calling functions to install apk.

final InstallParams installParams = makeInstallParams(52488426l);              try {                 int sessionId = runInstallCreate(installParams);                  runInstallWrite(44334187,sessionId, "1_base.apk", "/sdcard/com.airbnb.android-1/base.apk");                  runInstallWrite(1262034,sessionId, "2_split_config.en.apk", "/sdcard/com.airbnb.android-1/split_config.en.apk");                  runInstallWrite(266117,sessionId, "3_split_config.hdpi.apk", "/sdcard/com.airbnb.android-1/split_config.hdpi.apk");                  runInstallWrite(6626088,sessionId, "4_split_config.x86.apk", "/sdcard/com.airbnb.android-1/split_config.x86.apk");                   if (doCommitSession(sessionId, false )                         != PackageInstaller.STATUS_SUCCESS) {                 }                 System.out.println("Success");              } catch (RemoteException e) {                 e.printStackTrace();             }  private int runInstallCreate(InstallParams installParams) throws RemoteException {     final int sessionId = doCreateSession(installParams.sessionParams);     System.out.println("Success: created install session [" + sessionId + "]");     return sessionId; }  private int doCreateSession(PackageInstaller.SessionParams params)         throws RemoteException {      int sessionId = 0 ;     try {         sessionId = packageInstaller.createSession(params);     } catch (IOException e) {         e.printStackTrace();     }     return sessionId; }  private int runInstallWrite(long size, int sessionId , String splitName ,String path ) throws RemoteException {     long sizeBytes = -1;      String opt;     sizeBytes = size;     return doWriteSession(sessionId, path, sizeBytes, splitName, true /*logSuccess*/); }   private int doWriteSession(int sessionId, String inPath, long sizeBytes, String splitName,                            boolean logSuccess) throws RemoteException {     if ("-".equals(inPath)) {         inPath = null;     } else if (inPath != null) {         final File file = new File(inPath);         if (file.isFile()) {             sizeBytes = file.length();         }     }      final PackageInstaller.SessionInfo info = packageInstaller.getSessionInfo(sessionId);      PackageInstaller.Session session = null;     InputStream in = null;     OutputStream out = null;     try {         session = packageInstaller.openSession(sessionId);          if (inPath != null) {             in = new FileInputStream(inPath);         }          out = session.openWrite(splitName, 0, sizeBytes);          int total = 0;         byte[] buffer = new byte[65536];         int c;         while ((c = in.read(buffer)) != -1) {             total += c;             out.write(buffer, 0, c);         }         session.fsync(out);          if (logSuccess) {             System.out.println("Success: streamed " + total + " bytes");         }         return PackageInstaller.STATUS_SUCCESS;     } catch (IOException e) {         System.err.println("Error: failed to write; " + e.getMessage());         return PackageInstaller.STATUS_FAILURE;     } finally {         try {             out.close();             in.close();             session.close();         } catch (IOException e) {             e.printStackTrace();         }      } }   private int doCommitSession(int sessionId, boolean logSuccess) throws RemoteException {     PackageInstaller.Session session = null;     try {         try {             session = packageInstaller.openSession(sessionId);         } catch (IOException e) {             e.printStackTrace();         }         session.commit(PendingIntent.getBroadcast(getApplicationContext(), sessionId,                 new Intent("android.intent.action.MAIN"), 0).getIntentSender());         System.out.println("install request sent");          Log.d(TAG, "doCommitSession: " + packageInstaller.getMySessions());          Log.d(TAG, "doCommitSession: after session commit ");          return 1;     } finally {         session.close();     } }    private static class InstallParams {     PackageInstaller.SessionParams sessionParams; }  private InstallParams makeInstallParams(long totalSize ) {     final PackageInstaller.SessionParams sessionParams = new PackageInstaller.SessionParams(PackageInstaller.SessionParams.MODE_FULL_INSTALL);     final InstallParams params = new InstallParams();     params.sessionParams = sessionParams;     String opt;     sessionParams.setSize(totalSize);     return params; } 

This is the list of commands that are actually received in Pm.java when we do adb install-multiple

04-01 16:04:40.626  4886  4886 D Pm      : run() called with: args = [[install-create, -S, 52488426]] 04-01 16:04:41.862  4897  4897 D Pm      : run() called with: args = [[install-write, -S, 44334187, 824704264, 1_base.apk, -]] 04-01 16:04:56.036  4912  4912 D Pm      : run() called with: args = [[install-write, -S, 1262034, 824704264, 2_split_config.en.apk, -]] 04-01 16:04:57.584  4924  4924 D Pm      : run() called with: args = [[install-write, -S, 266117, 824704264, 3_split_config.hdpi.apk, -]] 04-01 16:04:58.842  4936  4936 D Pm      : run() called with: args = [[install-write, -S, 6626088, 824704264, 4_split_config.x86.apk, -]] 04-01 16:05:01.304  4948  4948 D Pm      : run() called with: args = [[install-commit, 824704264]] 

So for apps which are not system priv-app, I don't know how can they can install split apks. Play store being a system priv-app can use these apis and install split apks without any issues.