Develop Reference

Install APK using root, handling new limitations of "/data/local/tmp/" folder

Background
So far, I was able to install APK files using root (within the app), via this code:
pm install -t -f fullPathToApkFile
and if I want to (try to) install to sd-card :
pm install -t -s fullPathToApkFile
The problem
Recently, not sure from which Android version (issue exists on Android P beta, at least), the above method fails, showing me this message:
avc: denied { read } for scontext=u:r:system_server:s0 tcontext=u:object_r:sdcardfs:s0 tclass=file permissive=0
System server has no access to read file context u:object_r:sdcardfs:s0 (from path /storage/emulated/0/Download/FDroid.apk, context u:r:system_server:s0)
Error: Unable to open file: /storage/emulated/0/Download/FDroid.apk
Consider using a file under /data/local/tmp/
Error: Can't open file: /storage/emulated/0/Download/FDroid.apk
Exception occurred while executing:
java.lang.IllegalArgumentException: Error: Can't open file: /storage/emulated/0/Download/FDroid.apk
at com.android.server.pm.PackageManagerShellCommand.setParamsSize(PackageManagerShellCommand.java:306)
at com.android.server.pm.PackageManagerShellCommand.runInstall(PackageManagerShellCommand.java:884)
at com.android.server.pm.PackageManagerShellCommand.onCommand(PackageManagerShellCommand.java:138)
at android.os.ShellCommand.exec(ShellCommand.java:103)
at com.android.server.pm.PackageManagerService.onShellCommand(PackageManagerService.java:21125)
at android.os.Binder.shellCommand(Binder.java:634)
at android.os.Binder.onTransact(Binder.java:532)
at android.content.pm.IPackageManager$Stub.onTransact(IPackageManager.java:2806)
at com.android.server.pm.PackageManagerService.onTransact(PackageManagerService.java:3841)
at android.os.Binder.execTransact(Binder.java:731)
This seems to also affect popular apps such as "Titanium backup (pro)", which fails to restore apps.
What I've tried
Looking at what's written, it appears it lacks permission to install APK files that are not in /data/local/tmp/.
So I tried the next things, to see if I can overcome it:
set the access to the file (chmod 777) - didn't help.
grant permissions to my app, of both storage and REQUEST_INSTALL_PACKAGES (using ACTION_MANAGE_UNKNOWN_APP_SOURCES Intent) - didn't help.
create a symlink to the file, so that it will be inside the /data/local/tmp/, using official API:
Os.symlink(fullPathToApkFile, symLinkFilePath)
This didn't do anything.
create a symlink using this :
ln -sf $fullPathToApkFile $symLinkFilePath
This partially worked. The file is there, as I can see it in Total Commander app, but when I try to check if it exists there, and when I try to install the APK from there, it fails.
Copy/move (using cp or mv) the file to the /data/local/tmp/ path, and then install from there. This worked, but it has disadvantages: moving is risky because it temporarily hides the original file, and it changes the timestamp of the original file. Copying is bad because of using extra space just for installing (even temporarily) and because it wastes time in doing so.
Copy the APK file, telling it to avoid actual copy (meaning hard link), using this command (taken from here) :
cp -p -r -l $fullPathToApkFile $tempFileParentPath"
This didn't work. It got me this error:
cp: /data/local/tmp/test.apk: Cross-device link
Checking what happens in other cases of installing apps. When you install via via the IDE, it actually does create the APK file in this special path, but if you install via the Play Store, simple APK install (via Intent) or adb (via PC), it doesn't.
Wrote about this here too: https://issuetracker.google.com/issues/80270303
The questions
Is there any way to overcome the disadvantages of installing the APK using root on this special path? Maybe even avoid handling this path at all?
Why does the OS suddenly require to use this path? Why not use the original path instead, just like in the other methods of installing apps? What do the other methods of installing apps do, that somehow avoids using the spacial path?

One solution, in case you don't mind the moving procedure, is to also save&restore the timestamp of the original file, as such:
val tempFileParentPath = "/data/local/tmp/"
val tempFilePath = tempFileParentPath + File(fullPathToApkFile).name
val apkTimestampTempFile = File(context.cacheDir, "apkTimestamp")
apkTimestampTempFile.delete()
apkTimestampTempFile.mkdirs()
apkTimestampTempFile.createNewFile()
root.runCommands("touch -r $fullPathToApkFile ${apkTimestampTempFile.absolutePath}")
root.runCommands("mv $fullPathToApkFile $tempFileParentPath")
root.runCommands("pm install -t -f $tempFilePath")
root.runCommands("mv $tempFilePath $fullPathToApkFile")
root.runCommands("touch -r ${apkTimestampTempFile.absolutePath} $fullPathToApkFile")
apkTimestampTempFile.delete()
It's still a bit dangerous, but better than copying files...
EDIT: Google has shown me a nice workaround for this (here) :
We don't support installation of APKs from random directories on the device. They either need to be installed directly from the host using 'adb install' or you have to stream the contents to install --
$ cat foo.apk | pm install -S APK_SIZE
While I think this is incorrect that they don't support installing of APK files from random paths (always worked before), the workaround does seem to work. All I needed to change in the code of installing an APK file is as such:
val length = File(fullPathToApkFile ).length()
commands.add("cat $fullPathToApkFile | pm install -S $length")
Thing is, now I have some other questions about it :
Does this workaround avoid the moving/copying of the APK into storage, and without affecting the original file ? - seems it does
Will this support any APK file, even large ones? - seems it succeeds in doing it for an APK that takes 433MB, so I think it's safe to use for all sizes.
This is needed only from Android P, right? - so far seems so.
Why does it need the file size as a parameter ? - No idea, but if I remove it, it won't work

Thanks for the answers! I looked everywhere else as well to get a whole setup for OTA to work for Android 10 and so on. It 100% works on Samsung Galaxy Tab 10.1 running Android 10.
Here is a medium article with the code:
https://medium.com/#jnishu1996/over-the-air-ota-updates-for-android-apps-download-apk-silent-apk-installation-auto-launch-8ee6f342197c
The magic is running this command with root access:
process = Runtime.getRuntime().exec("su");
out = process.getOutputStream();
DataOutputStream dataOutputStream = new DataOutputStream(out);
// Get all file permissions
dataOutputStream.writeBytes("chmod 777 " + file.getPath() + "\n");
// Perform silent installation command, all flags are necessary for some reason, only this works reliably post Android 10
String installCommand = "cat " + file.getAbsolutePath() + "| pm install -d -t -S " + file.length();
// Data to send to the LaunchActivity to the app knows it got updated and performs necessary functions to notify backend
// es stands for extraString
// In LaunchActivity onCreate(), you can get this data by running -> if (getIntent().getStringExtra("OTA").equals("true"))
String launchCommandIntentArguments = "--es OTA true --es messageId " + MyApplication.mLastSQSMessage.receiptHandle();
// Start a background thread to wait for 8 seconds before reopening the app's LaunchActivity, and pass necessary arguments
String launchCommand = "(sleep 8; am start -n co.getpresso.Presso/.activities.LaunchActivity " + launchCommandIntentArguments + ")&";
// The entire command is deployed with a ";" in the middle to launchCommand run after installCommand
String installAndLaunchCommand = installCommand + "; " + launchCommand;
// begins the installation
dataOutputStream.writeBytes(installAndLaunchCommand);
dataOutputStream.flush();
// Close the stream operation
dataOutputStream.close();
out.close();
int value = process.waitFor();

Android : Create a file in /data/local/tmp from an automated test

Goal:
Taking a screenshot during an automated test on a device. Pull the screenshot file using adb once the test is done.
Context:
I'm currently trying to write automated tests to take snapshots of the device screen. Using UiDevice to navigate, I would like to take a screenshot in the middle of a test. UiDevice has a method takeScreenshot that I call when I would like to take a snapshot.
After some investigation, I realised that the class responsible to write the image into file UiAutomatorBridge catches an Exception :
java.io.FileNotFoundException:
/data/local/tmp/screenshots/screen2.png: open failed: EACCES
(Permission denied)
Using adb, I created the file and set all permissions to all users.
adb shell touch /data/local/tmp/screenshots/screen1.png
adb shell chmod 777 /data/local/tmp/screenshots
Once done, I can take a screenshot with :
#Test
public void takeSnapShot() {
String filename = "/data/local/tmp/screenshots/screen1.png";
File file = new File(filename);
assertEquals(true, mDevice.takeScreenshot(file));
}
Problem :
I would like to be able to create a file directly while the test is executing, without the need of using adb.
I tried to create a file directly from Java using createNewFile.
try {
file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
But I get an IOException
java.io.IOException: open failed: EACCES (Permission denied)
Has anyone an idea of what is going on ? I'm quite new to Linux, so don't hesitate to suggest something even if it seems obvious to you ;)
Should I post this on superuser instead ?
EDIT
The directory /data has these permissions
drwxrwx--x system system 2016-01-14 14:03 data
I can't list the content of /data, which makes me believe the user "shell" doesn't belong to the group "system". I can't list the content of /data/local neither.
However, the /data/local/tmp is owned by "shell".
drwxrwx--x shell shell 2016-01-14 12:20 . (tmp)
/data/local/tmp gives +x permission to all users.
Finally, the directory "screenshots" belongs to shell with permissions 777.
drwxrwxrwx shell shell 2016-01-14 11:46 screenshots
To my understanding, any user should be able to access /data/local/tmp/screenshots

Instead of saving under /data/local/tmp/, use Environment.getExternalStorageDirectory().
You need a read/write permission to do that. You have to add these two lines into the Manifest of the application ! (I tried to add those lines into the /androidTest/Manifest.xml file, but it has no effects).
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
While it solves the problem of finding a common directory to save/read screenshots, it brings a new one as well.
Having to add these 2 permissions isn't a big deal if you already had them. But if you don't want to ask the user for those permissions, you have to add/remove these lines every time you test/sign your application, which is far from ideal.
EDIT :
In this post, someone proposed to make use of the build differentials (debug, release) to have two different Manifests.
In the end, I have 3 Manifests :
Release Manifest (without external read/write permissions)
Debug Manifest (with external read/write permissions)
AndroidTest Manifest for
tools:overrideLibrary="android.support.test.uiautomator.v18"

How to read a text file from SD card in Android device through command prompt?

There is a folder called "D_Permision" SD Card and there is a text file called "permission.txt" in it.
I want to read this text file through command prompt and display its content in the command prompt(Not in a separate file)
When I use
adb pull permission.txt /sdcard/D_Permission
it gives following error
remote object 'permission.txt' does not exist.
but I used
adb push permission.txt /sdcard/D_Permission
(successfully added permission.txt to D_Permission folder)
and the tried to pull.but I get same error.
sdcard/D_permission has both read / write permission
So how to read this text file through command prompt and display its content in the cmd?

You don't need to pull the file.
adb provides shell acces, so you can do a cat:
adb shell cat /sdcard/D_Permission/foo.txt
If the file does not exist though, you'll still get "does not exists" error of course, which is normal.

I directly use the path "/mnt/external_sd/.. Path of File.".
But it was only work with my Device
Maybe you forget these permissions.
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />

Libgit2 running on Android unable to perform clone operation - returns "failed to set permissions" error

I have just built Libgit2 (v0.20.0) for Android (target SDK version 18, debugging on a rooted device running Cyanogenmod 10.1.2, Android 4.2.2) and a simple function like getting the version number of Libgit2 works fine through the JNI. But when I use the git_clone function it stops right after the objects/info folder is created and returns this error:
Error -1 cloning repository - Failed to set permissions on '/storage/sdcard0/it/ptt/.git/objects/info': Operation not permitted
I have given the application the WRITE_EXTERNAL_STORAGE permission but I guess it still can't chmod unless owner of the file. When I use adb shell to check out the permission mode of the info folder I get:
d---rwxr-x system sdcard_rw 2014-05-15 09:31 info
And by using pwd.h functions I get the username that the c code (that is calling git_clone) is under to be u0_a92. How am I suppose to get pass this I suppose very Android related issue? Is there a simple way to stop Libgit2 from calling p_chmod or can I give it permissions to do so?

I ended up defining p_chmod as a method always returning true to get passed the error. In the bash script I use to build libgit2 I inserted the following lines that leaves the source files in an unmodified condition after building for android:
LIBGIT2_POSIX_PATH="$LIBGIT2_SOURCE_PATH/src/posix.h"
LIBGIT2_POSIX_BACKUP_PATH="$LIBGIT2_SOURCE_PATH/src/posix_original.h"
printf "#include \"always_success.h\"\nint always_success() { return 0; }" > "$LIBGIT2_SOURCE_PATH/src/always_success.c"
printf "int always_success();" > "$LIBGIT2_SOURCE_PATH/src/always_success.h"
cp $LIBGIT2_POSIX_PATH "$LIBGIT2_POSIX_BACKUP_PATH"
sed -i "s/^#define\sp_chmod(p, m).*$/#include \"always_success.h\"\n#define p_chmod(p, m) always_success()\nextern int always_success();\n/" $LIBGIT2_POSIX_PATH
# run the build process with cmake ...
# restore chmod manipulated source header
mv $LIBGIT2_POSIX_BACKUP_PATH $LIBGIT2_POSIX_PATH
There is probably a cleaner way to solve this but at least now I dont get that error anymore. Thanks to Carlos for his help!
UPDATE
Running adb shell mount | grep sdcard I could see that the sdcard which I am trying to clone the repository into uses the vfat file system which according to this forum thread doesn't support unix-style permissions.

Where to I place the OBB file to test Android Expansion Pack Files (OBB) on my Nexus 4?

I'm trying to test the Expansion Pack Files (OBB) In Android following the guide here:
http://developer.android.com/google/play/expansion-files.html
I'm in the step where I need to test my app on my Nexus 4.
I generated my .obb file with jobb and adb-pushed it in the device in this location:
/mnt/shell/emulated/0/Android/obb/my.package/main.1.my.package.obb
When the app run it doesn't find the file.
Method:
Helpers.doesFileExist(context, fileName, xf.mFileSize, false)
return false for my file.
I debugged and found out it is looking for the file in:
/storage/emulated/0/Android/obb/my.package/main.1.my.package.obb
Specifically this is the path returned by:
Helpers.generateSaveFileName(c, fileName)
The /storage/emulated/0, returned by Environment.getExternalStorageDirectory() doesn't exist browsing the device with adb shell.
But it DOES at runtime, inside the app, I also checked what it contains: it contains almost the same things I found in /mnt/shell/emulated/0, it contains the Android/obb dir, which is empty.
How I found out the path /mnt/shell/emulated/0/Android/obb/my.package/main.1.my.package.obb where I placed my obb file:
$ adb shell
$ ls -ld sdcard
lrwxrwxrwx root root 2013-10-16 17:34 sdcard -> /storage/emulated/legacy
$ ls -ld /storage/emulated/legacy
lrwxrwxrwx root root 2013-10-16 17:34 legacy -> /mnt/shell/emulated/0
And inside that I already found the Android/obb directory, empty.
So the question is: where should I put my obb file for it to be in the right position at runtime?
I did everything said there:
created a draft application in the Market to get the public key
generated a random array of 20 byte (salt)
integrated play_licensing/library and play_apk_expansion/download_library
wrote my Service / Receiver
did the check using the Helpers etc.. exactly like the documentation say.
I suppose everything works but I can't just yet release on Play Store! I need to test locally and I'll have the need to change my obb file pretty often in this initial phase of development.
I can't test on the Emulator because I use 3D and device camera.

Since Android 4.2 multi users support have been added.
To support that Android mount an emulated disk for each users acting as a sandbox layer around the actual filesystem: this let Android handle gracefully either sharing of files between users either personal files.
Long story short:
/storage/emulated
is the emulated filesystem.
if you enter that directory from adb shell you may see a
/storage/emulated/obb
directory. Sometimes it doesn't show up, for some reason (see below for what to do if this happen)
It's not in /Android/obb but that's the right directory where to place your app package / obb file!
If you don't see that directory try looking in:
/mnt/shell/emulated/obb
You should be able to put your file there.
It will be correctly picked up at runtime ending at the
/storage/emulated/0/Android/obb/my.package/main.1.my.package.obb
path.
I think the Android documentation should explain this.
(I answer my own question because I found out how to solve it while writing it.)

For me the correct location is : mnt/sdcard/Android/obb/nameofyourpackage/
NOT "/mnt/shell"