Develop Reference

Android Pie (9.0) - Writing a Shutdown or Restart Function - Application is Privileged

I have a security system in schools, where my tablets are the consoles for each classroom. I've noticed teachers and admin are not restarting the tablets very often (or ever), which has caused issues. I would like to take the task from the clients and program a weekly reboot or shutdown. I have taken a few steps in the right direction:
I have:
Spoken with the Tablet Provider/Scheme Provider, and they have added my app as a privileged app.
Added a whitelist for (what I think are) all required permissions.
Confirmed the privileges exist.
Code to Check Permissions:
public void getGrantedPermissions(final String appPackage) {
List<String> granted = new ArrayList<String>();
try {
PackageInfo pi = getPackageManager().getPackageInfo(appPackage, PackageManager.GET_PERMISSIONS);
for (int i = 0; i < pi.requestedPermissions.length; i++) {
if ((pi.requestedPermissionsFlags[i] & PackageInfo.REQUESTED_PERMISSION_GRANTED) != 0) {
granted.add(pi.requestedPermissions[i]);
}
}
} catch (Exception e) {}
for(int i = 0; i < granted.size(); i++){
Log.e("Permissions", granted.get(i));
}
}
Below is what the log reported. The green permissions are all that I could get on my personal phone. The yellow permissions are what I was able to get, additionally, from the Tablet provider's whitelist. We can confirm by these permissions that I have a privileged app, as well as the shutdown and reboot permissions.
I was able to find a section of code to shutdown the app, but it seems that I can't quite figure out how to use it. Below is the code I have tried, and the error follows:
Intent intent = new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN");
intent.putExtra("android.intent.extra.KEY_CONFIRM", false);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);
Error upon running code:
android.content.ActivityNotFoundException: No Activity found to handle Intent { act=android.intent.action.ACTION_REQUEST_SHUTDOWN flg=0x10000000 (has extras) }
"This exception is thrown when a call to Context#startActivity or one of its variants fails because an Activity can not be found to execute the given Intent."
I am assuming that this may require me to modify my manifist.xml, is that correct? If so, I'm unsure how to do so. I feel that I may have to add an to my main activity, where the call is made. Though, I've tried this and it didn't work, or I wrote the code improperly.
Thank you in advance for any assistance!

Figured this one out. I didn't realize a PowerManager existed, but it does, and it works. My solution below. Also, if you didn't read the full question, my app is a privileged/System app, which gives me the authority to manage power. Normal apps will not be able to do this.
Currently running Android 9.0 (might matter, not sure)
try{
PowerManager powerManager = (PowerManager)getSystemService(Context.POWER_SERVICE);
powerManager.reboot(null);
} catch (Exception e){
Toast.makeText(this, "Error performing this action", Toast.LENGTH_LONG).show();
e.printStackTrace();
}

How to lock screen on button click?

I want to lock screen (actually to trigger long click to show system dialog "turn off the phone?") via click button. Is it possible ? I found some examples like:
KeyguardManager keyguardManager = (KeyguardManager)getSystemService(Activity.KEYGUARD_SERVICE);
KeyguardLock lock = keyguardManager.newKeyguardLock(KEYGUARD_SERVICE);
But they don't work. Maybe I can switch phone off programmatically in other way? I found information that it's impossible so I'm trying to implement it like long click on lock button.
UPD:
I found this:
try {
Process proc = Runtime.getRuntime()
.exec(new String[]{ "su", "-c", "reboot -p" });
proc.waitFor();
} catch (Exception ex) {
ex.printStackTrace();
}
But it also doesn't work. I'm testing it on emulator, will it work on real phone?
Thanks everyone for answers in advance !

Here is the most usual way of requesting shutdown:
Intent i = new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN");
i.putExtra("android.intent.extra.KEY_CONFIRM", true);
startActivity(i);
Other methods you mentioned don't work because a regular app does not have the permission to run those (for obvious security reasons).

Using adb to broadcast intent with extras

background
i wish to send a broadcast intent (even with root permission) that an app was removed, and for this, i have to broadcast an intent with extras.
problem
i just can't figure out what am i missing, since i can't find the correct way to do it.
what i've done so far
i think I've found where on android the OS broadcasts the intent (the file is called "PackageManagerService.java" ). I've also found out how to get the correct permission using root (and it works) , and also how to put extra data into the intent of the broadcast (link here) , all using the "adb" tool.
now i have to put all of the pieces together.
the code so far is :
String packageOfCurrentApp=..., packageOfAppToReportAbout=... ;
try
{
final java.lang.Process p=
Runtime.getRuntime().exec(
String.format("su -c pm grant %s android.permission.BROADCAST_PACKAGE_REMOVED",packageOfCurrentApp));
final int res=p.waitFor();
Logger.log(LogLevel.DEBUG,"got permission:"+(res==0));
if(res==0)
{
final java.lang.Process p2=Runtime.getRuntime().exec(//
"am broadcast -a android.intent.action.PACKAGE_REMOVED "+//
"--ei android.intent.extra.UID -1 "+//
"-eez android.intent.extra.DATA_REMOVED true"+//
" -d com.syncme.syncmeapp ");
final int res2=p2.waitFor();
Logger.log(LogLevel.DEBUG,"broadcast?"+(res2==0));
}
}
catch(final Exception e)
{
Logger.log(LogLevel.DEBUG,"error:"+e);
}
the permission getting works, but the broadcasting doesn't.
question
what is wrong with the code? what is missing? how can i fix it?
i would also like to know how to do the same via the shell (of the PC).

Like for battery :-
we use below
m broadcast "intent:#Intent;action=android.intent.action.BATTERY_CHANGED;i.status=5;i.voltage=4155;i.level=100;end"

Please refer to the source code of PackageManagerService.java
Bundle extras = new Bundle(1);
extras.putInt(Intent.EXTRA_UID, removedUid);
extras.putBoolean(Intent.EXTRA_DATA_REMOVED, false);
sendPackageBroadcast(Intent.ACTION_PACKAGE_REMOVED, removedPackage,
extras, null, null);

Power off Android device with system signed application

I am developing an Android application and we need to power off the device under certain circumstances.
I have read in many places that you need a rooted phone in order to do so. Then, you can issue the "reboot" command by using Java's API:
try {
Process proc = Runtime.getRuntime()
.exec(new String[]{ "su", "-c", "reboot -p" });
proc.waitFor();
} catch (Exception ex) {
ex.printStackTrace();
}
I have actually tried this in a Cyanogenmod 10 device (Samsung Galaxy S3), and it works. However, we do not want a rooted device in order to power it off, since the end user will then be able to do unintended things which are not allowed by our company.
On the other hand, our application is signed by the manufacturer's certificate, in this case Cyanogen's. I have read that by signing your application with the manufacturer's certificate, you should be able to issue privileged commands (as if root). However, even if I install my app as a system app signed with the manufacturer's certificate, the above code does not work:
If I leave the "su" part of the command, the "Superuser Request" screen is displayed, but that's something we are trying to avoid.
If I remove the "su" part (just leaving "reboot -p"), the command is silently ignored.
As a result, we are not being able to poweroff our device with our system app, which is signed with the manifacturer's certificate. So my question is, how am I supposed to do that?
EDITED
And, by the way, just in case someone is not sure about it: the application is properly signed and installed as a system application, because we can actually access some restricted APIs, such as PowerManager.goToSleep()

If you want the device to reboot (power off and on), then try PowerManager.reboot()
PowerManager powerManager = (PowerManager)getSystemService(Context.POWER_SERVICE);
powerManager.reboot(null);
android.os.PowerManager:
/**
* Reboot the device. Will not return if the reboot is successful.
* <p>
* Requires the {#link android.Manifest.permission#REBOOT} permission.
* </p>
*
* #param reason code to pass to the kernel (e.g., "recovery") to
* request special boot modes, or null.
*/
public void reboot(String reason) {
try {
mService.reboot(false, reason, true);
} catch (RemoteException e) {
}
}
UPDATE
If you want the device to completely turn off, use PowerManagerService.shutdown():
IPowerManager powerManager = IPowerManager.Stub.asInterface(
ServiceManager.getService(Context.POWER_SERVICE));
try {
powerManager.shutdown(false, false);
} catch (RemoteException e) {
}
com.android.server.power.PowerManagerService:
/**
* Shuts down the device.
*
* #param confirm If true, shows a shutdown confirmation dialog.
* #param wait If true, this call waits for the shutdown to complete and does not return.
*/
#Override // Binder call
public void shutdown(boolean confirm, boolean wait) {
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.REBOOT, null);
final long ident = Binder.clearCallingIdentity();
try {
shutdownOrRebootInternal(true, confirm, null, wait);
} finally {
Binder.restoreCallingIdentity(ident);
}
}

This was working fine for me:
startActivity(new Intent("android.intent.action.ACTION_REQUEST_SHUTDOWN"));
you need this permission ( depends on being system-app ):
<uses-permission android:name="android.permission.SHUTDOWN"/>
source:
https://github.com/sas101/shutdown-android-app/wiki

OK, my mistake.
As I performed some tests, I did not realize that I had removed "android:sharedUserId="android.uid.system" from the manifest.
Once the sharedUserId is included, the following code works without prompting the user to confirm root access:
try {
Process proc = Runtime.getRuntime()
.exec(new String[]{ "su", "-c", "reboot -p" });
proc.waitFor();
} catch (Exception ex) {
ex.printStackTrace();
}
I tried to remove "su" (because the system may not provide such a command), but in that case it does not work. Surprisingly, the file system is remounted in read-only mode, so I must remount it again with write permissions.

this is for kotlin
(requireContext().getSystemService(Context.POWER_SERVICE) as PowerManager)
.reboot("reason")

How to programmatically answer a call in Android 4.0.3?

So as the subject states I need to be able to answer a phone call programmatically in Android 4.0.3 on an HTC OneX. I have read several places that the MODIFY_PHONE_STATE permission has been revoked by Google so to do this task you need a work around.
I have looked into two avenues so far:
(1) Following Guy's post here and using a BroadcastReceiver
(2) Using the following code to try and hit a key event through a shell command.
final Runtime r = Runtime.getRuntime();
try {
Process process = r.exec("input keyevent 5");
InputStream stream = process.getErrorStream();
log.v("Process Error Stream: " +stream.toString());
log.v("Sending shell command to Answer Call");
} catch (Exception e) {
log.v("Stack Trace: " + e.getStackTrace().toString());
e.printStackTrace();
}
I use this because keyevent 5 is KeyEvent.CALL according to Google and it works in adb using
adb shell input keyevent 5
My question is, what am I doing wrong? Because logically both of these methods makes sense but neither are working or even generating runtime errors of any kind.
Cheers

After days of research, I found that using both a broadcast receiver route and a runtime.exec() route it is simply not possible to answer a phone call in Android 4.0.3 using the Android API.
For those of you still wondering, I did find some useful information...You CAN answer a call through adb using the command adb shell input keyevent 5 5 is the key code for the call button and in Android it is the KEYEVENT_CALL

This works from Android 2.2 to 4.0 and now after adding the try catch to the last line it works for 4.1.2 and 4.2 Frankly speaking dont know how it works but it works for me.
Log.d(tag, "InSecond Method Ans Call");
// froyo and beyond trigger on buttonUp instead of buttonDown
Intent buttonUp = new Intent(Intent.ACTION_MEDIA_BUTTON);
buttonUp.putExtra(Intent.EXTRA_KEY_EVENT, new KeyEvent(
KeyEvent.ACTION_UP, KeyEvent.KEYCODE_HEADSETHOOK));
sendOrderedBroadcast(buttonUp, "android.permission.CALL_PRIVILEGED");
Intent headSetUnPluggedintent = new Intent(Intent.ACTION_HEADSET_PLUG);
headSetUnPluggedintent.addFlags(Intent.FLAG_RECEIVER_REGISTERED_ONLY);
headSetUnPluggedintent.putExtra("state", 0);
headSetUnPluggedintent.putExtra("name", "Headset");
try {
sendOrderedBroadcast(headSetUnPluggedintent, null);
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
This is working for me in Android 4.1.2 as well as i have tested on 4.2
This still gives an exception which is handled.

Here are several useful links, check them:
Answer automatically to Incoming Call
How to auto answer call programmatically
Auto answer