CODEWITHSUNDEEP
android
Knuckles the Echidna
Knuckles the Echidna

Reputation: 1737

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:

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()

Upvotes: 12

Views: 14552

Answers (5)

Brent K.
Brent K.

Reputation: 1076

It's an old thread, but still relevant. I tested this on Android R.

For a platform signed application, you can use the private SDK via reflection.

First, your manifest needs

<uses-permission android:name="android.permission.REBOOT" tools:ignore="ProtectedPermissions" />

Then you can shutdown using

private void shutdown() {
    final PowerManager powerManager = (PowerManager) getSystemService(Context.POWER_SERVICE);
    try {
        Method shutdownMethod = PowerManager.class.getMethod("shutdown", boolean.class, String.class, boolean.class);
        boolean confirm = false;     // If true, shows a shutdown confirmation dialog.
        String reason = "shutdown";
        boolean wait = true;         // If true, this call waits for the shutdown to complete and does not return.
        shutdownMethod.invoke(powerManager, confirm, reason, wait);
    } catch (Exception e) {
        Log.e(TAG, "Cannot shutdown", e);
    }
}

Upvotes: 1

Terry Hope
Terry Hope

Reputation: 21

this is for kotlin

(requireContext().getSystemService(Context.POWER_SERVICE) as PowerManager)
                        .reboot("reason")

Upvotes: 0

ligi
ligi

Reputation: 39529

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

Upvotes: 4

ozbek
ozbek

Reputation: 21183

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);
    }
}

Upvotes: 9

Knuckles the Echidna
Knuckles the Echidna

Reputation: 1737

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.

Upvotes: 0

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