How to Check If an App is System App or Not

Definition

The definition of system app is not very clear. There are at least three different definitions:

  1. Apps in system partition (/system)
    • These apps will get the flag ApplicationInfo.FLAG_SYSTEM
    • If an updated version is installed (probably not under /system), it will get ApplicationInfo.FLAG_UPDATED_SYSTEM_APP
  2. Apps signed with platform signature
  3. Apps in /system/priv-apps and /system/framework
    • These apps will get the flag ApplicationInfo.PRIVATE_FLAG_PRIVILEGED
    • The flag is set in PackageManagerService.java
    • These apps will be granted signatureOrSystem level permissions (corresponding to the System in signatureOrSystem)
    • For Samsung, apps in /system/carrier/priv-app and /odm/priv-app will also get this flag

Check

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import android.content.pm.ApplicationInfo;
import android.content.pm.PackageInfo;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import java.lang.reflect.*;

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "XKXXXX";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        PackageManager pm = getApplicationContext().getPackageManager();
        List<PackageInfo> list = pm.getInstalledPackages(0);
        for(PackageInfo pi : list) {
            try {
                ApplicationInfo ai = pm.getApplicationInfo(pi.packageName, 0);
                String strSignedBySys = isSignedBySystem(pm, pi.packageName)?"SYS_SIGN":"NONSYS_SIGN";
                String strUnderSys = isAppInSystemPartition(pm, pi.packageName)?"UNDER_SYS":"NOT_UNDER_SYS";
                String strPrivileged = isPrivilegedApp(ai)?"PRIV":"NON_PRIV";
                Log.d(TAG, String.format(">>>>>> %s <<<<<<<< %s %s %s %s",
                        pi.packageName,
                        ai.publicSourceDir,
                        strSignedBySys,
                        strUnderSys,
                        strPrivileged));
            }catch (Exception e) {
                Log.d(TAG, "exception ", e);
            }
        }
    }

    /**
     * Check if an App is under /system or has been installed as an update to a built-in system application.
     */
    public static boolean isAppInSystemPartition(PackageManager pm, String packageName) {
        try {
            ApplicationInfo ai = pm.getApplicationInfo(packageName, 0);
            return ((ai.flags & (ApplicationInfo.FLAG_SYSTEM | ApplicationInfo.FLAG_UPDATED_SYSTEM_APP)) != 0);
        }catch (NameNotFoundException e) {
            Log.d(TAG, "exception", e);
            return false;
        }
    }

    /**
     * Check if an App is signed by system or not.
     */
    public boolean isSignedBySystem(PackageManager pm, String packageName) {
        try {
            PackageInfo pi_app = pm.getPackageInfo(packageName, PackageManager.GET_SIGNATURES);
            PackageInfo pi_sys = pm.getPackageInfo("android", PackageManager.GET_SIGNATURES);
            return (pi_app != null
                    && pi_app.signatures != null
                    && pi_sys.signatures[0].equals(pi_app.signatures[0]));
        }catch (NameNotFoundException e) {
            Log.d(TAG, "exception", e);
            return false;
        }
    }

    /**
     * Check if an App has ApplicationInfo.PRIVATE_FLAG_PRIVILEGED (under /system/priv-app or /system/framework)
     */
    public static boolean isPrivilegedApp(ApplicationInfo ai) {
        try {
            Method method = ApplicationInfo.class.getDeclaredMethod("isPrivilegedApp");
            return (Boolean)method.invoke(ai);
        } catch(Exception e) {
            Log.d(TAG, "exception", e);
            return false;
        }
    }
}

Reference

Definition of PRIVATE_FLAG_PRIVILEGED in ApplicationInfo.java
How to check if application is system app or not (By signed signature)
Android permission element