Android root access script

Question

I need help with this script, can someone tell me what did I do wrong? I'm trying to make a root checker on startup.

1. Check write access
2. ReturnaAlert of no root
3. Exit on press exit (TO DO)

Here's the exact Java snippet I'm building

{
        Process p;
    try
    { 
        //  Run root command
        p = Runtime.getRuntime().exec("su"); 

        // Attempt to write a file to system
        DataOutputStream os = new DataOutputStream(p.getOutputStream()); 
        os.writeBytes("echo \"Do I have root?\" >/system/temporary.txt\n");

        // Close the stream
        os.writeBytes("exit\n"); 
        os.flush(); 
        try
        { 
            p.waitFor(); 
            if (p.exitValue() != 255)
            { 
                // Code to run on ROOTED
                //  NOTHING JUST GO FORWARD
            }
            else
            { 
                // Code to run on NON ROOTED

            } 
        }
        catch (InterruptedException e)
        { {
            // TODO Code to run with interrupted exception

            }
        } 
    }
    catch (IOException e)
    { 
        // TODO Code to run in input/output exception

    }}}

The APK file is built here for testers.

The root snippets source comment here

Answer 1

Usually to check for root, you have to check your "userid", from the Linux command id.

So instead of:

os.writeBytes("echo \"Do I have root?\" >/system/temporary.txt\n");

use:

os.writeBytes("id\n"); os.flush();

Then read the response, with something such as:

DataInputStream data = new DataInputStream(p.getInputStream());

And check the result with:

if (data .readLine().contains("uid=0"));

Edit:

I use the following Root Privileges class on my apps:

import java.io.BufferedReader;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * Root related operations.
 */
public class RootPrivileges {
    public static final String TAG = "RootPrivileges";

    private RootPrivileges() {
        Log.e(TAG, "RootPrivileges should not be instantiated");
    }

    /**
     * Checks and asks for Root privileges
     *
     * @return true if has root privileges, false otherwise
     */
    public static boolean hasRoot() {
        boolean resp = false;
        Process suProcess;
        try {
            suProcess = Runtime.getRuntime().exec("su");
            DataOutputStream os = new DataOutputStream(suProcess.getOutputStream());
            DataInputStream osRes = new DataInputStream(suProcess.getInputStream());
            if (os != null && osRes != null) {
                os.writeBytes("id\n");
                os.flush();
                String currUid = osRes.readLine();
                boolean exitSu;
                if (null == currUid) {
                    resp = false;
                    exitSu = false;
                    Log.e(TAG, "No root privileges, or denied by user");
                } else if (currUid.contains("uid=0")) {
                    resp = true;
                    exitSu = true;
                    Log.v(TAG, "Root privileges given");
                } else {
                    resp = false;
                    exitSu = true;
                    Log.e(TAG, "Not enough privileges.\n   Received: " + currUid + "\n   Expected: 0");
                }
                if (exitSu) {
                    os.writeBytes("exit\n");
                    os.flush();
                }
            }
        } catch (Exception e) {
            resp = false;
            Log.e(TAG, "Root privileges denied. [" + e.getClass().getName() + "] : " + e.getMessage());
        }
        return resp;
    }

    /**
     * Executes a command as root.
     *
     * @param cmd the command.
     * @return if code was sent to execute
     */
    public static final boolean execute(String cmd) {
        try {
            if (cmd != null && cmd.length() > 0) {
                Process suProcess = Runtime.getRuntime().exec("su");
                DataOutputStream dataOutputStream = new DataOutputStream(suProcess.getOutputStream());
                DataInputStream dataInputStream = new DataInputStream(suProcess.getInputStream());
                DataInputStream dataErrorStream = new DataInputStream(suProcess.getErrorStream());

                dataOutputStream.writeBytes(cmd);
                dataOutputStream.writeBytes("\n");
                dataOutputStream.flush();
                dataOutputStream.writeBytes("exit\n");

                BufferedReader reader = new BufferedReader(new InputStreamReader(dataInputStream));
                BufferedReader err_reader = new BufferedReader(new InputStreamReader(dataErrorStream));
                String resp;
                while ((resp = reader.readLine()) != null) {
                    Log.v(TAG, "[resp]" + resp);
                }
                while ((resp = err_reader.readLine()) != null) {
                    Log.v(TAG, "[err_resp]" + resp);
                }
                reader.close();
                err_reader.close();
                dataOutputStream.flush();
                try {
                    int suProcessRetval = suProcess.waitFor();
                    suProcess.destroy();
                    return (suProcessRetval != 255);
                } catch (Exception ex) {
                    Log.e(TAG, "Error in Root command execution");
                    ex.printStackTrace();
                }
            } else {
                Log.e(TAG, "command is null or empty");
            }
        } catch (IOException ex) {
            Log.e(TAG, "IOException");
            ex.printStackTrace();
        } catch (SecurityException ex) {
            Log.e(TAG, "SecurityException");
            ex.printStackTrace();
        } catch (Exception ex) {
            Log.e(TAG, "Generic Exception");
            ex.printStackTrace();
        }
        return false;
    }
}