Check to see whether root was granted?

Question

I have set up my app to execute the su command using this code:

try {
            Runtime.getRuntime().exec("su");
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            altDialog.setTitle("No Root");
            altDialog
                    .setMessage("I am afraid I have been unable to execute the su binary. Please check your root status.");
            altDialog.setCancelable(false);
            altDialog.setButton("Exit App",
                    new DialogInterface.OnClickListener() {

                        @Override
                        public void onClick(DialogInterface arg0, int arg1) {
                            // TODO Auto-generated method stub
                            Log.e("Android .img Flasher",
                                    "Exiting due to root error");
                            finish();
                        }
                    });
        }

This catches if the su command doesn't exist (I believe), but not if root was actually granted.

How would I be able to check if root was actually granted?

On a side note, how would I be able to store the output of a command using the Runtime.getRuntime.exec() command?

Answer 1

 public static boolean isRootAvailable(){
            Process p = null;
            try{
               p = Runtime.getRuntime().exec(new String[] {"su"});
               writeCommandToConsole(p,"exit 0");
               int result = p.waitFor();
               if(result != 0)
                   throw new Exception("Root check result with exit command " + result);
               return true;
            } catch (IOException e) {
                Log.e(LOG_TAG, "Su executable is not available ", e);
            } catch (Exception e) {
                Log.e(LOG_TAG, "Root is unavailable ", e);
            }finally {
                if(p != null)
                    p.destroy();
            }
            return false;
        }
 private static String writeCommandToConsole(Process proc, String command, boolean ignoreError) throws Exception{
            byte[] tmpArray = new byte[1024];
            proc.getOutputStream().write((command + "\n").getBytes());
            proc.getOutputStream().flush();
            int bytesRead = 0;
            if(proc.getErrorStream().available() > 0){
                if((bytesRead = proc.getErrorStream().read(tmpArray)) > 1){
                    Log.e(LOG_TAG,new String(tmpArray,0,bytesRead));
                    if(!ignoreError)
                        throw new Exception(new String(tmpArray,0,bytesRead));
                }
            }
            if(proc.getInputStream().available() > 0){
                bytesRead = proc.getInputStream().read(tmpArray);
                Log.i(LOG_TAG, new String(tmpArray,0,bytesRead));
            }
            return new String(tmpArray);
        }

Answer 2

You can use the code bellow. I've wrote it for generic command use, but it works with su command as well. It returns if the command succeed as well as the command output (or error).

public static boolean execCmd(String command, ArrayList<String> results){
    Process process;
    try {
        process = Runtime.getRuntime().exec(new String [] {"sh", "-c", command});
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    } 

    int result;
    try {
        result = process.waitFor();
    } catch (InterruptedException e1) {
        e1.printStackTrace();
        return false;
    }

    if(result != 0){ //error executing command
        Log.d("execCmd", "result code : " + result);
        String line; 
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getErrorStream())); 
        try {
            while ((line = bufferedReader.readLine()) != null){
                if(results != null) results.add(line);
                Log.d("execCmd", "Error: " + line);
            }
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
        return false;
    }

    //Command execution is OK
    BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(process.getInputStream())); 

    String line; 
    try {
        while ((line = bufferedReader.readLine()) != null){
            if(results != null) results.add(line);
            Log.d("execCmd", line);
        }
    } catch (IOException e) {
        e.printStackTrace();
        return false;
    }
    return true;
}

You call it with two arguments:

• command - string with command to execute
• results - empty ArrayList to return the command output. If null, output is not returned.

To check sucommand you can do the following:

//Array list where the output will be returned
ArrayList<String> results = new ArrayList<String>();
//Command to be executed
String command = "su -c ls";
boolean result = execCmd(command,results);
//result returns command success
//results returns command output

Regards.